Lawrence R. Benson
Lawrence R. Benson
Library of Congress Cataloging-in-Publication Data

 

Benson, Lawrence R.

 Quieting the boom : the shaped sonic boom demonstrator and the quest 

for quiet supersonic flight / Lawrence R. Benson.

 pages cm

 Includes bibliographical references and index.

1. Sonic boom--Research--United States--History. 2. Noise control--

Research--United States--History. 3. Supersonic planes--Research--United 

States--History. 4. High-speed aeronautics--Research--United States--

History. 5. Aerodynamics, Supersonic--Research--United States--History. I. 

Title.

 TL574.S55B36 2013

 629.132’304--dc23

 2013004829

Copyright © 2013 by the National Aeronautics and Space Administration.

The opinions expressed in this volume are those of the authors and do not 

necessarily reflect the official positions of the United States Government or 

of the National Aeronautics and Space Administration.

This publication is available as a free download at

http://www.nasa.gov/ebooks.

9 781626 830042

9 0 0 0 0 >

ISBN 978-1-62683-004-2
iii

Preface and Acknowledgments v

Introduction: A Pelican Flies Cross Country ix

Chapter 1: Making Shock Waves:

 The Proliferation and Testing of Sonic Booms ����������������������������� 1

Exceeding Mach 1

A Swelling Drumbeat of Sonic Booms

Preparing for an American Supersonic Transport

Early Flight Testing

Enter the Valkyrie and the Blackbird

The National Sonic Boom Evaluation

Last of the Flight Tests

Chapter 2: The SST’s Sonic Boom Legacy ����������������������������������������������������� 39

Wind Tunnel Experimentation

Mobilizing Brainpower To Minimize the Boom

Laboratory Devices and Experiments

Losing the Battle Against the Boom

A Decade of Progress in Understanding Sonic Booms

Chapter 3: Continuing the Quest:

 Supersonic Cruise Research ����������������������������������������������������������67

Changing Acronyms: An Overview of the AST/SCAR/SCR Program

Learning More About Sonic Booms

The Early Promise of Computational Fluid Dynamics

Progress in Prediction and Minimization Techniques

Chapter 4: Resuming the Quest:

 High-Speed Research ������������������������������������������������������������������� 89

SST Reincarnated: Birth of the High-Speed Civil Transport

Phase I of the High-Speed Research Program

Exploiting the CFD Revolution

Flight Tests and Acceptability Studies

HSR Phase II: Surrendering Again to the Sonic Boom

Chapter 5: The Quiet Supersonic Platform:

 Innovative Concepts and Advanced Technologies �����������������������121

Making the Case for a Supersonic Business Jet

Previous SSBJ Studies and Proposals

Birth of the QSP Program

QSP Phase I: Defining Concepts and Technologies

QSP Phase II: Refining Concepts and Technologies
iv

Quieting the Boom

Chapter 6: Planning and Starting the SSBD Project ������������������������������������� 149

Selecting a Demonstrator

The Northrop F-5 Story

Forming the SSBD Working Group

The First Flight Test: Inlet Spillage Shock Measurements

Integrating Flight Data with Computational Fluid Dynamics

Chapter 7: Creating the Shaped Sonic Boom Demonstrator �������������������������171

An Evolutionary Design Process

Wind Tunnel Testing at NASA’s Glenn Research Center

Initial Fabrication and Final Wind Tunnel Testing

Obtaining the F-5E

Final Fabrications and Modification

Test Plan Approval and Flight Clearance

Chapter 8: Proof at Last:

 Making and Measuring Softer Sonic Booms ������������������������������ 203

Functional Check Flights

Preparations at Edwards Air Force Base

Making Aviation History

Preparing for the Shaped Sonic Boom Experiment

Conducting the SSBE: Twenty-One Flights in 10 Days

Collecting and Analyzing the Data

Chapter 9: Continuing Research; Postponing Development ����������������������� 247

Losing the Momentum for a Low-Boom Demonstrator

Inventing the Low Boom/No Boom Maneuver

Silencing the Bow Shock with Quiet Spike

Focusing on Fundamentals: The Supersonics Project

Measuring Tail Shocks: The LaNCETS Tests

Simulated, Softened, and Super Booms

Keeping Focused on the Future

Appendix A: Key SSBD and SSBE Personnel 287

Appendix B: F-5 SSBD Flight Chronology 294

Appendix C: F-5E SSBD Modifications and Specifications 297

Appendix D: Key SSBD and SSBE Reports 300

Selected Bibliography 302

Acronyms List 341

About the Author 346

Index 347
v

Preface and 

Acknowledgments

Quieting the Boom: The Shaped Sonic Boom Demonstrator and the Quest for 

Quiet Supersonic Flight follows up on a case study I was privileged to write in 

early 2009, “Softening the Sonic Boom: 50 Years of NASA Research.” That 

relatively short survey was published in volume I of NASA’s Contributions to 

Aeronautics (NASA SP-2010-570). Although I was previously familiar with 

aviation history, initially, I was hesitant to take on what seemed to be such an 

esoteric and highly technical topic. Thankfully, some informative references 

on related supersonic programs of the past were already available to help get 

me started, most notably Erik M. Conway’s High-Speed Dreams: NASA and 

the Technopolitics of Supersonic Transportation, 1945–1999, which is cited frequently in “Softening the Sonic Boom” and the first four chapters that follow.

After a 2-year hiatus, I resumed sonic boom research in March 2011 on 

this new book. I greatly appreciate the opportunity afforded me to write 

about this fascinating subject by the eminent aviation historian Dr. Richard P. 

Hallion, editor of NASA’s Contributions to Aeronautics and the new National 

Aeronautics and Space Administration (NASA) book series of which this one 

is a part. While expanding, updating, and, hopefully, improving on my previous account, this book’s primary focus is on the breakthrough achieved by the 

Northrop Grumman Corporation (NGC) and a diverse team of Government 

and industry partners who proved that aircraft can be designed to significantly 

lower the strength of sonic booms.

My research into primary sources benefited immeasurably from the help 

given to me during visits to the Dryden Flight Research Center (DFRC), 

Edwards, CA, in December 2008 and April 2011 and additional telephone 

and e-mail communications with DFRC personnel. Librarian Dr. Karl A. 

Bender introduced me to NASA’s superb scientific and technical information 

resources and, assisted by Freddy Lockarno, helped me collect numerous essential documents. Aviation historian Peter W. Merlin found other sources for me 

in Dryden’s archival collection. Edward A. Haering, Dryden’s principal sonic 

boom investigator, provided valuable source materials, answered questions, and 

reviewed the chapters covering his projects. Fellow engineer Timothy R. Moes 

and test pilots James W. Smolka and Dana D. Purifoy helped with additional 
vi

Quieting the Boom

information and reviewed sections of the draft. Dryden’s superb online image 

gallery provided many of the photographs, and Tony R. Landis provided me 

with others from his files. Also at Edwards Air Force Base, CA, the long-time 

Flight Test Center Historian Dr. James O. Young provided me with additional 

photos and later reviewed and made helpful comments on the first chapter.

Writing a credible history about this subject would have been impossible 

without extensive help from two of the world’s top sonic boom experts—

Domenic J. Maglieri of Eagle Aeronautics and Dr. Kenneth J. Plotkin of Wyle 

Laboratories—both of whose names are scattered throughout the text and 

notes. In addition to reviewing and commenting on drafts of the chapters, 

they answered numerous questions and offered valuable suggestions both over 

the phone and via the Internet. The second and third chapters also benefitted 

from being reviewed by one of the pioneers of sonic boom theory, professor 

Albert R. George of Cornell University. Dr. Christine M. Darden and Peter G. 

Coen, who in turn led NASA’s sonic boom research efforts after the mid-1970s, 

also provided information and reviewed my original study. Peter Coen, who 

managed the Shaped Supersonic Boom Experiment and has been the principal 

investigator for NASA’s Supersonics Project since 2006, continued to help on 

this book. His comments, corrections, and guidance were critical to completing chapter 9. Because this final chapter attempts to bring various facets of the 

as yet unfinished quest for civilian supersonic flight up to date through 2011, 

its discussion of recent events should be considered provisional pending the 

availability of more information and the historical perspective that will only 

come in future years.

For transforming my manuscript into both a printed and electronic book, 

the author is indebted to the staff of the Communication Support Services 

Center at Headquarters NASA, especially the careful proofreading and editorial suggestions of Benjamin Weinstein and the attractive design of the final 

product by Christopher Yates. Because many of the historically significant 

diagrams, drawings, and other illustrations found in the source materials were 

of rather poor visual quality, I greatly appreciate the efforts of Chris and his 

graphics team in trying to make these figures as legible as possible.

The Shaped Sonic Boom Demonstrator culminated four decades of study 

and research on mitigating the strength of sonic booms. Writing chapters 5 

through 8—which cover the origins, design, fabrication, and flight testing 

of this innovative modification of an F-5E fighter plane—was made possible 

through the auspices of the Northrop Grumman Corporation. As is evident 

in the text and notes, the NGC’s Joseph W. Pawlowski, David H. Graham, 

M.L. “Roy” Martin, and Charles W. Boccadoro generously provided informative interviews, detailed documentation, and valuable comments, and they 

patiently answered numerous questions as I researched, wrote, and coordinated 
vii

Preface and Acknowledgments

these chapters. I would also like to thank Robert A. “Robbie” Cowart of 

Gulfstream Aerospace Corporation for his review of the section in chapter 9 

on the company’s Quiet Spike invention, which subsequently demonstrated 

another means of mitigating sonic booms. And for his careful review of the

final manuscript, I am indebted to Dr. Michael H. Gorn, a former Dryden

Chief Historian and colleague of mine in the Air Force History Office.

This book is intended to be a general history of sonic boom research, emphasizing the people and organizations that have contributed, and not a technical 

study of the science and engineering involved. Any errors in fact or interpretation are those of the author. For more detailed information, interested readers 

may refer to primary sources referenced in the notes, many of which are available online from the NASA Technical Reports Server; through the American 

Institute of Aeronautics and Astronautics (AIAA); and in the other professional 

journals, periodicals, and books cited. I relied on graphs, charts, and drawings 

in some of these and other original sources for many of the figures presented 

in this book. Their quality and legibility was often not up to the visual standards desired in current NASA publications, but I believe including them was 

necessary to illustrate the evolution of knowledge about sonic booms and the 

related advances in aeronautical design and technology described in the text. 

In the near future, NASA will also publish what will undoubtedly become the 

definitive reference work on all aspects of sonic boom science and technology, tentatively titled Sonic Boom: A Compilation and Review of Six Decades of 

Research. Among its coauthors are some of the aforementioned experts who 

have been so helpful to me.

LAWRENCE R. BENSON

Albuquerque, NM

January 14, 2012
viii

The F-5 Shaped Sonic Boom Demonstrator, piloted by Roy Martin, arriving over Palmdale, 

California, on July 29, 2003. (Mike Bryan)
ix

INTRODUCTION

A Pelican Flies 

Cross Country

On a hot and humid July day in 2003, a pair of small supersonic jet airplanes 

took off together from Cecil Field, a former naval air station on the eastern edge 

of Jacksonville, FL. Even though the Northrop Corporation had built both 

planes based on a common design, it was hard at first glance to tell that the two 

aircraft flying side by side were so closely related. One was a sleek T-38 Talon, 

a two-seat aircraft that has served as the U.S. Air Force’s (USAF’s) advanced 

trainer since the early 1960s. The other was originally an F-5E Tiger II, one 

of more than 2,000 Northrop F-5s that had equipped air forces around the 

world with a low-cost, high-performance combat and reconnaissance aircraft. 

Because of the F-5E’s agility and compact size, the U.S. military adopted it 

as an aggressor aircraft to hone the skills of its own fighter pilots. Both planes 

attested to the competence of Northrop’s design teams. Of all of the many 

supersonic jets developed for the Air Force and U.S. Navy in the 1950s, the 

T-38 and F-5 are the only ones still in general use.

Although on loan from the Navy’s aggressor training squadron, this particular F-5E no longer looked much like a fighter jet. With what appeared 

to be a pouch hanging under its chin, the aircraft somewhat resembled an 

overgrown pelican. In addition to lettering identifying Northrop Grumman 

Integrated Systems, its white fuselage was decorated with sharply angled blue 

and red pinstripes along with emblems containing the acronyms “NASA” and 

“DARPA” while its tail bore an oval logo with the letters “QSP.”

After gaining altitude, this odd couple turned west toward their ultimate 

destination of Palmdale, CA. Roy Martin, the chief test pilot at the Northrop 

Grumman Corporation’s facility in Palmdale, was at the controls of the F-5. 

Mike Bryan, a Boeing test pilot from Seattle, WA, was flying the T-38. Despite 

its enlarged nose section, the F-5 no longer had navigational equipment except 

for a hand-held Global Positioning System (GPS) receiver in the cockpit, so 

Martin had to stay near the T-38. Their first refueling stop was Huntsville, 

AL, home of NASA’s Marshall Space Flight Center. Next, it was on to the vast 

Tinker Air Force Base (AFB) in Oklahoma City, OK, where Martin and Bryan 
x

Quieting the Boom

The T-38 and modified F-5E together at Cecil Field, FL, before flying to California. (NGC)

spent the night. The next morning, they stopped to refuel in Roswell, NM, 

at what had once been Walker Air Force Base, and then they stopped at the 

former Williams AFB, southeast of Phoenix, AZ, before flying on to California.

At each of these stops, the planes attracted the attention of flight-line personnel and others nearby, most of whom could recognize the strange white jet 

as some kind of F-5. But many of them still had questions. What’s with the 

big nose? Why is Boeing helping a Northrop Grumman pilot fly across the 

country? What do those jagged red and blue stripes signify? And why all the 

various logos?

Unlike a lot of projects sponsored by the Defense Advanced Research Projects 

Agency (DARPA), the one involving this F-5 was not classified. So the two 

pilots were happy to explain that the F-5 had been modified for a test to be conducted with the help of NASA called the Shaped Sonic Boom Demonstration 

(SSBD). It was part of a DARPA program called Quiet Supersonic Platform 

(QSP). Although Northrop Grumman had won the SSBD contract, Boeing 

and some other rival companies were also participating and would share in 

the data collected. The goal of the SSBD was to do something that had never 

before been accomplished: prove that it was possible to reduce the strength 

of sonic booms. This experimentation was being undertaken in the hope that 

civilian airplanes could someday fly at supersonic speeds without disturbing 
xi

A Pelican Flies Cross Country

people below. The SSBD team was going to perform this demonstration at 

Edwards AFB in the very same airspace where supersonic flight had its birth 

more than 50 years earlier. The pinstripes on the F-5 illustrated the shape of 

the pressure waves that the team had expected a normal F-5 and the modified 

F-5 to register on special recording devices.

Since jet aircraft had been making sonic booms for more than half a century, 

why had this not been done already? Why had the United States, which could 

land men on the Moon and invent the Internet, never been able to build a 

supersonic airliner or business jet? With all the advances in science and technology, what is so complicated about the sonic boom that has so far defied 

solution? Would the SSBD be a significant step toward finding a solution? The 

rest of this book will attempt to answer these questions.
Bell XS-1 photographed on its way to becoming the first aircraft to exceed Mach 1 in level 

flight. (USAF)
1

CHAPTER 1

Making Shock Waves

The Proliferation and Testing of Sonic Booms

Humans have long been familiar with—and often frightened by—natural 

sonic booms in the form of thunder. Caused by sudden spikes in pressure 

when strokes of lightning instantaneously heat surrounding columns of air 

molecules, the sound of thunder varies from low-pitched rumbles to earsplitting bangs, depending on distance. Perhaps the most awesome of sonic booms, 

heard only rarely, are generated when certain large meteors speed through the 

atmosphere at just the right trajectories and altitudes. On an infinitesimally 

smaller scale, the first acoustical shock waves produced by human invention 

were the modest cracking noises caused by the snapping of a whip. With the 

perfection of high-powered explosive propellants in the latter half of the 19th 

century, the muzzle velocity of bullets and artillery shells began to routinely 

exceed the speed of sound (about 1,125 feet, or 343 meters, per second at 

sea level), producing noises that firearms specialists call ballistic cracks. These 

sharp noises result when air molecules cannot be pushed aside fast enough by 

objects moving at or faster than the speed of sound. The molecules are thereby 

compressed together into shock waves that surge away from the speeding object 

at a higher pressure than the atmosphere through which they travel.

Exceeding Mach 1

In the 1870s, an Austrian physicist-philosopher, Ernst Mach, was the first 

to explain this sonic phenomenon, which he later displayed visually in the 

1880s with cleverly made schlieren photographs (from the German word for 

streaks) showing shadow-like images of the acoustic shock waves formed by 

high-velocity projectiles. The specific speed of sound, he also determined, 

depends on the medium through which an object passes. In the gases that make 

up Earth’s atmosphere, sound waves move faster in warm temperatures than 

cold. In 1929, a Swiss scientist named this variable the “Mach number” in his 

honor.1

 At 68 degrees Fahrenheit (F) at sea level in dry air, the speed of sound 
2

Quieting the Boom

is about 768 miles per hour (mph), or 1,236 kilometers per hour (kph); but 

at above 40,000 feet at about –70 °F, it is only about 659 mph, or 1,060 kph.2

The shock waves produced by passing bullets and artillery rounds would be 

among the cacophony of fearsome sounds heard by millions of soldiers during 

the two world wars.3

On Friday evening, September 8, 1944, a sudden explosion blew out a 

large crater in Stavely Road, west of London. The first German V-2 ballistic 

missile aimed at England had announced its arrival. “After the explosion came 

a double thunderclap caused by the sonic boom catching up with the fallen 

rocket.”4

 For the next 7 months, millions of people would hear this new sound 

(which became known by the British as a sonic bang) from more than 3,000 

V-2s launched at Britain as well as liberated portions of France, Belgium, and 

the Netherlands. These shock waves would always arrive too late to warn any of 

those unfortunate enough to be near the missiles’ points of impact.5 After the 

end of World War II, these strange noises faded into memory until the arrival 

of supersonic, turbojet-powered fighter planes in the 1950s.

Jet airplanes were preceded in supersonic flight by experimental aircraft 

powered by rocket engines at Muroc Army Airfield in California’s Mojave 

Desert. Here, a small team of Air Force, National Advisory Committee on 

Aeronautics (NACA), and contractor personnel were secretly exploring the still 

largely unknown territory of transonic and supersonic flight. On October 14, 

1947, more than 40,000 feet over the desert east of Rogers Dry Lake, Capt. 

Chuck Yeager broke the fabled sound barrier by flying at Mach 1.06 in a Bell 

XS-1 (later redesignated the X-1).6

Despite hazy memories and legend perpetuated by the best-selling book and 

hit movie The Right Stuff, the shock waves from Yeager’s little (31-foot-long) 

airplane did not reach the ground with a loud boom on that historic day.7

 He 

flew only 20 seconds at what is considered aerodynamically just a transonic 

speed (less than Mach 1.15).8 Yeager’s memoir states that NACA personnel in a 

tracking van heard a sound like distant thunder.9 This could only have resulted 

if there had been a strong tailwind and a layer of cooler air near the surface.10

However, a record of atmospheric soundings from Bakersfield, CA, indicates 

that a headwind of about 60 knots was more likely.11 Before long, however, 

the stronger acoustical signatures generated by faster-flying X-1s and other 

supersonic aircraft became a familiar sound at and around the isolated air base.

A Swelling Drumbeat of Sonic Booms

In November 1949, the NACA designated its growing detachment at Muroc as 

the High-Speed Flight Research Station (HSFRS). This came 1 month before 
3

Making Shock Waves

the Air Force renamed the installation Edwards Air Force Base after Capt. Glen 

Edwards, who had perished in the crash of a Northrop YB-49 flying wing the 

year before.12 By the early 1950s, the barren dry lakes and jagged mountains 

around Edwards reverberated with the sonic booms of experimental and prototype aircraft, as did other flight-test locations in the United States, United 

Kingdom, and Soviet Union. Scientists and engineers were familiar with the 

ballistic waves of axisymmetric projectiles such as artillery shells (shapes referred 

to scientifically as “bodies of revolution”).13 This was a reason the fuselage of 

the XS-1 was shaped like a 50-caliber bullet, which was known to be stable at 

three times the speed of sound. But these new acoustic phenomena—many of 

which featured the double-boom sound—hinted that they were more complex 

than conventional ballistic waves. In late 1952, the editors of the world’s oldest 

aeronautical weekly stated with some hyperbole that “the ‘supersonic bang’ 

phenomenon, if only by reason of its sudden incidence and the enormous 

public interest it has aroused, is probably the most spectacular and puzzling 

occurrence in the history of aerodynamics.”14

A perceptive English graduate student, Gerald B. Whitham, accurately 

analyzed the abrupt rise in air pressure upon arrival of a supersonic object’s bow 

wave, followed by a more gradual but deeper fall in pressure for a fraction of a 

second, and then a recompression with the passing of the vehicle’s tail wave.15

As shown in a simplified fashion in the upper left corner of figure 1-1, this can 

be illustrated graphically by an elongated capital N (the solid line) transecting 

a horizontal axis. The plot of this line represents ambient air pressure during a 

second or less of elapsed time along a short path, the distance of which depends 

on the length and altitude of the supersonic body. For Americans, the pressure 

change (Δp) is usually expressed in pounds per square foot (psf—also abbreviated as lb/ft2

). The shock waves left behind by an aircraft flying faster than 

Mach 1 on a straight and level course will spread out in a cone-shaped pattern 

with the sector intersecting the ground being heard as a sonic boom.16 Even 

though the shock waves are being 

left behind by the speeding aircraft 

(where the pilot and any passengers 

do not hear their sound), the cone’s 

shock waves are moving forward in 

the form of acoustic rays, the nature 

of which would become the subject 

of future research.

Because a supersonic aircraft is 

much longer than an artillery shell, 

the human ear can detect a double 

boom (or double bang) if the shock 

Figure 1-1.Sonic boom signature and shock 

cone. (NASA)
4

Quieting the Boom

wave from its tail area arrives a tenth of a second or more after the shock wave 

from its front portion (sometimes compared to the bow wave of a boat). In some 

respects, all the sound heard from a subsonic jet airplane as it approaches, flies 

overhead, and fades away is concentrated in this fraction of a second. Gerald 

Whitham was first to systematically examine these multiple shock waves, which 

he called the F-function, generated by the complex nonaxisymmetrical configurations applicable to airplanes.17 The U.S. Air Force conducted its earliest sonic boom flight test at Edwards AFB in 1956 with an F-100 making 

in-flight measurements of another F-100 flying at Mach 1.05. Although the 

instrumentation used was relatively simple, the test found the decay of bow 

shock pressure and other results to be consistent with Whitham’s theory.18 Later 

in-flight pressure measurements near supersonic aircraft as well as wind tunnel 

experiments would reveal a jagged sawtooth pattern that only at much greater 

distances consolidated into the form of the double-boom-creating N-wave signature. (It would later be determined that the sound waves resulting from the 

abruptness of the pressure spikes, rather than the overall pressure differential 

from the ambient level, is what people hear as noise.) 

The number of these double booms at Edwards AFB multiplied in the latter 

half of the 1950s as the Air Force Flight Test Center (AFFTC) at Edwards 

(assisted by the HSFRS) began putting a new generation of Air Force jet fighters and interceptors of various configurations, known as the Century Series, 

through their paces. The remarkably rapid advance in aviation technology and 

priorities of the Cold War arms race is evident in the sequence of their first 

flights at Edwards (most as prototypes): the YF-100 Super Sabre, May 1953; 

YF-102 Delta Dagger, October 1953; XF-104 Starfighter, February 1954; 

F-101 Voodoo, September 1954; YF-105 Thunderchief, October 1955; and 

F-106 Delta Dart, December 1956.19

With the sparse population living in California’s Mojave Desert region at 

the time, disturbances caused by the flight tests of new jet aircraft were not yet 

an issue, but the Air Force had already become concerned about their future 

impact. In November 1954, for example, its Aeronautical Research Laboratory 

at Wright-Patterson AFB, OH, submitted a study to the Air Force Board of top 

generals on early findings regarding the still-puzzling nature of sonic booms. 

Although concluding that low-flying aircraft flying at supersonic speeds could 

cause considerable damage, the report hopefully predicted the possibility of 

supersonic flight without booms at altitudes over 35,000 feet.20

As the latest Air Force and Navy fighters went into full production and 

began flying from bases throughout the Nation, more of the American public 

was exposed to jet noise for the first time. This included the thunderclap-like 

thuds characteristic of sonic booms—often accompanied by rattling windowpanes. Under certain conditions, as the U.S. armed services and British 
5

Making Shock Waves

Six Century Series fighters and interceptors at Edwards AFB. Clockwise from top right: F-100, 

F-101, F-102, F-104, F-105, F-106. (USAF)

Royal Air Force (RAF) had learned, even maneuvers below Mach 1 (e.g., 

accelerations, dives, and turns) could generate and focus transonic shock 

waves in such a manner as to cause localized but powerful sonic booms.21

Indeed, residents of Southern California began hearing such booms in the 

late 1940s when North American Aviation was flight testing its new F-86 

Sabre. The first civilian claim against the USAF for sonic boom damage was 
6

Quieting the Boom

apparently filed at Eglin AFB, FL, in 1951, when only subsonic jet fighters 

were assigned there.22

Much of the rapid progress in supersonic flight was made possible by the 

famous area rule, discovered in 1951 by the legendary NACA engineer Richard 

Whitcomb. He subsequently showed how to reduce transonic drag by smoothing out the shock waves that developed along where the wings joined the 

fuselage of an aircraft approaching Mach 1. The basic solution was to reduce 

the cross section of the fuselage between the wings so that the combined cross 

section of the fuselage and wings would gradually increase and decrease in an 

ideal streamlined shape, allowing jet planes to achieve supersonic speeds much 

more easily.23 (Hence the pinched coke-bottle-shaped fuselages of the F-102, 

F-104, F-105, and F-106 in the photograph.)

Adolf Busemann, a colleague at Langley Research Center in Hampton, VA 

(the NACA’s oldest and largest lab), who had inspired Whitcomb to think of 

the area rule, also made major contributions to sonic boom theory. For his 

work as an engineer in Germany before World War II, Busemann is considered 

the father of supersonic aerodynamics; he is remembered especially for the 

concept of a swept wing, which he introduced in 1935. By, at the same time, 

exploring how to eliminate wave drag caused by aircraft volume, he could also 

be considered as the godfather of sonic boom minimization, even at a time 

when supersonic flight was only a distant dream. He later contributed more 

directly to the development of sonic boom theory in a 1955 paper titled “The 

Relation Between Minimizing Drag and Noise at Supersonic Speeds,” which 

showed the importance of lift effects in creating sonic booms.24

Both the area rule and findings about lift during supersonic flight were critical to understanding the effects of wing-body configurations on sonic booms. 

In 1958, another bright, young English mathematician, Frank Walkden, 

showed in a series of insightful equations how the lift effect of airplane wings 

could magnify the strength of sonic booms more than previously estimated.25

The pioneering work of Whitham and Walkden laid the foundation for the 

systematic scientific study of sonic booms, especially the formation of N-wave 

signatures, and provided many of the algorithms and assumptions used in 

planning future flight tests and wind tunnel experiments.26

Sonic boom claims against the U.S. Air Force first became statistically significant in 1957, reflecting the branch’s growing inventory of Century fighters 

and the types of maneuvers they sometimes performed. Such actions could 

focus the acoustical rays projected by shock waves into what became called 

super booms. (It was found that these powerful but localized booms had a 

U-shaped signature with the tail shock as well as that from the nose of the airplane being above ambient air pressure—unlike N-wave signatures, in which 

the tail shock causes pressure to return only to the ambient level.) Most claims 
7

Making Shock Waves

Convair B-58 Hustler, the first airplane capable of sustained supersonic flight and a major 

contributor to early sonic boom research. (USAF)

involved broken windows or cracked plaster, but some were truly bizarre, 

such as the death of pets or the insanity of livestock. In addition to these 

formal claims, Air Force bases, local police switchboards, and other agencies 

received an uncounted number of phone calls about booms, ranging from 

merely inquisitive to seriously irate.27 Complaints from constituents brought 

the issue to the attention of the U.S. Congress.28 Between 1956 and 1968, 

some 38,831 claims were submitted to the Air Force, which approved 14,006 

in whole or in part—65 percent for broken glass, 21 percent for cracked plaster (usually already weakened), 8 percent for fallen objects, and 6 percent for 

other reasons.29

The military’s problem with sonic boom complaints peaked in the 1960s. 

One reason for this peak was the sheer number of fighter-type aircraft stationed 

around the Nation (more than three times as many as today). Secondly, many 

of these aircraft had air defense as their mission. This often meant flying at high 

speed over populated areas to train for defending cities and other key targets 

from aerial attack, sometimes practicing against Strategic Air Command (SAC) 

bombers. The North American Air Defense Command (NORAD) conducted 

the largest such air exercises in history—Skyshield I in 1960, Skyshield II in 
8

Quieting the Boom

1961, and Skyshield III in 1962. The Federal Aviation Agency (FAA) shut 

down all civilian air traffic while numerous flights of SAC bombers (augmented 

by some Vulcans from the RAF) attacked from the Arctic and off the coasts. 

Hundreds of NORAD’s interceptors flying thousands of sorties created a sporadic drum beat of sonic booms as F-101, F-102, F-104, and F-106 pilots 

lit their afterburners in pursuit of the intruders. (About three quarters of the 

bombers were able to reach their targets, a result kept secret for 35 years.)30

Although most fighters and interceptors deployed in the 1960s could readily 

fly faster than sound, they could only do so for a short distance because of the 

rapid fuel consumption of jet-engine afterburners. Thus their sonic boom “carpets” (the term used to describe the areas affected on the surface) were relatively 

short. However, one supersonic American warplane that became operational in 

1960 was designed to fly faster than Mach 2 for more than a thousand miles, 

laying down a continuous sonic boom carpet all the way.

This innovative but troublesome aircraft was SAC’s new Convair-built B-58 

Hustler medium bomber. On March 5, 1962, the Air Force showed off the 

long-range speed of the B-58 by flying one from Los Angeles to New York in 

just over 2 hours at an average pace of 1,215 mph (despite having to slow down 

for an aerial refueling over Kansas). After another refueling over the Atlantic, 

the same Hustler “outraced the sun” (i.e., flew faster than Earth’s rotation) back 

to Los Angeles with one more refueling, completing the record-breaking round 

trip at an average speed of 1,044 mph.31 The accompanying photo shows one 

flying over a populated area (presumably at a subsonic speed).

Capable of sustained Mach 2+ speeds, the 

four-engine, delta-winged Hustler (weighing 

up to 163,000 pounds) helped demonstrate 

the feasibility of a supersonic civilian transport. 

But the B-58’s performance revealed at least one 

troubling omen. Almost wherever it flew supersonic over populated areas, the bomber left 

sonic boom complaints and claims in its wake. 

Indeed, on its record-shattering flight of March 

1962, flown mostly at an altitude of 50,000 feet 

(except when coming down to 30,000 feet for 

refueling), “the jet dragged a sonic boom 20 to 

40 miles wide back and forth across the country—frightening residents, breaking windows, 

cracking plaster, and setting dogs to barking.”32

As indicated by figure 1-2, the B-58 (despite 

its small numbers) became a symbol for sonic 

boom complaints.

Figure 1-2. Air Force pamphlet 

for sonic boom claim investigators. (USAF)
9

Making Shock Waves

Most Americans, especially during times of increased Cold War tensions, 

tolerated occasional disruptions that were justified by national defense. But how 

would they react to constantly repeated sonic booms generated by civilian transports? Could a practical passenger-carrying supersonic airplane be designed to 

minimize its sonic signature enough to be acceptable to people below? Attempts 

to resolve these two questions occupy the remainder of this book.

Preparing for an American Supersonic Transport

After its formation in 1958, the National Aeronautics and Space 

Administration—in keeping with the reason for its creation—began devoting 

the lion’s share of its growing resources to the Nation’s new civilian space programs. Yet 1958 also marked the start of a new program in the time-honored 

aviation mission that the new Agency inherited from the NACA. This new task 

was to help foster an advanced passenger plane that would fly at rates at least 

twice the speed of sound, a concept initially named the Supersonic Commercial 

Air Transport (SCAT).

By the late 1950s, the rapid pace of aeronautical progress—with new turbojet-powered airliners flying twice as fast and high as the propeller-driven 

transports they were replacing—promised even higher speeds in coming years. 

At the same time, the perceived challenge to America’s technological superiority implied by the Soviet Union’s early space triumphs inspired a willingness 

to pursue ambitious new aerospace ventures. One of these was the Supersonic 

Commercial Air Transport. This program was further motivated by proposals being made in Britain and France to build a supersonic airliner, a type of 

airplane that was expected to dominate the future of mid- and long-range 

commercial aviation.33

Because of economic and political factors, developing such an aircraft became 

more than a purely technological challenge—and thus proved to be in some ways 

even more problematic than sending astronauts to the Moon. One of the major 

barriers to producing a supersonic transport involved the still-mysterious phenomenon of how atmospheric shock waves were generated by supersonic flight. 

Studying sonic booms and learning how to control them became a specialized 

and enduring field of NASA research for the next five decades.

The recently established Federal Aviation Agency became the major advocate within the U.S. Government for a supersonic transport, with key personnel at three of NACA’s former laboratories eager to help in this challenging 

new program. The Langley Research Center (the NACA’s oldest and largest 

lab), and the Ames Research Center at Moffett Field in Sunnyvale, CA, both 

had airframe-design expertise and facilities while the Lewis Research Center 
10

Quieting the Boom

in Cleveland, OH (later renamed in honor of astronaut and Senator John H. 

Glenn), specialized in the kind of advanced propulsion technologies needed 

for supersonic cruise.

The strategy for developing SCAT depended heavily on leveraging technologies being developed for another Air Force bomber—one much larger, faster, and 

more advanced than the B-58. This would be the revolutionary B-70, designed 

to cruise several thousand miles at speeds of Mach 3. NACA experts had been 

helping the Air Force plan this giant intercontinental bomber since the mid1950s (with aerodynamicist Alfred Eggers of the Ames Laboratory conceiving 

the innovative design for it to ride partially on compression lift created by its own 

supersonic shock waves). North American Aviation won the B-70 contract in 

1958, but the projected expense of the program and advances in missile technology led President Dwight D. Eisenhower to cancel all but one prototype in 1959. 

The administration of President John F. Kennedy eventually approved production of two XB-70As. Their main purpose would be to serve as Mach 3 test beds 

for what was becoming known simply as the SST, for “Supersonic Transport.”

NASA continued to refer to specific design concepts for the SST using the 

older acronym for Supersonic Commercial Air Transport. As shown by the 25 

SCAT configurations in figure 1-3, the designers were very creative in exploring 

a wide variety of shapes for fuselages, wings, tails, engine nacelles, and other 

surfaces.34 By early 1963, about 40 concepts had been narrowed down to three 

Langley designs contributed by well-known Langley aerodynamicists, such as 

Richard Whitcomb and A. Warner Robins (SCAT-4, SCAT-15, and SCAT16), and one by a team from Ames (SCAT-17). These became the baselines for 

subsequent industry studies and proposals.

SCAT-16, with variable sweep wings for improved low-speed handling, 

and SCAT-17, with a front canard and rear delta wing (based to some extent 

on the XB-70), were judged as the most promising concepts.35 But they were 

still only notional designs. In the judgment of two of the Langley Research 

Center’s supersonic experts, William Alford and Cornelius Driver, “It was 

obvious that ways would have to be found to obtain further major increases in 

flight efficiency. It was clear that major attention would have to be paid to the 

sonic boom, which was shown to have become a dominant factor in aircraft 

design and operation.”36 Whitcomb later withdrew from working on the SST 

because of his judgment that it would never be a practical commercial aircraft.37

Meanwhile, NASA continued research on SCAT concepts 15 through 19.38

Even though Department of Defense (DOD) resources—especially the Air 

Force’s—would be important in supporting SST development, the aerospace 

industry made it clear that direct Federal funding and assistance would be essential. Thus, research and development (R&D) of the SST became a split responsibility between the Federal Aviation Agency and the National Aeronautics and 
11

Making Shock Waves

Figure 1-3. SCAT configurations, 1959–1966. (NASA)

Space Administration—with NASA conducting and sponsoring the supersonic 

research and the FAA overseeing the SST’s overall development. The first two 

leaders of the FAA, retired Lt. Gen. Elwood R. “Pete” Quesada (1958–61) and 

Najeeb E. Halaby (1961–65), were both staunch proponents of producing an 

SST, as to a slightly lesser degree was retired Gen. William F. “Bozo” McKee 

(1965–68). As heads of an independent agency that reported directly to the 

President, they were at the same level as NASA Administrators T. Keith Glennan 

(1958–61) and James Webb (1961–68). The FAA and NASA administrators, 

together with Secretary of Defense Robert McNamara (somewhat of a skeptic on 

the SST program), provided interagency oversight and composed the Presidential 

Advisory Committee (PAC) for the SST established in April 1964. This arrangement lasted until 1967, when the Federal Aviation Agency became the Federal 

Aviation Administration under the new U.S. Department of Transportation 

(DOT), whose secretary became responsible for the program.39

Much of NASA’s SST-related research involved advancing the state of the 

art in such technologies as propulsion, fuels, materials, and aerodynamics. The 

last item included designing airframe configurations for sustained supersonic 

cruise at high altitudes, suitable subsonic maneuvering in civilian air-traffic patterns at lower altitudes, safe takeoffs and landings at commercial airports, and 

acceptable noise levels—to include the still-puzzling matter of sonic booms. 
12

Quieting the Boom

Although the NACA, especially at Langley and Ames, had been doing research 

on supersonic flight since World War II, none of its technical reports (and only 

one conference paper) published through 1957 dealt directly with sonic booms.40

That situation began to change when Langley’s long-time manager and advocate 

of supersonic programs, John P. Stack, formalized the SCAT venture in 1958. 

During the next year, three Langley employees, whose names would become wellknown in the field of sonic boom research, began publishing NASA’s first scientific papers on the subject. These were Harry W. Carlson, a versatile supersonic 

aerodynamicist; Harvey H. Hubbard, chief of the Acoustics and Noise Control 

Division; and Domenic J. Maglieri, a young engineer who became Hubbard’s 

top sonic boom specialist. Carlson would tend to focus on wind tunnel experiments and sonic boom theory while the two other men specialized in planning 

and monitoring field tests and recording and analyzing the data collected. Within 

NASA, the Langley Research Center continued to be the focal point for sonic 

boom studies throughout the 1960s with the Flight Research Center (FRC) at 

Edwards AFB increasingly conducting most supersonic tests, often with Air Force 

support.41 (The “High Speed” prefix was dropped from the FRC’s name in 1959 

to indicate a broadening of its experimental activities.)

These research activities began to proliferate under the new pro-SST 

Kennedy administration in 1961. After the president formally approved development of the supersonic transport in June 1963, sonic boom research really 

took off. Langley’s experts, augmented by NASA contractors and grantees, 

published 26 papers on sonic booms just 3 years later, with Ames also conducting related research.42

Dealing with the sonic boom demanded a multifaceted approach: (1) performing flight tests to better quantify the fluid dynamics and atmospheric physics involved in generating and propagating shock waves as well as their physical 

effects on structures and people; (2) conducting community surveys to gather public opinion data from 

sample populations exposed to booms; (3) building 

and using acoustic simulators to further evaluate 

human and structural responses in controlled settings; (4) performing field studies of possible effects 

on animals, both domestic and wild; (5) evaluating 

shock waves from various aerodynamic configurations in wind tunnel experiments; and (6) analyzing 

flight-test and wind tunnel data to refine theoretical 

constructs and create mathematical models for lowerboom aircraft designs. The remainder of this chapter 

focuses on the first four activities with the final two 

to be the main subject of the next chapter.

Langley Research Center’s 

first sonic boom testers, 

Harvey Hubbard and 

Domenic Maglieri. (NASA)
13

Making Shock Waves

Early Flight Testing

The systematic sonic boom testing that NASA began in 1958 would expand 

exponentially the heretofore largely theoretical and anecdotal knowledge about 

sonic booms with a vast amount of empirical, real-world data. The new information would make possible increasingly sophisticated experiments and provide feedback for checking and refining theories and mathematical models. 

Because of the priority bestowed on sonic boom research by the SST program 

and the numerous types of aircraft then available for creating booms (including some faster than any flying today), the data and findings from the tests 

conducted in the 1960s are still of great value in the 21st century.43

The Langley Research Center (often referred to as “NASA Langley”) served 

as the Agency’s team leader for supersonic research. Langley’s acoustics specialists conducted NASA’s initial sonic boom tests in 1958 and 1959 at the 

Wallops Island Station on Virginia’s isolated Delmarva Peninsula. During the 

first year, they used six sorties by NASA F-100 and F-101 fighters, flying at 

speeds between Mach 1.1 and Mach 1.4 and altitudes from 25,000 feet to 

45,000 feet, to make the first good ground recordings and measurements of 

sonic booms generated in steady and level flights (the kind of profile a future 

airliner would mostly fly). Observers judged some of the booms above 1.0 psf 

to be objectionable, likening them to nearby thunder, and a sample plate glass 

window was cracked by one plane flying at 25,000 feet. The 1959 test measured 

shock waves from 26 flights of a Chance Vought F8U-3 (a highly advanced prototype based on the Navy’s supersonic Crusader fighter) at speeds up to Mach 

2 and altitudes up to 60,000 feet. A much larger B-58 from Edwards AFB also 

made two supersonic passes at 41,000 feet. Boom intensities from these higher 

altitudes seemed to be tolerable to observers, with negligible increases in measured overpressures between Mach 1.4 and Mach 2.0 (showing that loudness 

of sonic booms is based more on aircraft size, altitude, and factors other than 

extreme speeds). The human response results were, however, very preliminary.44

In July 1960, NASA and the Air Force conducted Project Little Boom at a 

bombing range north of Nellis AFB, NV, to measure the effects on structures 

and people of extremely powerful sonic booms (which the Air Force thought 

might have some military value). F-104 and F-105 fighters flew slightly over 

the speed of sound (Mach 1.09 to Mach 1.2) at altitudes down to 50 feet 

above ground level. There were more than 50 incidents of sample windows 

being broken at 20 psf to 100 psf but only a few possible breakages below 20 

psf, and there was no physical or psychological harm to volunteers exposed to 

overpressures as high as 120 psf.45 At Indian Springs, NV, Air Force fighters 

flew supersonically over an instrumented C-47 transport from Edwards, both 

while the aircraft was in the process of landing and while it was on the ground. 
14

Quieting the Boom

Chance Vought’s F8U-3 prototype at Wallops Island. (NASA)

Despite 120-psf overpressures, the aircraft was only very slightly damaged when 

on the ground and there were no problems while it was in flight.46

Air Force fighters once again would test powerful sonic booms during 1965 

in remote mountain and desert terrain near Tonopah, NV. This was where 

a special military testing organization from Sandia Base, NM, called Joint 

Task Force II, was evaluating the low-level penetration capabilities of various 

fighter aircraft for the Joint Chiefs of Staff. To learn more about possible effects 

from this kind of low-level training in remote areas, the USAF Aerospace 

Medical Division’s Biomedical Laboratory observed and analyzed the responses 

of people, structures, and animals to strong sonic booms. As in other tests, 

the damage to buildings (many in poor condition to begin with) consisted 

of cracked plaster, items falling from shelves, and broken windows. In some 

cases, glass fragments were propelled up to 12 feet—a condition not recorded 

in previous testing. Some campers near the so-called starting gates to the three 

low-level corridors used for testing also experienced damage, probably from 

super booms as the fighters maneuvered into the tracks. Cattle and horses did 

not seem to react much to the noise. Test personnel located in a flat area where 

the fighters flew at less than 100 feet above ground level and generated shock 

waves of more than 100 psf felt a jarring sensation against their bodies and 

were left with temporary ringing or feelings of fullness in their ears, but they 

experienced no real pain or ill effects. Most, however, could not help involuntarily flinching in anticipation of the booms whenever the speeding jets passed 
15

Making Shock Waves

overhead. An Air Force F-4C Phantom II flying Mach 1.26 at 95 feet during 

this test generated the strongest sonic boom yet recorded: 144 psf.47 (To put 

this in perspective, normal air pressure at sea level equates to 14.7 pounds per 

square inch, or about 2,116 pounds per square foot.)

In late 1960 and early 1961, NASA and AFFTC followed up on Little 

Boom with Project Big Boom. B-58 bombers made 16 passes flying Mach 1.5 

at altitudes of 30,000 feet to 50,000 feet over arrays of sensors, which measured 

a maximum overpressure of 2.1 psf. Varying the bomber’s weight from 82,000 

pounds to 120,000 pounds provided the first hard data on how an aircraft’s 

weight and related lift produced higher overpressures than existing theories 

based on volume alone would indicate.48

Throughout the 1960s, Edwards Air Force Base—with its unequalled combination of Air Force and NASA expertise, facilities, instrumentation, airspace, 

emergency landing space, and types of aircraft—hosted the largest number of 

sonic boom tests. NASA researchers from Langley’s Acoustics Division spent 

much of their time there working with the Flight Research Center in a wide 

variety of flight experiments. The Air Force Flight Test Center usually participated as well.

In an early test in 1961, Gareth Jordan of the FRC led an effort to collect 

measurements from F-104s and B-58s flying at speeds of Mach 1.2 to Mach 

2.0 over sensors located along Edward AFB’s supersonic corridor and at Air 

Force Plant 42 in Palmdale, about 20 miles south. Most of the Palmdale measurements were under 1.0 psf, which the vast majority of people surveyed there 

and in adjacent Lancaster (where overpressures tended to be somewhat higher) 

considered no worse than distant thunder. But there were some exceptions.49

Other experiments at Edwards in 1961 conducted by Langley personnel 

with support from the FRC and AFFTC contributed a variety of new data. 

With help from the Goodyear blimp Mayflower, hovering at 2,000 feet, they 

made the first good measurements of atmospheric effects, such as how temperature variations can bend the paths of acoustic rays and how air turbulence in the 

lower atmosphere near the surface (known as the boundary layer) significantly 

affected N-wave shape and overpressure.50

Testing at Edwards also gathered the first data on booms from very high 

altitudes. Using an aggressive flight profile, AFFTC’s B-58 crew managed to 

zoom up to 75,000 feet—25,000 feet higher than the bomber’s normal cruising 

altitude and 15,000 feet over its design limit! The overpressures measured from 

this high altitude proved stronger than predicted (not a promising result for 

the planned SST). Much lower down, fighter aircraft performed accelerating 

and turning maneuvers to generate the kind of acoustical rays that amplified 

shock waves and produced multiple booms and super booms. The various 

experiments showed that a combination of atmospheric conditions, altitude, 
16

Quieting the Boom

speed, flight path, aircraft configuration, and sensor location determined the 

shape and strength of the pressure signatures.51

Of major significance for future boom minimization efforts, NASA 

also began taking in-flight shock wave measurements. The first of these, at 

Edwards in 1960, had used an F-100 with a sensor probe to measure supersonic shock waves from the sides of an F-100, F-104, and B-58 as well as 

from F-100s speeding past with only 100 feet of separation. The data confirmed Whitham’s overall theory with some discrepancies. In early 1963, an 

F-106 equipped with a sophisticated new sensor probe designed at Langley 

flew seven sorties both above and below a B-58 at speeds of Mach 1.42 to 

Mach 1.69 and altitudes of approximately 40,000 feet to 50,000 feet. The 

data gathered confirmed Walkden’s theory about how lift as well as volume 

increase peak shock wave pressures. As indicated by figure 1-4, analysis of 

the readings also found that the bow and tail shock waves spread farther 

apart as they flowed from the B-58. Perhaps most significant, the probing 

measurements revealed how the multiple, or saw tooth, shock waves (sudden 

increases in pressure) and expansions (regions of decreasing pressure) produced by the rest of an airplane’s structure (canopy, wings, engine nacelles, 

weapons pod, etc.) merged with the stronger bow and tail waves until—at 

a distance of between 50 body lengths and 90 body lengths—they began to 

coalesce into the classic N-shaped signature.52 This historic flight test, which 

hinted at how shock waves might be modified to reduce peak overpressures, 

marked a major milestone in sonic boom research.

One of the most publicized and extended flight-test programs at Edwards 

had begun in 1959 with the first launch from a B-52 of the fastest piloted 

aircraft ever flown: the rocket-propelled X-15. Three of these legendary aerospace vehicles expanded the envelope and gathered data on supersonic and 

hypersonic flight for the next 8 

years. Although the X-15 was 

not specifically dedicated to sonic 

boom tests, the Flight Research 

Center did begin placing microphones and tape recorders under 

the X-15s’ flight tracks in the fall of 

1961 to gather boom data. Much 

later, FRC researchers reported on 

the measurements of these sonic 

booms, which were made at speeds 

of Mach 3.5 and Mach 4.8.53

For the first few years, NASA’s 

sonic boom tests occurred in 

Figure 1-4. Shock wave signature of a B-58 at 

Mach 1.6. (NASA)
17

Making Shock Waves

relative isolation within military airspace in the desert Southwest or over 

Virginia’s rural Eastern Shore and 

adjacent waters. A future SST, however, would have to fly over heavily 

populated areas. Thus, from July 1961 

through January 1962, NASA, the 

FAA, and the Air Force carried out the 

Community and Structural Response 

Program at St. Louis, Missouri. In 

an operation nicknamed “Bongo,” 

the Air Force sent B-58 bombers on 

76 supersonic training flights over 

the city at altitudes from 31,000 to 

41,000 feet, announcing them as 

routine SAC radar bomb-scoring missions. F-106 interceptors flew 11 additional flights at 41,000 feet. Langley 

personnel installed sensors on the ground, which measured overpressures 

up to 3.1 psf. Investigators from Scott AFB, Illinois, or for a short time, a 

NASA-contracted engineering firm, responded to damage claims, finding 

some possibly legitimate minor damage in about 20 percent of the cases. 

Repeated interviews with more than 1,000 residents found 90 percent were 

at least somewhat affected by the booms and about 35 percent were annoyed. 

Scott AFB (a long distance phone call from St. Louis) received about 3,000 

complaints during the test and another 2,000 in response to 74 sonic booms 

in the following three months. The Air Force eventually approved 825 claims 

for $58,648. These results served as a warning that repeated sonic booms 

could indeed pose an issue for SST operations.54

To obtain more definitive data on structural damage, NASA in December 

1962 resumed tests at Wallops Island using various sample buildings. Air Force 

F-104s and B-58s and Navy F-4H Phantom IIs flew at altitudes from 32,000 

feet to 62,000 feet, creating overpressures up to 3 psf. Sonic booms triggered 

cracks to plaster, tile, and other brittle materials in spots where the materials were already under stress (a finding that would be repeated in later, more 

comprehensive tests).55

In February 1963, NASA, the FAA, and the USAF conducted Project 

Littleman at Edwards AFB to measure the results of subjecting two specially 

instrumented light aircraft to sonic booms. F-104s made 23 supersonic passes 

as close as 560 feet from a small Piper Colt and a two-engine Beech C-45, 

creating overpressures up to 16 psf. Their responses were “so small as to be 

insignificant,” dismissing one possible concern about SST operations.56

Shock waves from an X-15 model in 

Langley’s 4-by-4-foot Supersonic Pressure 

Tunnel. (NASA)
18

Quieting the Boom

The St. Louis survey had left many unanswered questions about public 

opinion. To learn more, the FAA’s Supersonic Transport Development Office 

with support from NASA Langley and the USAF (including Tinker AFB) 

conducted the Oklahoma City Public Reaction Study from February through 

July 1964. This was a much more intensive and systematic test. In an operation named Bongo II, B-58s, F-101s, F-104s, and F-106s were called upon 

to deliver sonic booms eight times per day, 7 days a week for 26 weeks, with 

another 13 weeks of followup activities. The aircraft flew a total of 1,253 

supersonic flights at Mach 1.2 to Mach 2.0 and altitudes between 21,000 feet 

and 50,000 feet.

The FAA (which had the resources of a major field organization available 

in Oklahoma City) instrumented nine control houses scattered throughout 

the metropolitan area with various sensors to measure structural effects while 

experts from Langley instrumented three houses and set up additional sensors 

throughout the area to record overpressures, wave patterns, and meteorological conditions. The National Opinion Research Center at the University of 

Chicago interviewed a sample of 3,000 adults three times during the study.57 By 

the end of the test, 73 percent of those surveyed felt that they could live with 

the number and strength of the booms experienced, but 40 percent believed 

they caused some structural damage (even though the control houses showed 

no significant effects), and 27 percent would not accept indefinite booms 

at the level tested. Analysis of the shock wave patterns by NASA Langley 

showed that a small number of overpressure measurements were significantly 

higher than expected, indicating probable atmospheric influences, including 

heat rising from urban landscapes.58 Sometimes, the effects of even moderate 

turbulence near the surface could be dramatic, as shown in figure 1-5 by the 

rapid change in pressure measurements from an F-104 flying Mach 1.4 at 

28,000 feet recorded by an array of closely spaced microphones.59

The Oklahoma City study added to the growing knowledge of sonic booms 

and their acceptance or nonacceptance by the public at the cost of $1,039,657, 

seven lawsuits, and some negative 

publicity for the FAA. In view of 

the public and political reactions 

to the St. Louis and Oklahoma 

City tests, plans for another 

extended sonic boom test over a 

different city, including flights at 

night, never materialized.60

The FAA and Air Force conducted the next series of tests from 

November 1964 into February 

Figure 1-5. Effect of turbulence in just 800 feet of 

an F-104’s sonic boom carpet. (NASA)
19

Making Shock Waves

1965 in a much less populated place: the remote Oscura camp in the Army’s 

vast White Sands Missile Range, NM. Here, 21 structures of various types 

and ages with a variety of plaster, windows, and furnishings were studied 

for possible damage. F-104s from nearby Holloman AFB and B-58s from 

Edwards AFB generated 1,494 booms, producing overpressures from 1.6 psf 

to 19 psf. The 680 sonic booms of up to 5.0 psf caused no real problems, 

but those above 7.9 psf caused varying degrees of damage to glass, plaster, 

tile, and stucco that were already in vulnerable condition. A parallel study of 

several thousand incubated chicken eggs showed no reduction in hatchability, 

and audiology tests on 20 personnel subjected daily to the booms showed 

no hearing impairment.61

Before the White Sands tests ended, NASA Langley personnel began collecting boom data from a highly urbanized setting in winter weather. During 

February 1965 and March 1965, they recorded data at five ground stations 

as B-58 bombers flew 22 training missions in a corridor over downtown 

Chicago at speeds from Mach 1.2 to Mach 1.66 and altitudes from 38,000 

feet to 48,000 feet. The results demonstrated further that amplitude and 

wave shape varied widely depending upon atmospheric conditions. These 

22 flights and 27 others resulted in the Air Force approving 1,442 of 2,964 

damage claims for a total of $114,763. Figure 1-6 shows how a gusty day 

in the “Windy City” greatly increased the strength of sonic booms (N-wave 

signatures, shown on the right) over those created by a B-58 flying at the same 

speed and altitude on a more tranquil day (left) as measured by microphones 

placed at 100-foot intervals in a cruciform pattern.62 The planned SST would, 

of course, encounter similar enhanced boom conditions.

Also in March 1965, the FAA and NASA, in cooperation with the U.S. 

Forest Service, studied the effects of Air Force fighters creating boom overpressures up to 5.0 psf over hazardous mountain snow packs in 

the Colorado Rockies. Because of 

the stable snow conditions, these 

booms did not created any avalanches. Interestingly enough, in 

the early 1960s, the National Park 

Service tried to use newly deployed 

F-106s at Geiger Field, WA, to 

create controlled avalanches in 

Glacier National Park (known as 

Project Safe Slide), but, presumably, it found traditional methods 

such as artillery fire more suitable.63

Figure 1-6. Effect of winds on B-58 sonic boom 

signatures. (NASA)
20

Quieting the Boom

XB-70 Valkyrie, the largest of the sonic boom test aircraft. (USAF)

Enter the Valkyrie and the Blackbird

From the beginning of the SST program, the aircraft most desired for experiments was, of course, the North American XB-70 Valkyrie. The first of the 

giant test beds (XB-70-1) arrived at Edwards AFB in September 1964, and the 

better-performing, better-instrumented second aircraft (XB-70-2) arrived in 

July 1965. With a length of 186 feet, a wingspan of 105 feet, and a gross weight 

of about 500,000 pounds, the six-engine would-be bomber was considerably 

heavier but less than two thirds as long as some of the later SST concepts, but 

it was the best real-life surrogate available.64

Even during the initial flight-envelope expansion by contractor and AFFTC 

test pilots, the Flight Research Center began gathering sonic boom data, including direct comparisons of its shock waves with those of a B-58 flying only 800 

feet behind.65 Using an array of microphones and recording equipment at several 

ground stations, NASA researchers built a database of boom signatures from 

39 flights made by the XB-70s (10 with B-58 chase planes) from March 1965 

through May 1966.66 Because “the XB-70 is capable of duplicating the SST 

flight profiles and environment in almost every respect,” the FRC was looking 

forward to beginning its own experimental research program using the second 

Valkyrie on June 15, 1966, with sonic boom testing listed as the first priority.67
21

Making Shock Waves

On June 8, however, the XB-70-2 crashed on its 47th flight as the result 

of a midair collision during an infamous publicity flight for General Electric 

(GE) to advertise its jet engines. Despite this tragic setback to the overall 

test program, the less capable XB-70-1 (which underwent modifications until 

November) eventually proved useful for many purposes. After 6 months of 

joint AFFTC-FRC operations (with a total of 60 flights, including the boom 

testing described below), the Air Force turned the plane over full time to NASA 

in April 1967. The FRC, with a more limited budget, then used the Valkyrie 

for 23 more test missions until February 1969, when the unique aircraft was 

retired to the USAF Museum in Dayton, OH.68 All told, NASA acquired sonic 

boom measurements from 51 of the 129 total flights made by the XB-70s using 

two ground stations on Edwards AFB, one at nearby Boron, CA, and two in 

Nevada.69 These data would be of great value in the future.

The loss of one XB-70 and retirement of the other from supersonic testing 

was made somewhat less painful by the availability of two smaller (107 feet 

long) but even faster products of advanced aviation technology: the Lockheed 

YF-12 and its cousin, the SR-71—both nicknamed Blackbirds. On May 1, 

1965, shortly after arriving at Edwards, a YF-12A set nine new world records, 

including a closed-course speed of 2,070 mph (Mach 3.14) and a sustained 

altitude of 80,257 feet. Four of that day’s five flights also yielded sonic boom 

measurements. At speeds of Mach 2.6 to Mach 3.1 and altitudes of 60,000 

feet to 76,500 feet above ground level, overpressures varied from 1.2 psf to 

1.7 psf depending on distance from the flight path. During another series of 

flight tests at slower speeds and lower altitudes, overpressures up to 5.0 psf 

were measured during accelerations after having slowed down to refuel. These 

early results proved consistent with previous B-58 data.70 Data gathered from 

ground arrays measuring the sonic signatures from YF-12s, XB-70s, B-58s, and 

smaller aircraft flying at various altitudes also showed that the lateral spread 

of a boom carpet (without the influence of atmospheric variables) could be 

roughly equated to 1 mile for every 1,000 feet of altitude with the N-signatures 

becoming more rounded with distance until degenerating into the approximate shape of a sine wave.71 In all cases, however, acoustic rays reflected off the 

ground along with those that propagated above the aircraft could be refracted 

or bent by the conditions in the thermosphere and intersect the ground as a 

much weaker over-the-top or secondary boom carpet.

Although grateful to benefit from the flights of the AFFTC’s Blackbirds, 

the FRC wanted its own YF-12 or SR-71 for supersonic research. It finally 

gained the use of two YF-12s through a NASA-USAF Memorandum of 

Understanding signed in June 1969, paying for operations with funding left 

over from the termination of the X-15 and XB-70 programs.72
22

Quieting the Boom

The National Sonic Boom Evaluation

In the fall of 1965, with public acceptance of sonic booms becoming a 

significant public and political issue, the White House Office of Science 

and Technology established the National Sonic Boom Evaluation Office 

(NSBEO) under the interagency Coordinating Committee on Sonic Boom 

Studies. The new organization, which was attached to Air Force Headquarters 

for administrative purposes, planned a comprehensive series of tests known 

as the National Sonic Boom Evaluation Program, which was to be conducted 

primarily at Edwards AFB. NASA (in particular, the Flight Research Center 

and Langley Research Center) would be responsible for test operations and 

data collection with the Stanford Research Institute (SRI) hired to help 

analyze the findings.73

After careful preparations (including specially built structures and extensive 

sensor and recording arrays), the National Sonic Boom Evaluation began in 

June 1966. Its main objectives were to address the many issues left unresolved 

from previous tests. Unfortunately, the loss of the XB-70-2 on June 8 forced a 

4-month break in the test schedule, and the limited events completed in June 

became designated as Phase I. The second phase began in November 1966, 

when the XB-70-1 returned to flight status, and lasted into January 1967. A 

total of 367 supersonic missions were flown by XB-70s, B-58s, YF-12s, SR-71s, 

F-104s, and F-106s during the two phases. These were supplemented by 256 

subsonic flights by KC-135s, WC-135Bs, C-131Bs, and Cessna 150s. In addition, the Goodyear blimp Mayflower was used in the June phase to measure 

sonic booms at 2,000 feet.74

By the end of testing, the National Sonic Boom Evaluation had obtained 

new and highly detailed acoustic and seismic signatures from all the different 

supersonic aircraft in various flight profiles during a variety of atmospheric 

conditions. The data from 20 XB-70 flights at speeds from Mach 1.38 to 

Mach 2.94 were to be of particular long-term interest. For example, Langley’s 

sophisticated nose probe used for the pioneering in-flight flow-field measurements of the B-58 in 1963 was installed on one of the FRC’s F-104s to do the 

same for the XB-70. A comparison of data between blimp and ground sensors 

and variations between the summer and winter tests confirmed the significant 

influence that atmospheric conditions, such as turbulence and convective 

heating near the surface, have on boom propagation.75 (In general, rising 

temperatures near the surface bend the path followed by the acoustic rays 

accompanying the shock waves upward, sometimes away from the ground 

altogether while cooler air near the surface, as with a temperature inversion, 

does just the opposite, bending the rays downward so that they bounce off 

the ground.76) Also, the evaluation provided an opportunity to gather data 
23

Making Shock Waves

An Air Force YF-12, which provided valuable sonic boom data for NASA, taking off at Edwards 

AFB. (USAF)

on more than 1,500 sonic boom signatures created during 35 flights by the 

recently available SR-71s and YF-12s at speeds up to Mach 3.0 and altitudes 

up to 80,000 feet.77

Some of the findings portended serious problems for planned SST operations. The program obtained responses from several hundred participating 

volunteers, both outdoors and inside houses, to sonic booms of different intensities produced by each of the supersonic aircraft. The time between the peak 

overpressure of the bow and tail shocks for aircraft at high altitudes ranged 

from about one-tenth of a second for the F-104, two-tenths of a second for 

the B-58, and three-tenths of a second for the XB-70. (See figure 1-7.) The 

respondents also compared sonic booms to the jet-engine noise of subsonic 

aircraft. Although data varied for each of the criteria measured, significant 

minorities tended to find the booms either just acceptable or unacceptable 

and the sharper N-wave signature from the lower flying F-104 more annoying 

outdoors than the more rounded signatures from the larger aircraft, which had 

to fly at higher altitudes to create the same overpressure. Other factors included 

the frequency, time of day or night, and type of boom signature. Correlating 

how the subjects responded to jet noise (measured in decibels) and sonic booms 

(normally measured in psf), the SRI researchers used a criterion called the 
24

Quieting the Boom

Figure 1-7. Variations in N-waves caused by 

aircraft size and atmospheric conditions. (NASA)

perceived noise decibel (PNdB) 

level to assess how loud booms 

seemed to human ears.78

Employing sophisticated sensors, civil engineers measured the 

physical effects on houses and 

a building with a large interior 

space (the base’s bowling alley) 

from varying degrees of booms 

created by the F-104s, B-58s, and 

XB-70. Of special concern for 

the SST’s acceptability, the engineers found the XB-70’s elongated 

N-wave (although less bothersome to observers outdoors) created more of the 

ultralow frequencies that cause indoor vibrations, such as rattling windows, 

which many of the respondents considered objectionable. And although no 

significant harm was detected to the instrumented structures, 57 complaints of 

damage were received from residents in the surrounding area, and three windows were broken on the base. Finally, monitoring by the U.S. Department of 

Agriculture detected no ill effects on farm animals in the area, although avian 

species (chickens, turkeys, etc.) reacted more than livestock.79 The National 

Sonic Boom Evaluation remains the most comprehensive test program of its 

kind ever conducted.80

Last of the Flight Tests

Even with the advantages offered by sophisticated simulators, researchers continued to look for ways to obtain human-response data from live sonic booms. 

In the spring of 1967, the opportunity for collecting additional survey data 

presented itself when the FAA and NASA learned that SAC was starting an 

extensive training program for its growing fleet of SR-71s. TRACOR, Inc., 

of Austin, TX, which was already under contract to NASA doing surveys on 

airport noise, had its contract’s scope expanded in May 1967 to include public 

responses to the SR-71s’ sonic booms in Dallas, Los Angeles, Denver, Atlanta, 

Chicago, and Minneapolis. Between July 3 and October 2, Air Force SR-71s 

made 220 high-altitude supersonic flights over these cities, ranging from 5 over 

Atlanta to 60 over Dallas. Those sonic booms that were measured were almost 

all N-waves with overpressures ranging from slightly less than 1.0 psf to 2.0 psf. 

Although the data from this impromptu test program were less than definitive, its overall findings (based on 6,375 interviews) were fairly consistent with the 
25

Making Shock Waves

previous human-response surveys. For example, after an initial dropoff, the level 

of annoyance with the booms tended to increase over time, and almost all those 

who complained were worried about damage. Among 15 different adjectives 

supplied to describe the booms (e.g., disturbing, annoying, irritating), the word 

“startling” was chosen much more frequently than any other.81 The tendency of 

people to be startled by the suddenness of sonic booms was becoming recognized 

as their most problematic attribute in gaining public acceptance.

Although the FRC and AFFTC continued their missions of supersonic flight 

testing and experimentation at Edwards, what might be called the heroic era of 

sonic boom testing was drawing to a close. The FAA and the Environmental 

Science Services Administration (a precursor of the Environmental Protection 

Agency) did some sophisticated testing of meteorological effects at Pendleton, 

OR, from September 1968 until May 1970, using a dense grid of recently 

invented, unattended transient data recorders to measure random booms from 

SR-71s. On the other side of the continent, NASA and the Navy studied sonic 

booms during Apollo missions in 1970 and 1971.82

The most significant NASA testing in 1970 took place from August to 

October at the Atomic Energy Commission’s Jackass Flats test site in Nevada. 

In conjunction with the FAA and the National Oceanic and Atmospheric 

Administration (NOAA), NASA took advantage of the 1,527-foot tall Bare 

Reactor Experiment Nevada (BREN) Tower, which had been named for its 

original nuclear radiation tests in 1962. The researchers installed a vertical 

array of 15 microphones as well as meteorological sensors at various levels 

Interagency team at the base of the BREN Tower. NASA personnel include Herbert Henderson, 

second from left; Domenic Maglieri, third from left; and David Hilton, far right. (Maglieri)
26

Quieting the Boom

Figure 1-8. BREN Tower measurements of Mach 

cutoff signatures. (NASA)

along the tower. (Until then, a 

250-foot tower at Wallops Island 

had been the highest used in sonic 

boom testing.83)

During the summer and fall 

of 1970, the FRC’s F-104s made 

121 boom-generating flights from 

Edwards AFB to provide measurements of several still inadequately 

understood aspects of the sonic 

boom, especially the conditions 

known as caustics, in which acoustical rays can converge and focus in a nonlinear manner.84 Frequently caused 

by aircraft at transonic speeds or during acceleration, they can result in normal 

N-wave signatures being distorted as they pass through caustic regions into 

U-shaped signatures, sometimes with bow and tail wave overpressures strong 

enough to create super booms. Such signatures, however, are also sensitive to 

turbulence and prone to refracting before reaching the surface (rather than 

reflecting off the ground as with N-waves). The BREN Tower allowed such 

measurements to be made in the vertical dimension for the first time. This testing resulted in definitive data on the formation and nature of caustics as well as 

the Mach cutoff—information that would be valuable in planning boomless 

transonic flights and helping pilots to avoid making focused booms.85 Figure 

1-8 illustrates the combined results of 3 days of testing by F-104s flying at 

about Mach 1.1 at 30,000 feet (with the solid lines representing shock waves 

and the dotted lines their reflection).86

For all intents and purposes, the results of earlier testing and humanresponse surveys had already helped seal the fate of the SST before the reports 

on this latest test began coming in. Even so, the test results garnered from 1958 

through 1970 during the SCAT and SST programs contributed tremendously 

to the international aeronautical and scientific communities’ understanding 

of one of the most baffling and complicated aspects of supersonic flight. As 

Harry W. Carlson told the Nation’s top sonic-boom experts on the same day 

the last F-104 flew over Jackass Flats: “The importance of flight-test programs 

cannot be overemphasized. These tests have provided an impressive amount 

of high-quality data.”87 Unfortunately, however, learning about the nature of 

sonic booms did not yet translate into learning how to control them.

As will be described in the next chapter, the American SST program proved 

to be too ambitious for the technology of its time despite a concerted effort 

by many of the best minds in aeronautical science and engineering. Yet for all 
27

Making Shock Waves

its disappointments and controversies, the program’s proliferation of data and 

scientific knowledge about supersonic flight, including sonic booms, would 

be indispensable for progress in the future.
28

Quieting the Boom

Endnotes

1. Paul Pojman, “Ernst Mach,” in The Stanford Encyclopedia of 

Philosophy (Summer 2011 Edition), ed. Edward N. Zalta, accessed 

ca. June 1, 2011, http://plato.stanford.edu/archives/sum2011/entries/

ernst-mach/.

2. Because the effects of pressure and density on the speed of sound 

offset each other in most gases, temperature is the major variable. As 

a result, the speed of sound in Earth’s lower atmosphere (the troposphere) typically decreases as air cools with altitude until reaching 

the tropopause, which is a boundary layer of stable (isothermal) 

temperatures between the troposphere and the upper stratosphere. 

Although the altitude of the tropopause varies depending on season 

and latitude, the speed of sound usually travels at its uniformly slowest speed between about 36,000 feet and 85,000 feet. See “Layers of 

the Earth’s Atmosphere,” Windows to the Universe, accessed June 

9, 2011, http://www.windows2universe.org/earth/Atmosphere/layers.

html; Steven A. Brandt et al., Introduction to Aeronautics: A Design 

Perspective (Reston, VA: American Institute of Aeronautics and 

Astronautics [AIAA], 2004), Appendix B, 449–451.

3. J.W.M. Dumond et al., “A Determination of the Wave Forms and 

Laws of Propagation and Dissipation of Ballistic Shock Waves,” 

Journal of the Acoustical Society of America (JASA) 18, no. 1 (January 

1946): 97–118. By the end of World War II, ballistic waves were 

well understood.

4. David Darling, The Complete Book of Spaceflight: From Apollo 1 to 

Zero Gravity (Hoboken, NJ: John Wiley and Sons, 2003), 457. 

See also “Airpower: Missiles and Rockets in Warfare,” accessed 

December 21, 2009, http://www.centennialofflight.gov/essay/

Air_Power/Missiles/AP29.htm; and Bob Ward, Dr. Space: The Life of 

Wernher von Braun (Annapolis, MD: Naval Institute, 2005), 43.

5. The definitive biography, Michael J. Neufeld’s Von Braun: Dreamer of 

Space, Engineer of War (New York: Alfred A. Knopf, 2007), 133–36, 

leaves open the question of whether the Germans at Peenemünde 

heard the first humanmade sonic booms in 1942 when their A-4 test 

rockets exceeded Mach 1 about 25 seconds after launch.

6. For its development and testing, see Richard P. Hallion, Supersonic 

Flight: Breaking the Sound Barrier and Beyond—The Story of the Bell 

X-1 and Douglas D-558 (New York: The Macmillan Co. in association with the Smithsonian Institution National Air and Space 

Museum, 1972). For a detailed analysis of the XS-1’s first supersonic 
Making Shock Waves

29

flight by a former NASA engineer, see Robert W. Kempel, The 

Conquest of the Sound Barrier (Beirut, Lebanon: HPM Publications, 

2007), 31–49.

7. Tom Wolfe, The Right Stuff (New York: Bantam Books, 1980), 47. 

Some personnel stationed at Muroc when Yeager broke the sound 

barrier would later recall hearing a full sonic boom, but these may 

have been memories of subsequent flights at higher speeds.

8. One of NASA’s top sonic boom experts, using a computer program 

called PCBoom4, has calculated that at Mach 1.06 and 43,000 feet 

in a standard atmosphere, refraction and absorption of the shock 

waves would almost certainly have dissipated the XS-1’s sonic boom 

before it could reach the surface; Edward A. Haering, Dryden Flight 

Research Center (DFRC), to Lawrence R. Benson, e-mail message, 

April 8, 2009.

9. Chuck Yeager and Leo Janis, Yeager (New York: Bantam Books, 

1985), 165.

10. Domenic J. Maglieri to Christine M. Darden, NASA Dryden, 

January 13, 1993, with “A Note on the Existence of Sonic 

Booms from Aircraft Flying at Speeds Less Than Mach 1,” Eagle 

Engineering (January 1993). This analysis shows that it is physically 

possible that Bell test pilot Chalmers (“Slick”) Goodlin may have 

created a localized sonic boom when making an 8-g pull-up from 

a Mach 0.82 dive during an XS-1 envelope-expansion flight many 

months earlier.

11. Domenic Maglieri to Lawrence Benson, e-mail message, September 

22, 2011.

12. For the authoritative history of the NACA-NASA mission at 

Edwards AFB, see Richard P. Hallion and Michael H. Gorn, On the 

Frontier: Experimental Flight at NASA Dryden (Washington, DC: 

Smithsonian Institution Press, 2003).

13. Kenneth J. Plotkin and Domenic J. Maglieri, “Sonic Boom Research: 

History and Future,” AIAA paper no. 2003-3575 (June 2003), 2. 

This publication is recommended for any reader who would like a 

succinct introduction to the subject. Maglieri and Percy J. Bobbitt 

also compiled a highly detailed, 372-page reference, “History of Sonic 

Boom Technology Including Minimization” (Hampton, VA: Eagle 

Aeronautics, November 1, 2001), a copy of which was kindly provided to the author in early 2009 for his reference.

14. Introduction to “The Battle of the Bangs,” Flight and Aircraft 

Engineer 61, no. 2289 (December 5, 1952): 696, accessed 
30

Quieting the Boom

ca. January 15, 2009, http://www.flightglobal.com/pdfarchive/

view/1952/1952%20-%203468.html.

15. G.B. Whitham, “The Flow Pattern of a Supersonic Projectile,” 

Communications on Pure and Applied Mathematics 5, no. 3 (1952): 

301–348, accessed ca. January 30, 2009, http://www3.interscience.

wiley.com/journal/113395160/issue. Whitham received his Ph.D. 

from the University of Manchester in 1953.

16. Figure 1-1 copied from Peter Coen and Roy Martin, “Fixing the 

Sound Barrier: Three Generations of U.S. Research into Sonic 

Boom Reduction ... and What it Means to the Future,” PowerPoint 

presentation presented at the Experimental Aircraft Association 

AirVenture Oshkosh, Oshkosh, WI, July 2004, slide no. 3, “Sonic 

Boom Basics.”

17. G.B. Whitham, “On the Propagation of Weak Shock Waves,” 

Journal of Fluid Dynamics 1, no. 3 (September 1956): 290–318, 

accessed ca. January 30, 2009, http://journals.cambridge.org/action/

displayJournal?jid=JFM. Both papers are described in Larry J. 

Runyan et al., “Sonic Boom Literature Survey. Volume 2. Capsule 

Summaries,” Boeing Commercial Airplane Co. for the FAA 

(September 1973), Defense Technical Information Center (DTIC) 

no. AD 771274, 6-8 and 59-60. Whitham later taught at both the 

Massachusetts and California Institutes of Technology.

18. Marshall E. Mullens, “A Flight Test Investigation of the Sonic 

Boom,” AFFTC Technical Note (TN) no. 56-20 (May 1956), as 

summarized in Runyan, “Sonic Boom Capsule Summaries,” 46–47.

19. Air Force Flight Test Center History Office, Ad Inexplorata: The 

Evolution of Flight Testing at Edwards Air Force Base (Edwards, CA: 

AFFTC, 1996), appendix B, 55. Photo provided courtesy of this 

office. Most aircraft names are assigned in later stages of development or production.

20. John G. Norris, “AF Says ‘Sonic Boom’ Can Peril Civilians,” 

Washington Post and Times Herald, November 9, 1954, 1, 12.

21. One of the first studies on focused booms was G.M. Lilley et al., 

“Some Aspects of Noise from Supersonic Aircraft,” Journal of the 

Royal Aeronautical Society 57 (June 1953): 396–414, as described in 

Runyan, “Sonic Boom Capsule Summaries,” 54. 

22. History of the 3201 Air Base Group, Eglin AFB, July–September 

1951, abstract from Information Retrieval and Indexing System 

(IRIS), no. 438908, Air Force Historical Research Center, Maxwell 

AFB, AL.
31

Making Shock Waves

23. F. Edward McLean, Supersonic Cruise Technology, Special Publication 

(SP)-472 (Washington, DC: NASA, 1985), 31–32; Richard P. 

Hallion, “Richard Whitcomb’s Triple Play,” Air Force Magazine 93, 

no. 2 (February 2010): 70–71. The following abbreviations are used 

for NASA publications cited in the notes: Conference Publication 

(CP), Contractor Report (CR), Reference Publication (RP), Special 

Publication (SP), Technical Memorandum (TM), formerly classified 

Tech Memo (TM-X), Technical Note (TN), Technical Paper (TP), 

and Technical Report (TR). Bibliographic information and, often, 

full-text copies can be accessed through the NASA Technical Reports 

Server (NTRS), http://ntrs.nasa.gov/search.jsp. The NTRS is a publicly accessible database maintained by NASA’s Center for AeroSpace 

Information (CASI).

24. Richard Seebass, “Sonic Boom Minimization,” paper presented 

at the North Atlantic Treaty Organization (NATO) Research and 

Technology Organization Applied Vehicle Technology course 

“Fluid Dynamics Research on Supersonic Aircraft,” Rhode SaintGenèse, Belgium, May 25–29, 1998; Robert T. Jones, “Adolf 

Busemann, 1901–1986,” in Memorial Tributes: National Academy 

of Engineering 3 (Washington, DC: The National Academies Press, 

1989), 62–67, accessed June 7, 2011, http://www.nap.edu/openbook.

php?record_id=1384.

25. F. Walkden, “The Shock Pattern of a Wing-Body Combination Far 

from the Flight Path,” Aeronautical Quarterly 9, pt. 2 (May 1958): 

164–94; described in Runyan, “Sonic Boom Capsule Summaries,” 

8–9. Both Walkden and Whitman did their influential studies at the 

University of Manchester.

26. Plotkin and Maglieri, “Sonic Boom Research,” 2.

27. Fred Keefe and Grover Amen, “Boom,” New Yorker, May 16, 1962, 

33–34.

28. Albion B. Hailey, “AF Expert Dodges Efforts to Detail ‘Sonic Boom’ 

Loss,” Washington Post, August 25, 1960, A15.

29. J.P. and E.G.R. Taylor, “A Brief Legal History of the Sonic Boom 

in America,” in Aircraft Engine Noise and Sonic Boom, Conference 

Proceedings (CP) no. 42, presented at the NATO Advisory Group 

for Aerospace Research and Development (AGARD), Neuilly sur 

Seine, France, 1969, 2-1–2-11.

30. Roger A. Mola, “This Is Only a Test,” Air & Space Magazine 21, no. 

2 (March–April 2006), accessed ca. March 1, 2011, http://www. 

airspacemag.com/history-of-flight/this-is-only-a-test.html. For contemporary accounts, see “Warplanes Fill Skies Over U.S. and Canada,” 
Quieting the Boom

32

Los Angeles Times, September 10, 1960, 4; Albion B. Halley and 

Warren Kornberg, “U.S. Tests Air Defenses in 3000-Plane 

‘Battle,’ ’’ Washington Post, October 15, 1961, A1, B1; Richard 

Witkin, “Civilian Planes Halted 12 Hours in Defense Test,” New 

York Times, October 15, 1961, 1, 46.

31. Marcelle S. Knaack, Post–World War II Bombers, 1945–1973

2 of Encyclopedia of U.S. Air Force Aircraft and Missile Systems

(Washington, DC: USAF, 1988), 394–395. 

32. “Jet Breaks 3 Records—and Many Windows,” Los Angeles Times, 

March 6, 1962, 1. In reality, most of the damage was done while 

accelerating after the refuelings. The Air Force pamphlet shown 

in figure 1-2 is in the Dryden Flight Research Center’s archival 

collection.

33. For the political and economic aspects of the SST, see Mel 

Horwitch, Clipped Wings: The American SST Conflict (Cambridge: 

Massachusetts Institute of Technology [MIT] Press, 1982) and Erik 

M. Conway’s definitive account High-Speed Dreams: NASA and the 

Technopolitics of Supersonic Transportation, 1945–1999 (Baltimore, 

MD: Johns Hopkins University Press, 2005), which also covers subsequent programs and includes many technical details. For an informative earlier study by an insider, see the previously cited McLean, 

Supersonic Cruise Technology.

34. M. Leroy Spearman, “The Evolution of the High-Speed Civil 

Transport,” NASA TM no. 109089 (February 1994), figure 1-3 

extracted from 26.

35. McLean, Supersonic Cruise Technology, 35–46; Joseph R, Chambers, 

Innovation in Flight: Research of the NASA Langley Research Center on 

Revolutionary Concepts for Aeronautics, SP-2005-4539 (Washington, 

DC: NASA, 2005), 25–28.

36. William J. Alford and Cornelius Driver, “Recent Supersonic 

Transport Research,” Astronautics & Aeronautics 2, no. 9 (September 

1964): 26.

37. Conway, High-Speed Dreams, 55.

38. Spearman, “Evolution of the HSCT,” 7.

39. FAA Historical Chronology, 1926–1996, accessed February 15, 2009, 

http://www.faa.gov/about/media/b-chron.pdf. For Quesada’s role, see 

Stuart I. Rochester, Takeoff at Mid-Century: Federal Civil Aviation 

Policy in the Eisenhower Years, 1953–1961 (Washington, DC: FAA, 

1976). For the activism of Halaby and the demise of the SST after 

his departure, see Richard J. Kent, Jr., Safe, Separated, and Soaring: A 
33

Making Shock Waves

History of Civil Aviation Policy, 1961–1972 (Washington, DC: FAA, 

1980). 

40. Based on author’s review of Section 7.4, “Noise, Aircraft,” in volumes of the Index of NACA Technical Publications (Washington DC: 

NACA Division of Research Information, n.d.) covering the years 

1915–1957.

41. For an overall summary of Langley’s supersonic activities, see 

Chambers, Innovations in Flight, chapter 1, “Supersonic Civil 

Aircraft: The Need for Speed,” 7–70; Domenic Maglieri by 

Lawrence Benson, telephone interview, February 6, 2009. 

42. A.B. Fryer et al., “Publications in Acoustics and Noise Control from 

the NASA Langley Research Center during 1940–1976,” NASA 

TM-X-74042 (July 1977).

43. For a chronological summary of selected projects during the first 

decade of sonic boom research, see Johnny M. Sands, “Sonic Boom 

Research (1958–1968),” FAA, DTIC no. AD 684806, November 

1968.

44. Domenic J. Maglieri, Harvey H. Hubbard, and Donald L. Lansing, 

“Ground Measurements of the Shock-Wave Noise from Airplanes in 

Level Flight at Mach Numbers to 1.4 and Altitudes to 45,000 Feet,” 

NASA TN D-48 (September 1959); Lindsay J. Lina and Domenic J. 

Maglieri, “Ground Measurements of Airplane Shock-Wave Noise at 

Mach Numbers to 2.0 and at Altitudes to 60,000 Feet,” NASA TN 

D-235 (March 1960).

45. Domenic J. Maglieri, Vera Huckel, and Tony L. Parrott, “Ground 

Measurements of Shock-Wave Pressure for Fighter Airplanes Flying 

at Very Low Altitudes and Comments on Associated Response 

Phenomena,” NASA TN D-3443 (July 1966) (which superseded 

classified TM-X-611 [1961]).

46. Gareth H. Jordan, “Flight Measurements of Sonic Booms and 

Effects of Shock Waves on Aircraft,” in Society of Experimental Test 

Pilots Quarterly Review 5, no. 1 (1961): 117–131, presented at the 

Society of Experimental Test Pilots (SETP) Supersonic Symposium, 

September 29, 1961.

47. C.W. Nixon et al., “Sonic Booms Resulting from Extremely LowAltitude Supersonic Flight: Measurements and Observations on 

Houses, Livestock, and People,” Aerospace Medical Research 

Laboratories (AMRL) Technical Report (TR) 68-52 (October 

1968), DTIC AD 680800; USAF Fact Sheet, “Sonic Boom,” 

February 23, 2011, http://www.af.mil/information/factsheets/factsheet.
34

Quieting the Boom

asp?id=184; Domenic Maglieri by Lawrence Benson, telephone 

interview, March 19, 2009.

48. Domenic J. Maglieri and Harvey H. Hubbard, “Ground 

Measurements of the Shock-Wave Noise from Supersonic Bomber 

Airplanes in the Altitude Range from 30,000 to 50,000 Feet,” 

NASA TN D-880 (July 1961). 

49. Jordan, “Flight Measurements of Sonic Booms.”

50. Domenic J. Maglieri and Donald L. Lansing, “Sonic Booms from 

Aircraft in Maneuvers,” NASA TN D-2370 (July 1964) (based on 

the tests in 1961); Domenic Maglieri, Sonic Boom Research: Some 

Effects of Airplane Operations and the Atmosphere on Sonic Boom 

Signature, NASA SP-147 (1967), 25–48. D.J. Maglieri, J.O. Powers, 

and J.M. Sands, “Survey of United States Sonic Boom Overflight 

Experimentation,” NASA TM-X-66339 (May 30, 1969), 15–17.

51. Harvey H. Hubbard et al., “Ground Measurements of Sonic-Boom 

Pressures for the Altitude Range of 10,000 to 75,000 Feet,” NASA 

TR R-198 (July 1964) (this report was based on testing in 1961). 

52. Harriet J. Smith, “Experimental and Calculated Flow Fields 

Produced by Airplanes Flying at Supersonic Speeds,” NASA TN 

D-621 (November 1960); D.J. Maglieri and V.S. Richie, “In-Flight 

Shock-Wave Measurements Above and Below a Bomber Airplane at 

Mach Numbers from 1.42 to 1.69,” NASA TN D-1968 (October 

1963). Figure 1-4 extracted with permission from Domenic Maglieri 

and Percy Bobbitt from “History of Sonic Boom Technology 

Including Minimization,” Eagle Aeronautics (November 1, 2001), 

145.

53. NASA Flight Research Center, “X-15 Program” (monthly report), 

September 1961, Dryden archive, file LI-6-10A-13. (Peter Merlin 

assisted the author in finding this and other archival documents.); 

Karen S. Green and Terrill W. Putnam, “Measurements of Sonic 

Booms Generated by an Airplane Flying at Mach 3.5 and 4.8,” 

NASA TM-X-3126 (October 1974). (Since hypersonic speeds were 

not directly relevant for the SST, a formal report was delayed until 

NASA began planning re-entry flights by the Space Shuttle.) For the 

X-15 program, see Hallion and Gorn, On the Frontier, 101–125. For 

a discussion of its shock wave propagation, see Wendell H. Stillwell, 

X-15 Research Results, SP-60 (Washington, DC: NASA, 1965), 

46–66.

54. Charles W. Nixon and Harvey H. Hubbard, “Results of the USAFNASA-FAA Flight Program to Study Community Response to Sonic 

Booms in the Greater St. Louis Area,” NASA TN no. D-2705 (May 
35

Making Shock Waves

1965); Clark et al., “Studies of Sonic Boom Damage,” NASA CR 

227 (May 1965).

55. Sands, “Sonic Boom Research (1958–1968),” 3.

56. Domenic J. Maglieri and Garland J. Morris, “Measurement of 

Response of Two Light Airplanes to Sonic Booms,” NASA TN 

D-1941 (August 1963).

57. Paul M. Borsky, “Community Reactions to Sonic Booms in the 

Oklahoma City Area—Volume II: Data on Community Reactions 

and Interpretations,” USAF Aerospace Medical Research Laboratory, 

Wright-Patterson AFB (August 1965), accessed ca. February 15, 

2009, http://www3.norc.org/NR/rdonlyres/255A2AA2-B953-4305-

9AD0-B8ABCC824FA9/0/NORCRpt_101B.pdf.

58. D.A. Hilton, D.J. Maglieri, and R. Steiner, “Sonic-Boom Exposures 

during FAA Community Response Studies over a 6-Month Period in 

the Oklahoma City Area,” NASA TN D-2539 (December 1964).

59. Source for figure 1-5: Ibid., 68.

60. D.J. Maglieri (NASA), D.J. Powers, and J.M. Sands (FAA), “Survey 

of United States Sonic Boom Overflight Experimentation,” NASA 

TM-X-66339 (May 30, 1969), 37–39; Conway, High-Speed Dreams, 

121–122.

61. Thomas H. Higgins, “Sonic Boom Research and Design 

Considerations in the Development of a Commercial Supersonic 

Transport,” JASA 39, no. 5, pt. 2 (November 1966): 526–531.

62. David. A. Hilton, Vera Huckel, and Domenic J. Maglieri, “Sonic 

Boom Measurements During Bomber Training Operations in the 

Chicago Area,” NASA TN D-3655 (October 1966), figure 1-6 on 

N-wave signatures copied from 7.

63. Histories of the 4700 Air Defense Wing, January–March and 

April–June 1960, IRIS abstracts; History of the 84th Fighter Group, 

January–December 1961, IRIS abstract; Benson, Maglieri interview, 

March 19, 2009.

64. For a definitive history of this remarkable aircraft, see Dennis R. 

Jenkins and Tony R. Landis, Valkyrie: North America’s Mach 3 

Superbomber (North Branch, MN: Specialty Press, 2004). 

65. William H. Andrews, “Summary of Preliminary Data Derived from 

the XB-70 Airplanes,” NASA TM-X-1240 (June 1966), 11–12. 

Despite being more than three times heavier than the B-58, the 

XB-70’s bow wave proved to be only slightly stronger, reflecting its 

more tailored aerodynamic design and the benefits of its large size.

66. Domenic J. Maglieri et al., “A Summary of XB-70 Sonic Boom 

Signature Data, Final Report,” NASA CR 189630 (April 1992). 
36

Quieting the Boom

Until this report, the 1965–1966 findings were filed away unpublished. The original oscillographs were also scanned and digitized at 

this time for use in the High-Speed Research (HSR) program.

67. FRC, “NASA XB-70 Flight Research Program,” April 1966, 

Dryden archive, File L2-4-4D-3, 10 quoted. See also C.M. Plattner, 

“XB-70A Flight Research: Phase 2 to Emphasize Operational Data,” 

Aviation Week (June 13, 1966): 60–62.

68. NASA Dryden Fact Sheet, “XB-70,” accessed May 10, 2011, http://

www.nasa.gov/centers/dryden/news/FactSheets/FS-084-DFRC.html; 

Hallion and Gorn, On the Frontier, 176–85, 421.

69. Maglieri, “Summary of XB-70 Sonic Boom,” 4–5. Photo of BREN 

Tower courtesy of Mr. Maglieri.

70. R.T. Klinger, “YF-12A Flight Test Sonic Boom Measurements,” 

Lockheed Advanced Development Projects Report SP-815 (June 1, 

1965), Dryden archive, File LI-4-10A-1.

71. John O. Powers, Johnny M. Sands, and Domenic J. Maglieri, 

“Survey of United States Sonic Boom Overflight Experimentation,” 

NASA TM-X-66339 (May 1969), 9, 12–13.

72. Peter W. Merlin, From Archangel to Senior Crown: Design and 

Development of the Blackbird (Reston, VA: AIAA, 2008), 106–107, 

116–118, 179; Hallion and Gorn, On the Frontier, 187.

73. NSBEO, “Sonic Boom Experiments at Edwards Air Force Base; 

Interim Report” (July 28, 1967), 1–2 (hereinafter cited as the 

Stanford Research Institute [SRI], “Edwards AFB Report” as it 

was prepared under contract by the SRI). For background on the 

NSBEO, see Conway, High-Speed Dreams, 122–123. 

74. SRI, “Edwards AFB Report,” 9.

75. D.A. Hilton, D.J. Maglieri, and N.J. McLeod, “Summary of 

Variations of Sonic Boom Signatures Resulting from Atmospheric 

Effects,” NASA TM-X-59633 (February 1967), and D.J. Maglieri, 

“Preliminary Results of XB-70 Sonic Boom Field Tests During 

National Sonic Boom Evaluation Program,” March 1967, annexes 

C-1 and C-2, in SRI, “Edwards AFB Report;” H.H. Hubbard 

and D.J. Maglieri, “Sonic Boom Signature Data from Cruciform 

Microphone Array Experiments during the 1966–67 EAFB National 

Sonic Boom Evaluation Program,” NASA TN D-6823 (May 1972).

76. Maglieri and Bobbitt, “History of Sonic Boom Technology,” 60–63. 

77. SRI, “Edwards AFB Report,” 17–20, annexes C–F; Domenic J. 

Maglieri et al., “Sonic Boom Measurements for SR-71 Aircraft 

Operating at Mach Numbers to 3.0 and Altitudes to 24834 Meters,” 

NASA TN D-6823 (September 1972).
37

Making Shock Waves

78. SRI, “Edwards AFB Report,” 11–16, annex B; K.D. Kryter, 

“Psychological Experiments on Sonic Booms Conducted at Edwards 

Air Force Base, Final Report,” SRI (1968), summarized by Richard 

M. Roberds, “Sonic Boom and the Supersonic Transport,” Air 

University Review 22, no. 7 (July–August 1971): 25–33.

79. SRI, “Edwards AFB Report,” 20–23, annexes G and H; David 

Hoffman, “Sonic Boom Tests Fail to Win Any Boosters,” Washington 

Post, August 3, 1967, A3; A.J. Bloom, G. Kost, J. Prouix, and R.L. 

Sharpe, “Response of Structures to Sonic Booms Produced by XB-70, 

B-58, and F-104 Aircraft: Based on Sonic Boom Experiments at 

Edwards Air Force Base, Final Report,” NSBEO 2-67, (October 1967); 

D.S. Findley et al., “Vibration Responses of Test Structure No. 1 

During the Edwards Air Force Base Phase of the National Sonic Boom 

Program,” NASA TM-X-72706 (June 1975), and “Vibration Responses 

of Test Structure No. 2 During the Edwards Air Force Base Phase of the 

National Sonic Boom Program,” NASA TM-X-72704 (June 1975).

80. Source for figure 1-4: D.J. Maglieri (NASA), J.O. Powers, and J.M. 

Sands (FAA), “Survey of United States Sonic Boom Overflight 

Experimentation,” NASA TM-X-66339 (May 30, 1969), 4. 

81. TRACOR, Inc., “Public Reactions to Sonic Booms,” NASA CR 

1665 (September 1970).

82. David A. Hilton and Herbert R. Henderson documented the sonic 

boom measurements from the Apollo 15, 16, and 17 missions in 

NASA TNs D-6950 (1972), D-7606 (1974), and D-7806 (1974).

83. Maglieri and Bobbitt, “History of Sonic Boom Technology,” 69–72. 

84. For the governing equations for the wave field near a caustic, see 

J.P. Guiraud, “Acoustique Géométrique Bruit Ballistique des Avions 

Supersoniques et Focalisation,” Journal Mécanique, 4 (1965): 

215–267, cited by Plotkin and Maglieri, “Sonic Boom Research,” 5.

85. George T. Haglund and Edward J. Kane, “Flight Test Measurements 

and Analysis of Sonic Boom Phenomena Near the Shock Wave 

Extremity,” NASA CR 2167 (February 1973); Benson, Maglieri, 

interview, March 19, 2009.

86. Domenic Maglieri et al.,” Measurement of Sonic Boom Signatures 

from Flights at Cutoff Mach Number,” in Third Conference on Sonic 

Boom Research, October 29–30, 1970, ed. Ira R. Schwartz, SP-255 

(Washington, DC: NASA, 1971), 243–254. Figure 1-7 extracted 

from 252.

87. Harry W. Carlson, “Some Notes on the Present Status of Sonic 

Boom Prediction and Minimization Research,” in Schwartz, Third 

Conference on Sonic Boom Research, 395.
38

Langley’s Unitary Plan Wind Tunnel, shown here upon completion in 1955, had two 4-by-4-by7-foot test sections and could generate speeds up to Mach 4.63. (NASA)
39

CHAPTER 2

The SST’s Sonic Boom Legacy

The rapid progress made in understanding the nature and significance of sonic 

booms during the 1960s stemmed from the synergy among flight testing, 

wind tunnel experiments, psychoacoustical studies, theoretical refinements, 

and powerful new computing capabilities. Vital to this process was the largely 

free exchange of information by NASA, the FAA, the USAF, the airplane 

manufacturers, academia, and professional organizations such as the American 

Institute of Aeronautics and Astronautics (AIAA) and the Acoustical Society 

of America (ASA). The sharing of much of this information even extended to 

counterparts in Europe, where the rival Anglo-French Concorde supersonic 

airliner got off to a head start on the more ambitious American program.

Designing commercial aircraft has long required a variety of tradeoffs 

involving cruising, landing, and takeoff speeds; range; passenger or cargo 

capacity; weight, with and without payload; durability; comfort; safety; and, 

of course, costs—both for manufacturing and operations. Balancing such factors was especially challenging with an aircraft as revolutionary as the SST, 

which was expected to cruise at about Mach 3 while still being able to take off 

and land at existing airports. Unlike with previous supersonic military aircraft, 

NASA’s scientists and engineers and their partners in industry increasingly 

had to also consider the environmental impacts of their designs, including 

engine noise around airports, the effects of high-altitude exhaust on the upper 

atmosphere—especially the little understood ozone layer—and, of course, the 

inevitable sonic boom.1

As the program progressed, the FAA set a desired goal for the SST’s sonic 

boom level of 2.0 psf when accelerating and 1.5 psf during cruise in hopes that 

this would be acceptable to the average person exposed to the booms on the 

ground. At NASA’s aeronautical centers, especially Langley, aerodynamicists 

tried to incorporate the growing knowledge about the physics of sonic booms 

into their equations, models, and wind tunnel experiments to meet or exceed 

this goal—even as the research described in the previous chapter revealed more 

about the psychoacoustics of human response.
40

Quieting the Boom

Wind Tunnel Experimentation

The National Advisory Committee for Aeronautics, in making many if not 

most of its contributions to aviation technology, had relied heavily on ever 

more powerful and inventive wind tunnels. By nurturing the development and 

improvement of both military and civilian aircraft, the NACA’s wind tunnels 

became true national treasures. “They were logical and flexible instruments, 

useful for theoretical explorations as well as highly applied studies. More crucially, tunnels allowed researchers to shift back and forth from mathematical 

models to flight [data], thus increasing the reliability of models while also 

serving to predict aircraft performance.”2 These wind tunnels remained just as 

essential during the early years of NASA, especially in helping design supersonic and hypersonic vehicles.

The aerodynamic and structural characteristics traditionally examined in a 

wind tunnel—including lift, drag, stability, control, angle of attack (AOA)—

were determined largely by measuring forces applied to the model itself, measuring air pressure with special sensors, and using schlieren photography and 

other techniques to show shock waves or airflow close to its surface. Air is 

considered a fluid when moving past objects (hence the inseparable relationship 

between aerodynamics and fluid dynamics). The effects of air flowing over the 

surfaces of a wind tunnel model, whether laminar (smooth) or turbulent, can 

be correlated directly with those of full-scale airframes by a scaling parameter 

known as the Reynolds number.3

Using models in supersonic wind tunnels to examine sonic booms posed 

new and difficult challenges. Ever since Whitham’s analyses, sonic boom 

researchers have known the area within a few body lengths of an airframe—

where it generates multiple shock waves at transonic and supersonic speeds—as 

the near field. Wind tunnel models could provide fairly accurate results at this 

distance but not too far beyond. To examine how these shock waves propagate 

and begin to coalesce, researchers needed to measure them many more body 

lengths away in the midfield. And to determine the final outcome—specifically, 

how they evolve into the typical N-shaped signature of a sonic boom—results 

were needed at an even greater distance, known as the far field. As time went 

on, researchers developed clever innovations and techniques to work around 

these inherent limitations as best as they could.

In 1959, Harry W. Carlson of Langley conducted what may have been 

the first wind tunnel experiment on sonic boom generation. As reported that 

December, he had tested seven models of various geometrical and airplane-like 

shapes at differing angles of attack in Langley’s original 4-by-4-foot supersonic 

wind tunnel (not the one in the photo) at a speed of Mach 2.01. The tunnel’s 

relatively limited interior space mandated building extremely small models to 
41

The SST’s Sonic Boom Legacy

obtain useful shock wave signatures: about 2 inches in length for measuring 

them at 8-body-lengths distance and only three-quarters of an inch for trying 

to measure them at 32 body lengths (as close as possible to the far field). 

Compatible with Whitham’s theory, many of Carlson’s models consisted of 

the better understood and easier to measure “equivalent bodies of revolution.” 

(This was the accepted technique for translating the complex shape of airframes 

with their wings and other surfaces using the area rule into standard aerodynamic principles governing simpler projectiles with rounder cross sections). 

Carlson determined these models to be suitable substitutes for more realistic, 

nonaxisymmetrical airplane-shaped models in obtaining theoretical estimates 

of far-field bow shock pressures. Although his more realistic, airplane-shaped 

model could not reach far-field conditions, the overall results correlated with 

existing theory, such as Whitham’s formulas on volume-induced overpressures 

and Walkden’s on those caused by lift.4

 Carlson’s attempt to design one of the 

models to alleviate the strength of the bow shock was unsuccessful, but this 

can be considered NASA’s first experimental attempt at boom minimization.

In April 1959, before the results of either Carlson’s wind tunnel or those of 

the first flight tests at Wallops Island were published, he and Domenic Maglieri 

advised about sonic boom implications early in the Supersonic Commercial Air 

Transport program. Based on existing theory, some USAF and British reports, 

and preliminary findings in their own experiments, they concluded “that for 

the proposed supersonic transport airplanes of the future, booms on the ground 

will most probably be experienced during the major portion of the flight plan. 

The boom pressures will be most severe during the climb and descent phases of 

the flight plan.”5

 Although they warned that sonic booms during cruise would 

extend laterally for many miles, it was hoped that special operating procedures 

and high altitudes could help alleviate both problems to some extent.

The extreme precision demanded in making the tiny models needed for 

early sonic boom experiments, the disruptive effects of the sting assemblies 

needed to mount them (which inevitably distorted tail shocks), the vibration by the models, the extra sensitivity required of pressure-sensing devices, 

and the interactions with a tunnel’s walls all limited a wind tunnel’s ability to 

measure the type of shock waves that would reach the ground from a full-sized 

aircraft, especially one as large as the planned SST. Even so, substantial progress 

continued, and the data served as useful cross-checks on flight-test data and 

mathematical formulas.6

 For example, in 1962 Harry Carlson used a 1-inch 

model of a B-58 to make the first direct correlation of recent flight-test data 

(described in the previous chapter) with wind tunnel results and sonic boom 

theory. His findings proved that wind tunnel readings, with appropriate analysis, could be used with some confidence to estimate sonic boom signatures.7

Several months later, he concluded that locating the major portion of an SST’s 
42

Quieting the Boom

Examining a 1-inch model of the XB-70 in 

1961. (NASA) 

lift-generating surface aft of the maximum cross-sectional area could lower 

sonic boom overpressure, a principle 

thereafter considered in the design of 

most planned SST configurations.8

Exactly 5 years after publishing 

results of his first wind tunnel sonic 

boom experiment, Harry Carlson 

was able to report, “In recent years, 

intensive research efforts treating all 

phases of the problem have served to 

provide a basic understanding of this 

phenomenon. The theoretical studies [of Whitham and Walkden] have 

resulted in correlations with the wind 

tunnel data...and with the flight data.”9

As for the prospect of minimizing the 

strength of sonic booms, wind tunnel 

tests of SCAT models had revealed that 

some configurations (e.g., the arrow wing) produced lower overpressures.10 The 

challenge was to find configurations that would reduce sonic booms without 

significantly sacrificing other needed attributes.

In 1967, Ames researchers Raymond Hicks and Joel Mendoza greatly 

improved the ability of wind tunnels to predict sonic boom characteristics. 

Experimenting with a 12-inch model of the XB-70 in the Ames 7-by-9-foot 

supersonic wind tunnel at Mach 1.8, they applied Whitham’s near-field 

F-function theory to compare pressure readings at one body length in the 

wind tunnel with actual flight-test data from 4.5 body lengths and 290 body 

lengths from a real XB-70. This resulted in a new, more reliable method for 

extrapolating near-field F-function measurements to the far field, allowing 

the use of much larger and therefore more accurate models for that purpose.11

Mobilizing Brainpower To Minimize the Boom

Motivated by the SST and Concorde programs, scientists and engineers rapidly 

expanded the knowledge and understanding of sonic boom theory during the 

1960s. Much of their efforts focused on ways to predict the sonic booms that 

would be produced by various aircraft configurations and how to modify them 

to lower the impact of the shock waves that reached the surface—a goal that 

became known as minimization or mitigation.
43

The SST’s Sonic Boom Legacy

At the very start of the decade, when the British Aircraft Corporation (BAC) 

was exploring options for a supersonic airliner, L.B. Jones, an aerodynamicist at 

English Electric Aviation (a BAC subsidiary), added to the fundamental understanding of sonic booms (or bangs) pioneered by Whitham and Walkden.12

Noting with some understatement that “the sonic bangs caused by supersonic 

aircraft can be a nuisance [with] a level of noise...on the borderline of acceptable value,” Jones introduced his theory by observing that “it seems important 

to examine ways of reducing them at the aircraft design stage.” He presented 

equations for ways of lowering shock waves in the far field caused by lift, 

volume, and lift plus volume.13 Although these hypothetical designs were too 

blunt to be practical, his work marked the first significant theory on how 

supersonic aircraft might be designed to reduce boom intensity. Such possibilities were soon being explored by NASA aerodynamicists and a growing 

number of NASA partners in the American aerospace industry and university 

engineering departments.

In addition to publishing results of their tests and experiments in technical 

reports and academic journals, researchers began presenting their findings at 

special conferences and professional symposia dealing with supersonic flight. 

One of the earliest such gatherings took place from September 17 to September 

19, 1963, when NASA Headquarters sponsored an SST feasibility studies 

review at the Langley Research Center—attended by Government, contractor, and airline personnel—that examined every aspect of the planned SST. 

In a session on noise, Harry Carlson warned that “sonic boom considerations 

alone may dictate allowable minimum altitudes along most of the flight path 

and have indicated that in many cases the airframe sizing and engine selection depend directly on sonic boom.”14 On top of that, Harvey Hubbard and 

Domenic Maglieri discussed how atmospheric effects and community response 

to building vibrations might pose problems with the current SST sonic boom 

objectives (2 psf during its acceleration and 1.5 psf while cruising).15

The conferees discussed various other technological challenges for the 

planned American SST, some indirectly related to the sonic boom issue. For 

example, because of frictional heating, an airframe covered largely with stainless steel (such as the XB-70) or with titanium (such as the still-top-secret 

A-12/YF-12) would cruise at Mach 2.7+ and over 60,000 feet, an altitude 

which many still hoped would allow the sonic boom to weaken by the time 

it reached the surface. Manufacturing such a plane, however, would be much 

more expensive than manufacturing a Mach 2.2 SST with aluminum skin, 

such as the design being planned for the British-French Concorde, which the 

United Kingdom and France had formally approved for joint development on 

November 29, 1962. (Interestingly, this agreement had no provision for either 

side to back out.)16
44

Quieting the Boom

Despite serious and potentially incurable problems raised at the NASA conference concerning cost and feasibility, the FAA, spurred on by the Concorde 

agreement, had already released the SST Request for Proposals (RFP) on 

August 15, 1963. Thereafter, as explained by Langley’s long-time supersonic 

expert, F. Edward McLean, “NASA’s role changed from one of having its own 

concepts evaluated by the airplane industry to one of evaluating the SST concepts of the airplane industry.”17 By January 1964, Boeing, Lockheed, North 

American, and their jet-engine partners had submitted initial proposals, with 

Boeing drawing upon NASA’s swing-wing SCAT-16 concept and Lockheed’s 

proposal resembling the SCAT-17 with its canard and delta-wing configuration. North American’s design, which relied heavily on its XB-70 but did not 

benefit from NASA’s concepts, was soon eliminated from the competition.18

In retrospect, the manufacturers and Government advocates of the SST were 

obviously hoping that technology would catch up with requirements before 

it went into production. The SST program schedule was too compressed, 

however, for many of the emerging concepts on controlling sonic booms to 

be incorporated or retrofitted into the contractors’ designs.

With the SST program now well under way, a growing awareness of the 

public response to booms became one factor among those that tri-agency 

(FAA-NASA-DOD) groups in the mid-1960s, including the PAC chaired by 

Robert McNamara, considered in evaluating the proposed SST designs. The 

sonic boom issue also became the focus of a rather skeptical committee of the 

National Academy of Sciences between 1964 and 1965 and attracted growing 

attention from the academic and scientific community at large, much of it 

increasingly negative.19

By 1965, NASA specialists at Langley had been studying possible ways 

to address the sonic boom problem for the past 5 years. In June, Ed McLean 

pointed out that, contrary to current asymptotic far-field theory, the near-field 

shock waves from a transonically accelerating SST do not necessarily have to 

evolve into the final form of an N-wave. This opened the prospect for a properly 

designed, large supersonic aircraft flying at the right altitude to avoid projecting 

a full sonic boom to the surface.20

Of major significance at the time and even more potentially for the 

future, improved data-reduction methods and numerical evaluations of sonic 

boom theory were being adapted for processing with new codes in the latest 

International Business Machines (IBM) computers. Langley used this capability for the first application of high-speed computers on the aerodynamic design 

of supersonic aircraft—which was considered a “quantum leap in engineering 

analysis capability.”21 Meanwhile, Boeing developed one of the most widely 

known of the early sonic boom computer programs to help in designing its 

SST candidate.22 Automated data processing allowed faster and more precise 
45

The SST’s Sonic Boom Legacy

Wind tunnel test of SCAT-15F model. (NASA)

correlations between wind tunnel and flight-test data, leading to continued 

refinements in sonic boom theory (although still mainly applicable to bow 

shocks during steady and level flight in a standard atmosphere).23 Applying 

these new capabilities, Carlson, McLean, A. Warner Robins, and their colleagues at Langley designed the SCAT-15F, an improved SST concept with a 

highly swept “arrow wing” optimized for highly efficient cruise (and, to some 

extent, a lower sonic boom).24 Solving resultant problems with stability and 

control at low speeds was more difficult and came too late for Boeing to adapt 

this design for its SST in the late 1960s, but the lessons learned from the SCAT15F would be of value in future supersonic transport studies.25

The Acoustical Society of America, made up of professionals from all fields 

involving sound (ranging from music to audiology, and from noise to vibration), sponsored its first Sonic Boom Symposium on November 3, 1965, as part 

of its 70th meeting in—appropriately enough—St. Louis. McLean, Hubbard, 

Carlson, Maglieri, and other Langley experts presented papers on the background and techniques of sonic boom research as well as their latest findings.26

The paper by McLean and Barrett L. Shrout included details on the potential 

breakthrough in using near-field shock waves to evaluate wind tunnel models 

for boom minimization—in this case, a reduction in maximum overpressure 
46

Quieting the Boom

in a climb profile from 2.2 psf to 1.1 psf. This technique also allowed for the 

use of 4-inch models, which were easier to fabricate to the close tolerances 

required for accurate shock wave measurements.27 Harry Carlson described 

how the Langley Research Center’s latest high-speed computer programs for 

analyzing the lift and drag of aerodynamic configurations were being used by 

both NASA and the manufacturers to calculate F-function results and theoretical pressure signatures at various distances.28

In addition to the scientists and engineers employed by the aircraft manufactures, many eminent researchers in academia took on the challenge of 

discovering ways to minimize the sonic boom, usually with NASA’s sponsorship and support. These included the influential team of Albert R. George 

and A. Richard Seebass of Cornell University, which had one of the Nation’s 

premier aeronautical laboratories. Seebass, already prominent in the field of 

aerospace engineering at 29 years old, edited the proceedings of NASA’s first 

sonic boom research conference, held on April 12, 1967. The meeting was 

chaired by Wallace D. Hayes of Princeton University, who was now devoting much of his attention to sonic boom mitigation. Hayes was well known 

for his groundbreaking work in supersonic and hypersonic aerodynamics, 

which began with his 1947 dissertation, “Linearized Supersonic Flow,” written while at the California Institute of Technology (which, in mathematical 

terms, foreshadowed Whitcomb’s area rule).29 The conference was attended 

by more than 60 other Government, industry, and university experts in 

aeronautics and related fields. In reviewing the area rule as it applied to 

supersonic flight, Hayes cautioned “that the total equivalent source strength 

connected with the sonic boom cannot ever be zero. Thus the sonic boom 

below the aircraft is truly inescapable. The best we can hope for is that the 

boom is a minimum for given values of this parameter, with limits on the 

magnitude of the drag.”30

Boeing had been selected over Lockheed as the SST prime contractor less 

than 4 months earlier, but public acceptance of even a somewhat reduced 

sonic boom was becoming recognized far and wide as a possibly fatal flaw 

for its future production or at least for allowing it to fly supersonically over 

land.31 The two most obvious theoretical ways to minimize sonic booms during 

supersonic cruise—flying much higher with no increase in weight or building 

an airframe 50-percent longer at half the weight—were not considered realistic.32 Furthermore, as was made apparent from a presentation by Domenic 

Maglieri on flight-test findings, such an airplane would still have to deal with 

the problem of the as-yet somewhat unpredictable, stronger booms caused by 

maneuvering, accelerating, and atmospheric conditions.33

The stated purpose of this conference was “to determine whether or not all 

possible aerodynamic means of reducing sonic boom overpressure were being 
47

The SST’s Sonic Boom Legacy

explored.”34 In that regard, Harry 

Carlson showed how the various computer programs being used at Langley 

(mentioned above) were complementing improved wind tunnel experiments 

for examining boom minimization 

concepts. As shown by figure 2-1, even 

minor changes in an aircraft’s configuration could result in a significant alteration of its shock waves. In this case, 

a wind tunnel comparison of 4-inch 

models at Mach 1.4 confirmed that the shape on the right rendered a quieter 

flattop signature for shock waves, albeit at a distance of only five body lengths.35

Boeing’s sonic boom expert, Edward J. Kane, presented recent research on 

dealing with the tricky problems of atmospheric effects, while Albert George 

from Cornell explored the potential for reducing sonic boom overpressures 

reaching the surface by designing airframes that could disperse some portion 

of shock waves caused by volume off to the sides of the flightpath.36

Notable aeronautics pioneer Adolf Busemann (see chapter 1), now at the 

University of Colorado, expressed both frustration with the current situation 

and guarded hope for a solution. His outlook probably reflected the feelings 

of many other SST proponents in both Government and industry.

Since people are not satisfied with the sonic boom reduction which 

the reasonable altitude for supersonic flights provides naturally, 

further means for reductions must either be found or proved to be 

impossible. However, to call something impossible is dangerous. 

Our time is full of innovations in physics and technology, and 

although we have certain laws of conservation which we accept as 

being invariably valid, many scientists who declared that desirable 

effects were impossible have been proved wrong.37

After all the papers were read and discussed, many of the attendees agreed 

that additional avenues of research were promising enough to be explored, but 

they were still concerned whether low-enough sonic booms were possible using 

existing technologies. Accordingly, NASA’s Office of Advanced Research and 

Technology, which hosted the conference, established specialized research programs on seven aspects of sonic boom theory and mitigation at five American universities—Columbia, Colorado, Cornell, Princeton, and New York University 

(NYU)—and the Aeronautical Research Institute of Sweden.38 This mobilization 

of aeronautical brainpower almost immediately began to pay dividends.

Figure 2-1. Wind tunnel verification of a flattop signature. (NASA)
48

Quieting the Boom

Seebass and Hayes cochaired NASA’s second sonic boom conference from 

May 9 to May 10, 1968. This came just a few weeks after Boeing replaced its 

variable-sweep 2707-200 SST design, which was found to be too heavy, with 

the 2707-300 (figure 2-2), a delta-wing configuration similar to the losing 

Lockheed proposal. The conference included 19 papers on the latest boomrelated testing, research, experimentation, and theory by specialists from NASA 

and participating universities. The advances made in 1 year were impressive. In 

the area of theory, for example, the fairly straightforward linear techniques for 

predicting the propagation of sonic booms from slender airplanes such as the 

SST had proven reliable, even for calculating some nonlinear (mathematically 

more complex and unpredictable) aspects of their signatures. Additional field 

testing had improved understanding of the geometrical acoustics caused by 

atmospheric conditions. Many of the papers—including those from Seebass, 

George, Hayes, McLean, and Carlson—presented promising aerodynamic 

techniques for reducing the strength of sonic booms.39

One of the most celebrated aerodynamicists recruited by NASA to work 

on the sonic boom problem was Antonio Ferri of New York University. An 

Italian air force officer and pioneer of supersonic research in prewar Italy, he had 

joined the anti-Nazi resistance movement after the collapse of the Mussolini 

regime and became a partisan leader before escaping in 1944 to the United 

States. There, he continued advancing high-speed research for the NACA at 

Langley for several years before entering the academic world. At the conference, he reported several innovative ideas on how to design a 300-foot SST 

airframe with reduced sonic booms by spreading lift along almost its entire 

length by means of suitable volume adjustments. Following these principles, 

he predicted, could yield maximum overpressures of about 1 psf while cruising 

at 60,000 feet (as compared to the 2 psf expected with existing SST designs) 

without seriously hurting their lift-to-drag ratio.40

In retrospect, two of the papers that would prove most significant to 

future progress dealt with new computer processing capabilities. Representing 

Aeronautical Research Associates of Princeton (ARAP), Wallace Hayes reported 

on what became known as the ARAP Program. Using the then-ubiquitous 

FORTRAN computer language, it consisted of a master program called 

SONIC with 19 subroutines. NASA had sponsored this project to clarify the 

confusion that existed among the various complex numerical techniques being 

used for calculating the propagation of sonic boom signatures and comparisons with flight-test measurements. Based on linear geometric acoustics, the 

ARAP Program used F-function effects from a supersonic airframe at various 

Mach numbers and lift coefficients combined with acoustic-ray tracing and 

an age variable to define (if not yet solve) the nonlinear effects that help shape 

sonic boom signatures. It was the first computer program with an algorithm 
49

The SST’s Sonic Boom Legacy

comprehensive enough to accurately calculate a full range of overpressure 

signatures in a standard, horizontally stratified atmosphere with winds—a 

major advance.41 Using this, Hayes extended McLean’s 1965 hypothesis on 

the persistence of near-field pressure signatures by showing that effects in the 

real atmosphere would tend to “freeze” the signature from supersonic aircraft 

at cruise altitudes before it reached the surface.42

Harvard Lomax of Ames offered a sneak preview of a more distant digital 

future that would eventually be possible through the marriage of computational fluid dynamics (CFD), which was being pioneered at Ames, with computer graphics. He reported preliminary results on using a cathode-ray tube 

monitor directly connected to the core processor of a mainframe computer 

to show in real time the results of three-dimensional, nonlinear flow-field 

analyses of a dozen diverse aircraft configurations in a search for lower boom 

signatures. After describing the mathematical principles involved, Lomax presciently predicted that “the ability to compute flow fields for airplanes traveling at supersonic speeds with the aid of an immediate visual display of the 

calculations as they proceed opens the possibility of devising new, or revising 

parts of old, numerical techniques.”43 As will be shown in later chapters, the 

full realization of this capability with the development of super computers 

and massively parallel processors would eventually prove to be the key to the 

successful design of low-boom airplane configurations.

Despite these signs of considerable progress made by 1968, several important theoretical problems remained unresolved, such as the prediction of sonic 

boom signatures near a caustic (a major objective of the 1970 Jackass Flats 

testing described in the previous chapter), the diffraction of shock waves into 

“shadow zones” (areas normally skipped over between primary and secondary 

sonic boom carpets), nonlinear shock wave behavior near an aircraft, and the 

still somewhat mystifying effects of turbulence. Ira R. Schwartz of NASA’s 

Office of Advanced Research and Technology summed up the state of sonic 

boom minimization as follows: “It is yet too early to predict whether any of 

these design techniques will lead the way to development of a domestic SST 

that will be allowed to fly supersonic over land as well as over water.”44

The challenge to the SST posed by the sonic boom became even more 

serious shortly after the conference. In July 1968, President Lyndon Johnson 

signed into law a bill requiring the Federal Aviation Administrator to “prescribe 

and amend such rules and regulations as he may find necessary to provide for 

the control and abatement of aircraft noise and sonic boom.”45 Many expected 

this authority would effectively prohibit supersonic flight over land as several 

other nations were already considering.

Rather than conduct another meeting the following year, NASA deferred 

to a conference hosted by the North Atlantic Treaty Organization’s (NATO’s) 
50

Quieting the Boom

Advisory Group for Aerospace Research & Development (AGARD) on aircraft 

engine noise and sonic boom, which was held in Paris in May 1969. Experts 

from the United States and five other nations—including the two facing similar 

issues with the Concorde—attended this forum, which consisted of seven sessions. Three sessions and a roundtable dealt with the status of boom research 

and the challenges ahead.46

As reflected in these conferences, the three-way partnership between NASA, 

Boeing, and the academic aeronautical community during the late 1960s continued to yield new knowledge about sonic booms as well as scientific and technological advances in exploring ways to deal with them. In addition to the flight-test 

and wind tunnel data described in the previous chapter, some of this progress 

came from new experimental techniques, some of them quite ingenious.

Laboratory Devices and Experiments

NASA and its contractors developed several types of simulators, both large and 

small, that proved useful in studying the physical and psychoacoustic effects of 

sonic booms. The smallest (and least expensive) was a spark-discharge system. 

Langley and other laboratories used these bench-type devices for basic research 

into the physics of pressure waves. Langley’s system created miniature sonic 

booms by using parabolic, or two-dimensional mirrors to focus the shock 

waves caused by discharging high-voltage bolts of electricity between tungsten 

electrodes toward precisely placed microphones. Such experiments were used 

to verify laws of geometrical acoustics. The system’s ability to produce shock 

waves that spread out spherically proved useful for investigating how the coneshaped waves generated by aircraft will interact with buildings.47

For studying the effects of temperature gradients on boom propagation, 

Langley used a ballistic range consisting of a helium-gas launcher that shot 

miniature projectiles at constant Mach numbers through a partially enclosed 

chamber. The atmosphere inside could be heated to ensure a stable atmosphere 

for accuracy in boom measurements.

Innovative NASA-sponsored simulators included Ling-Temco-Vought’s shockexpansion tube—basically a mobile, 13-foot-diameter conical horn mounted on a 

trailer—and General American Research Division’s explosive, gas-filled envelopes 

suspended above sensors at Langley’s sonic boom simulation range.48 Other simulators were devised to handle both human and structural response to sonic booms. 

(The need to better understand effects on people was called for in a report released 

in June 1968 by the National Academy of Sciences.)49 Unlike the previously 

described studies using actual sonic booms created by aircraft, these devices had 

the advantages of a controlled laboratory environment. They allowed researchers 
51

The SST’s Sonic Boom Legacy

Langley’s Low-Frequency Noise Facility, built originally for testing the extremely loud sounds of 

Apollo booster rockets. (NASA)

to produce multiple boom signatures of varying shapes, pressures, and durations 

as often as needed at a relatively low cost.50

Langley’s Low-Frequency Noise Facility—built earlier in the 1960s to generate the intense, chest-pounding, eardrum-splitting sounds of giant Saturn boosters during Apollo launches—also performed informative sonic boom simulation 

experiments. As indicated by the photograph, it was a large, cylindrical test 

chamber 24 feet in diameter and 21 feet long that could accommodate people, 

small structures, and materials for testing. The facility’s electrohydraulically operated 14-foot piston was capable of producing low-frequency sound waves from 

1 hertz (Hz) to 50 Hz (sort of a super subwoofer) and sonic boom N-waves 

from 0.5 psf to 20 psf at durations from 100 milliseconds to 500 milliseconds.51

To provide an even more versatile system designed specifically for sonic 

boom research, NASA contracted with General Applied Sciences Laboratories 

(GASL) of Long Island, NY, to develop an ideal simulator using a quickaction valve and shock-tube design. (Antonio Ferri was the president of GASL, 

which he had cofounded with the illustrious Hungarian-born scientist and 

airpower visionary Theodore von Kármán in 1956). Completed in 1969, this 

new simulator consisted of a high-speed flow valve that sent pressure-wave 

bursts through a heavily reinforced, 100-foot long conical duct that expanded 
52

Quieting the Boom

into an 8-by-8-foot test section with an instrumentation and model room. It 

could generate overpressures up to 10 psf with durations from 50 milliseconds 

to 500 milliseconds. Able to operate at less than a 1-minute interval between 

bursts, its sonic boom signatures proved very accurate and easy to control.52

In the opinion of Ira Schwartz, “the GASL/NASA facility represents the most 

advanced state of the art in sonic boom simulation.”53

Losing the Battle Against the Boom

While NASA and its partners were learning more and more about the nature 

of sonic booms, the SST was becoming mired ever deeper in controversy. 

Many in the public, the press, and the political arena were concerned about 

the noise SSTs would create—both around airports with its powerful engines 

and elsewhere with its sonic boom carpet—with a growing number expressing hostility to the entire SST program. As one of the more reputable critics 

wrote in 1966, with a map showing a dense network of future boom carpets 

crossing the United States, “the introduction of supersonic flight, as it is at 

present conceived, would mean that hundreds of millions of people would 

not only be seriously disturbed by the sonic booms ... they would also have 

to pay out of their own pockets (through subsidies) to keep the noise-creating 

activity alive.”54

Opposition to the SST grew rapidly in the late 1960s, becoming a cause 

célèbre for the emerging environmental movement as well as a target for 

small-Government conservatives opposed to federal subsidies.55 Typical of the 

growing trend among opinion makers, the New York Times published its first 

strongly anti–sonic boom editorial in June 1968, linking the SST’s potential 

sounds with an embarrassing incident the week before when an F-105 flyover 

shattered 200 windows at the Air Force Academy, injuring a dozen people.56

The next 2 years brought a swelling crescendo of complaints about the supersonic transport, both for its expense and the problems it could cause—even as 

research on controlling sonic booms began to bear some fruit.

By the time 150 scientists and engineers gathered in Washington, DC, for 

NASA’s third sonic boom research conference on October 29 and 30, 1970, 

the American supersonic transport program had less than 6 months left to live. 

Thus, the 29 papers presented at this conference and other papers at the ASA’s 

second sonic boom symposium in Houston, TX, the following month might 

be considered, in their entirety, a final status report on sonic boom research 

during the SST decade. The reports in Washington, many of which followed 

up on presentations at the 1968 conference, covered the full range of topics 

related to nature, measurement, and mitigation of sonic booms. The otherwise 
53

The SST’s Sonic Boom Legacy

more limited agenda in Houston also included papers on the issues of human 

and animal response.57

Of future if not near-term significance, NASA and its partners were making 

considerable progress in understanding how to design airplanes that could fly 

faster than sound while leaving behind a gentler sonic footprint. As summarized by Ira Schwartz:

In the area of boom minimization, the NASA program has utilized 

the combined talents of Messrs. E. McLean, H.L. Runyan, and 

H.R. Henderson at NASA Langley Research Center, Dr. W.D. 

Hayes at Princeton University, Drs. R. Seebass and A.R. George 

at Cornell University, and Dr. A. Ferri at New York University 

to determine the optimum equivalent bodies of rotation that 

minimize the overpressure, shock pressure rise, and impulse [i.e., 

the total amount of pressure variation] for given aircraft weight, 

length, Mach number, and altitude of operation. Simultaneously, 

research efforts of NASA and those of Dr. A. Ferri at New York 

University have provided indications of how real aircraft can be 

designed to provide values approaching these optimums.... This 

research must be continued or even expanded if practical supersonic transports with minimum and acceptable sonic boom characteristics are to be built.58

Any consensus among the attendees about the progress they were making 

on the sonic boom issue was tempered by their awareness of the financial 

problems now plaguing the Boeing Company and the political difficulties 

facing the administration of President Richard M. Nixon in continuing to 

subsidize the American SST. Many attendees also seemed resigned to the reality that Boeing’s final 2707-300 design (figure 2-2), with its 306-foot length 

and 64,000-foot cruising altitude, 

would never come close to passing the 

overland sonic boom criteria for civil 

aircraft being proposed by the FAA.59

Although the noise level ultimately 

deemed acceptable by the public was 

still uncertain, the consensus was that 

the N-wave signature of an acceptable 

SST must be reduced to at least 1 psf 

to allow cruising at supersonic speeds 

over the United States. As Antonio 

Ferri lamented, “programs for the first 

Figure 2-2. Boeing 2707-300 SST, final 

design. (NASA)
54

Quieting the Boom

generation of these airplanes have been initiated without a complete understanding of the effects of the sonic boom on the population and their reaction 

against it.”60 For designing the next generation of large supersonic transports, 

he offered several concepts developed since the last conference (including an 

imaginative biplane configuration) as well as operational techniques and flight 

profiles to reduce overpressures to a suitable level.61

The shock waves from cruising at a low supersonic speed (up to about 

840 mph) and the right altitude, a condition known as Mach cutoff (see 

figure 1-8), would under the proper conditions either refract away from the 

surface or not coalesce enough to cause a full sonic boom. In view of this, 

there was some hope that carefully planned operations while over land might 

still make the SST economically practical. This, however, would require solutions to issues associated with such variables as meteorological conditions, 

topographical effects, building vibrations, caustics, and super booms—some

of which were being clarified by the BREN Tower tests described at the end 

of the previous chapter.62

On related issues, Albert George and one of his graduate students, Kenneth 

Plotkin, substantiated much about the complex relationship between turbulence and shock wave scattering as well as N-wave distortions,63 phenomena 

that were further refined by an examination of multiple scattering of shock 

waves in a turbulent atmosphere by two researchers at Columbia University, 

W.J. Cole and M.B. Freidman.64 George had reported earlier on how ways of 

lowering tail shock as well as bow shock and other factors could reduce the 

lower bounds for sonic booms well below the accepted levels calculated by 

L.B. Jones and at shorter distances.65 For his part, Jones continued to extend 

his earlier results on lower bounds for bow-pressure shocks to the midfield and 

far field, although only in a homogenous atmosphere.66

Thanks to new computer capabilities, Richard Seebass reported on progress 

in using linear equations to study the nonlinear characteristics of shock waves 

at a caustic by means of automated numerical analysis and graphical representation.67 Figure 2-3, representing acoustic rays interacting to create a caustic, 

shows this early computer-generated graphing capability (which can be compared with the increasingly detailed and sophisticated CFD images illustrated 

in later chapters).68 Much more study and testing would be needed, however, 

to make the necessary quantitative predictions of sonic boom intensities needed 

for even transonic civilian flight.

In view of such unresolved technical issues as well as overriding political 

and economic factors, Seebass generally echoed Ferri’s opinion, noting, “We 

should adopt the view that the first few generations of supersonic transport 

(SST) aircraft, if they are built at all, will be limited to supersonic flight over 

oceanic and polar regions.”69 In view of such concerns, some of the attendees were 
55

The SST’s Sonic Boom Legacy

even looking toward a more distant 

future when hypersonic aerospace 

vehicles might be able to cruise high 

enough to leave only an acceptable 

boom carpet down at the surface.

As for the ongoing and future 

technological challenges of quieter 

supersonic flight, Lynn Hunton of 

the Ames Research Center warned 

that “with regard to experimental 

problems in sonic boom research, it 

is essential that the techniques and 

assumptions used be continuously 

questioned as a requisite for assuring the maximum in reliability.”70

Harry Carlson probably expressed 

the general opinion of NASA’s aerodynamicists when he cautioned that “the problem of sonic boom minimization 

through airplane shaping is inseparable from the problems of optimization of 

aerodynamic efficiency, propulsion efficiency, and structural weight.... In fact, 

if great care is not taken in the application of sonic boom design principles, the 

whole purpose can be defeated by performance degradation, weight penalties, 

and a myriad of other practical considerations.”71

In view of the SST’s other technical, operational, political, and economic 

hurdles, lowering its sonic boom in time for the final design of the Boeing 

2707-300 would probably not have been enough to save the program. In any 

case, after both the U.S. House of Representatives and U.S. Senate voted in 

March 1971 to discontinue SST funding, a joint conference committee confirmed its termination in May.72

Figure 2-3. An early computer-generated 

depiction of a simple shock wave (shaded area) 

among acoustic rays at a caustic, by Richard 

Seebass, 1970. (NASA)

A Decade of Progress in Understanding Sonic Booms

The cancellation of the SST and related cuts in supersonic research inevitably 

slowed the momentum for dealing with sonic booms. Even so, the ill-fated 

SST program, which invested approximately $1 billion in supersonic research, 

left behind a wealth of data and discoveries about sonic booms—including 

measurements of more than 100,000 booms. As documented evidence of part 

of this effort, the Langley Research Center alone produced or sponsored more 

than 200 technical publications on the subject over a span of 19 years, most 

related to the SST program. (Many of those published in the early 1970s were 
56

Quieting the Boom

Figure 2-4. Reports produced or sponsored by NASA Langley, 1958–1976. (Author)

based on previous SST-related research and testing.) This literature, graphically 

depicted in figure 2-4, would be of enduring value in the future.73

Thanks mostly to the SST program, great progress had been made in the 

understanding and application of sonic boom theory at speeds up to Mach 

3.0. Using the latest algorithms and geometric techniques, experts could now 

predict the evolution of a sonic boom signature from its shock pattern near 

an aircraft configuration to the surface either by extrapolating measurements 

from several body lengths away in a supersonic wind tunnel model or by using 

Whitham’s F-function as calculated from the volume and lift distribution of 

the aircraft. By using acoustic-ray tracing and other techniques, sonic boom 

theory could also account for the effects of variations of temperature, humidity, 

winds, and turbulence on sonic boom strength and behavior, and it could even 

predict the approximate location of focused super booms.74

As for the need to mitigate sonic booms, the research of the SST era pointed 

toward the avenues to be followed in the future. Flying careful profiles at speeds 

of about Mach 1.15 could avoid creating sonic booms on the surface,75 but this 

probably would not provide enough of a speed advantage over conventional 

airliners, unless most of a supersonic airplane’s route could be flown at much 

faster speeds. (Some would later consider such low-Mach speeds as appropriate 

on overland routes for small passenger airplanes.)

For cruising at higher Mach numbers, it had become apparent that lowering sonic booms to acceptable levels would require either a reduction in a bow 

shock’s overpressure or an increase in its rise time (i.e., lessening the steepness 
57

The SST’s Sonic Boom Legacy

of the initial spike in pressure). The latter solution was deemed impractical 

since extending and smoothing out the N-wave to lengthen the rise time and 

make the initial shock wave less shocking would require an extremely long 

airplane. Also, as indicated by the XB-70 tests and other human-response data, 

this proposed solution would not necessarily help to reduce annoying indoor 

vibrations caused by sonic booms, which some experts (such as George and 

Seebass) proposed were the result of a sonic boom’s impulse. That impulse was 

a measure of the total momentum that a sonic boom signature could impart, 

for example, on a building, which tends to vibrate at low frequencies. (The 

rapid pressure changes heard during an N-wave’s double boom will produce 

sound waves at a rate of 30 Hz to 300 Hz, but the relatively gradual drop in 

pressure between the bow shock and rear shock will produce vibrations between 

3 Hz to 8 Hz, which is far below the range of human hearing.76) The impulse 

of a simplified signature is depicted along with an N-wave’s initial rise time in 

figure 2-5.77

To help alleviate sonic booms, 

one futuristic idea that received 

some attention at the time was the 

projection of a heat or force field 

to create a long phantom body in 

the front and rear of the fuselage 

for eliminating troublesome shock 

waves. Although not quite impossible (assuming new inventions and ideal conditions), aerodynamic issues as well 

as enormous power requirements (not to mention the additional weight) made 

this proposal exceedingly unrealistic.78

Reducing overpressure—which could be predicted based on an aircraft’s 

Mach number, length, weight, altitude, and equivalent area distribution—

therefore seemed to be the most feasible solution. As pointed out in numerous 

studies, the two basic ways of doing so were to lighten aircraft weight, thereby 

decreasing its need for boom-producing lift, and specially shaping an airframe 

to modify its shock waves, such as by creating a flattop signature.79 The challenges lay in knowing exactly how to design such an airframe and knowing 

what level of overpressure would be acceptable to the general public.

In May 1971, the same month that the House-Senate conference committee 

put the last nails in the coffin of an American SST, Albert George and Richard 

Seebass completed a short but extremely influential treatise on sonic boom 

minimization theory that culminated their past several years of collaborative 

NASA-sponsored research. Published in the AIAA Journal that October under 

the descriptive title “Sonic Boom Minimization Including Both Front and 

Rear Shocks,” its compact presentation of equations and graphs analyzed the 

Figure 2-5. Simplified illustration of impulse and 

rise time. (NASA)
58

Quieting the Boom

parametric relations of shock waves to lift and area distribution as they affect 

the full sonic boom signature. Their findings offered the prospect of designing aircraft not only for controlling abrupt pressure rises to achieve what they 

referred to as “a bangless boom” but also for possibly reducing the vibrations 

that annoy people indoors.80 Future psychoacoustical studies would show that 

this outcome indeed would seem significantly quieter than the normal N-wave 

signature. Efforts during the coming decades to design supersonic aircraft that 

could reshape the sonic boom would cite the George and Seebass minimization 

theory as a cornerstone.81
59

The SST’s Sonic Boom Legacy

Endnotes

1. The previously cited McLean, Supersonic Cruise Technology, provides 

an overview of these challenges from the perspective of a designer 

and program manager.

2. Robert G. Ferguson, “Evolution of Aeronautics Research at NASA,” 

in NASA’s First 50 Years: Historical Perspectives, ed. Steven J. Dick, 

SP-2010-4704 (Washington, DC: NASA, 2010), 208–209. For an 

earlier summary, see Donald D. Baals and William R. Corliss, Wind 

Tunnels of NASA, SP-440 (Washington, DC: NASA, 1981).

3. Named after Osborne Reynolds of the University of Manchester 

in the 1880s. See Jeremy Kinney, “NASA and the Evolution of 

the Wind Tunnel,” in, NASA’s Contributions to Aeronautics 2, ed. 

Richard P. Hallion (Washington, DC: NASA, 2011), 313.

4. Harry W. Carlson, “An Investigation of Some Aspects of the Sonic 

Boom by Means of Wind-Tunnel Measurements of Pressures About 

Several Bodies at a Mach Number of 2.01,” NASA TN D-161 

(December 1959). Carlson used Langley’s 4-by-4-foot Supersonic 

Pressure Tunnel, completed in 1948, for most of his experiments.

5. Domenic J. Maglieri and Harry W. Carlson, “The Shock-Wave 

Noise Problem of Supersonic Aircraft in Steady Flight,” NASA 

Memo 3-4-59L (April 1959), 9.

6. For numerous examples of these wind tunnel experiments, see 

Runyan, “Sonic Boom Capsule Summaries” as well as the NTRS 

bibliographical database.

7. Harry W. Carlson, “Wind Tunnel Measurements of the Sonic-Boom 

Characteristics of a Supersonic Bomber Model and a Correlation 

with Flight-Test Ground Measurements,” NASA TM-X-700 (July 

1962).

8. Harry W. Carlson, “The Lower Bound of Attainable Sonic-Boom 

Overpressure and Design Methods of Approaching This Limit,” 

NASA TN D-1494 (October 1962).

9. Harry W. Carlson, “Correlation of Sonic-Boom Theory with Wind 

Tunnel and Flight Measurements,” NASA TR R-213 (December 

1964), 1.

10. Evert Clark, “Reduced Sonic Boom Foreseen for New High-Speed 

Airliner,” New York Times, January 14, 1965, 7, 12 (based on a visit 

to NASA Langley).

11. Raymond M. Hicks and Joel P. Mendoza, “Prediction of Sonic 

Boom Characteristics from Experimental Near Field Results,” NASA 

TM-X-1477 (November 1967).
60

Quieting the Boom

12. As research progressed, some experts began to define the sharp noise 

accompanying the sudden spikes in pressure as a sonic bang and 

the overall sound and vibrations of an extended N-wave as a sonic 

boom.

13. L.B. Jones, “Lower Bounds for Sonic Bangs,” Journal of the Royal 

Aeronautical Society 65, no. 606 (June 1961): 433–436; sentences 

quoted are on page 433.

14. Harry W. Carlson, “Configuration Effects on Sonic Boom,” in 

Proceedings of NASA Conference on Supersonic-Transport Feasibility 

Studies and Supporting Research, September 17–19, 1963, Hampton, 

Virginia, NASA TM-X-905 (December 1963), 381.

15. Harvey H. Hubbard and Domenic J. Maglieri, “Factors Affecting 

Community Acceptance of the Sonic Boom,” in Proceedings of NASA 

Conference on Supersonic-Transport Feasibility Studies and Supporting 

Research, 399–412. 

16. “Anglo-French Agreement,” London, UK, November 29, 1962, 

accessed ca. February 1, 2009, http://www.concordesst.com/history/

docs/agreement.html.

17. McLean, Supersonic Transport Technology, 46.

18. M. Leroy Spearman, “The Evolution of the High-Speed Civil 

Transport,” NASA TM no. 109089 (February 2004), 6–7.

19. Conway, High-Speed Dreams, 122–124.

20. F. Edward McLean, “Some Nonasymptotic Effects of the Sonic 

Boom of Large Airplanes,” NASA TN D-2877 (June 1965).

21. Chambers, Innovations in Flight, 32.

22. M.P. Friedman, E.J. Kane, and A. Sigalla, “Effects of Atmosphere 

and Aircraft Motion on the Location and Intensity of a Sonic 

Boom,” AIAA Journal 1, no. 6 (June 1963): 1327–1335.

23. Ibid.; Carlson, “Correlation of Sonic-Boom Theory,” 2–23.

24. For a status report on supersonic work at Langley and some 

at Ames, see William J. Alford and Cornelius Driver, “Recent 

Supersonic Transport Research,” Astronautics and Aeronautics 2, no. 

9 (September 1964): 26–37.

25. Chambers, Innovation in Flight, 32–35.

26. JASA 39, no. 5, pt. 2 (November 1966).

27. F. Edward McLean and Barrett L. Shrout, “Design Methods for 

Minimization of Sonic Boom Pressure-Field Disturbances,” JASA

39, no. 5, pt. 2 (November 1966): 519–525. See also Harry W. 

Carlson, F. Edward McLean, and Barrett L. Shrout, “A Wind Tunnel 

Study of Sonic-Boom Characteristics for Basic and Modified Models 
61

The SST’s Sonic Boom Legacy

of a Supersonic Transport Configuration,” NASA TM-X-1236 (May 

1966).

28. Harry W. Carlson, Robert J. Mack, and Odell A. Morris, “Sonic 

Boom Pressure-Field Estimation Techniques,” JASA 39, no. 5, pt. 2 

(November 1966): 510–518.

29. Lane E. Wallace, “The Whitcomb Area Rule: NACA Aerodynamics 

Research and Innovation,” chapter 5 in From Engineering Science to 

Big Science, ed. Pamela E. Mack, NASA SP-4219 (Washington, DC: 

NASA, 1998), 8, available online at http://history.nasa.gov/SP-4219/

Chapter5.html.

30. Wallace Hayes, “Brief Review of the Basic Theory,” JASA 39, no. 5, 

pt. 2 (Nov. 1966): 6.

31. Evert Clark, “Sonic Boom to Limit Speed of Superjets Across 

U.S.,” New York Times, October 31, 1966, 1, 71; George Gardner, 

“Overland Flights by SST Still in Doubt,” Washington Post, July 10, 

1967, A7.

32. A.R. Seebass, ed., “Preface,” in Sonic Boom Research: Proceedings of a 

Conference Held at the National Aeronautics and Space Administration, 

Washington, DC, April 12, 1967, SP-147 (Washington, DC: NASA, 

1967), iv.

33. Domenic J. Maglieri, “Sonic Boom Flight Research—Some Effects 

of Airplane Operations and the Atmosphere on Sonic Boom 

Signatures,” in Sonic Boom Research: Proceedings of a Conference, 

25–48.

34. Seebass, “Preface,” in Sonic Boom Research: Proceedings of a 

Conference, iii.

35. Harry Carlson, “Experimental and Analytic Research on Sonic 

Boom Generation at NASA,” in Sonic Boom Research: Proceedings of 

a Conference, 9–23. Figure 2-1 is extracted from page 21.

36. Harry W. Carlson, “Experimental and Analytical Research on Sonic 

Boom Generation at NASA,” in Sonic Boom Research: Proceedings 

of a Conference, 9–23; Edward J. Kane, “Some Effects of the 

Atmosphere on Sonic Boom,” in Sonic Boom Research: Proceedings of 

a Conference, 49–64; A.R. George, “The Possibilities for Reducing 

Sonic Booms by Lateral Redistribution,” in Sonic Boom Research: 

Proceedings of a Conference, 83–93.

37. Adolf Busemann, “Sonic Boom Reduction,” in Sonic Boom Research: 

Proceedings of a Conference, 79. Among Busemann’s later accomplishments was suggesting the use of ceramic tiles for the Space Shuttle.

38. Ira R. Schwartz, ed., “Preface,” Second Conference on Sonic Boom 

Research: Proceedings of a Conference Held at the National Aeronautics 
62

Quieting the Boom

and Space Administration, Washington, DC, May 9–10, 1968, SP-180 

(Washington, DC: NASA, 1968), iv–v.

39. Ibid., vi.

40. Antonio Ferri and Ahmed Ismail, “Analysis of Configurations,” in 

Second Conference on Sonic Boom Research, 73–88. See also Percy J. 

Bobbitt and Domenic Maglieri, “Dr. Antonio Ferri’s Contribution 

to Supersonic Transport Sonic-Boom Technology,” Journal of 

Spacecraft and Rockets 40, no. 4 (July–August 2003): 459–466.

41. Wallace D. Hayes and Rudolph C. Haefeli, “The ARAP Sonic 

Boom Computer Program,” in Second Conference on Sonic Boom 

Research, 151–158. For a more complete description, see Wallace D. 

Hayes, “Sonic Boom Propagation in a Stratified Atmosphere with 

Computer Program,” NASA CR 1299 (April 1969).

42. Wallace Hayes, “State of the Art of Sonic Boom Theory,” in Second 

Conference on Sonic Boom Research, 182.

43. Harvard Lomax, “Preliminary Investigation of Flow Field Analysis 

on Digital Computers with Graphic Display,” in Second Conference 

on Sonic Boom Research, 72.

44. Schwartz, “Preface,” Second Conference on Sonic Boom Research, vii.

45. Ibid., iii.

46. Aircraft Engine Noise and Sonic Boom, Conference Proceedings (CP) 

no. 42, Paris, France, May 1969 (Neuilly Sur Seine, France: NATO 

AGARD, 1969).

47. W.D. Beasley, J.D. Brooks, and R.L. Barger, “A Laboratory 

Investigation of N-Wave Focusing,” NASA TN D-5306 (July 

1969); R.L. Barger, W.D. Beasley, and J.D. Brooks, “Laboratory 

Investigation of Diffraction and Reflection of Sonic Booms by 

Buildings,” NASA TN D-5830 (June 1970).

48. Phillip M. Edge and Harvey H. Hubbard, “Review of Sonic 

Boom Simulation Devices and Techniques,” JASA 51, no. 2, pt. 3 

(February 1972): 724–728; Hugo E. Dahlke et al., “The ShockExpansion Tube and its Application as a Sonic Boom Simulator,” 

NASA CR-1055 (June 1968); R.T. Sturgielski et al., “The 

Development of a Sonic Boom Simulator with Detonable Gases,” 

NASA CR 1844 (November 1971).

49. David Hoffman, “Report Sees Need for Study on Sonic Boom 

Tolerance,” Washington Post, June 26, 1968, A3.

50. Ira R. Schwartz, “Sonic Boom Simulation Facilities,” AGARD, 

Aircraft Engine Noise and Sonic Boom, 29-1.

51. Philip M. Edge and William H. Mayes, “Description of Langley 

Low-Frequency Noise Facility and Study of Human Response to 
63

The SST’s Sonic Boom Legacy

Noise Frequencies below 50 cps,” NASA TN D-3204 (January 

1966).

52. Roger Tomboulian, “Research and Development of a Sonic Boom 

Simulation Device,” NASA CR-1378 (July 1969); Stacy V. Jones, 

“Sonic Boom Researchers Use Simulator,” New York Times, May 10, 

1969, 37, 41.

53. Ira R. Schwartz, “Sonic Boom Simulation Facilities,” 29-6.

54. B.K.O. Lundberg, “Aviation Safety and the SST,” Astronautics and 

Aeronautics 3, no. 1 (January 1966), 28. Lundberg, a distinguished 

Swedish engineer, was a very effective critic of SSTs.

55. See Conway, High-Speed Dreams, 118–156.

56. “The Shattering Boom,” New York Times, June 8, 1968, 30.

57. Ira R. Schwartz, ed., Third Conference on Sonic Boom Research: 

Proceedings of a Conference Held at the National Aeronautics and 

Space Administration, Washington, DC, Oct. 29–30, 1970, SP-255 

(Washington, DC: NASA, 1971). The papers from the ASA’s 

Houston symposium were published in JASA 51, no. 2, pt. 2 

(February 1972).

58. Ira Schwartz, “Preface,” Third Conference on Sonic Boom Research, iv.

59. “Civil Aircraft Sonic Boom,” Federal Register 35, no. 4 (April 16, 

1970): 6189–6190. Source for figure 2-3: Spearman, “Evolution of 

the HSCT,” 36.

60. Antonio Ferri, “Airplane Configurations for Low Sonic Boom,” 

Third Conference on Sonic Boom Research, 255.

61. Ibid., 255–256.

62. Domenic Maglieri et al., “Measurements of Sonic Boom Signatures 

from Flights at Cutoff Mach Number,” Third Conference on Sonic 

Boom Research, 243–254.

63. Albert George, “The Effects of Atmospheric Inhomogeneities on 

Sonic Boom,” and Kenneth J. Plotkin, “Perturbations Behind 

Thickened Shock Waves,” both in Third Conference on Sonic Boom 

Research, 33–66.

64. M.J. Cole and M.B. Freeman, “Analysis of Multiple Scattering of 

Shock Waves by a Turbulent Atmosphere,” in Third Conference on 

Sonic Boom Research, 67–74.

65. A.R. George, “Lower Bounds for Sonic Booms in the Midfield,” 

AIAA Journal 7, no. 8 (August 1969): 1542–1545. Plotkin recalled 

George receiving the draft of this article back from the publisher 

with a comment by an anonymous reviewer: “This paper must be 

published!” They deduced that Wallace Hayes must have been the 

reviewer.
Quieting the Boom

64

66. L.B. Jones, “Lower Bounds for Sonic Bang in the Far Field,” 

Aeronautical Quarterly 18, pt. 1 (February 1967): 1–21; L.B. Jones, 

“Lower Bounds for the Pressure Jump of the Bow Shock of a 

Supersonic Transport,” Aeronautical Quarterly, 21 (February 1970): 

1–17.

67. A.R. Seebass, “Nonlinear Acoustic Behavior at a Caustic,” in 

Third Conference on Sonic Boom Research, 87–122, with figure 2-3 

extracted from page 100.

68. Although sonic boom shock waves expand behind a moving supersonic body in a three-dimensional, cone-shaped band (figure 1-1), 

their energy is disseminated outward and thereby forward as acoustic 

rays. Aircraft maneuvers, atmospheric conditions, and other factors 

determine the paths they follow, which can take the form of discrete 

ray tubes.

69. A.R. Seebass, “Comments on Sonic Boom Research,” in Third 

Conference on Sonic Boom Research, 411.

70. Lynn W. Hunton, “Comments on Low Sonic Boom Configuration 

Research, in Third Conference on Sonic Boom Research, 417.

71. Harry W. Carlson, “Some Notes on the Status of Sonic Boom 

Prediction and Minimization Research,” in Third Conference on Sonic 

Boom Research, 397.

72. For a detailed postmortem, see Edward Wenk, “SST—Implications 

of a Political Decision,” Astronautics and Aeronautics 9, no. 10 

(October 1971): 40–49.

73. Compiled by screening B.A. Fryer, “Publications in Acoustics and 

Noise Control from the NASA Langley Research Center During 

1940–1976,” NASA TM-X-7402 (July 1977). Five reports for 1967 

that Domenic Maglieri (in reviewing the draft of this chapter) found 

to be missing from Fryer’s compilation have been added to that 

column.

74. Comments by Herbert Ribner in The Proceedings of the Second Sonic 

Boom Symposium of the Acoustical Society of America, Houston, 

TX, November 1970, cited by Christine M. Darden, “Affordable/

Acceptable Supersonic Flight: Is It Near?” 40th Aircraft Symposium, 

Japan Society for Aeronautical and Space Sciences, Yokohama, 

Japan, October 9–11, 1973, 2.

75. This cutoff speed is based on a standard atmosphere without winds.

76. John Morgenstern, “Fixing the Sonic Boom,” a presentation at the 

FAA Workshop on Advanced Technologies and Supersonics, Palm 

Springs, CA, March 1, 2009, slide no. 3.
65

The SST’s Sonic Boom Legacy

77. Figure 2-5 extracted from Peter G. Coen and Roy Martin, “Fixing 

the Sound Barrier: The DARPA/NASA/Northrop-Grumman 

Shaped Sonic Boom Flight Demonstration,” PowerPoint presentation, July 2004, slide no. 3. Later analysis by civil engineers determined that impulse is only an approximate parameter for assessing 

structural response; e-mail, Kenneth Plotkin, Wyle Laboratories, to 

Lawrence Benson, June 5, 2011.

78. David S. Miller and Harry W. Carlson, “A Study of the Application 

of Heat or Force Fields to the Sonic-Boom-Minimization Problem,” 

NASA TN D-5582 (December 1969).

79. Domenic J. Maglieri, Harry L. Carlson, and Norman J. McLeod, 

“Status of Studies of Sonic Boom,” in NASA Aircraft Safety and 

Operating Problems (Washington, DC: GPO, 1971), 439–456.

80. A.R. George and R. Seebass, “Sonic Boom Minimization Including 

Both Front and Rear Shocks,” AIAA Journal 9, no. 10 (October 

1971): 2091–2093. They published a more detailed description, 

“Sonic-Boom Minimization,” in JASA 51, no. 2, pt. 3 (February 

1972): 686–694. See also next chapter.

81. Plotkin and Maglieri, Sonic Boom Research, 5.
66

Vincent R. Mascitti, F. Edward McLean, and Cornelius Driver in the mid-1970s with a Lockheed 

AST model. (NASA)
67

CHAPTER 3

Continuing the Quest 

Supersonic Cruise Research

“The number one technological tragedy of our time.”1 That was how President 

Nixon characterized the votes by Congress to stop funding an American 

supersonic transport. Despite the SST’s cancellation, the White House, the 

Department of Transportation and its Federal Aviation Administration, and 

NASA—with help from some members of Congress—did not allow the SST’s 

progress in supersonic technologies to completely dissipate. During 1971 and 

1972, the DOT and NASA allocated funds for completing some of the research 

and experiments that were under way when the program was terminated. The 

administration then added line-item funding to NASA’s fiscal year (FY) 1973 

budget for scaled-down supersonic research, especially as related to environmental issues raised during the SST program. In response, NASA established 

the Advanced Supersonic Technology (AST) program in July 1972. Thus 

resumed what became a half-century pattern of on-again, off-again efforts to 

solve the problems of faster-than-sound civilian flight, with the sonic boom 

remaining one of the most difficult challenges of all.

Changing Acronyms: 

An Overview of the AST/SCAR/SCR Program

To indicate more clearly the exploratory nature of this effort and allay fears 

that it might be a potential follow-on to the SST, the overall AST program was 

renamed Supersonic Cruise Aircraft Research (SCAR) in 1974. When the term 

“aircraft” in the program’s title continued to raise suspicion in some quarters 

that the goal might be some sort of prototype, NASA shortened the program’s 

name to Supersonic Cruise Research (SCR) in 1979, not long before the program’s demise.2

 For the sake of simplicity, the latter name is often applied to 

all 9 years of the program’s existence.

To NASA, the principal purpose of the AST/SCAR/SCR program was to 

conduct and support focused research into the problems of supersonic flight 
68

Quieting the Boom

while advancing related technologies. As with the SST (albeit more modestly), 

NASA’s aeronautical centers, most of the major airframe manufactures, and 

many research organizations and universities participated.3 From Washington, 

NASA’s Office of Aeronautics and Space Technology (OAST) provided 

overall supervision but delegated day-to-day management to the Langley 

Research Center, which established an AST Project Office in its Directorate 

of Aeronautics (soon placed under a new Aeronautical Systems Division). 

The AST program was organized into several major elements: propulsion; 

structure and materials; stability and control; aerodynamic performance; and 

airframe-propulsion integration. NASA spun off propulsion work on a variable 

cycle engine (VCE) as a separate program in 1976. (A variable cycle engine is 

similar to a conventional mixed-flow turbofan except that it has an additional 

secondary outer duct to increase the overall bypass ratio and, thus, the airflow 

handling capability desirable at very high speeds.) Sonic boom research, which 

fell under aerodynamic performance, was but one of 16 AST subelements.4

At Langley’s Aeronautical Systems Division, Cornelius “Neil” Driver, who 

headed the Vehicle Integration Branch, and F. Edward McLean, as chief of 

the AST Project Office, were key officials in planning and managing the AST/

SCAR effort. After McLean retired in 1978, the AST Project Office passed 

on to a fellow aerodynamicist, Vincent R. Mascitti, while Driver took over 

the Aeronautical Systems Division. (All three are shown in the accompanying photo.) One year later, Domenic Maglieri replaced Mascitti in the AST 

Project Office.5

 Despite Maglieri’s sonic boom expertise, the goal of minimizing the AST’s sonic boom for overland cruise had by then long since ceased 

being an SCR objective. As later explained by McLean: “The basic approach 

of the SCR program ... was to search for the solution of supersonic problems 

through disciplinary research. Most of these problems were well known, but no 

satisfactory solution had been found. When the new SCR research suggested 

a potential solution ... the applicability of the suggested solution was assessed 

by determining if it could be integrated into a practical commercial supersonic 

airplane and mission.... If the potential solution could not be integrated, it 

was discarded.”6

To meet the practicality standard for integration into a supersonic airplane, 

the scientists and engineers trying to solve the sonic boom problem had to clear 

a new and almost insurmountable hurdle less than a year into the AST effort. 

In April 1973, responding to concerns raised since the SST program, the FAA 

announced a new rule, effective on September 30, banning commercial or civil 

aircraft from supersonic flight over the landmass or territorial waters of the 

United States if measurable overpressure would reach the surface.7 One of the 

initial objectives of AST’s sonic boom research had been to establish a metric 

for public acceptability of sonic boom signatures for use in the aerodynamic 
69

Continuing the Quest

design process. The FAA’s stringent new regulation seemed to rule out any 

such flexibility.

As a result, when Congress cut FY 1974 funding for the AST program from 

$40 million to about $10 million, the subelement for sonic boom research 

went on NASA’s chopping block. The design criteria for the SCAR program 

became a 300-foot-long, 270-passenger airplane that could fly as effectively as 

possible over land at subsonic (or possibly low-transonic) speeds yet still cruise 

efficiently at 60,000 feet and Mach 2.2 over water. To meet these less ambitious 

criteria, Langley aerodynamicists modified their SCAT-15F design from the 

late 1960s into a notional concept with better low-speed performance (but 

higher sonic boom potential) called the ATF-100. This served as a baseline for 

three industry teams in coming up with their own designs.8

Learning More About Sonic Booms

Back when the AST program began, however, prospects for a significant quieting of its sonic footprint for operations over land still appeared possible. Sonic 

boom theory had advanced significantly during the 1960s, and some promising 

ideas for reducing boom signatures had begun to emerge. As indicated in figure 

2-4, these endeavors continued to bear fruit into the early 1970s.

As far back as 1965, NASA’s Ed McLean had predicted that the sonic boom 

signature from a very long supersonic aircraft flying at the proper altitude could 

be nonasymptotic (i.e., not reach the ground in the form of an N-wave).9 The 

most radical ideas for lengthening an aircraft by projecting a phantom body 

as with a heat shield continued to be set aside (but another idea—projecting 

a long extension from its nose to slow the rise of the bow shock wave—would 

eventually prove more realistic).10 Most of the ongoing research on sonic boom 

minimization, however, tended to follow the general course set by Albert 

George and Richard Seebass with their landmark treatise in 1971.

George and Seebass went into more detail about their sonic boom minimization concepts during the next few years.11 This culminated in “Design and 

Operation of Aircraft to Minimize their Sonic Boom,” an article published in 

its final form in October 1974.12 Although by then not especially relevant to the 

AST, since overland supersonic operations were no longer part of the program, 

it marked another milestone in the development of sonic boom theory. Because 

there was as yet no accepted standard on “what is to be reduced or minimized 

in order to make the sonic boom more acceptable,”13 they considered remedies 

for treating each of its symptoms individually. These included shock strength 

(both front and rear), overpressure, rise time, and impulse. Based on common 

assumptions, such as an isothermal atmosphere (a standard formula on how air 
70

Quieting the Boom

temperature and density change with altitude), and premised on the supersonic 

area rule, they examined “how we can shape the equivalent body of revolution 

for the vertical plane to minimize a given signature parameter below the aircraft.”14 In addition to the obvious ways of reducing overpressure and impulse 

by lowering aircraft weight and improving efficiency (e.g., ratios of lift to drag 

and thrust to weight), they looked at specific aerodynamic design principles, 

citing key findings from the growing literature on the topic while presenting 

their own remedies.

By way of creating general rules to be considered, George and Seebass 

showed mathematically and graphically the relationships and tradeoffs between 

various aircraft-design features and sonic boom characteristics. For example, 

higher Mach numbers can somewhat lower impulse but not overpressure. 

They calculated and described how the proper combinations of shape, weight, 

length, and altitude (lower than previously thought) 

can practically eliminate the explosive sound of 

the bow shock wave (but not the signature’s total 

overpressure). “Thus, for example, a Mach 2.7, 

600,000 lb., 300-foot aircraft can have a shock-free 

[but not silent] signature at altitudes below 30,000 

ft.”15 They also mathematically examined various 

operational techniques, such as the transonic speeds 

that could prevent sonic booms from reaching the 

ground. At the other extreme, they predicted that 

hypersonic speeds might help with lowered shock 

waves but would not solve other problems—especially impulse. They concluded “that aircraft could 

be designed that would achieve overpressure levels 

just below 1/lb/ft2

 (for both positive and negative 

phases of the pressure signature) and impulses of 

about 1/10 lb/sec/ft2. These numbers are not too different from the sonic boom generated by the SR-71, 

and experience with SR-71 overflights should give 

some indication of whether or not overpressures and 

impulses of this magnitude will prove acceptable.”16

Unfortunately for the future of supersonic 

transports, the public’s apparent tolerance of occasional sonic booms from the Air Force’s small fleet 

of SR-71s did not transfer to the more frequent 

booms that scheduled supersonic airline traffic 

would generate along their routes. Although most 

of Seebass’s and George’s work at the time applied to 

Albert George in 1978 

(Cornell) and Richard 

Seebass in the early 1980s. 

(University of Colorado)
71

Continuing the Quest

large transports, their analysis of various types of airframe shaping to alter the 

formation and evolution of shock waves—such as slightly blunting the nose 

without significantly penalizing performance—would be relevant to smaller 

supersonic aircraft as well. Based on their insightful analyses, George and 

Seebass are considered the fathers of sonic boom minimization.

Meanwhile, other researchers under contract to NASA also continued to 

advance the state of the art. For example, Antonio Ferri of New York University 

in partnership with Hans Sorensen of the Aeronautical Research Institute of 

Sweden used new three-dimensional measuring techniques in Sweden’s trisonic 

wind tunnel to more accurately correlate near-field effects with linear theory. 

Testing NYU’s model of a 300-foot-long SST cruising at Mach 2.7 at 60,000 

feet projected sonic booms of less than 1.0 psf.17 Ferri’s death in 1975 at the 

age of 63 left a big void in the field of supersonic aerodynamics, including 

sonic boom research.18

In addition to theoretical refinements and wind tunnel techniques, important new computer-modeling capabilities continued to appear in the early 

1970s. In June 1972, Charles Thomas of the Ames Research Center published 

details on a computer program he called the waveform parameter method, 

which used new algorithms to extrapolate the evolution of far-field N-waves. 

This offered an alternative to using the F-function (the pattern of near-field 

shock waves emanating from an airframe) as required by the previously discussed program developed by Wallace Hayes and colleagues at Princeton’s 

ARAP. Although both methods accounted for acoustical-ray tracing and would 

arrive at almost identical results, Thomas’s code allowed for easier inputs of 

wind tunnel pressure measurements as well as such variables as Mach number, 

altitude, flightpath angle, acceleration, and atmospheric conditions for automated data processing.19

Both Thomas’s waveform parameter program and Hayes’s ARAP program 

remain relevant well into the 21st century. As explained 30 years after Thomas 

released his program by an expert in sonic boom modeling, “Both are full 

implementations of fundamental theory, accounting for arbitrarily maneuvering aircraft in horizontally stratified atmospheres with wind.... Moreover, 

virtually every full ray trace sonic boom program in use today is evolved in one 

way or another from one of these two programs.”20

In June 1973, at the end of the AST program’s first year, Harry Carlson, 

Raymond Barger, and Robert Mack of the Langley Research Center published a 

study on the applicability of sonic boom minimization concepts for an overland 

supersonic transport based on “the airplane design philosophy, most effectively presented by Ferri, in which sonic-boom considerations play a dominant 

role.”21 They examined two baseline AST designs and two reduced-boom concepts. The objective for all four was a commercially viable Mach 2.7 supersonic 
72

Quieting the Boom

transport with a range of 2,500 nautical miles (nm) (the coast-to-coast distance 

across the United States). Applying the experimentally verified minimization 

concepts of George, Seebass, Hayes, Ferri, Barger, and L.B. Jones, and using the 

ARAP computer program, Carlson’s team explored various ways to manipulate 

the F-function to project a quieter sonic boom signature. As with similar previous efforts, their options were limited by the lack of established signature characteristics (combinations of initial rise time, shock strength, peak overpressure, 

and duration) that people would best tolerate, both outdoors and especially 

indoors. Also, the complexity of aircraft geometry made measuring effects on 

tail shocks difficult. They therefore settled on lowering peak overpressure, with 

the goal being a plateau or flattopped signature.22

Considering this objective along 

with numerous other parameters 

deemed necessary for a practical airliner, their study confirmed the advantages of highly swept wings located 

toward the rear of the fuselage with 

carefully designed twist and camber for 

sonic boom shaping. It also confirmed 

the use of canards (small airfoils used 

as horizontal stabilizers near the nose 

of rear-winged aircraft) and positive 

dihedral (angled up) wings to optimize 

lift distribution for sonic boom benefits. Although two designs (one with 

a delta wing and another with an arrow wing) showed bow shocks of less 

than 1.0 psf at an optimum cruising altitude of 53,000 feet to 59,000 feet, 

their report noted “that there can be no assurance at this time that [their] 

shock-strength values ... if attainable, would permit unrestricted overland 

operations of supersonic transports.”23

In October 1973, Edward J. Kane of Boeing, who had been a key sonic 

boom specialist during the SST program, released the results of a similar 

NASA-sponsored study on the feasibility of a commercially viable low-boom 

transport using technologies projected to be available in 1985. Applying the 

latest theories (including the just-discussed Langley study), Boeing explored 

two longer range concepts: a high-speed (Mach 2.7) arrow-wing design that 

would produce a sonic boom of 1.0 psf or less at 55,000 feet and a mediumspeed (Mach 1.5) highly swept wing design with a signature of 0.5 psf or less 

at 45,000 feet.24 Ironically, these results were published just as the new FAA 

rule rendered them largely irrelevant. In retrospect, this study represented a 

final industry perspective on the prospects for boom minimization before the 

SCAR program dropped plans for supersonic cruise over land.

Figure 3-1. Aft arrow-wing configuration 

for low peak overpressure. (NASA)
73

Continuing the Quest

Obviously, the FAA’s virtual ban on civilian supersonic flight in the United 

States dampened any enthusiasm by the major aircraft manufacturers to continue investing much capital in sonic boom research. Within NASA, funding 

for academic studies slowed to a trickle and many of its own employees with 

experience in sonic boom research redirected their efforts into other areas of 

expertise. Of the approximately 1,000 technical reports, conference papers, 

and articles by NASA and its contractors listed in bibliographies of the SCR 

program from 1972 to 1980, only eight dealt directly with the sonic boom.25

The Early Promise of Computational Fluid Dynamics

Even so, some foundations were being laid that would benefit future sonic 

boom research. Of great benefit to supersonic aerodynamics and other aeronautical endeavors, NASA was fostering the development and use of powerful 

new digital computer capabilities. In early March 1975, the Langley Research 

Center hosted a major conference, “Aerodynamic Analyses Requiring Advanced 

Computers,” on the progress being made. In introductory remarks, J. Lloyd 

Jones, NASA’s Deputy Associate Administrator for Aeronautics Technology, 

extolled the advances made since NASA’s last aerodynamics conference in 1969. 

Rather than having to rely on simple shapes and various shortcuts to formulate 

solvable equations, usually involving only two dimensions, researchers were 

now able to calculate such phenomena as transonic mixed flows with embedded shock waves and flows around complex wing-body configurations.26 The 

future promised much greater improvements. Dean R. Chapman of the Ames 

Research Center discussed the accelerating advances in the digital-modeling 

and analysis capabilities of computational fluid dynamics. CFD, he asserted, 

offered “tremendous potential for revolutionizing the way our profession has 

been doing business.”27 With the expected arrival of super computers, he envisaged CFD overcoming the inherent limitations of wind tunnels and, eventually, allowing timely processing of heretofore virtually unsolvable differential 

equations governing fluid flows over solid surfaces with the effects of friction.

Using advanced calculus, the brilliant 18th century mathematician 

Leonhard Euler had devised two nonlinear partial differential equations governing the momentum (velocity and pressure) and the continuity of flowing 

fluids. Euler’s momentum equation did not account for the viscous effects of 

friction on fluid flow along the surface of an object (known later in aerodynamics as “boundary conditions”). This required highly complex, nonlinear 

partial equations developed independently in the first half of the 19th century 

by Claude-Louis Navier and George Gabriel Stokes that account for interdependent variables such as pressure, density, and velocity. These became known 
74

Quieting the Boom

as the Navier-Stokes equations. During the late 19th century, advances in the 

field of thermodynamics would lead to an energy equation for the high-speed 

fluid flows that also would be needed later in aerodynamics. Unfortunately, the 

Euler and Navier-Stokes equations had no general analytical solutions when 

applied to practical problems (such as airflow over a wing) without simplifying 

selected factors to permit linear solutions. Future progress in computational 

fluid dynamics, however, would allow the partial derivatives or integrals in 

these equations to be replaced by discrete algebraic forms. Eventually, the 

data-processing capability of high-speed computers could repeatedly generate 

flow-field values for each variable at specific points in space and time, known 

as grid points, with results improving with each iteration. The end products, 

although not classic stand-alone mathematical solutions, would be of great 

practical use for aerodynamic design purposes, including (as will be seen) 

shock wave calculations.28

Although the revolutionary potential of CFD was still some years in the 

future, 2 of the 52 papers presented at this 1975 conference presented two 

evolutionary computer programs of value for sonic boom minimization. 

A NASA-sponsored paper by Richard Seebass and three others at Cornell 

reported on several recent advances in sonic boom theory and introduced 

an easy-to-use computer program for aerodynamic minimization calculations 

written by Joseph Liu Lung as his master’s thesis.29 The other paper by H. Harris 

Hamilton of Langley and Frank Marconi and Larry Yeager of the Grumman 

Aerospace Corporation reported a new technique for accurately and efficiently 

computing high-speed inviscid (frictionless) flows in three dimensions around 

real airframe configurations. Although this research was prompted by NASA’s 

need to learn more about the aerodynamics of the Space Shuttle orbiter during 

return flights, their innovation could be applied to all supersonic and hypersonic vehicles.30 NASA published full details on the procedure and its related 

computer code the following year.31

Progress in Prediction and Minimization Techniques

By 1975 Christine M. Darden of NASA Langley had developed an innovative computer code specifically for use in sonic boom minimization. She 

wrote it to convert Seebass and George’s minimization theory, which was based 

on an isothermal (uniform) atmosphere, into a program that applied to the 

real (stratified) atmosphere. She did this with new equations for calculating 

pressure-signature changes, ray-tube areas, and acoustic impedance. Although 

reliance on an isothermal atmosphere allowed reasonable estimates of sonic 

boom signatures for many conditions, Darden’s modification offered more 
75

Continuing the Quest

accurate equivalent area distribution calculations, such as for flying at low 

Mach numbers and for designing better aerodynamics in the nose area (a goal 

she would continue to pursue).32 Darden, who had earned a mathematics 

degree with highest honors from the Hampton Institute in 1962, taught high 

school before beginning her career at Langley in 1967. Even as she became 

NASA’s top sonic boom expert, Darden continued her education—earning a 

master’s in mathematics from Virginia State College in Petersburg in 1978 and 

a doctorate in mechanical engineering (specializing in fluid mechanics) from 

George Washington University in 1983.33

Christine Darden and Robert Mack presented a paper on current sonic 

boom research at the first SCAR conference, held at Langley from November 9 

to 12, 1976. The conference took place after both the Concorde and the Soviet 

Tu-144 began scheduled supersonic flights that, because of their sonic booms, 

were restricted to routes over oceans and sparsely populated land areas.34 Theirs 

was the only paper on the sonic boom issue among the 47 presentations at 

the conference.35 In other areas, NASA and its industry partners were making 

significant advances over the Concorde and Tu-144 in the areas of engine 

noise, fuel consumption, lift-to-drag (L/D) ratio, airframe structure (using 

new titanium fabrication processes), and direct operating costs (estimated at 

50-percent lower than the Concorde’s). The major problem left unsolved for 

any second-generation supersonic transport was the sonic boom.36

One of the main obstacles to progress in sonic boom minimization was 

what Darden and Mack called the low-boom, high-drag paradox (figure 3-2). 

“Contrary to earlier beliefs,” they explained, “it has now been found that 

improved efficiency and lower sonic boom characteristics do not always go 

hand in hand.”37 Both theory and 

experiments had shown that (as 

would be expected) an aerodynamically efficient sharp-nosed 

supersonic airframe generates a 

weaker bow shock than one with 

a less streamlined nose. Yet with 

a blunt-nose section, there is less 

propensity for the strong shock 

waves generated along the rest of 

an airframe to merge with the bow shock and create the typical N-wave sonic 

boom at the surface. Unfortunately, the excess drag of a truly blunt-nosed 

supersonic aircraft would make it aerodynamically unacceptable.38

The two Langley researchers were exploring ways to deal with this dilemma, 

a full solution of which they said would require extensive tradeoff studies by 

engineering design teams. Meanwhile, they reported on preliminary results 

Figure 3-2. Low-boom, high-drag paradox. (NASA)
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Quieting the Boom

of their ongoing experiments using Darden’s revision of the George-Seebass 

methodology to design lower-boom wind tunnel models that did not pay too 

great a penalty in aerodynamic efficiency. As for any progress on the still-critical 

question of what would be an acceptable sonic boom, the only research being 

done in North America was by the University of Toronto. Its Institute for 

Aerospace Studies was testing humans, animals, and materials with various 

sonic boom simulators. Other research there included focused booms, effects 

of turbulence, and signatures in the shadow zone.39

Another NASA contribution to understanding sonic booms came in 

early 1978 with the publication of Harry Carlson’s “Simplified Sonic-Boom 

Prediction,” a how-to guide on a relatively quick and easy method to determine 

sonic boom characteristics in a standard atmosphere. It could be applied to a 

wide variety of supersonic aircraft configurations as well as spacecraft at altitudes up to 76 kilometers (km) and cover the entire width of a boom carpet. 

Although his clever series of graphs and equations did not provide the accuracy 

needed for predicting booms from maneuvering aircraft or in designing airframe configurations, Carlson explained that “for many purposes (including 

the conduct of preliminary engineering studies or environmental impact statements), sonic-boom predictions of sufficient accuracy can be obtained by using 

a simplified method that does not require a wind tunnel or elaborate computing equipment. Computational requirements can in fact be met by hand-held 

scientific calculators, or even slide rules.”40 This procedure would be especially 

helpful to the armed services in preparing recently required environmental 

studies for areas where military aircraft flew supersonically.

Although it was drawing funds away from aeronautics, one aspect of NASA’s 

Space Transportation System (STS) led to additional sonic boom research 

involving the full range of shock waves—from hypersonic speeds at the top 

of the atmosphere down to transonic speeds near the surface. In April 1978, 

NASA headquarters released its final environmental impact statement (EIS) 

for the Space Shuttle. It benefited greatly from the Agency’s previous research 

on sonic booms, including the X-15 and Apollo programs as well as the adaptations of Charles Thomas’s waveform-based computer program.41 While the 

entire STS was ascending, the EIS estimated maximum overpressures of 6 psf 

(possibly up to 30 psf with focusing effects) about 40 miles downrange over 

open water. This would be caused by both its long exhaust plumes (which acted 

somewhat as a “phantom body”) and its curving flight profile while accelerating toward orbit. During reentry of the orbiter, the sonic boom was estimated 

at a more modest 2.1 psf (comparable to the Concorde), which would affect 

about 500,000 people as it crossed the Florida peninsula or 50,000 people 

when landing at Edwards.42 In the following decades, as populations in those 
77

Continuing the Quest

areas boomed, millions more would be hearing the sonic booms of returning 

Shuttles, more than 120 of which would be monitored for their signatures.43

Some other limited experimental and theoretical work on sonic booms 

continued in the late 1970s—even if it was no longer based on an American 

supersonic transport. For example, Richard Seebass delved deeper into the 

tricky phenomena of caustics and focused booms, an area on which French 

researcher John Pierre Guiraud had written the governing equations and 

derived a related scaling law.44 After a numeric solution of Seebass’s ideas by 

one of his graduate students,45 Kenneth Plotkin (who began working for Wyle 

Laboratories in 1972 after receiving his Ph.D. from Cornell) applied these 

techniques to analyzing predicted focused booms from the Shuttle for the 

Marshall Space Flight Center as part 

of the studies described in the previous 

paragraph.46 At the end of the decade, 

Langley’s Raymond Barger published a 

study on the relationship of caustics to 

the shape and curvature of acoustical 

wave fronts caused by aircraft maneuvers. To display these effects graphically, he programmed a computer to 

draw simulated three-dimensional 

line plots of acoustical rays in the wave 

fronts. Figure 3-3 shows how even a simple decelerating turn—in this case, 

from Mach 2.4 to Mach 1.5 in a radius of 23 km (14.3 miles)—can merge the 

rays into the kind of caustic that might cause a super boom.47

Unlike in the 1960s, there was little if any NASA sonic boom flight testing 

during the 1970s. As a case in point, NASA’s YF-12 Blackbirds at Edwards AFB 

(where the Flight Research Center was renamed the Dryden Flight Research 

Center in 1976) flew numerous productive supersonic missions in support 

of the AST/SCAR/SCR program, but none of them were dedicated to sonic 

boom issues.48 On the other hand, flight testing of the Concorde provided 

some new sonic boom data from a real supersonic transport. For example, an 

Anglo-American aeronautical conference in London in early June 1973 (just 

a few weeks after the FAA’s new rule prohibited civilian supersonic flight in 

the United States) included an informative paper on sonic boom measurements and their effects on people, buildings, and wildlife during Concorde 

test flights along Great Britain’s west coast.49 Once these swift new airliners 

became operational, however, most of their supersonic flying was done over 

the open ocean, where there was presumably only limited opportunity for 

gathering sonic boom data.

Figure 3-3. Acoustic wave front above a 

maneuvering aircraft. (NASA)
78

Quieting the Boom

One strange and unexpected discovery about secondary booms came after 

British Airways and Air France began regular Concorde service to the United 

States, first to Dulles International Airport near Washington, DC, in May 

1976 and then (after much local opposition due mainly to jet-engine noise) 

to New York’s Kennedy International Airport in November 1977.50 Although 

the Concordes slowed to subsonic speeds while well off shore, residents along 

the Atlantic seaboard began hearing what were called the East Coast mystery 

booms. These were detected all the way from Nova Scotia to South Carolina, 

some of them measurable on seismographs.51 Although a significant number 

of the sounds defied explanation, studies by the Naval Research Laboratory 

(NRL), the Federation of American Scientists, a committee of the DOD’s 

JASON scientific advisory group, and the FAA eventually determined that 

most of the low rumbles heard in Nova Scotia and New England were secondary booms from the Concorde. These sounds were caused by distorted shock 

waves that were being bent or reflected by temperature variations high up in 

the thermosphere while Concordes were still about 75 miles to 150 miles offshore.52 In July 1978, the FAA issued new rules prohibiting the Concord from 

creating sonic booms that could be heard in the United States. Although the 

FAA did not consider that this applied to secondary booms because of their 

low intensity, the affair apparently made the FAA even more sensitive to the 

sonic boom potential inherent in AST designs.53 (As part of the NRL investigation, Harvey Hubbard and Domenic Maglieri determined that Aerospace 

Defense Command F-106s, scrambled from Langley AFB to intercept Soviet 

Tu-20 Bear long-range bombers flying along the Atlantic coast on their regular 

flights to or from Cuba, created many of the sonic booms heard farther south 

to the Carolinas.)54

At Langley, Christine Darden and Robert Mack continued to pursue their 

research on sonic boom minimization during the late 1970s. Using the SeebassGeorge procedure as modified for a stratified atmosphere, they followed up on 

the previously described studies by Kane’s team at Boeing and, in particular, the 

studies by Carlson’s team at Langley. They used wing analysis and wave-drag 

area rule computer programs, including viscous effects, to help design three 

specially shaped wing-body models with low-boom characteristics for comparison with two of Carlson’s models that had been designed mainly for aerodynamic efficiency (figure 3-4). One of their models was configured for cruise at 

Mach 1.5 (the lowest speed for a truly supersonic transport) and two for cruise 

at Mach 2.7 (which approached the upper limit for applying near-field sonic 

boom theory). At 6 inches in length, these were the largest yet tested for sonic 

boom propagation within the confines of the Langley 4-foot-by-4-foot Unitary 

Plan Wind Tunnel—an improvement made possible by continued progress in 

applying the ARAP code to extrapolate near-field pressure signatures to the 
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Continuing the Quest

far field. These low-boom models showed much more reduced overpressure 

than the standard (unconstrained) delta-wing model and significantly lower 

overpressures than the unconstrained arrow-wing design, especially at Mach 

1.5, where the tail shocks were softened as well. The low-boom models’ pressure 

signatures also showed definite flattop characteristics. Darden and Mack first 

presented their findings at an AIAA conference in March 1979 and published 

them in a NASA technical paper that October as well as in an article in the 

Journal of Aircraft in March 1980.55

To Christine Darden, it had 

become obvious that “because 

extreme nose bluntness produces 

large drag, a method of relaxing 

the bluntness is needed to offer 

the opportunity for compromise 

between blunt-nose low-boom 

and sharp-nose low-drag configurations.”56 She wrote about this 

attempt in another NASA technical paper published in 1979 titled 

“Sonic Boom Minimization with Nose-Bluntness Relaxation.” It focused on 

findings that “because the shape of the aircraft does influence the shape of a 

mid-field pressure signature, aircraft shaping has now become a powerful tool 

in reducing the sonic boom.”57 Using numerous equations and the previously 

mentioned NASA-sponsored computer code developed by Grumman for calculating supersonic and hypersonic inviscid flow around various configurations, she explored theoretical options for eliminating the bow shock, allowing 

unrestricted tail shock, and eliminating both shocks. Her calculations showed 

how to relax a blunt nose into a more conical shape to reduce drag. “Thus,” she 

concluded, “the boom levels could be reduced significantly without prohibitive 

drag penalties by defining the proper ratio [of] y 58

f

 / l.” (In area distribution 

terms, this was the width of the shock wave spike along the front of the fuselage 

relative to the entire equivalent length of the airplane.)

Although premised on airliner-sized supersonic aircraft, Darden and Mack’s 

rather lonesome work in the late 1970s on how carefully designed airframe 

shaping could in turn shape the signature of a sonic boom would help set 

the stage for future research on various-sized supersonic aircraft. Because of 

funding limitations, however, this promising approach could not be sustained 

beyond 1979.59 It was apparently the last significant NASA experimentation 

on sonic boom minimization for almost another decade. Yet by validating 

the Seebass-George minimization theory and verifying design approaches for 

sonic boom reductions, their findings would serve as a point of departure 

Figure 3-4. Models used in sonic boom minimization study. (NASA)
80

Quieting the Boom

Figure 3-5. Features of low-boom models. (NASA)

Figure 3-6. North American Rockwell SSBJ concept. 

(NASA)

when such research finally did 

resume. (Figure 3-5 illustrates 

the aerodynamic design characteristics for boom minimization confirmed by Darden and 

Mack’s studies.60)

The second conference on 

Supersonic Cruise Research, 

held at Langley in November 

1979, was the first and last 

under its new name. More than 

140 people from NASA, other 

Government agencies, and the 

aerospace industry attended. 

This time, there were no presentations on the sonic boom, 

but Robert Kelly from North 

American Rockwell did put 

forth the concept of a Mach 2.7 

business jet for 8 to 10 passengers or possibly a military aircraft that could generate a sonic 

boom of only 0.5 psf. Because of 

the difficulty of developing a big supersonic airliner in one step, he proposed 

an alternate course: “to validate the critical supersonic technologies in a small 

research vehicle prior to the building of a full-size supersonic vehicle.... But,” 

he asked, “would the research vehicle have only one use? Why not have the 

additional capability for military use or as a supersonic business jet?”61 The 

concept he presented was a blended-variable camber arrow-wing/body design 

using fiber-reinforced titanium structures with superplastic forming and diffusion bonding (SPF/DB) and either of two different propulsion systems. The 

basic configuration is shown in figure 3-6.62 Although it was not proposed as 

a business jet per se, Boeing had also submitted a study in 1977 on building 

a subscale (93-foot-long) Mach 2.4 SCAR demonstrator to test numerous 

characteristics and capabilities, including sonic boom acceptability and possible boom reducing modifications.63 It would take another 20 years for ideas 

about either a low-boom demonstrator or a supersonic business jet (SSBJ) to 

go anywhere beyond paper studies.

Despite SCR’s relatively modest cost versus its significant technological 

accomplishments, the program suffered a premature death in 1981. Reasons for 

this included the discouragingly high cost of Concorde operations, opposition 
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Continuing the Quest

to civilian R&D spending by some key officials in the new administration 

of President Ronald Reagan, and the growing Federal deficit. These factors, 

combined with cost overruns for the Space Shuttle, forced NASA to abruptly 

cancel Supersonic Cruise Research without even funding completion of many 

final reports.64 As regards sonic boom studies, an exception to this was a compilation of useful charts for estimating minimum sonic boom levels for various combinations of aircraft length, weight, altitude, and Mach numbers by 

Christine Darden published in 1981.65
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Quieting the Boom

Endnotes

1. Stephen D. Ambrose, Nixon: Triumph of a Politician 2 (New York: 

Simon and Schuster, 1989), 433, cited in Conway, High-Speed 

Dreams, 153. For the background of the AST program, see Conway, 

153–158.

2. F. Edward McLean, “SCAR Program Overview,” in Proceedings of the 

SCAR Conference Held at Langley Research Center, Hampton, Virginia, 

November 9–12, 1976, pt. 1, NASA CP-001 (1976), 1–3; McLean, 

Supersonic Cruise Technology, 101–102. 

3. Marvin Miles, “Hopes for SST are Dim but R&D Continues—Just 

in Case,” Los Angeles Times, November 23, 1973, G-1, 11.

4. McLean, Supersonic Cruise Technology, 104–108; Sherwood 

Hoffman, “Bibliography of Supersonic Cruise Aircraft Research 

(SCAR),” NASA RP-1003 (November 1977), 1–5.

5. Chambers, Innovation in Flight, 39–40.

6. McLean, Supersonic Cruise Technology, 103. NASA photo of McLean 

with Driver and Mascitti provided courtesy of Joseph Chambers. 

Based on a drawing on page 38 in Spearman, “Evolution of the 

HSCT,” NASA TM-109089, the model in the photo appears to be 

Lockheed’s Mach 2.2 AST, no later than 1975.

7. FAA, “April 27, 1973,” FAA Historical Chronology, 1926–1996, 

section 1973. The rule was included as Federal Aviation Regulation 

(FAR) section 91.817, Civil Aircraft Sonic Boom, effective 

September 30, 1973.

8. Miles, “Hopes for SST Are Dim,” G1, 11; McLean, Supersonic 

Cruise Technology, 117–118; Conway, High-Speed Dreams, 176–180.

9. F. Edward McLean, “Some Non-Asymptotic Effects on the Sonic 

Boom of Large Airplanes,” NASA TN D-2877 (June 1965).

10. Rudolph J. Swigart, “An Experimental Study in the Validity of the 

Heat-Field Concept for Sonic Boom Alleviation,” NASA CR 2381 

(March 1974). 

11. For example, A.R. George and R. Seebass, “Sonic-Boom 

Minimization,” JASA 51, no. 2, pt. 3 (February 1972): 686–694; 

A.R. Seebass and A.R. George, Sonic Boom Minimization through 

Aircraft Design and Operation, AIAA paper no. 73-241 (January 

1973). 

12. A.R. Seebass and A.R. George, “Design and Operation of Aircraft 

to Minimize their Sonic Boom,” Journal of Aircraft 11, no. 9 

(September 1974): 509–517.

13. Ibid., 509.
83

Continuing the Quest

14. Ibid., 510.

15. Ibid., 513.

16. Ibid., 516.

17. Antonio Ferri, Huai-Chu Wang, and Hans Sorensen, “Experimental 

Verification of Low Sonic Boom Configuration,” NASA CR 2070 

(June 1973).

18. For a retrospective, see Percy J. Bobbitt and Domenic J. Maglieri, 

“Dr. Antonio Ferri’s Contribution to Supersonic Transport SonicBoom Technology,” Journal of Spacecraft and Rockets 40, no. 4 (July–

August 2003): 459–466.

19. Charles L. Thomas, “Extrapolation of Sonic Boom Pressure 

Signatures by the Waveform Parameter Method,” NASA TN 

D-6823 (June 1972).

20. Kenneth J. Plotkin, “State of the Art of Sonic Boom Modeling,” 

JASA 111, no. 1, pt. 2 (January 2002): 532.

21. Harry W. Carlson, Raymond L. Barger, and Robert J. Mack, 

“Application of Sonic-Boom Minimization Concepts in Supersonic 

Transport Design,” NASA TN D-7218 (June 1973), 2.

22. Ibid., 6-16, with figure 3-1 extracted from 15.

23. Ibid., 28.

24. Edward J. Kane, “A Study To Determine the Feasibility of a Low 

Sonic Boom Supersonic Transport,” AIAA paper no. 73-1035 

(October 1973); see also NASA CR 2332 (December 1973).

25. Sherwood Hoffman, “Bibliography of Supersonic Cruise Aircraft 

Research (SCAR) Program from 1972 to Mid-1977,” NASA 

RP-1003 (November 1977); “Bibliography of Supersonic Cruise 

Research (SCR) Program from 1977 to Mid-1980,” NASA RP-1063 

(December 1980).

26. Langley Research Center, Aerodynamic Analysis Requiring Advanced 

Computers, pt. 1, NASA SP-347 (Washington, DC: National 

Technical Information Service, 1975), 3.

27. Ibid., 5.

28. For a layperson’s introduction to this topic, see John D. Anderson, 

Jr., “NASA and the Evolution of Computational Fluid Dynamics,” 

in Hallion, ed., NASA’s Contributions to Aeronautics 1, 431–434.

29. J.L. Lung, B. Tiegerman, N.J. Yu, and A.R. Seebass, “Advances in 

Sonic Boom Theory,” in Aerodynamic Analysis Requiring Advanced 

Computers, pt. 2, 1033–1047.

30. Frank Marconi, Larry Yeager, and H. Harris Hamilton, 

“Computation of High-Speed Inviscid Flows About Real 
84

Quieting the Boom

Configurations,” in Aerodynamic Analysis Requiring Advanced 

Computers, pt. 2, 1411–1453.

31. Frank Marconi, Manuel Salas, and Larry Yeager, “Development 

of Computer Code for Calculating the Steady Super/Hypersonic 

Inviscid Flow Around Real Configurations,” 1: Computational 

Technique, NASA CR 2675 (April 1976); 2: Computer Code, 

NASA CR 2676 (May 1976).

32. Christine M. Darden, “Minimization of Sonic-Boom Parameters 

in Real and Isothermal Atmospheres,” NASA TN D-7842 (March 

1975).

33. “Dr. Christine Mann Darden,” accessed January 8, 2009, http://

www.rbc.edu/library/specialcollections/women_history_ 

resources/vfwposter2002_darden.pdf; “Dr. Christine M. Darden,” 

accessed January 8, 2009, http://blackhistorypages.net/pages/cdarden.

php. Darden, who was valedictorian of her graduating class at Allen 

High School in Asheville, NC, taught high school mathematics in 

Hampton for several years before being hired by NASA.

34. In January 1976, British Overseas Airways Corporation initiated 

Concorde flights between London and Bahrain, and Air France initiated Concorde service between Paris and Rio de Janeiro.

35. Christine M. Darden and Robert J. Mack, “Current Research in 

Sonic-Boom Minimization,” in Proceedings of the SCAR Conference

(1976), pt. 1, 525–541. Darden had discussed some of these topics 

in “Sonic Boom Theory–Its Status in Prediction and Minimization,” 

AIAA paper no. 76-1, presented at the AIAA Aerospace Sciences 

Meeting, Washington, DC, January 26–28, 1976.

36. Craig Covault, “NASA Advances Supersonic Technology,” Aviation 

Week (January 10, 1977): 16–18.

37. Darden and Mack, “Current Research in Sonic Boom 

Minimization,” 526. 

38. Ibid., 528–529. Figure 3-3 extracted from page 44.

39. Ibid., 530–532; J.J. Gottlieb, “Sonic Boom Research at UTIAS,” 

Canadian Aeronautics and Space Journal 20, no. 3 (May 1974): 

199–222, cited in Harvey H. Hubbard, Domenic J. Maglieri, and 

David G. Stephens, “Sonic Boom Research—Selected Bibliography 

with Annotation,” NASA TM 87685 (September 1, 1986), 1. 

40. Harry W. Carlson, “Simplified Sonic-Boom Prediction,” NASA TP 

1122 (March 1978), page 1 quoted.

41. Paul Holloway of Langley and colleagues from the Ames, Marshall, 

and Johnson Centers presented an early analysis in “Shuttle Sonic 
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Continuing the Quest

Boom—Technology and Predictions,” AIAA paper no. 73-1039 

(October 1973).

42. Myron S. Malkin, “Environmental Impact Statement: Space 

Shuttle Program (Final)” NASA Headquarters (HQ) (April 1978), 

106–116.

43. Including measurements in Hawaii with the Shuttle entering the 

atmosphere at 253,000 feet and decelerating from Mach 23; telephone interview, Domenic Maglieri by Lawrence Benson, March 18, 

2009.

44. Plotkin and Maglieri, “Sonic Boom Research,” AIAA paper no. 

2003-3575, 5–6. For a description of Guiraud’s findings in English, 

see J.P. Guiraud, “Focalization in Short Non-Linear Waves,” NASA 

Technical Translation F-12,442 (September 1969); See also his 

previously cited “Acoustique géométrique bruit ballistique des avions 

supersoniques et focalisation,” 215–267.

45. Peter M. Gill, “Nonlinear Acoustic Behavior at a Caustic,” Ph.D. 

thesis, Cornell University, June 1974.

46. K.J. Plotkin and J.M. Cantril, “Prediction of Sonic Boom at a 

Focus,” AIAA paper no. 76-2 (January 1976).

47. Raymond L. Barger, “Sonic-Boom Wave-Front Shapes and 

Curvatures Associated with Maneuvering Flight,” NASA TP 1611 

(December 1979). Figure 3-3 is from page 23.

48. James and Associates, ed., YF-12 Experiments Symposium: A 

Conference Held at Dryden Flight Research Center, Edwards, 

California, September 13–15, 1978, NASA CP-2054 (1978); Hallion 

and Gorn, On the Frontier, appendix P (YF-12 Flight Chronology, 

1969–1978), 423–429. Dryden tested an oblique wing aircraft, the 

AD-1, from 1979 to 1982. Although this configuration might have 

sonic boom benefits at mid-Mach speeds, it was not a consideration 

in this experimental program. The AD-1 program is the subject of 

another study in this NASA book series by Bruce Larrimer.

49. C.H.E. Warren, “Sonic Bang Investigations Associated with 

the Concorde’s Test Flying,” paper presented at the 13th Royal 

Aeronautical Society (RAeS), AIAA, and Center for AeroSpace 

Information (CASI) Anglo-American Aeronautical Conference, 

London, June 4–8, 1973, AIAA paper no. 73-41174, cited in 

Hubbard et al., “Sonic Boom Research—Selected Bibliography,” 1.

50. John L. McLucas et al., Reflections of a Technocrat: Managing Defense, 

Air, and Space Programs During the Cold War (Montgomery, AL: Air 

University Press, 2006), 265. McLucas was FAA administrator at the 

time.
86

Quieting the Boom

51. “Second Concorde Noise Report for Dulles Shows Consistency,” 

Aviation Week (July 19, 1976): 235; William Claiborne, “Mystery 

Booms Defy Expert Explanation,” Washington Post, December 24, 

1977, A1.

52. Recall that sound travels faster in warmer gases, as prevalent in the 

ozone layer.

53. Deborah Shapely, “East Coast Mystery Booms: A Scientific Suspense 

Tale,” Science 199, no. 4336 (March 31, 1978): 1416–1417; 

“Concordes Exempted from Noise Rules,” Aviation Week (July 

3, 1978): 33; G.J. MacDonald et al., “Jason 1978 Sonic Boom 

Report,” JSR-78-09 (Arlington, VA: SRI International, November 

1978); Richard Kerr, “East Coast Mystery Booms: Mystery Gone 

but Booms Linger On,” Science 203, no. 4337 (January 19, 1979): 

256; John H. Gardner and Peter H. Rogers, “Thermospheric 

Propagation of Sonic Booms from the Concorde Supersonic 

Transport,” Naval Research Laboratory Memo Report 3904 

(February 14, 1979) (DTIC AD A067201).

54. Maglieri to Benson, e-mail message, August 18, 2011.

55. Robert J. Mack and Christine M. Darden, “Wind-Tunnel 

Investigation of the Validity of a Sonic-Boom-Minimization 

Concept,” NASA TP-1421 (October 1979), with figure 3-4 

extracted from page 22. The earlier paper was presented at an AIAA 

conference in Seattle on March 12–14, 1979, as “Some Effects of 

Applying Sonic Boom Minimization to Supersonic Cruise Aircraft 

Design,” AIAA paper no. 79-0652, and later published in Journal of 

Aircraft 17, no. 3 (March 1980): 182–186.

56. Christine M. Darden, “Sonic Boom Minimization with NoseBluntness Relaxation,” NASA TP 1348 (January 1979), 1.

57. Ibid., 4.

58. Ibid., 12.

59. Christine M. Darden, “Affordable/Acceptable Supersonic Flight: Is It 

Near?” 40th Aircraft Symposium, Japan Society for Aeronautical and 

Space Sciences (JSASS), Yokohama, October 9–11, 2002, 2.

60. Figure 3-5 extracted from Mack and Darden, “Wind-Tunnel 

Investigation of...Sonic-Boom-Minimization Concept,” NASA 

TP-1421, 26.

61. Robert Kelly, “Supersonic Cruise Vehicle Research/Business Jet,” in 

Supersonic Cruise Research ’79: Proceedings of a Conference Held at the 

Langley Research Center, Hampton, Virginia, November 13–16, 1979, 

NASA CP 2108, pt. 2, 935–944, quotation from page 935.

62. Ibid. Figure 3-6 extracted from page 945.
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Continuing the Quest

63. The Boeing Company, “Supersonic Cruise Research Airplane Study,” 

NASA CR 145212 (September 1977). This report does not appear 

in the NTRS database, but it is summarized by Domenic J. Maglieri 

in “Compilation and Review of Supersonic Business Jet Studies from 

1963 through 1995,” NASA CR 2011-217144 (May 2011). The 

proposal is also mentioned and illustrated in Spearman, “Evolution 

of the HSCT,” NASA TM 109089, 8, 41–42.

64. Conway, High-Speed Dreams, 180–188; Chambers, Innovations in 

Flight, 48.

65. Christine M. Darden, “Charts for Determining Potential Minimum 

Sonic-Boom Overpressures for Supersonic Cruise Aircraft,” NASA 

TP 1820 (May 1981).
88

F-16XL and SR-71 during in-flight shock wave measurements in 1995. (NASA)
89

CHAPTER 4

Resuming the Quest

High-Speed Research

For much of the next decade, the most active sonic boom research took place 

as part of the U.S. Air Force’s Noise and Sonic Boom Impact Technology 

(NSBIT) program. This was a comprehensive effort begun in 1981 to study the 

noise resulting from military training and operations, especially those involving 

environmental impact statements and similar assessments. Although NASA 

was not intimately involved with NSBIT, Domenic Maglieri (just before his 

retirement from Langley) and the recently retired Harvey Hubbard compiled 

a comprehensive annotated bibliography of sonic boom research, organized 

into 10 major subject areas, to help inform NSBIT participants of the most 

relevant sources of information.1

One of the noteworthy achievements of the NSBIT program was building a detailed sonic boom database (known as Boomfile) on U.S. supersonic 

aircraft, first by flying them over a large array of newly developed sensors at 

Edwards AFB in the summer of 1987.2 Called Boom Event Analyzer Recorders 

(BEARs), these unattended devices captured the full sonic boom waveform in 

digital format.3 Other contributions of NSBIT were the long-term sonic boom 

monitoring of air combat training areas, continued assessment of structures 

exposed to sonic booms, studies on the effects of sonic booms on livestock 

and wildlife, and intensified research on focused booms (long an issue with 

maneuvering fighter aircraft).4 Although Harry Carlson’s simplified boom prediction program worked well for straight and level flights, the Air Force Human 

Systems Division at Wright-Patterson AFB attempted to supplement it in 1987 

with a companion program called PCBoom to predict these focused booms. 

Its ray-tracing routines were adapted from a proposed mainframe computer 

program called BOOMAP2 to run on the basic desktop computers of the late 

1980s.5 Both programs were based on Albion D. Taylor’s Tracing Rays and 

Aging Pressure Signatures (TRAPS) program, which adapted the ARAP code 

to account for caustics and focused booms.6

 Kenneth Plotkin later achieved 

this goal using the waveform parameter code of the Ames Research Center’s 

Charles Thomas (described in the previous chapter) to create the widely used 
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Quieting the Boom

PCBoom3. In one interesting application of sonic boom focusing that was first 

envisioned in the 1950s, fighter pilots were successfully trained to lay down 

super booms at specified locations.7

SST Reincarnated: 

Birth of the High-Speed Civil Transport

By the mid-1980s, the growing economic importance of nations in Asia was 

drawing attention to the long flight times required to cross the Pacific Ocean 

from North America or to reach most of Asia from Europe. Meanwhile, in the 

face of growing competition from Europe and Japan for high-tech exports, the 

White House reversed its initial opposition to funding civilian aeronautical 

research. As part of this new policy, in March 1985, the Office of Science and 

Technology (OST) released a report, “National Aeronautical R&D Goals: 

Technology for America’s Future,” that included renewed support for a longrange supersonic transport.8

 Then, in his State of the Union address of January 

1986, President Reagan ignited interest in the possibility of even a hypersonic 

transport—the National Aero-Space Plane (NASP)—dubbed the “Orient 

Express.” In April the Battelle Memorial Institute established the Center for 

High-Speed Commercial Flight, which became a focal point and influential 

advocate for these proposals.9

NASA had been working behind the scenes with the Defense Advanced 

Research Projects Agency on the hypersonic technology that led to the NASP 

since the early 1980s. In February 1987, the OST issued an updated report 

on National Aeronautical R&D Goals subtitled “Agenda for Achievement,” 

with an eight-point strategy for sustaining American leadership in aviation. 

It called for aggressively pursuing the NASP and developing the “fundamental technology, design, and business foundation for a long-range supersonic 

transport.”10 In response, NASA accelerated its hypersonic research and began 

a rejuvenated effort to help develop commercially viable supersonic technology. This started with contracts to Boeing and Douglas aircraft companies 

in October 1986 for market and feasibility studies, on what was now named 

the High-Speed Civil Transport (HSCT), accompanied by several internal 

NASA assessments. These studies soon ruled out hypersonic speeds (Mach 5 

and above) as being impractical for passenger service because of technological, 

operational, and cost considerations. Eventually, NASA and its industry partners, after considering speeds from Mach 1.8 to Mach 3.2, settled on a fairly 

modest cruise speed of Mach 2.4 (which would allow the use of conventional 

jet fuel).11 Although this would be only marginally faster than the Concorde, 

the HSCT was expected to double the Concorde’s range and carry three times 
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Resuming the Quest

as many passengers. For its part, the high-risk, single-stage-to-orbit NASP 

survived until 1994 as a NASA-DOD experimental program (designated the 

X-30), with its sonic boom potential studied by current and former NASA 

and Air Force specialists.12

The contractual studies on the HSCT emphasized the need to resolve 

environmental issues, especially the restrictions on cruising over land because 

of sonic booms, before it could meet the goal of economically viable longdistance supersonic passenger service. As a first step toward this objective, 

Langley hosted a workshop on the status of sonic boom physics, methodology, and understanding on January 19 and January 20, 1988. Coordinated 

by Christine Darden, 60 representatives from Government, academia, and 

industry attended—including many who had been involved in the SST and 

SCR efforts and several from the Air Force’s NSBIT program. Princeton’s 

Wallace Hayes led a working group on theory, Cornell’s Albert George led one 

on minimization, Pennsylvania State University’s Allan D. Pierce led one on 

atmospheric effects, and Langley’s Clemans A. Powell led a group on human 

response. Panels of experts from each of the working groups determined that 

the following areas most needed more research: boom carpets, focused booms, 

high-Mach predictions, atmospheric effects, acceptability metrics, signature 

prediction, and low-boom airframe designs. The report from this workshop 

served as a baseline on the latest knowledge about sonic booms and some of the 

challenges that lay ahead. As regards aerodynamics, it was recognized that the 

high-drag paradox (figure 3-2) would have to be resolved before a supersonic 

transport could be both quiet and efficient.13

Phase I of the High-Speed Research Program

While Boeing and Douglas were reporting on early phases of their HSCT 

studies, Congress approved an ambitious new High-Speed Research (HSR) 

program in NASA’s budget for FY 1990. This effort envisioned Government 

and industry sharing the cost with NASA taking the lead for the first several 

years and industry expanding its role as research progressed. Because of the 

intermingling of sensitive and proprietary information, much of the work done 

during the HSR program was protected by a limited distribution system and 

some has yet to enter the public domain (or this book). Although the aircraft 

companies were making some progress on lower-boom concepts for the HSCT, 

they identified the need for more sonic boom research by NASA, especially on 

public acceptability and minimization techniques, before they could design a 

practical HSCT quiet enough to cruise over land without unacceptable performance penalties.14
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Quieting the Boom

Because solving environmental issues would be a prerequisite to developing 

the HSCT, NASA structured the HSR program into two phases. Phase I—

focusing on engine emissions, noise around airports, and sonic booms as well as 

preliminary design work—was scheduled for 1990 to 1995. Among the objectives of Phase I were predicting HSCT sonic boom signatures, determining 

feasible reduction levels, and finding a scientific basis on which to set acceptability criteria. After, ideally, making sufficient progress on the environmental 

problems, Phase II would begin ramping up in 1994. With more industry 

participation and greater funding, it would focus on economically realistic 

airframe and propulsion technologies and, it was hoped, extend until 2001.15

NASA convened its first workshop for the entire High-Speed Research 

program in Williamsburg, VA, from May 14 to May 16, 1991. Because of the 

sensitivity and proprietary nature of much of the information, attendance was 

by invitation only. Thirteen separate sessions covered every aspect of high-speed 

flight with 86 of the papers presented published subsequently with limited 

distribution. Robert Anderson of NASA’s Aeronautics Directorate opened the 

meeting by noting that the market for an environmentally acceptable, technically feasible, and economically viable HSCT might be as high as 300,000 

passengers per day by 2000. But as a cautionary reminder on the challenges 

that lay ahead, he quoted from Ed McLean’s portrayal of previous programs:16

Past experience indicates that there will be little room for design 

compromises in the development of a successful SST. To meet the 

stringent environmental constraints of noise, sonic boom, and 

pollution in a safe, economically competitive SST will require 

the best possible combination of aerodynamic, structural, and 

propulsion technologies...integrated into a congruent airplane 

that meets all mission requirements.

A NASA Headquarters status report specifically warned that “the importance of reducing sonic boom cannot be overstated.”17 The stakes for the 

HSCT were high. One of the Douglas studies had projected that even by 

2010, overwater-only routes would account for just 28 percent of long-range 

air traffic; but with supersonic overland cruise, the proposed HSCT could 

capture up to 70 percent of all such travel. Yet despite widespread agreement 

on the inherent advantages of a low-boom airliner, NASA’s detailed programmanagement flowcharts included periodic decision points on whether or not 

to continue including sonic boom minimization as an essential criterion for the 

HSR designs. Based on previous efforts, the study admitted that research on 

low-boom designs “is viewed with some skepticism as to its practical application. Therefore an early assessment is warranted.”18
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As it is made evident by 15 of the presentations, NASA, its contractors, 

academic grantees, and the manufactures were already busy conducting a wide 

range of sonic boom research and minimization projects, including the longpostponed issue of human response. The main goals were to demonstrate a 

waveform shape that would be acceptable to the general public, to prove that 

a viable airplane could be built to generate such a waveform, to determine 

that such a shape would not be too badly disrupted during its propagation 

through the atmosphere, and to estimate that the economic benefit of overland 

supersonic flight would make up for any performance penalties imposed by a 

low-boom design.19

During the next 3 years, NASA and its partners went into a full-court press 

against the sonic boom.20 They began several dozen major experiments and 

studies, results of which were published in reports and presented at several 

workshops dealing solely with the sonic boom. These were held at the Langley 

Research Center in February 1992,21 the Ames Research Center in May 1993,22

Langley in June 1994,23 and again at Langley in September 1995.24 These 

meetings, like the HSR’s sonic boom effort itself, were organized into three 

major areas of research: (1) configuration design and operations (managed by 

Langley’s Advanced Vehicles Division), (2) atmospheric propagation, and (3) 

human acceptability (both managed by Langley’s Acoustics Division). The 

reports from these workshops were well over 500 pages long and included 

dozens of papers on the progress or completion of various projects, experiments, and research topics.25

The HSR program precipitated major advances in the design of supersonic 

configurations even for reduced sonic boom signatures. Many of these advances 

were made possible by the rapidly expanding field of computational fluid 

dynamics. With CFD, engineers and researchers were now able to use complex 

Figure 4-1. Structure and scope of HSR sonic boom studies. (NASA)
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Quieting the Boom

Christine Darden (second from left) and Robert Mack (right) examining a 12-inch low-boom 

HSCT model with Matthew Overholt and Kathy Needleman. (NASA)

computational algorithms processed by supercomputers and parallel computers to calculate the nonlinear aspects of near-field shock waves, including the 

Navier-Stokes equations, even at high Mach numbers and angles of attack. 

Results could be graphically displayed in mesh and grid formats that emulated 

three dimensions. (In simple terms: before CFD, the nonlinear characteristics 

of shock waves generated by a realistic airframe had involved far too many 

variables and permutations to calculate by conventional means.)

The great progress that had been made in recent years was already evident at the 1991 HSR Workshop’s session on Sonic Boom and Aerodynamic 

Performance, which included minimization strategies. At Langley, Christine 

Darden, Robert Mack, and Raymond Barger—among the few to remain 

actively involved in sonic boom minimization ever since the demise of the SCR 

program—had recently been joined by talented new researchers, such as Peter 

G. Coen. With the help of a new computer program for predicting sonic booms 

devised by Coen,26 Langley’s 11-person design team applied two theoretical 

approaches and an iterative process of modifications to build two 12-inch wind 

tunnel models of HSCT-size airframes, including engine nacelles, intended 

to combine reduced sonic boom signatures with aerodynamic efficiency. One 

was designed for Mach 3 cruising at 65,000 feet and the other for cruising at 

Mach 2 and 55,000 feet.27
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The finished models were first tested during October 1990 in the 9-foot-by7-foot and 8-foot-by-7-foot supersonic sections of the Ames Research Center’s 

very busy Unitary Plan Wind Tunnel, which allowed pressure measurements 

out to between five and six body lengths. With extrapolations confirmed 

for closer distances, they were then able to use the much tighter confines of 

Langley’s 4-foot-by-4-foot Unitary Plan Wind Tunnel for additional experiments during the next 3 months with a specially made sting (the connecting 

device upon which a wind tunnel model is affixed) and angle-of-attack mounting mechanism. The tests found excellent agreement between the forward part 

of the extrapolated wind tunnel measurements and the predicted sonic boom 

signatures, and they validated the theory-derived design process, especially 

for the Mach 2 model. There were some disappointments. For example, even 

using 12-inch models, the openings to the nacelles proved too small to allow 

a sufficient airflow to pass through them at Ames, so they were removed for 

the testing at Langley.28

Exploiting the CFD Revolution

Although using the latest in wind tunnel technology, the limitations of these 

experiments also showed signs that a new era in sonic boom minimization 

research was dawning with the use of computational fluid dynamics. The wind 

tunnel tests revealed anomalies in the rear portions of the near-field pressure 

signatures caused by three-dimensional flows that could not be accounted for by 

the axisymmetric propagation methods. They also failed to reveal downstream 

shocks from the wings or capture the effects of exhaust plumes. CFD, on the 

other hand, indicated that these plumes might completely obscure the benefits 

of sonic boom shaping for Langley’s Mach 3 design cruising at 60,000 feet.29

In addition to being unable to model complex airframe geometries and the 

effects of propulsion systems, traditional linear supersonic aerodynamics based 

on wind tunnel experimentation as well as quasi-linear acoustic propagation 

theory—sometimes referred to as modified linear theory (MLT)—had difficulty with analysis of nonlinear three-dimensional effects near the aircraft and 

higher Mach numbers or angles of attack. These limitations would seriously 

hamper designing the new HSCTs for optimum performance and low sonic 

booms. The Ames Research Center, with its location in the rapidly growing 

Silicon Valley area, had been a pioneer in applying CFD capabilities to aerodynamics, especially after establishing the Numerical Aerodynamic Simulation 

Facility with a powerful new Cray supercomputer in 1987.30 At the 1991 HSR 

workshop, a report by the Ames sonic boom team led by Thomas Edwards 

and including modeling expert Samson Cheung predicted that “in many ways, 
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Quieting the Boom

CFD paves the way to much more rapid progress in boom minimization.... 

Furthermore, CFD offers fast turnaround and low cost, so high-risk concepts 

and perturbations to existing geometries can be investigated quickly.”31

The Ames researchers started off by using three previously tested supersonic models (a cone cylinder, a rectangular wing section, and a delta-winged 

airframe) to validate their new CFD codes for sonic boom predictions as well 

as those of several existing CFD programs. After obtaining good correlation 

of CFD and wind tunnel data, the Ames researchers concluded that “at this 

point it can be said without reservation that CFD can be used in conjunction with quasi-linear extrapolation methods to predict sonic booms in the 

near and far field accurately.”32 The experimentation showed the importance 

of using precise airframe geometry and adequate grid resolution. Results also 

indicated that inviscid Euler flow analysis (i.e., without the need to account 

for laminar flow) was sufficient for accurate sonic boom predictions. After 

validating their CFD codes, they next began applying them to the two Langley 

models tested in the Ames 9-foot-by-7-foot wind tunnel (see above), work 

that was still ongoing at the time of the HSR workshop. Both Ames and 

Langley would use the HSCT as a demonstration project for analyses on 

massively parallel computers under NASA’s High Performance Computing 

and Communications Program (HPCCP).33

In a project sponsored by Christine Darden, Michael Siclari of the Grumman 

Corporate Research Center at Bethpage, NY, presented the results of applying 

a three-dimensional Euler code for multigrid-implicit marching, as modified 

to predict sonic boom signatures, from the two Langley HSCT models. (This 

new code accordingly was referred to as MIM3D-SB, or Multigrid Implicit 

Marching in Three Dimensions for Sonic Booms.) Stated as simply as possible, 

the code used a simple wave-drag geometry to input data, from which the computer calculated the propagation of shock waves from digitized replications of 

the models (with different length stings attached) in a series of more than 100 

steps, with each new step calculated from the results of prior steps. The program 

recorded the propagation of shock waves on three-dimensional adaptive mesh 

grids, featuring denser grid points near the aircraft and (for faster processing) a 

coarser adaptive grid pattern farther out on which additional data points were 

progressively marched a specified distance from the airframe. From there, a 

waveform parameter code (derived from that of Charles Thomas) extrapolated 

the near-field signatures through atmospheric conditions to the ground. Figure 

4-2 depicts a side view of one of the grid patterns used for Langley’s Mach 

3 model (just visible in the front apex of the grid system), swept back at the 

approximate angle of the shock waves to save computer time compared to a 

more complete grid system. Figure 4-3 shows the shock waves calculated on this 

grid network as pressure contours (something like they would appear in a wind 
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Resuming the Quest

tunnel shadowgraph). For 

visualizing the complex 

three-dimensional, coneshaped expansion of the 

shock waves on paper, this 

early CFD application 

could also display slices of 

the pressure waves. Figure 

4-4 shows the computed 

isobars in two vertical 

planes aft of the Mach 2 

model, clearly indicating the complexity of its 

flow pattern—something 

not really possible with a 

wind tunnel. To achieve 

signatures at three body 

lengths from the aircraft 

axis (which at supersonic 

speeds meant 12 to 15 

body lengths downstream 

of the aircraft) required 

approximately 2 million 

data points.34

At the 1992 sonic boom workshop, Darden and Mack admitted how recent 

experiments at Langley had revealed limitations in using near-field wind tunnel 

data for extrapolating sonic boom signatures.35 During this and the two subsequent sonic boom workshops and at other venues, experts from Ames, Langley, 

and their contractors reported optimistically on the potential of new CFD 

computer codes to help design configurations optimized for constrained sonic 

booms and aerodynamic efficiency. In another potential application of CFD, 

former Langley researcher Percy “Bud” Bobbitt, who had joined Domenic 

Maglieri at Eagle Engineering, pointed out the potential of hybrid laminar flow 

control (HLFC) for both aerodynamic and low-boom purposes.36

Even the numbers-crunching capabilities of the supercomputers of that era 

were not yet powerful enough for CFD codes and the grids they produced to 

accurately depict effects much beyond the near field, but the use of massively 

parallel computing held the promise of eventually being able to do so. It was 

becoming apparent that, for most aerodynamic purposes, CFD was the design 

tool of the future, with wind tunnel models becoming more a means of verification. As predicted by Ames researchers in 1991, “the role of the wind tunnel in 

Figure 4-2. Side view of 

MIM3DSB grid topology for 

Mach 3 HSCT model. (NASA)

Figure 4-3. Pressure 

contours from Mach 3 HSCT 

model. (NASA)

Figure 4-4. Isobars showing propagation of midfield pressure 

patterns downstream from Mach 2 HSCT model. (NASA)
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Quieting the Boom

low-boom model design is to benchmark progress at significant intermediate 

stages and at the final design point of numerical model development.”37

By the second sonic boom workshop in February 1992, there were already 

signs of progress in applying CFD methods for predicting sonic boom signatures. Both Susan Cliff of Ames and Michael Siclari of Grumman included 

the effects of engine nacelles in analyses of the Langley Mach 2 and Mach 3 

configurations and a Boeing Mach 1.7 design. Cliff described lessons learned 

doing analyses with the Three-dimensional Euler/Navier-Stokes Aerodynamic 

Method (TEAM) and a faster Euler code-based program called AIRPLANE 

that relied on an unstructured tetrahedral mesh to calculate pressure signatures, including those from the nacelles that had defied wind tunnel measurements.38 Siclari followed up on his earlier work using the efficient multiblock 

Euler marching code (MIM3D-SB) with Grumman’s innovative mesh technology. It was able to calculate accurate three-dimensional pressure footprints 

at one body length (using 1.9 million grid points) and extrapolate them to 

the ground by using a linear waveform parameter method (derived from that 

of Charles Thomas). Besides the nacelles themselves, his modeling included 

an engine exhaust simulation to predict the effects of the plumes on the sonic 

boom signatures. As can be seen from the graphics printed out from one of 

these exercises in figure 4-5, the state of the art in CFD during the early 1990s 

was advancing rapidly.39 Unfortunately, it would not yet progress enough 

to design a low-boom but also aerodynamically 

efficient supersonic transport.

Among a dozen other aerodynamic papers at 

the 1992 workshop, the work by Samson Cheung 

and Thomas Edwards reported on progress in their 

CFD modeling using the UPS3D parabolized 

(simplified) Navier-Stokes code and a hyperbolic 

(curved in three dimensions) grid-generation 

scheme for minimization purposes. They were 

able to improve the lift-to-drag ratio for a simplified model of Boeing’s baseline low-boom HSCT 

configuration (without nacelles or a complete tail 

assembly) by almost 4 percent while at the same 

time extrapolating a quieter flattop signature. To 

save expensive computer time, they relied on a 

course grid for their design work and only ran the 

end result on a fine grid to check for discrepancies.40

Despite the signs of rapid progress with CFD, 

designing low-boom characteristics into a practical airliner would not be easy. John Morgenstern 

Figure 4-5. Computational 

grid and resulting pressure 

contours from the wings and 

nacelles on Langley’s Mach 3 

HSCT configuration. (NASA)
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described McDonnell Douglas’s strategy, after exploring numerous configurations, to optimize its HSCT for efficient Mach 2.4 cruising over water while 

slowing down to Mach 1.8 for reduced sonic boom over land.41 In something 

of a reality check, veteran sonic boom specialist George Haglund and a Boeing 

colleague described analyses of their company’s two low-boom designs: “Since 

L/D alone is not a good measure of airplane performance, each airplane was 

evaluated in sufficient depth to determine an operating empty weight...and 

maximum takeoff weight...for a 5000 n mi. mission [to allow] a meaningful 

performance comparison to a conventional baseline configuration.” Although 

meeting some objectives, they found that “achieving a practical HSCT lowboom configuration with low drag, high payload, and good performance is a 

formidable design problem.”42

Documentation of the work on configuration design and analysis presented 

at the Ames sonic boom workshop in 1993 is not publicly available; therefore, the papers presented at the Langley workshop in 1994 represent 2 years’ 

worth of progress, especially in applying CFD techniques. By then, results 

were in from an Ames experiment comparing computational fluid dynamics 

with traditional, modified linear theory for predicting sonic boom signatures, 

something that would be essential for designing HSCTs that could shape such 

signatures in the near, mid, and far fields. Although modified linear theory was 

well established, fast, and efficient, with an inverse design capability, it had 

trouble modeling the effects of complex geometries on pressure signatures. The 

limitations of CFD were not yet fully understood, but it did have the capability 

to do complex geometrical modeling—at the cost of expensive computer time.

To compare CFD with MLT, the Ames Computational Aerospace Branch 

selected a modified Boeing arrow-wing, low-boom configuration as a test case. 

They then evaluated several CFD techniques—UPS3D, AIRPLANE, and 

HFL03 (a Euler time-relaxation code)—along with results contributed by 

Grumman with its very efficient MIM3D-SB code and Boeing’s MLT techniques and ARAP-based extrapolations. Although calibration problems limited 

the use of wind tunnel data, the analysis found that all the CFD methods, 

although not consistent in their far-field pressure signatures, could more accurately predict the effects of lift and pitching as well as sonic booms as measured 

by perceived loudness (in decibels) at ground level. Measuring the effects of drag, 

however, was highly dependent on dense grid resolution. The results indicated 

that CFD predictions would continue to improve with experience.43

Eight more of the papers at the 1994 workshop described projects related 

to sonic boom minimization, most using CFD as well as wind tunnel analyses. 

As an example of the latter, Robert Mack reported some success in preventing 

the inlet shocks that had stymied previous experiments so as to obtain pressure signatures from four nacelles on a low-boom wind model in Langley’s 
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Quieting the Boom

Design Optimization Code

NPSOL

Evaluate Sonic Boom Objective 

Function/Gradient for Each 

Design Variable

Ground Extrapolation

Sonic Boom Signature

Thomas ANET Code

CFD Code/MIM3DSB 

Analysis

Near-Field Signatures

Aerodynamic Coefficients

Generate New Wave Drug 

Geometry Data Set

Replaces Specified Part of 

Geometry with Cubic Spline Fit

New Geometric 

Design Variables

Figure. 4-6. CFD design process for sonic boom minimization. (NASA)

4-foot-by-4-foot Unitary Plan Wind Tunnel.44 Meanwhile, Ames and Princeton 

researchers reported on using CFD to design an airframe that generated a type 

of multishock signature that might reach the ground with a quieter sonic boom 

than either the ramp or flattop wave forms that were a goal of traditional 

minimization theories.45 (Although not part of the HSCT effort, Ames and 

its contractors also used CFD to continue exploring the possible advantages of 

oblique-wing aircraft, including sonic boom minimization.)46 As an excellent 

case in point of how CFD was becoming more practical, Grumman’s Michael 

Siclari described how his NASA-sponsored MIM3D-SB code and numerical 

optimization techniques, coupled with an aerodynamic code (in this case, 

one called NPSOL), could now analyze wing-body configurations in a matter 

of minutes rather than hours of supercomputer time, making it efficient and 

economical enough to be practical as a design tool. As examples, he showed 

results of this automated process (depicted in figure 4-6) with four HSCT 

configurations.47

Even with the advances being made in designing airframes for lower sonic 

booms, the issue of overall performance was still a critical concern for the HighSpeed Research program. To get a better perspective on the relationship between 

sonic boom acceptability and other performance requirements, an eight-person 

team that included Donald Baize and Peter Coen from NASA Langley and 

former NASA intern Kathy Needleman from Lockheed Engineering & Sciences 

Company assessed eight of the current low-boom HSCT configurations against 

an unconstrained reference configuration. Predicated on some technologies 
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Resuming the Quest

projected to be available in 2005 

(e.g., advanced composite materials, aeroelastic tailoring, mixed-flow 

turbofan engines, and multipurpose 

displays), the team evaluated such 

factors as L/D ratios, fuel capacity 

and consumption, passenger payload, takeoff distance, gross weight, 

and mission block time. Under these 

criteria, all of the designs achieved 

a total gross weight per passenger 

only slightly higher than the reference configuration, but all were heavier than 

originally assumed and would require at least another design cycle to ensure 

successful low-boom shaping. As with studies dating back to the SST, the 

most highly swept wing planforms did not have enough lift at low speeds. 

Reinforcing previous aircraft company projections, being able to fly supersonic 

over land areas—even on relatively short segments of routes—offered better 

block time and therefore economic advantages. Figure 4-7, showing the lowboom HSCT configurations studied in this project, offers an excellent idea of 

the various design options being explored during the first phase of the HighSpeed Research program.48

Flight Tests and Acceptability Studies

Neither wind tunnels nor CFD could as yet empirically prove the physical 

persistence of a shaped waveform for more than a tiny fraction of the 200 

to 300 body lengths needed to represent the distance from an HSCT to the 

surface. To fill this credibility gap, Domenic Maglieri and a team at Eagle 

Engineering looked at various options for performing relatively economical 

flight tests by using remotely piloted vehicles (RPVs) modified for low-boom 

characteristics, a proposal presented at the 1991 HSR workshop.49 In 1992, 

they provided results of a feasibility study on the most cost-effective ways to 

verify design concepts with realistic testing. After exploring a wide range of 

alternatives, the team selected the Teledyne-Ryan BQM-34E Firebee II, which 

the Air Force and Navy had long used as a supersonic target drone. Four of 

these 28-foot-long RPVs, which could sustain a speed of Mach 1.3 at 9,000 

feet (300 body lengths from the surface), were available as surplus. Modifying 

them with low-boom design features such as specially configured 40-inch nose 

extensions (shown in figure 4-8) could provide far-field measurements needed 

to verify the waveform shaping projected by CFD and wind tunnel models.50

Figure 4-7. Eight low-boom HSCT configurations in the early 1990s. (NASA)
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Quieting the Boom

Figure 4-8. Proposed modifications and signatures of BQM-34E Firebee II. (NASA)

Meanwhile, a similar but more ambitious plan at the Dryden Flight 

Research Center led to NASA’s first significant sonic boom testing there 

since 1970. SR-71 program manager David Lux, atmospheric specialist L.J. 

Ehernberger, aerodynamicist Timothy R. Moes, and principal investigator 

Edward A. Haering came up with a proposal to demonstrate CFD design 

concepts by having one of Dryden’s SR-71s modified with a low-boom configuration. As well as being much larger, faster, and higher flying than the 

little Firebee (thereby more closely emulating the HSCT), an SR-71 would 

also allow easier acquisition of near-field measurements for direct comparison 

with CFD predictions.51

To lay the groundwork for this modification, Dryden personnel gathered 

baseline data from a standard SR-71 using one of its distinctive “cranked arrow” 

(double angle delta-winged) F-16XL aircraft (shown in a photograph preceding 

this chapter). Built by General Dynamics in the early 1980s for evaluation by 

the Air Force as a long-range strike version of the short-range F-16 fighter, the 

elegant F-16XL had lost out to the rival McDonnell Douglas F-15E Strike 

Eagle, which had even greater range and payload capability. 

In tests at Edwards during July 1993, the F-16XL, flown by Dryden test 

pilot Dana Purifoy, probed as close as 40 feet below and behind an SR-71 

cruising at Mach 1.8 to collect near-field pressure measurements.52 Langley 

and McDonnell Douglas analyzed this data, which had been gathered using a 

standard flight-test nose boom. Both reached generally favorable conclusions 

about the ability of high-order CFD and McDonnell Douglas’s proprietary 

MDBOOM program to serve as design tools.53 Kenneth Plotkin and Juliet Page 

of Wyle Labs had developed MDBOOM from a focus version of the Thomas 

code that Plotkin and a colleague developed in 1976.54 (This focus code was also 

adapted for PCBoom3, which replaced the original TRAPS-based PCBoom.)55
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Based on these results, a team led by low-boom aerodynamicist John 

Morgenstern at McDonnell Douglas Aerospace West designed modifications 

to alter the bow and middle shock waves of the SR-71 by reshaping the front 

of the airframe with a nose glove and adding to the midfuselage cross section as 

partially illustrated in figure 

4-9. (In this figure, M∞

denotes Mach number and 

α denotes angle of attack.) 

An assessment of these 

modifications by Lockheed 

Engineering & Sciences 

Company found them feasible.56 The next step—a big 

one—would be to obtain 

the considerable funding 

that would be needed for the 

modifications and testing.

In May 1994, Dryden used two of its fleet of F/A-18 Hornets to measure 

how near-field shock waves merged to assess the feasibility of a similar low-cost 

experiment in waveform shaping using two SR-71s. Flying at Mach 1.2 with 

one aircraft below and slightly behind the other, the first experiment positioned 

the canopy of the lower F/A-18 in the tail shock extending down from the 

upper F/A-18 (called a tail-canopy formation). The second experiment had 

the lower F/A-18 fly with its canopy in the inlet shock of the upper F/A-18 

(an inlet-canopy formation). Ground sensor recordings revealed that the tailcanopy formation caused two separate N-wave signatures, but the inlet-canopy 

formation yielded a single modified signature, which two of the recorders measured as a flattop waveform. This low-cost technique, however, presented safety 

issues. Even with the excellent visibility from the F/A-18’s bubble canopy (one 

pilot used the inlet shock wave as a visual cue for positioning the aircraft) and 

its responsive flight controls, maintaining such precise positions was still not 

easy. The pilots recommended against doing the same with SR-71s considering 

their larger size, slower response, and limited cockpit visibility.57

Atmospheric effects had long posed many uncertainties in understanding 

sonic booms, but advances in acoustics and atmospheric science since the SCR 

program promised better results. Not only did the way air molecules absorb 

sound waves need to be better understood but so did the old issue of turbulence. In addition to using the Air Force’s Boomfile and other available material, 

Langley’s Acoustics Division had Eagle Engineering, in a project led by Domenic 

Maglieri, restore and digitize data from the irreplaceable XB-70 records.58

Figure 4-9. Proposed SR-71 low-boom modification. (NASA)
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Quieting the Boom

Historic schlieren photograph of shock waves from a T-38 flying Mach 1.1 at 13,000 feet. (NASA)

The Acoustics Division, assisted by Lockheed Engineering & Sciences 

Company, also took advantage of the NATO Joint Acoustic Propagation 

Experiment (JAPE) at the White Sands Missile Range in August 1991 to 

do some new flight testing. The researchers arranged for Air Force F-15, 

F-111, and T-38 aircraft and one of Dryden’s SR-71s to make 59 supersonic 

passes over an extensive array of BEAR and other recording systems as well 

as meteorological sensors—both early in the morning (when the air was 

still) and during the afternoon (when there was usually more turbulence).59

Although meteorological data was incomplete, results later showed the effects 

of molecular relaxation and turbulence on both the rise time and overpressure 

of bow shocks.60 Henry Bass of the University of Mississippi, a key participant 

in the JAPE, was an important researcher on the acoustics of turbulence. 

Another academic researcher, David Blackstock of the University of Texas, 

and his graduate students also discovered more new effects of turbulence 

as well as other atmospheric instabilities on sonic booms, some of these 

by using innovative laboratory experiments.61 Starting with the first HSR 

workshop, NASA and NASA-sponsored researchers, such as Allan D. Pierce 

of Penn State University, began producing a variety of papers on waveform 

freezing (persistence), measuring diffraction and distortion of sound waves, 
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and trying to ascertain the complex relationship among molecular relaxation, 

turbulence, humidity, and other weather conditions.62

For better visualizing sonic booms, Leonard Weinstein of Langley even 

developed a way to capture stunning images of actual shock waves in the real 

atmosphere. He did this using a ground-based schlieren imaging system (a 

specially masked and filtered tracking camera with the sun providing backlighting). As shown in the accompanying photo, this was first demonstrated 

in December 1993 with a T-38 flying just over Mach 1 at Wallops Island.63

All of the research into the theoretical, aerodynamic, and atmospheric 

aspects of sonic booms—no matter how successful—would not protect the 

High-Speed Research program from the Achilles’ heel of previous efforts: 

the subjective responses of human beings. As a result, Langley, led by Kevin 

Shepherd of the Acoustics Division with researchers such as Brenda Sullivan, 

Jack Leatherwood, and David McCurdy, began a systematic effort to measure 

human responses to different strengths and shapes of sonic booms to help 

determine acceptable levels. As an early step, the division built an airtight, 

foam-lined sonic boom simulator booth (known as the boom box) derived 

from a similar apparatus at the University of Toronto. Using the latest in 

computer-generated digital-amplification and loudspeaker technology, it was 

capable of generating shaped waveforms up to 4 psf and 140 decibels (dB). 

Based on responses from subjects, researchers selected the perceived-level decibel (PLdB) as the preferred metric. For responses outside a laboratory setting, 

the NASA Langley team planned several additional acceptance studies.64

By 1994, early results had become available from two of these human-response 

projects. Langley and Wyle Laboratories had developed mobile boom-simulator 

equipment for what was called the In-Home Noise Generation/Response System 

(IHONORS). Depicted in figure 4-10, it consisted of computerized sound systems installed in 33 houses for 8 weeks 

at a time in a network connected by 

modems to a monitor at Langley. From 

February 1993 to December 1993, 

these households were subjected to 

almost 58,500 randomly timed sonic 

booms of various signatures for 14 

hours a day. Although definitive analyses were not available until the following year, the initial results confirmed 

how the level of annoyance increased 

whenever subjects were startled or 

trying to rest.65 Figure 4-10. Schematic of the In-Home Noise 

Generation/Response System. (NASA)
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Quieting the Boom

Preliminary results were also in from the first phase of the Western USA 

Sonic Boom Survey of civilians who had been exposed to such sounds for many 

years. This part of the survey took place in remote desert towns and settlements 

located around the Air Force’s vast Nellis combat training range complex in 

Nevada. Unlike previous community surveys, it correlated citizen responses 

to accurately measured sonic boom signatures (using BEAR devices) in places 

where booms were a regular occurrence yet where the subjects did not live on 

or near a military installation (where the economic benefits of the base to the 

local economy might influence their opinions). Although findings were not 

yet definitive, these 1,042 interviews proved more decisive than any of the 

many other research projects in determining the future direction of the HSCT 

effort. Based on a metric called day-night average noise level, the respondents 

found the booms much more annoying than previous studies on other types 

of aircraft noise even at the levels projected for low-boom designs. Their negative responses, in effect, dashed hopes that the HSR program might lead to an 

acceptable overland supersonic transport.66

HSR Phase II: Surrendering Again to the Sonic Boom

Well before the paper on this survey was presented at the 1994 Sonic Boom 

Workshop, its early findings had prompted NASA Headquarters to reorient 

the High-Speed Research program toward an HSCT design that would fly 

supersonic only over water. Just as with the AST program 20 years earlier, this 

became the goal of Phase II of the HSR program (which began with the help 

of FY 1994 funding left over from the canceled NASP).67 Once again, public 

annoyance with the sonic boom had proved too big an obstacle for even a new 

generation of aeronautical technology to overcome. The revamped HSR program would continue intensive supersonic research for the rest of the decade, 

but after Boeing’s absorption of McDonnell Douglas in 1996, this single company’s continued willingness to invest in the program became crucial.

At the end of the 1994 workshop, Christine Darden discussed the progress 

and lessons learned to date as well as the next steps for sonic boom research. 

Regarding progress, she said, “tremendous advances in supercomputers, gridding schemes, and computational algorithms have allowed computational fluid 

dynamics...to become a new tool in the prediction of near field sonic-boom 

signatures.”68 Although major improvements were still needed in correlating 

this nonlinear data with the linear methodology used for effects in the midand far-fields, several achievements were already in evidence. In addition to 

the benefits of CFD for design concepts and analysis of near-field shock wave 

signatures, these achievements included improved F-function analysis and 
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methods to predict inlet shocks, increased use of nonlinear corrections for 

modified linear theory techniques, minimization theories for cambered wing 

bodies, measurements of flow-through nacelles on wind tunnel models, and 

improving some performance criteria of low-boom concepts to within 3 percent of unconstrained baseline configurations.69

While the lower-boom design efforts had shown outstanding progress, 

management of this effort had not been ideal. Dispersal of the work among 

two NASA centers and two major aircraft manufacturers had resulted in communication problems as well as a certain amount of unhelpful competition 

(presumably among the contractors as well as between Langley and Ames). The 

milestone-driven HSR effort required concurrent progress in various technical 

and scientific areas, which is inherently difficult to coordinate and manage. 

And even if low-boom airplane designs had been improved enough to meet 

acoustic criteria, they would have been heavier and performed more poorly at 

slow speeds than unconstrained designs.70

Under the new HSR strategy, any continued minimization research was 

now aimed at lowering the sonic boom of the baseline overwater design while 

propagation studies would concentrate on predicting boom carpets, focused 

booms, secondary booms, and ground disturbances. In view of the HSCT’s 

overwater mission, new environmental studies would devote more attention 

to the potential penetration of shock waves into water and the effects of sonic 

booms on the marine mammals and birds that might be affected.71 Concorde 

operations had revealed no such problems, but since the HSCT would be about 

twice the weight but only 50 percent longer, the sonic boom overpressures 

generated by the baseline designs would tend to be about 50 percent higher. As 

a result, aerodynamicists such as Robert Mack of Langley, John Morgenstern 

of McDonnell Douglas, George Haglund of Boeing, and Michael Siclari of 

Grumman (which merged with Northrop Corporation in April 1994) turned 

their attention to minor modifications that could reduce this level with only 

minimal performance penalties.72

Although the preliminary results of the first phase of the Western USA 

Survey had already had a decisive impact, Wyle Laboratories completed the 

second phase with a similar polling of civilians in Mojave Desert communities 

exposed regularly to sonic booms, mostly from Edwards AFB and China Lake 

Naval Air Station. Surprisingly, this phase of the survey found the Californians 

there much more amenable to sonic booms than the less tolerant desert dwellers 

in Nevada, but they were still more annoyed by booms than by other aircraft 

noise of comparable perceived loudness.73

With the decision to end work on a low-boom HSCT, the proposed modifications of the Firebee RPVs and SR-71 had of course been canceled (postponing for another decade the first live demonstrations of boom shaping). 
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Nevertheless, some flight testing that would prove of future value continued 

to be conducted. From February 1995 through April 1995, the Dryden Flight 

Research Center conducted more SR-71 and F-16XL sonic boom flight tests. 

Led by Ed Haering, this experiment included an instrumented YO-3A light 

aircraft from Ames, an extensive array of various ground sensors, a network 

of new differential Global Positioning System receivers accurate to within 12 

inches, and installation of a sophisticated new nose boom with four pressure 

sensors on the F-16XL.74

On eight long missions, one of Dryden’s SR-71s flew at speeds between 

Mach 1.25 and Mach 1.6 at 31,000 feet to 48,000 feet while the F-16XL 

(kept aloft by in-flight refuelings) made numerous near- and midfield measurements of bow, canopy, inlet, wing, and tail shock waves at distances 

from 80 feet to 8,000 feet. Some of 

these showed that the canopy shock 

waves were still distinct from the 

bow shock after 4,000 feet to 6,000 

feet. Comparisons of far-field measurements obtained by the YO-3A 

flying at 10,000 feet above ground 

level and the recording devices 

on the surface revealed effects of 

atmospheric turbulence. Analysis 

of the data validated two existing 

sonic boom propagation codes used 

for predicting far-field signatures 

(ZEPHYRUS and SHOCKN) and 

clearly showed how variations in the SR-71’s gross weight, speed, and altitude 

and atmospheric phenomena such as molecular absorption caused differences 

in shock wave patterns and their coalescence into N-shaped waveforms.75

Figure 4-11 depicts the participants and basic structure of these flight tests, 

which would serve as a precedent for others in the future.76

This innovative and successful experiment marked the end of dedicated 

sonic boom flight testing during the HSR program. Phase II testing focused 

on the many other issues involved in designing a practical, 320-foot-long, 

300-passenger, Mach 2.4 HSCT with a range of 5,000 nm that would fly only 

subsonically over land. For example, NASA’s creative partnership with Russia in 

using a Tu-144 as a supersonic laboratory from 1996 to 1999 did not include 

sonic boom measurements as originally planned.77

The last of the sonic boom workshops, held at Langley in September 1995, 

no doubt seemed rather anticlimactic for the 46 attendees in view of the new, 

less ambitious HSR goals for a high-speed civil transport. As with the SST and 

Figure 4-11. Measuring the evolution of shock 

waves from an SR-71. (NASA)
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SCR programs, however, their research—the latest of which would be published in a two-volume compendium—added greatly to the scientific knowledge and engineering skills that would be needed if and when another effort 

to develop a civilian supersonic airplane might be initiated.78 Several papers 

indicated that the behavior of shock waves and acoustic rays under a wide range 

of atmospheric conditions were now well understood.79 Yet the challenges in 

designing a practical airplane that could exploit this knowledge to control sonic 

boom signatures, especially in view of the disturbing new evidence collected 

on the sensitivity of human responses to them, were still daunting.80 Even with 

the rapid progress with computational fluid dynamics, results so far indicated 

the need for much more computing power and new techniques. As Kenneth 

Plotkin explained, “due to a combination of computational costs and numerical algorithms losing resolution after many steps, CFD cannot be brought all 

the way to the ground or even very many body lengths away from the aircraft.”81

Developing a high-speed civil transport ran into other barriers besides the 

sonic boom. By late 1998, the HSR program confronted a combination of 

economic, technological, political, and budgetary problems (including cost 

overruns for the International Space Station). The Boeing Company, now 

estimating that development of the HSCT would take $13 billion, cut its 

support, and the administration of President William J. Clinton, with the backing of NASA administrator Daniel S. Goldin, decided to terminate the HSR 

program at the end of FY 1999. Although other research programs picked up 

elements of the HSR, having to end it and a similar program for an Advanced 

Subsonic Transport deprived NASA of the focus these programs helped give 

to its aeronautical research.82 Ironically, NASA’s success in helping the aircraft 

industry develop quieter subsonic aircraft, which had the effect of moving 

the goal post for acceptable airport noise, was one of the factors convincing 

Boeing to drop plans for a supersonic airliner. Nevertheless, the High-Speed 

Research program was responsible for truly significant advances in technologies, techniques, and scientific knowledge, including a better understand of 

the sonic boom and ways to diminish it.83

To help identify areas for future research that might overcome the barriers to 

supersonic flight encountered by the HSR program, NASA in 2000 asked the 

National Research Council to conduct a comprehensive investigation of the relevant technologies that would be needed. The Council’s Aeronautics and Space 

Engineering Board formed an expert 14-person committee on breakthrough 

technologies to perform this task. Released in 2001, its in-depth study focused 

on “high-risk, high-payoff technologies where NASA research could make a 

difference over the next 25 years.”84 While advising that NASA “should have 

its eye on the grand prize—supersonic commercial transports,” the committee deemed it “quiet appropriate” for NASA to conduct sonic boom research 
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Quieting the Boom

related to supersonic business jets, which were increasingly seen as having 

a more realistic chance of meeting sonic boom requirements.85 Their study 

concluded with the following admonition:

If the United States intends to maintain its supremacy in the 

commercial aerospace sector, it has to take a long-term perspective and channel adequate resources into research and technology development. The technological challenges to commercial 

supersonic flight can be overcome, as long as the development of key 

technologies is continued. Without continued effort, an economically viable, environmentally acceptable, commercial supersonic 

aircraft is likely to languish.86
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Endnotes

1. Harvey H. Hubbard, Domenic J. Maglieri, and David G. Stephens, 

“Sonic-Boom Research—Selected Bibliography with Annotation,” 

NASA TM-87685 (September 1986).

2. Including F-4, F-14, F-15, F-16, F/A-18, F-111, T-38, and SR-71 

aircraft.

3. J. Micah Downing, “Lateral Spread of Sonic Boom Measurements 

from U.S. Air Force Boomfile Flight Tests,” in High-Speed Research: 

Sonic Boom—Proceedings of a Conference Held at Langley Research 

Center, Hampton, Virginia, February 25–27, 1992 1, NASA CR 

3172, 117–129. For a description, see Robert E. Lee and J. Micah 

Downing, “Boom Event Analyzer Recorder: The USAF Unmanned 

Sonic Boom Monitor,” AIAA paper no. 93-4431 (October 1993).

4. For example, see Kenneth J. Plotkin et al., “Sonic Boom 

Environment Under a Supersonic Military Operating Area,” Journal 

of Aircraft 29, no. 6 (November–December 1992): 1069–1072. 

(Study conducted at White Sands Missile Range, NM.)

5. Dwight E. Bishop, “Noise and Sonic Boom Impact Technology: 

PCBOOM Computer Program for Sonic Boom Research Technical 

Report,” 1, USAF, HSD-TR-88-014 (October 1988) (Defense 

Technical Information Center [DTIC] AD-A206290), 2–3; Plotkin 

and Maglieri, “Sonic Boom Research,” 6.

6. Albion D. Taylor, “The TRAPS Sonic Boom Program,” NOAA 

Technical Memorandum ERL ARL-87 (July 1980). In reviewing 

this chapter, Kenneth Plotkin pointed out Taylor’s contribution.

7. Micah Downing, Kenneth Plotkin, Domenic Maglieri et al., 

“Measurement of Controlled Focused Sonic Booms from 

Maneuvering Aircraft,” JASA 104, no. 1 (July 1998): 112–121.

8. Judy A. Rumerman, NASA Historical Data Book Volume VI: NASA 

Space Applications, Aeronautics, and Space Research and Technology, 

Tracking and Data Acquisition/Space Operations, Commercial 

Programs, and Resources, 1979–1988, NASA SP-2000-4012 

(Washington, DC: NASA, 2000), 177–178.

9. Conway, High-Speed Dreams, 201–215; Paul Proctor, “Conference 

[sponsored by Battelle] Cites Potential Demand for Mach 5 

Transports by Year 2000,” Aviation Week (November 10), 1986, 

42–46. Another potential use for a hypersonic transport was to economically deliver components of Reagan’s Space Defense Initiative 

into low orbit.
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10. Rumerman, NASA Historical Data Book, Volume VI, 178.

11. Conway, High-Speed Dreams, 218–228; Chambers, Innovations in 

Flight, 50.

12. Domenic J. Maglieri, Victor E. Sothcroft, and John Hicks, 

“Influence of Vehicle Configurations and Flight Profile on X-30 

Sonic Booms,” AIAA paper no. 90-5224 (October 29, 1990); 

Domenic J. Maglieri, “A Brief Review of the National Aero-Space 

Plane Sonic Booms Final Report,” USAF Aeronautical Systems 

Center TR 94-9344 (December 1992).

13. Christine Darden et al., Status of Sonic Boom Methodology and 

Understanding; Proceedings of a Workshop Sponsored by the National 

Aeronautics and Space Administration and Held at NASA Langley 

Research Center, Hampton, Virginia, January 19–20, 1988, NASA CP 

3027 (June 1989), 2–7.

14. Boeing Commercial Airplanes, “High-Speed Civil Transport Study; 

Final Report,” NASA CR 4234 (September 1989); Douglas Aircraft 

Company, “1989 High-Speed Civil Transport Studies,” NASA CR 

4375 (May 1991) (published late with an extension). For a summary 

of Boeing’s design process, see George T. Haglund, “HSCT Designs 

for Reduced Sonic Boom,” AIAA paper no. 91-3103 (September 

1991).

15. Allen H. Whitehead, ed., First Annual High-Speed Research 

Workshop; Proceedings of a Workshop Sponsored by the National 

Aeronautics and Space Administration, Washington, DC, and Held in 

Williamsburg, Virginia, May 14–16, 1991, NASA CP 10087 (April 

1992), pt. 1, 5–22, 202 (hereafter cited as 1991 HSR Workshop). 

Later sonic boom workshop titles will be similarly abbreviated with 

the year conducted. 

16. Robert E. Anderson, “First Annual HSR Program Workshop: 

Headquarters Perspective,” in Whitehead, 1991 HSR Workshop, 

pt. 1, 7, 20, quotation taken from McLean, Supersonic Cruise 

Technology, 6.

17. George Unger, “HSR Community Noise Reduction Technology 

Status Report,” in Whitehead, 1991 HSR Workshop, pt. 1, 272.

18. Ibid., 275.

19. Session V, “Sonic Boom (Aerodynamic Performance),” 665–810; 

Session IX, “Sonic Boom (Human Response and Atmospheric 

Effects,” in Whitehead, 1991 HSR Workshop, pt. 3, 1199–1366.

20. As examples of recent work at Langley, see Robert J. Mack and 

Kathy E. Needleman, “A Methodology for Designing Aircraft to 
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Low Sonic Boom Constraints,” NASA TM 4246 (February 1, 

1991); Kathy E. Needleman, Christine M. Darden, and Robert 

J. Mack, “A Study of Loudness as a Metric for Sonic Boom 

Acceptability,” AIAA paper no. 91-0496 (January 1991). 

21. Christine M. Darden, ed., High-Speed Research: Sonic Boom; 

Proceedings of a Conference Held at Langley Research Center, Hampton, 

Virginia, February 25–27, 1992, parts 1 and 2, NASA CR 3172 

(October 1992).

22. Thomas A. Edwards, ed., “High-Speed Research: Sonic Boom,” in

Proceedings of a Conference Sponsored by the National Aeronautics 

and Space Administration, Washington, DC, and Held at the Ames 

Research Center, Moffett Field, California, May 12–14, 1993, NASA 

CP 10132, 1. (The second volume, on configurations and design, 

including sonic boom minimization, has never been publicly 

released on the NTRS.)

23. David A. McCurdy, ed., “High-Speed Research: 1994 Sonic Boom 

Workshop, Atmospheric Propagation and Acceptability Studies, in

Proceedings of the Third High-Speed Research Sonic Boom Workshop, 

Hampton, Virginia, June 1–3, 1994, NASA CP 3209; “High-Speed 

Research: 1994 Sonic Boom Workshop: Configuration, Design, 

Analysis, and Testing,” in Proceedings of the Third High-Speed 

Research Sonic Boom Workshop, Hampton, Virginia, June 1–3, 1994, 

NASA CP 209669 (December 1999).

24. Daniel G. Baize, 1995 NASA High-Speed Research Program Sonic 

Boom Workshop: Proceedings of a Workshop Held at Langley Research 

Center, Hampton, Virginia, September 12–13, 1995, NASA CP 

3335 (July 1996); “Configuration, Design, Analysis, and Testing” 2, 

NASA CP 1999-209520 (December 1999).

25. For guidance in helping to choose which of the many research projects to cover, the author referred to Christine M. Darden, “Progress 

in Sonic-Boom Understanding: Lessons Learned and Next Steps,” 

1994 Sonic Boom Workshop, 269–292. Figure 4-1 is copied from 

page 270.

26. Peter G. Coen, “Development of a Computer Technique for 

Prediction of Transport Aircraft Flight Profile Sonic Boom 

Signatures,” NASA CR 188117 (March 1991) (based on M.S. thesis, George Washington University, Washington, DC.).

27. Christine M. Darden et al., “Design and Analysis of Low Boom 

Concepts at Langley Research Center,” 1991 HSR Workshop, pt. 2, 

676–679. Photo with HSCT model provided to author by Dr. Darden.
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28. Ibid., 680–698. 

29. Ibid., 685, 687, 693.

30. Kinney, “NASA and the Evolution of the Wind Tunnel,” in Hallion, 

NASA’s Contributions to Aeronautics 2, 346.

31. Thomas A. Edwards et al., “Sonic Boom Prediction and 

Minimization Using Computational Fluid Dynamics,” 1991 HSR 

Workshop, pt. 2, 728–732, quotation from 732.

32. Ibid., 732. The other CFD codes used were TRANAIR (a full potential code with local mesh refinement capability), TEAM (an Euler/

Navier-Stokes code with versatile zonal grid capability), AIRPLANE 

(an unstructured-grid Euler solver), and UPS (a parabolized Euler/

Navier-Stokes code).

33. Ibid., 736.

34. M.J. Siclari, “Sonic Boom Predictions Using a Modified Euler 

Code,” 1991 HSR Workshop, pt. 2, 760–784. Figures 4-2, 4-3, and 

4-4 extracted from 762, 766, and 772.

35. Robert J. Mack and Christine M. Darden, “Limitations on WindTunnel Pressure Signature Extrapolation,” 1992 Sonic Boom 

Workshop 2, 201–220.

36. Percy J. Bobbitt, “Application of Computational Fluid Dynamics 

and Laminar Flow Technology for Improved Performance and Sonic 

Boom Reduction,” 1992 Sonic Boom Workshop 2, 137–144.

37. Edwards et al., “Sonic Boom Prediction Using Computational Fluid 

Dynamics,” 1991 HSR Workshop, 732.

38. Susan E. Cliff, “Computational/Experimental Analysis of Three Low 

Sonic Boom Configurations with Design Modifications,” 1992 Sonic 

Boom Workshop 2, 89–118.

39. M.J. Siclari, “Ground Extrapolation of Three-Dimensional NearField CFD Predictions for Several HSCT Configurations,” 1992 

Sonic Boom Workshop 2, 175–200, with figure 4-5 copied from 192.

40. Samson H. Cheung and Thomas A. Edwards, “Supersonic Airplane 

Design Optimization Method for Aerodynamic Performance and 

Low Sonic Boom,” 1992 Sonic Boom Workshop 2, 31–44.

41. John M. Morgenstern, “Low Sonic Boom Design and Performance 

of a Mach 2.4/1.8 Overland High Speed Civil Transport,” 1992 

Sonic Boom Workshop 2, 55–63. 

42. George T. Haglund and Steven S. Ogg, “Two HSCT Mach 1.7 Low 

Sonic Boom Designs,” 1992 Sonic Boom Workshop 2, 65–88, quotations from 66 and 72.
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43. Eugene Tu, Samson Cheung, and Thomas Edwards, “Sonic Boom 

Prediction Exercise: Experimental Comparisons,” 1994 Sonic Boom 

Workshop: Configuration Design, Analysis, and Testing 2, 13–32.

44. Robert Mack, “Wind-Tunnel Overpressure Signatures from a LowBoom HSCT Concept with Aft-Mounted Engines,” 1994 Sonic 

Boom Workshop: Configuration Design, Analysis, and Testing 2, 59–70.

45. Susan E. Cliff et al., “Design and Computational/Experimental 

Analysis of Low Sonic Boom Configurations,” 1994 Sonic Boom 

Workshop: Configuration Design, Analysis, and Testing 2, 33–57. 

For a review of CFD work at Ames from 1989–1994, see Samson 

Cheung, “Supersonic Civil Airplane Study and Design: Performance 

and Sonic Boom,” NASA CR-197745 (January 1995).

46. Christopher A. Lee, “Design and Testing of Low Sonic Boom 

Configurations and an Oblique All-Wing Supersonic Transport,” 

NASA CR-197744 (February 1995).

47. Michael J. Siclari, “The Analysis and Design of Sonic Boom 

Configurations Using CFD and Numerical Optimization 

Techniques,” 1994 Sonic Boom Workshop 2, 107–128, figure 4-6 

extracted from 110.

48. Donald G. Baize et al., “A Performance Assessment of Eight LowBoom High-Speed Civil Transport Concepts,” 1994 Sonic Boom 

Workshop 2, 149–170, figure 4-7 copied from 155.

49. Domenic J. Maglieri, Victor E. Sothcott, Thomas N. Deffer, and 

Percy J. Bobbitt, “Overview of a Feasibility Study on Conducting 

Overflight Measurements of Shaped Sonic Boom Signatures Using 

RPV’s,” 1991 HSR Workshop, pt. 2, 787–807.

50. Domenic J. Maglieri et al., “Feasibility Study on Conducting 

Overflight Measurements of Shaped Sonic Boom Signatures Using 

the Firebee BQM-34E RPV,” NASA CR-189715 (February 1993). 

Figure 4-8 is copied from page 52, with waveforms based on a speed 

of Mach 1.3 at 20,000 feet rather than the 9,000 feet of planned 

flight tests.

51. David Lux et al., “Low-Boom SR-71 Modified Signature 

Demonstration Program,” 1994 Sonic Boom Workshop: Configuration, 

Design, Analysis and Testing 2, 237–248. 

52. Interview, Dana Purifoy by Lawrence Benson, Dryden Flight 

Research Center, April 8, 2011.

53. Wyle Laboratories developed MDBOOM to meld CFD with sonic 

boom prediction theory. J.A. Page and K.J. Plotkin, “An Efficient 
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Method for Incorporating Computational Fluid Dynamics into 

Sonic Boom Theory,” AIAA paper no. 91-3275 (September 1991).

54. Plotkin and Cantril, “Prediction of Sonic Boom at a Focus,” AIAA 

paper no. 76-2.

55. Kenneth Plotkin, Juliet Page, and J. Micah Downing, “USAF 

Single-Event Sonic Boom Prediction Model: PCBoom3,” 1994 

Sonic Boom Workshop 1, 171–184.

56. Edward H. Haering et al., “Measurement of the Basic SR-71 

Airplane Near-Field Signature, 1994 Sonic Boom Workshop: 

Configuration, Design, Analysis, and Testing, 171–197; John M. 

Morgenstern et al., “SR-71A Reduced Sonic Boom Modification 

Design,” 1994 Sonic Boom Workshop 2, 199–217; Kamran Fouladi, 

“CFD Predictions of Sonic-Boom Characteristics for Unmodified 

and Modified SR-71 Configurations,” 1994 Sonic Boom Workshop 2, 

219–235. Figure 4-9 is copied from 222.

57. Catherine M. Bahm and Edward A. Haering, “Ground-Recorded 

Sonic Boom Signatures of F/A-18 Aircraft in Formation Flight,” 

1995 Sonic Boom Workshop 1, 220–243.

58. J. Micah Downing, “Lateral Spread of Sonic Boom Measurements 

from US Air Force Boomfile Flight Tests,” 1992 Sonic Boom 

Workshop 1, 117–136; Domenic J. Maglieri et al., “A Summary 

of XB-70 Sonic Boom Signature Data, Final Report,” NASA CR 

189630 (April 1992).

59. William L. Willshire and David Chestnut, eds., “Joint Acoustic 

Propagation Experiment (JAPE-91) Workshop,” NASA CR 3231 

(1993).

60. William L. Willshire and David W. DeVilbiss, “Preliminary Results 

from the White Sands Missile Range Sonic Boom Propagation 

Experiment,” 1992 Sonic Boom Workshop 1, 137–144.

61. Bart Lipkens and David T. Blackstock, “Model Experiments to 

Study the Effects of Turbulence on Risetime and Waveform of N 

Waves,” 1992 Sonic Boom Workshop 1, 97–108; Robin O. Cleveland, 

Mark F. Hamilton, and David T. Blackstock, “Effect of Stratification 

and Geometrical Spreading on Sonic Boom Rise Time,” 1994 Sonic 

Boom Workshop 1, 19–38; Richard Raspet, Henry Bass, Lixin Yao, 

and Wenliang Wu, “Steady State Risetimes of Shock Waves in the 

Atmosphere,” 1992 Sonic Boom Workshop 1, 109–116. The author 

was alerted to the contributions of Bass and Blackwood by Kenneth 

Plotkin.
117

Resuming the Quest

62. Gerry L. McAnich, “Atmospheric Effects on Sonic Boom—A 

Program Review,” 1991 HSR Workshop, pt. 1, 1201–1207; Allan D. 

Pierce and Victor W. Sparrow, “Relaxation and Turbulence Effects 

on Sonic Boom Signatures,” 1991 HSR Workshop, pt. 1, 1211–1234; 

Kenneth J. Plotkin, “The Effect of Turbulence and Molecular 

Relaxation on Sonic Boom Signatures,” 1991 HSR Workshop, pt. 1, 

1241–1261; Lixin Yao et al., “Statistical and Numerical Study of the 

Relation Between Weather and Sonic Boom,” 1991 HSR Workshop, 

pt. 3, 1263–1284.

63. Leonard M. Weinstein, “An Optical Technique for Examining 

Aircraft Shock Wave Structures in Flight,” 1994 Sonic Boom 

Workshop, Atmospheric Propagation and Acceptability 1, 1–18. The 

following year, Weinstein demonstrated improved results using a 

digital camera: “An Electronic Schlieren Camera for Aircraft Shock 

Wave Visualization,” 1995 Sonic Boom Workshop 1, 244–258.

64. Kevin P. Shepherd, “Overview of NASA Human Response to Sonic 

Boom Program,” 1991 HSR Workshop, pt. 3, 1287–1291; Shepherd 

et al., “Sonic Boom Acceptability Studies,” 1991 HSR Workshop, pt. 

3, 1295–1311.

65. David A. McCurdy et al., “An In-Home Study of Subjective 

Response to Simulated Sonic Booms,” 1994 Sonic Boom Workshop: 

Atmospheric Propagation and Acceptability 1, 193–207; McCurdy and 

Sherilyn A. Brown, “Subjective Response to Simulated Sonic Boom 

in Homes,” 1995 Sonic Boom Workshop 1, 278–297, with figure 4-10 

copied from 279.

66. James M. Fields et al., “Residents’ Reactions to Long-Term Sonic 

Boom Exposure: Preliminary Results,” 1994 Sonic Boom Workshop: 

Atmospheric Propagation and Acceptability 1, 209–217.

67. Conway, High-Speed Dreams, 253.

68. Christine M. Darden, “Progress in Sonic-Boom Understanding: 

Lessons Learned and Next Steps,” 1994 Sonic Boom Workshop, 

Configuration, Design, and Testing 2, 272.

69. Ibid., 272–274.

70. Ibid., 275.

71. Ibid. 289–290.

72. 1995 Sonic Boom Workshop: Configuration, Design, Analysis, and 

Testing 2, NASA CP 1999-209520, 47–175.

73. James M. Fields, “Reactions of Residents to Long-Term Sonic Boom 

Noise Environments,” NASA CR-201704 (June 1997).
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Quieting the Boom

74. Edward A. Haering, L.J. Ehernberger, and Stephen A. Whitmore, 

“Preliminary Airborne Experiments for the SR-71 Sonic Boom 

Propagation Experiment,” 1995 Sonic Boom Workshop 1, 176–198.

75. Ibid., Stephen R. Norris, Edward A. Haering, and James E. Murray, 

“Ground-Based Sensors for the SR-71 Sonic Boom Propagation 

Experiment,” 1995 Sonic Boom Workshop 1, 199–218; Hugh W. 

Poling, “Sonic Boom Propagation Codes Validated by Flight Test,” 

NASA CR 201634 (October 1996).

76. Figure 4-11 copied from Edward A. Haering and James E. Murray, 

“Shaped Sonic Boom Demonstration/Experiment Airborne Data: 

SSBD Final Review,” PowerPoint presentation, August 17, 2004, 

slide no. 3.

77. Robert J. Mack, “A Whitham-Theory Sonic-Boom Analysis of 

the TU-144 Aircraft at Mach Number of 2.2,” 1995 Sonic Boom 

Workshop 2, 1–16. For a complete account of this cooperative project by one of the test pilots, see Robert A. Rivers, “NASA’s Flight 

Test of the Russian Tu-144 SST,” in Hallion, NASA’s Contributions to 

Aeronautics 2, 914–956.

78. Volume 1 of the 1995 NASA High-Speed Research Program Sonic 

Boom Workshop, published in July 1996 (without a subtitle) as 

CP-3335, covered theoretical and experimental sonic boom propagation, while the second volume, Configuration Design, Analysis, and 

Testing, was published in December 1999 as CP 1999-209520.

79. Ibid., 1, eight papers in Session 1 on atmospheric propagation 

effects, 1–175.

80. Ibid., 1, five papers in Session 3 on human response, 278–332.

81. Kenneth J. Plotkin, “Theoretical Basis for Finite Difference 

Extrapolation of Sonic Boom Signatures,” 1995 Sonic Boom 

Workshop: Configuration, Design, Analysis, and Testing 1, 55. 

82. Graham Warwick, “Cutting to the Bone,” Flight International (July 

17, 2001), accessed ca. June 15, 2011, http://www.flightglobal.com/

articles/2007/07/17/134122/cutting-to-the-bone.html.

83. Chambers, Innovations in Flight, 61–62; Conway, High-Speed 

Dreams, 286–300; James Schultz, “HSR Leaves Legacy of Spinoffs,” 

Aerospace America 37, no. 9 (September 1999): 28–32. The 

Acoustical Society held its third sonic-boom symposium in Norfolk 

from October 15–16, 1998. Because of HSR distribution limitations, many of the presentations could be oral only, but a few years 

later the ASA was able to publish some of them in a special edition 

of its journal. For a status report on one major spinoff at the end of 
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Resuming the Quest

the HSR, see Kenneth J. Plotkin, “State of the Art of Sonic Boom 

Modeling,” JASA 111, no. 1, pt. 3 (January 2002): 530–536.

84. National Research Council, Commercial Supersonic Technology: 

The Way Ahead (Washington, DC: National Academies Press, 

2001), 1, accessed ca. June 15, 2011, http://www.nap.edu/openbook.

php?record_id=10283.

85. Ibid.

86. Ibid., 43.
120

Image of Northrop Grumman’s QSP design concept. (NGC)
121

CHAPTER 5

The Quiet Supersonic Platform

Innovative Concepts and Advanced Technologies

With NASA’s High-Speed Research program having once again revealed how 

difficult it would be to design and produce a full-size airliner with a sonic boom 

quiet enough to fly over land, the alternative of small- or medium-size supersonic aircraft for civilian passengers began attracting more attention. One of 

the world’s top sonic boom experts was among those looking into this option. 

In November 1998, as the HSR program was winding down, Richard Seebass 

presented two papers on supersonic flight and the sonic boom at NATO’s 

von Kármán Institute in Belgium.1 One of his papers examined the general 

problems and prospects for commercial supersonic transports,2 while the other 

traced the history and current status of sonic boom minimization theory.3 In 

each of these and subsequent publications, he concluded by endorsing a less 

ambitious but more pragmatic way than the HSCT to surmount the sonic 

boom barrier: a supersonic business jet (SSBJ).

Making the Case for a Supersonic Business Jet

Although no company had yet to begin actual development of an SSBJ, the 

idea itself was not new. Fairchild Swearingen, McDonnell Douglass, LockheedCalifornia, and British Aerospace had all seriously looked at the possibility in 

the mid-1980s, and the fractional-ownership company NetJets had come to 

believe that an SSBJ would fit well with its business model.4

 Because smaller 

supersonic aircraft would inherently have a weaker sonic boom, Seebass was 

among those who became most interested in pursuing this concept.

At a 1995 NASA Langley workshop on transportation technologies beyond 

2000, Seebass helped Randall Greene, president of Aeronautical Systems 

Corporation, make a presentation on the market for and configuration of a 

proposed supersonic corporate jet. At 91 feet long and 66,000 pounds with a 

cranked-arrow wing similar to the F-16XL, this aircraft was designed to carry 

8 to 10 passengers 3,350 nautical miles at Mach 1.8. Greene predicted sales 
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of $1 billion a year for the plane, which he optimistically hoped (with enough 

outside financial support) to bring to market in 2000. Using Seebass’s minimization techniques, the design was projected to have a sonic boom overpressure 

as low as 0.4 psf, although locally focused booms during acceleration would 

still be a problem. FAA certification, especially for the sonic boom and jet 

noise near airports under the FAA’s Stage 3 standard of 1978, was identified as 

a potential “show stopper.”5

 Greene’s presentation emphasized the importance 

of Government help in developing such an aircraft. Although the United States 

had failed to be first to develop an SST, he argued that “it is NASA’s role to 

make the US first in business jets.”6

Based on the ongoing experience of the Concorde and related market analyses, Richard Seebass’s subsequent presentations in 1998 were decidedly pessimistic about the viability of a large supersonic passenger plane in the foreseeable 

future. With 350,000 mostly supersonic flying hours during the Concorde’s 

first 14 years of reliable operation, Seebass did consider the Concorde “a great 

technical success.”7 Economically, however, the case for another SST had yet to 

be made. The British and French governments paid for most of the Concorde’s 

development and production (essentially donating the last five of them to their 

national airlines). This allowed their small fleet of 12 aircraft to attract enough 

passengers willing and able to pay a high fare for the two airlines to break even 

on operations, even at a fuel-cost-per-passenger mile several times that of a 

Boeing 747. But because such a U.S. Government subsidy was highly unlikely 

in the future, Seebass observed how “the development of a supersonic transport 

that can be operated at a profit by the airlines and sold in sufficient numbers 

for the airframe and engine manufacturers to realize a profit as well remains a 

challenge.”8

 Specifically, “the challenge is to build, certify, and operate an SST 

at marginally increased fares while providing the airlines a return on investment 

comparable to a similar investment in subsonic aircraft.”9

As shown by repeated studies, generating sufficient passenger loads to justify the expense of a supersonic airliner would most likely require overland 

supersonic routes from a large number of airports. This meant solving the 

acoustic issues of jet noise, especially when taking off, and the sonic boom when 

accelerating and cruising. Recent NASA HSR data indicated that adequate 

sound suppression of 15 to 20 perceived noise decibels would add about 6,500 

pounds per engine, or the equivalent weight of 90 passengers.10 As researched 

by NASA as far back as the SCAR program of the 1970s (see chapter 3), a 

variable-cycle engine that could switch from a quieter high-bypass ratio during 

takeoff and landing to low-bypass ratio to limit drag during cruise could be 

needed. Although engine noise was an intimidating challenge, it might be 

potentially solvable with some future technical breakthroughs.
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When it came to sonic boom minimization, some immutable laws of physics posed even more intractable problems. One of these, warned Seebass, was 

that “the sonic boom due to lift cannot be avoided. The aircraft’s weight must 

be transmitted to the ground.”11 In general, as he verbally explained a key equation, the minimum achievable sonic boom is related to the aircraft’s weight 

divided by three-halves the power of its length. In addition to the easier-saidthan-done goal of reducing weight, the main way to alleviate the effects of lift 

was to find acceptable tradeoffs in designing an airframe (i.e., the aircraft’s 

volume) to shape the sonic boom signature in a manner tolerable to listeners 

but not too detrimental to aerodynamic performance.

As for the old problem of determining what would be acceptable to the 

public, the HSR’s human-response surveys and NASA Langley’s simulator 

experiments along with related research in Canada and Japan had improved 

ways to measure the apparent loudness of variously shaped sonic boom signatures. Although about 5 percent of people might find any sonic boom they 

can discern as unacceptable, some of the results indicated that a perceived level 

of 68 decibels outdoors would be acceptable to 95 percent of those exposed 

to it. This, Seebass predicted, could be achieved by a signature with an initial 

shock-pressure rise of 0.25 psf—if a maximum pressure of 1 psf is delayed 20 

milliseconds after the front shock arrives and then begins to recede 20 milliseconds before the onset of the rear shock. Still to be determined, however, were 

the effects of such waveform shaping on the longstanding issue of acceptable 

sonic boom vibrations indoors. This would need to be determined by flight 

testing with an aircraft designed for this purpose.12

Seebass was already convinced, however, that it would not be possible for 

an SST-size airplane’s elongated N-wave signature to avoid causing the structural vibrations that annoy people indoors, thereby continuing to restrict it 

to intercontinental routes over water and some unpopulated regions.13 The 

one possible exception, at least in theory, might be a supersonic oblique-wing 

transport. As Seebass explained in his sonic boom minimization paper, “The 

aerodynamic optimum supersonic aircraft [is] an elliptic wing flying obliquely, 

which we note is unusual in that its maximum sonic boom does not occur 

directly below the aircraft.”14 As regards market potential, “it appears that an 

oblique flying wing could provide a Mach 1.4–1.6 transport that operates with 

no surcharge over future subsonic transports and compete with them over 

land as well.”15 Such an unconventional configuration, with its long wingspan, 

would of course require some airport modifications, but even more daunting, it 

would require a very expensive R&D effort. One can also assume that passenger 

acceptance of such a strange-looking airplane and its interior accommodations 

might also pose a challenge.16
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Since building vibrations were not an inherent problem for a properly 

designed smaller airplane, Seebass asked a hypothetical question: “Could a 100 

ft. long, Mach 1.6 supersonic business jet, cruising at an altitude of 40,000 feet 

and weighing 60,000 lbs.[,] have an acceptable sonic boom?”17 The beneficial 

effects of vibrational relaxation from small aircraft “were well understood many 

years ago, but we did not consider them in sonic boom minimization because 

they are not important in the sonic boom of transport-sized aircraft.” The 

shock waves from a much smaller, slender-bodied supersonic airplane, however, 

could be so weak as to be “nearly inaudible” while also containing “less energy 

in the frequencies important in structural response and indoor annoyance.”18

The fact that business jets do not follow scheduled routes might also help in 

the certification of supersonic versions, since they would not create the repetitive sonic booms of supersonic airliners.This, Seebass concluded, “leads us to 

conclude that a small, appropriately designed supersonic business jet’s sonic 

boom may be nearly inaudible outdoors and hardly discernible indoors.”19

Such an airplane, he further stated, “appears to have a significant market ... if 

... certifiable over most land areas.”20

Previous SSBJ Studies and Proposals

Even though developing a supersonic business jet never became a goal of either 

the Supersonic Cruise Research or High-Speed Research programs, it had long 

been considered by some as a realistic possibility. The idea of building a small 

supersonic jet for general aviation, technology demonstrations, or potential 

military purposes had inspired a limited number but wide range of concepts in 

the past. After the HSR program dropped plans for a full-size overland supersonic airliner, Domenic Maglieri of Eagle Aeronautics—who by then had been 

involved with sonic boom research for 40 years—drafted a study for NASA in 

which he summarized all known proposals involving small supersonic aircraft 

intended mainly for business passengers.21

Between 1963 and 1995, there had been a total of at least 22 such studies 

or projects on developing small supersonic civilian airplanes. Academic institutions performed six of them, sometimes as student projects or theses, and 

all during either the 1960s or the early 1990s. The aircraft industry initiated 

eight more, starting with one by Spain’s Construcciones Aeronauticas Sociedad 

Anonima (CASA), which at the time was building supersonic Northrop F-5s 

under license.22 Although Boeing internally examined a supersonic 10-passenger plane concept in 1971, which was delta winged like its canceled 2707-300 

SST, Fairchild Swearingen conducted the first serious design project published 

by an American company. It started with a feasibility study involving several 
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The Quiet Supersonic Platform

major airframe and engine manufacturers. The company then drew up preliminary designs for four two-engine configurations with a range of 4,000 miles 

and an ability to cruise subsonically as well as supersonically using a modified 

version of the Concorde’s proven Rolls-Royce Snecma Olympus 493 engine. 

By 1985, concerns about weight, the FAA’s Stage 3 noise restrictions, and the 

sonic boom brought the project to an end.23

In early 1988, while Douglas and Boeing were engaged with NASA in studies for the HSCT, Gulfstream Aerospace began studying market and technical 

criteria for an SSBJ.24 (Grumman had started Gulfstream in 1958 as part of 

a diversification strategy into civilian aircraft but divested itself of the brand 

in 1972.25) The company, which catered to the high end of the executive jet 

market, drew up plans for a 125-foot, 100,000-pound, Mach 1.5 airplane 

with ogive-delta wings (i.e., with their trailing edges angled forward, much as 

the leading edges were swept back). In a preliminary attempt at sonic boom 

minimization, the designers were able to lower its predicted overpressure from 

1.0 psf to 0.6 psf but only at the expense of some increased wave drag.26

Meanwhile, the sudden ending of the Cold War (and the unraveling of state 

funding for the Russian aircraft industry) led the Sukhoi Design Bureau, which 

had been studying a 114-foot, cranked-arrow wing SSBJ (the Su-51), to seek an 

international partner. At the 1989 Paris Air Show, Sukhoi’s chief designer and 

Gulfstream’s chairman agreed to explore joint development, taking advantage 

of the former’s expertise with supersonic fighters and the latter’s expertise with 

successful business jets.27 The companies aimed at a speed of Mach 2 and range 

of 4,000 miles as they considered design options, but the problems of weight 

versus performance requirements proved to be beyond current technologies. 

Although variable-cycle and ejector-mixer engine designs might partly mitigate 

the level of jet noise, Gulfstream concluded that a concerted effort by the FAA, 

NASA, industry, and academia would be needed to solve the problem of sonic 

boom acceptability.28 Even after the two companies parted ways in 1992, Sukhoi 

continued pre-prototype design work in the hopes of forming another partnership in the future.29 As will be shown in later sections, Gulfstream too remained 

interested in a supersonic SSBJ, including sonic boom minimization technology.

In addition to the university and company projects, NASA conducted or 

sponsored eight SSBJ-related studies between 1977 (4 years after it dropped 

sonic boom minimization from the SCAR program) and 1986 (just as it initiated studies on the HSCT). The first, by Vincent Mascitti of Langley, explored 

five possible configurations for an eight-passenger, Mach 2.2 supersonic executive aircraft based on the latest SCAR research findings and technological 

advances. Although reduced engine noise was an objective, none of the options 

were designed with the expressed goal of sonic boom minimization, so a transatlantic range of 3,200 nautical miles was one of the criteria.30 Also in 1977, 
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Quieting the Boom

Boeing completed a feasibility study for NASA on a subscale SCAR demonstrator followed in 1979 by North American Rockwell’s proposed supersonic 

business jet presented at the last Supersonic Cruise Research Conference (both 

described in chapter 3). 

The next NASA study, left unpublished in 1981 as a possible casualty of 

the Reagan administration’s abrupt cancellation of the SCR program, was the 

first phase of what had been planned as a three-phase market survey for supersonic business jets.31 The same year, however, also marked the completion of 

the first of four SSBJ studies performed for Langley by the local technology 

division of Kentron International (later PRC Kentron). Each of the studies 

applied the latest technical advances to various SSBJ concepts during the period 

between the SCR and HSCT programs. Kentron’s 1981 report presented concepts for an advanced droop-nose, two-engine Mach 2.7 business jet carrying 

eight passengers a distance of 3,200 nautical miles. Reflecting advances since 

Mascitti’s study in 1977, the researchers assumed the use of the latest titaniumand superelastic-formed diffusion bonded materials to reduce its weight from 

74,000 pounds to 64,000 pounds and a scaled down version of the GE 21/

J11 variable-cycle turbofan engine for propulsion. As regards its sonic boom, 

the predicted overpressure of 1.0 psf at the start of cruise and 0.7 psf at the 

finish (due to reduced fuel weight) would still prohibit overland operations.32

The next study, completed in 1983, examined the use of a more fuel-efficient turbofan engine, the smallest possible eight-passenger compartment, and 

only one pilot to reduce takeoff weight to only 51,000 pounds. The result was 

a 103-foot-long, arrow-winged Mach 2.3 executive jet with a range of 3,350 

nautical miles at Mach 2.3. Using Carlson’s simplified overpressure prediction method with additional area-rule calculations, former NASA supersonic 

aerodynamicist A. Warner Robins hoped the combination of low wing loading, 

high cruise altitude, and modified flight profiles for climb and acceleration 

would alleviate the sonic boom problem on cross-country flights. The plane 

was also designed to fly 2,700 nautical miles at Mach 0.9 if necessary when 

cruising over land.33

In 1984, the same Kentron researchers completed the concept for a 

114-foot-long executive jet with variable-sweep wings for better low-speed 

performance, which would eliminate the need for a droop nose as on the previous configuration. Although such adjustable wings had been found infeasible 

for the SST in the 1960s, the researchers hoped lower weight materials and 

advances in stability and control technology would make them more practical 

(which subsequent analysis proved overly optimistic). This latest design (figure 

5-1) would have a ramp weight of 64,500 pounds with eight passengers and 

a two-person crew. Its performance included a range of almost 3,500 nautical 

miles at Mach 2.0 and over 5,000 miles at Mach 0.9 with takeoff and landing 
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The Quiet Supersonic Platform

Figure 5-1. Kentron’s concept for a swing-wing SSBJ. (NASA)

distances of less than 5,000 feet. Using the same prediction method as before, 

the overpressures at Mach 1.2 and Mach 2.0 varied from 0.9 psf to 2.0 psf 

depending on weight and altitude, making speeds no higher than Mach 0.9 

mandatory for overland cruise.34

The last of the NASA studies was completed in 1986. For possible expansion of the customer base, the Kentron design team assessed the feasibility 

of an eight-passenger, long-range SSBJ with a planform similar to the 1981 

and 1983 studies that could be converted into a missile-carrying interceptor 

(presumably for foreign sales). With a takeoff weight of 61,600 pounds for the 

civilian version and 63,246 pounds for the military version, its low-bypass-ratio 

turbofan engines would give it a range of more than 3,600 nautical miles or a 

combat radius of more than 1,600 nautical miles, both at Mach 2.0. Takeoffs 

would require a 6,600-foot runway. By flying an optimum profile for climb 

and acceleration, sonic boom overpressure was calculated at 1.0 psf, but the 

plane could also cruise transonically for 3,780 nautical miles at Mach 0.96.35

Although NASA and the major aircraft manufacturers focused on the 

HSCT for the next decade, the idea of a small supersonic plane continued to 

intrigue many in the small airplane manufacturing and general aviation communities. The rapidly growing corporate jet market appeared to have room 

for higher speeds, perhaps using more fractional ownership arrangements. The 

main roadblocks were the complex technology and considerable resources that 

would be required to develop, test, and produce such an advanced aircraft. This 

made Government support and partnerships among competing companies 

appear necessary. Overseas, France’s Dassault Aviation explored developing a 
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Quieting the Boom

supersonic version of its popular Falcon business jet in the 1990s before scaling 

back its effort because of the lack of a suitable engine.36

Sometime in the mid 1990s, Lockheed’s legendary but secretive Skunk Works 

(officially titled its Advanced Development Company), which 20 years earlier 

began work on the first jet airplane to have a very low radar signature, became 

interested in learning how to design airframes with a low sonic boom signature. (In March 1995, Lockheed merged with Martin Marietta Corporation to 

become Lockheed Martin.) Obviously, there would also be military advantages 

for some air vehicles—such as aircraft designed for high-speed reconnaissance—

not to betray their presence by laying down a loud sonic boom carpet. To help 

in this effort, the Skunk Works hired McDonnell Douglas aerodynamicist John 

Morgenstern, who had been that company’s lead boom analyst for the HSCT 

(see chapter 4). He was among those involved in designing a patented control 

surface near the nose of an airplane that could be extended to reduce the pressure 

and slope of the shock waves as a way of shaping its sonic boom.37 To further 

add to its expertise, the Skunk Works also brought in none other than Richard 

Seebass as a consultant.38 By 1998, Lockheed Martin had made enough progress 

on sonic boom minimization that it teamed up with Gulfstream to work on 

ways to develop a low-boom SSBJ.39 (General Dynamics acquired Gulfstream 

Aerospace Corporation in 1999 as a wholly owned subsidiary.40)

Meanwhile, the market for business jets was booming. It grew about 400 

percent from 1995 through 2000, much of this captured from the scheduled 

airlines’ business and first-class passenger categories. Furthermore, a good portion of this growth was in new models of more sophisticated and expensive 

corporate jets, whether privately purchased or under fractional ownership 

arrangements. Progress in understanding how to deal with the sonic boom 

reinforced a conviction that customers would be willing to pay the premium 

required to develop and produce an SSBJ. “With the advent of new technologies, and a travel market that increasingly desires time above all else, the business case is clearing emerging for new, fast transports.”41 The National Research 

Council’s study on “the way ahead” for commercial supersonic flight (described 

at the end of chapter 4) found that airframe manufacturers believed customers 

would be willing to pay about twice as much for a plane that could fly twice 

as fast as current business jets and estimated the potential market for such an 

SSBJ to be at least 200 aircraft over a 10-year period.42

Unlike the Skunk Works’ highly classified stealth technology, which did not 

have civilian applications, reducing the sonic boom could obviously benefit the 

private sector as well as have potential military advantages. The Department of 

Defense, however, had no current operational requirement to develop a new 

supersonic bomber, let alone one with a quiet sonic boom. Indeed, the Air Force’s 

“bomber roadmap,” released in March 1999, focused on sustaining its current 
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The Quiet Supersonic Platform

mix of B-1B Lancers, B-2 Spirits, and B-52H Stratofortresses for decades to come 

with fielding of a new bomber postponed until the 2030s.43 Internally, however, 

many in the Air Force were still interested in advanced strike concepts.

Birth of the QSP Program

One DOD agency is not bound by the pull of formal requirements. Instead, 

the mission of the Defense Advanced Research Projects Agency is to push 

innovative new technologies that might be of value in the future—including many with dual military and civilian uses. In February 2000, DARPA 

listed Supersonic Aircraft Noise Mitigation as a new program in its portion of 

the Department of Defense’s FY 2001 budget estimates.44 The new DARPA 

program resulted, at least in part, from lobbying by Lockheed Martin and 

Gulfstream (which had previously approached NASA for support)45 and an 

earmark from Senator Ted Stevens of Alaska.46 The Defense appropriation 

became law in August 2000.47 This allowed DARPA to begin funding projects for supersonic noise mitigation, which it had since renamed the Quiet 

Supersonic Platform, in October 2000. For fiscal years 2001 and 2002, the 

QSP was allocated approximately $35 million.48 A DARPA budget submission 

described the program—funded under Program Element (PE) 0603285E, 

Advanced Aerospace Systems—as follows:

The Quiet Supersonic Platform (QSP) program is directed toward 

development and validation of critical technology for long-range 

advanced supersonic aircraft with substantially reduced sonic 

boom, reduced takeoff and landing noise, and increased efficiency.... Improved capabilities include supersonic flight over land 

without adverse sonic boom consequences with boom overpressure rise less than 0.3 pounds per square foot, increased unrefueled range approaching 6,000 nmi [nautical miles], gross takeoff 

weight approaching 100,000 pounds, increased area coverage, 

and lower overall operational cost. Highly integrated vehicle concepts will be explored to simultaneously meet the cruise range and 

noise level goals. Advanced airframe technologies will be explored 

to minimize sonic boom and vehicle drag including natural laminar flow, aircraft shaping, plasma, heat and particle injection, and 

low weight structures.49

DARPA initially identified three potential military roles for quiet, efficient supersonic aircraft: a reconnaissance vehicle, a medium bomber, and a 
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Quieting the Boom

high-speed transport that could quickly deliver vital spares and other equipment to forward-operating locations (the function most related to an SSBJ). 

To manage the QSP program, DARPA chose Richard W. Wlezien, a researcher 

from NASA Langley recently assigned to DARPA to manage a program on 

microadaptive flow controls. His specialty, the manipulation and control of 

shear flows, was a good match for overseeing technologies relevant to the QSP 

program.50 In seeking participants from both industry and academia, Wlezien 

made sure to cast a wide net.

As DARPA’s initial step in disseminating information about the program, it 

hosted an Advanced Supersonic Platform Industry Day in Alexandria, VA, on 

March 28, 2000. The announcement for this event, released 1 month earlier, 

informed interested parties that “it is our desire to facilitate the formation 

of strong teams and business relationships in order to develop competitive 

responses to a forthcoming DARPA Request for Information (RFI) and any 

subsequent solicitation.”51 Although encouraging the participation of small 

technology companies and academic institutions with specialized expertise, 

DARPA needed major aerospace corporations to assess and assimilate the wide 

range of airframe and engine technologies that would be required for the type 

of quiet, long-range supersonic aircraft desired. With the consolidations in the 

defense industry after the end of the Cold War, the three corporations with the 

required expertise and resources to be these system integrators were Boeing, 

Lockheed Martin, and Northrop Grumman.

For help in formulating the program’s sonic boom strategy, Richard Wlezien 

received briefings from experts in the field such as Peter Coen of NASA Langley 

and Domenic Maglieri and Percy Bobbitt of Eagle Aeronautics.52 The latter 

two planted some seeds for a sonic boom demonstration to eventually become 

part of the QSP by reviewing their Firebee proposal from the early HSR program and pointing out the continued value of physically proving sonic boom 

minimization predictions with an actual airframe in the real atmosphere.53

(Through a Lockheed Martin contract, DARPA later had them prepare a survey 

on the findings of previous sonic boom research as background information 

for QSP participants.54)

In August 2000, the DARPA Tactical Technology Office issued its formal 

solicitation for QSP systems studies and technology integration to include 

seeking detailed proposals for fostering new technologies sufficient to mitigate 

the sonic boom for unrestricted supersonic flight over land. Phase I of the program was expected to last 12 months. Phase II contracts, to be awarded later 

through a down-select process, would extend through the second year. The 

solicitation informed interested participants that “the program is designed to 

motivate approaches to sonic boom reduction that bypass incremental ‘business as usual’ approach and is focused on the validation of multiple new and 
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innovative ‘breakthrough’ technologies for noise reduction that can ultimately 

be integrated into an efficient quiet supersonic vehicle.”55

The initial goal of the QSP program was “to develop and validate critical technology for long range advanced sonic boom, reduced take-off and landing noise, 

and increased efficiency relative to current-technology supersonic aircraft.”56 The 

only firm requirement at the start of the program, mentioned in the solicitation 

and succinctly put into context by Richard Wlezien, was a concept that would 

reduce the overpressure of the sonic boom to 0.3 psf—a level that “won’t rattle 

your windows or shake the china in your cabinet.”57 It was hoped a signature 

this low would allow unrestricted operations over land, although a sonic boom 

with 0.5 psf might be permissible in designated corridors.

System goals (less firm than the sonic boom requirement) included a speed 

of Mach 2.4, a gross weight of 100,000 pounds (about one-quarter that of the 

Concorde), a range of 6,000 miles, a 20-percent payload capacity, and meeting the FAA’s Stage 3 noise restrictions.58 Derived goals included a lift-to-drag 

ratio of 11 to 1, an engine-thrust-to-weight ratio of 7.5 to 1, a specified fuelconsumption rate, a 40-percent fuel fraction, and a 40-percent empty-weight 

fraction (both relative to gross takeoff weight). The concept aircraft was also 

expected to have adequate subsonic performance. As explained by Wlezien, 

“We have worked with NASA and the US Air Force to come up with numbers 

which make sense and are self-consistent. In our view, the numbers are reasonable given the state of the technologies, but still well off the projected trend 

lines.”59 Even so, meeting these multiple goals would not be easy. This was made 

clear by David Whelan, director of the DARPA Tactical Technology Office. 

“We do not see any ‘silver bullet’ solution.... But it might be possible to make 

improvements in many different areas that add up to a real net improvement.”60

Achieving these goals would require the R&D capabilities of major aircraft and engine manufacturers, scientific and technical ideas from university 

engineering departments and specialized contractors, and the support and 

facilities of Government agencies. The needed NASA contributions would 

include modeling skills, wind tunnel facilities, and eventual flight-test operations. NASA administrator Dan Goldin strongly approved the QSP’s approach. 

“Rather than a big point-design program that characterized HSR, [it] is a precompetitive study addressing core issues—efficiency, engine jet noise, sonic 

boom overpressure, and emissions.... Once we have sufficiently explored a 

broad range of promising technologies, we will work to develop and fund 

a more substantial industrial partnership.”61 The QSP emphasized potential 

military uses, but the sonic boom was currently a bigger problem for civilian 

aviation. Military aircraft had always been able to fly supersonic in designated 

airspace in the United States, so DARPA’s goal of a validated concept for boom 

minimization could be of greatest benefit to the development of an SSBJ.
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QSP Phase I: Defining Concepts and Technologies

DARPA awarded initial 1-year QSP contracts in November 2000 to the three 

systems integrators that would perform the large-scale design studies. Northrop 

Grumman’s Air Combat Systems Integrated Systems Sector (ISS) received the 

first, on November 7, for $2.5 million.62 Shortly thereafter, DARPA awarded 

contracts to the other two systems integrators, Lockheed Martin’s Skunk Works 

and Boeing’s Phantom Works. (The predecessor of the Phantom Works had 

been a part of McDonnell Douglas before that company’s merger with Boeing 

in December 1996.) Neither Northrop nor Grumman had been among the 

aircraft manufactures that submitted designs for the SST, AST, or HSCT in the 

past, but almost as soon as DARPA announced the new program, the Northrop 

Grumman Corporation (NGC) decided to participate. As explained by Charles 

W. Boccadoro, NGC’s future strike systems manager at the ISS Western Region 

in El Segundo, CA, upon award of the contract: “We started liking the capability offered by a long-range, efficient supersonic flight platform.”63

On March 1, 2000, the day after DARPA issued the invitation to its industry 

day, Boccadoro had flown to Washington, DC, to meet with Richard Wlezien. 

There, Boccadoro went over a study he had presented at Headquarters Air Force 

in January on concepts for next generation supersonic strike aircraft. This detailed 

report involved capabilities directly relevant to DARPA’s newly announced 

program.64 At the end of the month, four other Northrop Grumman officials 

attended DARPA’s industry day, including Steve Komadina. Shortly thereafter, Boccadoro was given the additional duty of program manager of Northrop 

Grumman’s participation in what became the QSP program, with Komadina 

becoming the chief engineer and later the deputy program manager.65

A graduate of MIT and the von Kármán Institute for Fluid Dynamics, 

Charles Boccadoro had been hired in 1980 by Northrop, where he worked 

on such state-of-the-art aircraft programs as the B-2 Spirit stealth bomber 

and the YF-23 advanced tactical fighter.66 In May 2000, he appointed an 

experienced systems engineer, Joseph W. Pawlowski, to lead a small team 

to develop the company’s strategy for responding to DARPA’s solicitation. 

Pawlowski’s duties included coordinating developmental activities among a 

number of subcontractors, which would be good experience for the QSP 

endeavor. To look for help from outside the company, NGC hosted its own 

industry day on July 13, 2000. The following month, in what would turn out 

to be a very shrewd move, Northrop Grumman hired Eagle Aeronautics and 

Wyle Laboratories—with their long experience in sonic boom analysis—as 

subcontractors. It also teamed up Raytheon Corporation as a cost-sharing 

QSP partner.67 Northrop Grumman submitted its response to DARPA’s QSP 

solicitation on September 29, 2000.68
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The Quiet Supersonic Platform

After the announcement of Northrop Grumman’s QSP contract, Boccadoro 

provided some insight into the company’s team-oriented approach. Because 

of its lack of commercial airplane experience, NGC sought out Raytheon, 

specifically the Raytheon Aircraft Company subsidiary that made Beechcraft 

and Hawker corporate jets, as its primary subcontractor.69 “They will be working principally the civil applications, and we’ll be working principally the 

military applications,” he explained.70 For help on engine technology and 

concepts, Northrop Grumman would be working with Pratt & Whitney, 

General Electric, and MIT’s Gas Turbine Laboratory (all awarded their own 

QSP contracts) as well as General Motors’ Allison Transmission and the Air 

Force Propulsion Laboratory.71 In addition to having the sonic boom expertise 

of Wyle Laboratories, Eagle Aeronautics, and Stanford University, Northrop 

Grumman’s own scientists and engineers had also gained some relevant knowledge in previous decades. As Boccadoro put it, “We understand the physics of 

boom mitigation.”72

By January 2001, all 16 of the QSP Phase I contracts had been announced. 

Many of them focused on engine technologies, where major innovations were 

considered essential. To study concepts for advanced propulsions systems 

using high-bypass turbofans to meet the QSP goals, DARPA selected General 

Electric and Pratt & Whitney. Other contracts called for analyses of specific 

propulsion subcategories: Aerodyne for a vaporization-cooled turbine blade; 

Honeywell for ceramic components and compressor flow control, Techsburg 

(of Blacksburg, VA) for controlling the boundary-layer thickness of engine passageways; and MIT’s Gas Turbine Laboratory for a two-stage, counter-rotating 

aspirated compressor.73

Most of the other QSP contracts involved innovative or even radical technologies for sonic boom mitigation. Gulfstream would follow up on some 

of its previous work by looking at integrated, top-mounted supersonic inlets 

that (being above the wings) could counter the contribution of inlet nacelle 

shocks to the sonic boom signature. Weidlinger Associates of New York City 

was engaged to investigate the previously dismissed theory of increasing virtual 

body length to spread out shock waves using the heat from a thermal keel or 

ramjet. Directed Technologies of Arlington, VA, in partnership with Reno 

Aeronautics, would assess using foamed metallic surfaces to promote natural 

laminar flow over a thin unswept wing (similar in shape to that of the F-104 

Starfighter). Laminar flow, which is easier to achieve at supersonic speeds than 

at subsonic speeds, would greatly decrease the boundary layer turbulence and 

friction that causes aerodynamic drag by keeping air adjacent to the surface in 

a thin, smoothly shearing layer. (Active laminar flow requires the use of airflow 

devices creating suction to draw air into tiny holes in a special material covering 

a wing’s surface.) In January 2000, NASA Dryden had tested a scale model 
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of Reno Aeronautics Corporation’s natural laminar flow wing attached to the 

center pylon of an F-15B on four supersonic flights with “remarkable results.”74

Universities were the recipients of the remaining sonic boom research 

contracts. DARPA chose Stanford (by then the university doing the most 

advanced sonic boom research) to develop an efficient boom propagation tool 

optimized for multidisciplinary design techniques, Princeton for integrating 

aircraft shaping with energy-generated ionization of plasmas to prevent shock 

wave strengthening, and Arizona State University to demonstrate and develop 

design tools for using distributed roughness to inhibit crossflow instabilities 

on natural laminar flow over moderately swept wings. Finally, the University 

of Colorado received a contract for a more conventional assessment of aircraftshaping techniques with a three-dimensional propagation tool to prevent shock 

waves from coalescing into the sonic boom.75 Sadly, Richard Seebass, chair of 

the University of Colorado’s Department of Aerospace Engineering Sciences 

until May 1999, passed away in November 2000 at the age of 64—just as the 

Quiet Supersonic Platform was getting ready to put his and Albert George’s 

longstanding sonic boom minimization theory into practice.76

These selections reflected DARPA’s policy to encourage smaller businesses 

and academic organizations to participate. As Richard Wlezien put it, “We 

are trying to get the traditional players to think out of the box and to bring 

in people with new ideas on an equal footing.”77 Not only did the QSP program aim to promote innovative technologies, it also employed an innovative 

management philosophy to get its contractors—including those who were 

traditional competitors—to work together. Although some of their techniques, 

findings, and data remained proprietary, DARPA required the major aircraft 

and engine companies to assess and integrate the impact of all the technologies under consideration. In Phase I of the QSP (which lasted through 2001), 

the three systems integrators developed conceptual airplane designs intended 

to meet the aforementioned sonic boom requirement and performance goals 

with promising technologies and configurations. In addition to relevant findings by the QSP technology contractors, the designs relied heavily on tools 

and methods developed during the HSR and previous NASA programs while 

incorporating the latest computational and optimization techniques, especially increasingly powerful CFD capabilities. Even with improved modeling 

and prediction of sonic boom propagation, however, the value of actually 

demonstrating the persistence of a reduced sonic boom signature through the 

atmosphere became increasingly apparent as the program continued.78

The three systems integration contractors, their partners, and all the technical and propulsion contractors worked intensely but quietly for the next year 

with relatively little about their progress appearing in the aerospace trade press 

or other media. The first task of Northrop Grumman, Boeing, and Lockheed 
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The Quiet Supersonic Platform

Martin was to perform 3-month studies on system scoping for their conceptual aircraft designs and technology assessments on developing and validating 

sonic boom mitigation measures. At the same time, the specialized sonic boom 

mitigation contractors worked on technology scoping studies of their own. 

Meanwhile, the advanced propulsion contractors worked on 6-month studies.79

By the end of the QSP program’s first 3 months, the technology and propulsion contractors provided their findings to date to the system integration teams, 

which also shared the results of their own sonic mitigation studies among 

themselves. For the remaining 9 months of Phase I, the three major contractors worked on their conceptual supersonic aircraft designs while completing 

technology evaluation reports on sonic boom mitigation. The sonic boom contractors also completed technology evaluation reports on their assigned areas 

while the propulsion contractors, upon completing their 6-month scoping 

studies, moved on to integrating technologies into conceptual designs.80 The 

progress being made to address the sonic boom problem using computational 

fluid dynamics was somewhat encouraging. “It doesn’t require new science,” 

said Richard Wlezien, “it requires good engineering.”81

Although most of the QSP program went pretty much according to plan, 

two major changes involving the sonic boom occurred toward the end of its 

first year. Despite the progress being made on minimization, the sonic boom 

requirement of 0.3 psf was downgraded to be just one of the goals, equivalent 

to such other goals as long-range and low takeoff weight. This reflected a course 

adjustment to move the program more in the direction of military missions 

(perhaps at least partly a response to the terrorist attacks of September 11). 

By then, however, QSP management had also decided that the most pressing 

issue involving the sonic boom was to actually demonstrate the persistence of 

a shaped signature through the atmosphere. This would be consistent with the 

Figure 5-2. QSP timeline and major program activities. (DARPA) 

Key: LFC = laminar flow control; MDO = multiple discipline optimization.
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Quieting the Boom

recently published report on supersonic technology by the National Research 

Council, which recommended proceeding to a “system/subsystem model or 

prototype demonstration in a relevant environment.”82

The Northrop Grumman QSP team had already made preliminary plans on 

how to do this in the 3 months before April 2001, when DARPA formally solicited proposals for this demonstration.83 After the NGC proposal was selected, 

this spinoff of the QSP program became known as the Shaped Sonic Boom 

Demonstration. The SSBD is the subject of the next three chapters, with the 

third of these also covering a follow-on project sponsored by NASA known as 

the Shaped Sonic Boom Experiment. Figure 5-2 depicts the final structure of 

the QSP program as it evolved after these changes.84 Although there had been 

some hopes for a full-scale QSP Phase III that would have continued work on 

the design concepts or lead to development of a truly low-boom X-plane,85

the SSBE was later considered by some sources to have been Phase III of the 

Quiet Supersonic Platform. 

QSP Phase II: Refining Concepts and Technologies

By the end of 2001, each of the three system integrators had completed their 

Phase I studies defining their preferred design concepts and identifying the 

technologies needed to produce a real airplane. The Northrop Grumman team 

had submitted its study on December 12. As the QSP moved into Phase II in 

January 2002, Richard Wlezien gave some hints on how the research was going. 

“We have changed the face of supersonics.... We have simultaneously looked 

at long range and low boom and found that they are not mutually exclusive.”86

Although using various configurations, the preliminary design concepts all 

featured long, thin aircraft with lift distributed along their length, low wave 

drag, and highly integrated propulsion systems. Because of the light weight of 

the airframes relative to their volume, advanced composites would be essential 

for strength and stiffness. To achieve the goal of a high lift-to-drag ratio, ways of 

achieving supersonic laminar flow also emerged as key factors. “The question is 

how to integrate laminar flow into a real vehicle,”87 cautioned Wlezien. Taken 

together, the QSP goals were a tremendous challenge. “Contractors have told 

us this is the toughest program they have ever worked, and we are surprised 

they have come up with ways to get there.”88

At about this same time, Charles Boccadoro revealed some details about 

Northrop Grumman’s overall design concept. It featured top-mounted, mixed 

compression inlets for the engines, which Gulfstream’s computational analysis 

of three engine positions in four basic configurations showed could significantly reduce the sonic boom by shielding the flow field below the aircraft 
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The Quiet Supersonic Platform

from the inlet shock.89 Boccadoro’s team also found that an above-airframe 

engine position resulted in less spillage as well as external compression and 

expansion fields. To achieve lower drag, the team was using Arizona State’s 

distributed roughness concept to enable laminar flow on the plane’s lifting 

surfaces while using natural laminar flow on some of its other surfaces. As for 

applying any of the more revolutionary methods, “a key finding of our studies 

was that the QSP goals could be achieved without active or exotic sonic boom 

reduction technologies.”90

More details on the QSP concepts came out during the annual AIAA meeting in Reno, NV, during mid-January. After studying 12 design concepts, 

Northrop Grumman and Raytheon came up with a preferred dual-relevant 

concept appropriate for civilian as well as military purposes. They expected 

this configuration would meet the QSP’s sonic boom mitigation goal with a 

slightly slower cruise speed of Mach 2.2 and a takeoff distance of 7,000 feet, 

which would be about halfway between the shorter business jet distance and the 

longer allowance for a military strike aircraft. The design featured a strut-braced 

(or joined-wing) configuration. A single vertical tail extended above the two 

engine nacelles nested on the rear of the aircraft.91 Steve Komadina, chief engineer on Northrop’s QSP team, later said this configuration is a design “we think 

can be evolved into a strike aircraft or business jet.”92 It could accommodate 

IMAGES FOR FIGURE 5-2: 

(See next page for a copy of the originally submitted image.) 

Figure 5-3. Northrop Grumman’s QSP program. (NGC)
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Quieting the Boom

either two 27-foot-long weapons bays or a 22-foot passenger cabin.93 A briefing slide released later (figure 5-3) depicts Northrop Grumman’s concept as it 

evolved during both phases of the QSP.94

Advance news of DARPA’s selection of Northrop Grumman and Lockheed 

Martin to continue developing their concepts under Phase II of the QSP first 

leaked out in early March 2002.95 Lockheed Martin’s concept had a slender fuselage (described as sinuous), highly contoured swept wings with engines beneath, 

and a V tail while Boeing, which later published a paper with details on its design 

effort, had probably the most radical configuration. It featured two sets of thin, 

unswept wings (with natural laminar flow) fore and aft and a swiveling main 

wing that could be stowed along the top of the fuselage during cruise.96

DARPA officially awarded its Phase II contracts in May 2002. Northrop 

Grumman’s Integrated Systems Sector received $2.7 million to validate the QSP 

concepts defined during the program’s first phase. This would include wind 

tunnel testing of its preferred aircraft configuration and work with Raytheon on 

the fabrication and testing of a structural component made with an advanced 

composite core. At the same time, DARPA also awarded the NGC Integrated 

Systems Sector a $3.4 million contract for what became the Shaped Sonic 

Boom Demonstration.97 Other contract awards included Lockheed Martin’s 

Skunk Works for its design concept, General Electric for its advanced propulsion system, and Arizona State University for its distributed-roughness laminar 

flow research. By the time these contracts were awarded, DARPA had decided 

to make a priority of the long-range supersonic bomber for the QSP’s military 

mission with the more liberal sonic boom goal of 0.5 psf overpressure, and it 

decided to place more emphasis on such factors as survivability.98 This reduced 

boom might allow the aircraft to fly in new supersonic corridors beyond the 

limited confines of military training airspace without causing the public relations problems experienced by the Air Force’s last midrange Mach 2 bomber, 

the B-58 Hustler (described in chapter 1).

On September 26, 2002, Northrop Grumman unveiled more about the 

preferred system concept of its QSP team, including an image of the sleek 

plane in flight (as pictured in front of this chapter). Its joined wing airframe 

was 156 feet long with a wingspan of 58 feet, a speed somewhat higher than 

Mach 2, and a range of 6,000 nautical miles. As had been a consideration 

with the Concorde, this speed would allow the use of lower cost materials, 

especially aluminum. The main wings were highly swept but thin and narrow 

for lower drag and better laminar flow, which would be easier to sustain with 

less turbulence across a shorter chord (wing width). These high-aspect-ratio 

cranked-arrow wings were braced by two much smaller wings swept forward 

from the rear of the aircraft. The concept also featured a dual top-mounted isentropic inlet (designed for smooth and steady airflow), extensive laminar flow 
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The Quiet Supersonic Platform

aerodynamics, and an adaptive leading edge on its wings. Team members from 

Raytheon Aircraft Company designed an SSBJ variant.99 Further refinements 

of the military concept gave it a cruise speed of Mach 2.2.100 To supplement its 

extensive CFD modeling, Northrop Grumman tested a scale model of its final 

QSP configuration at Mach 2.2 in the 9-foot-by-7-foot section of the NASA 

Ames Supersonic Wind Tunnel for 33 hours in April 2003.101

Richard Wlezien moved to NASA Headquarters in the early fall of 2002. 

He was replaced as QSP manager by Steven H. Walker, who had been assigned 

to DARPA from Defense Research and Engineering in the Pentagon.102 Walker 

later explained that even though the sonic boom goal had been relaxed, “What 

we ended up finding out was that if you improve lift and drag, if you improve 

specific fuel consumption, if you reduce your empty weight, all these things 

lend themselves to lower sonic boom as well.”103

Except for the ongoing Shaped Sonic Boom Demonstration, DARPA 

phased out the QSP program during the first half of 2003. Its biennial budget 

estimate submitted in February included $4.8 million for FY 2003 but nothing 

for FY 2004.104 Northrop Grumman’s QSP team submitted extensive documentation of its work on May 22, 2003. Results of its and Lockheed Martin’s 

QSP concepts went to the Air Force for use in its ongoing long-range-strike 

platform study.105 No longer comfortable with the rather unambitious projections in its 1999 bomber roadmap, the Air Force leadership was seeking 

the latest ideas on long-range strike from the aerospace industry. It eventually examined more than 20 proposals from Northrop Grumman, Lockheed 

Martin, and Boeing.106 None of these, however, led to a follow-on program 

like the QSP that could continue refining and demonstrating other supersonic 

technologies, such as reduced boom designs, as had once been contemplated.

Even so, the QSP participants had learned much and documented a great 

deal of data that could be of potential value in the future. The program had 

explored and evaluated a wide range of cutting-edge technologies, advancing 

the state of the art in aeronautics, propulsion, and related fields. For Northrop 

Grumman’s engineers, who had not had any major supersonic projects after 

developing the YF-23 and the supersonic inlets for the Boeing F/A-18E/F 

Super Hornet, the QSP afforded valuable experience and new skills. This helped 

sustain the company’s aerodynamic design capabilities for future projects, such 

as DARPA’s Switchblade oblique-wing study, and advanced work with the Air 

Force Research Laboratory (AFRL).107 The most publicized aspect of the QSP 

program, however, was the opportunity it provided for Northrop Grumman 

and its partners to make aviation history by being the first to demonstrate the 

creation of less intense sonic booms.
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Endnotes

1. Seebass, who had been born and raised in Denver before becoming 

a professor at Cornell and later the University of Arizona, moved in 

1981 to the University of Colorado at Boulder, where he served as 

dean of its College of Engineering until 1994.

2. Richard Seebass, “History and Economics of, and Prospects for, 

Commercial Supersonic Transport,” Paper 1, NATO Research 

and Technology Organization, Fluid Dynamics Research on 

Supersonic Aircraft (proceedings of a course held in Rhode SaintGenèse, Belgium, May 25–29, 1998), Research and Technology 

Organization (RTO)-EN-4 (November 1998).

3. Richard Seebass, “Sonic Boom Minimization,” Paper 6, NATO 

Research and Technology Organization, Fluid Dynamics Research on 

Supersonic Aircraft (proceedings of a course held in Rhode SaintGenèse, Belgium, May 25–29, 1998), RTO-EN-4 (November 

1998). A slightly expanded version was also published with Brian 

Argrow as “Sonic Boom Minimization Revisited,” AIAA paper no. 

98-2956 (November 1998).

4. Domenic Maglieri to Lawrence Benson, “Comments on QSP 

Chapter,” e-mail message, August 23, 2011.

5. Randall Greene and Richard Seebass, “A Corporate Supersonic 

Transport,” in Transportation Beyond 2000: Technologies Needed for 

Engineering Design, Proceedings of a Workshop Held in Hampton, 

Virginia, September 26–28, 1995, NASA CP-10184 (February 

1996), pt. 1, 491–508.

6. Ibid., 506.

7. Seebass, “Prospects for Commercial Supersonic Transport,” I-1.

8. Ibid., I-3, I-5.

9. Ibid.

10. Ibid., I-4; National Research Council, U.S. Supersonic Aircraft: 

Assessing NASA’s High-Speed Research Program (Washington, DC: 

National Academies Press, 1997), 46–49.

11. Seebass, “Sonic Boom Minimization Revisited,” 6.

12. Ibid., 8–9. As described in chapter 9, NASA Dryden later developed 

a way to repeatedly create reduced sonic booms using existing fighter 

aircraft.

13. Ibid., 8.

14. Ibid., 3.

15. Seebass, “Prospects for Commercial Supersonic Transport,” I-5.

16. Author’s speculation.
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The Quiet Supersonic Platform

17. Seebass, “Sonic Boom Minimization” (NATO version), VI-8. 

Although Seebass still attributed the structural vibrations specifically 

to the signature’s impulse (which he defined as “the integral of the 

positive phase of the pressure with respect to time”), other structural 

engineering factors related to the ultralow frequencies of the sound 

waves caused by the extended N-waves of larger aircraft were also 

found to be involved.

18. Seebass, “Sonic Boom Minimization Revisited,” 8–10.

19. Ibid., NTRS Abstract.

20. Seebass, “Prospects for Commercial Supersonic Transport,” I-6.

21. The study, originally completed in 1997, was finally published just 

in time for use in this book. See Domenic J. Maglieri, “Compilation 

and Review of Supersonic Business Jet Studies from 1963 through 

1995,” NASA CR 2011-217144 (May 2011).

22. CASA became part of the European Aeronautic Defence and Space 

Company N.V. (EADS) in 1999.

23. Maglieri, “Compilation and Review of SSBJ Studies,” NASA CR 

2011-217144, 13.

24. “Gulfstream Studies Development of Supersonic Business Jet,” 

Aviation Week (September 12, 1988): 47.

25. “The History of Gulfstream, 1958–2008,” accessed November 13, 

2011, http://www.gulfstream.com/history/.

26. Maglieri, “Compilation and Review of SSBJ Studies,” NASA CR 

2011-217144, 14.

27. Richard DeMeis, “Sukhoi and Gulfstream Go Supersonic,” Aerospace 

America 28, no. 4 (April 1990): 40–42.

28. H.S. Bruner, “SSBJ—A Technological Challenge,” ICAO Journal 46, 

no. 8 (August 1991): 9–13.

29. “Sukhoi Goes Supersonic,” Aviation Week (September 20, 1993): 

41; Graham Warwick, “Sonic Dreams,” Flight International (May 6, 

2003); 34.

30. Vincent R. Mascitti, “A Preliminary Study of the Performance and 

Characteristics of a Supersonic Executive Aircraft,” NASA TM 

74055 (September 1977).

31. Maglieri, “Compilation and Review of SSBJ Studies,” 21, summarizes from a draft copy of this study.

32. Roy A. Da Costa et al., “Concept Development Studies for a Mach 

2.7 Supersonic Cruise Business Jet,” NASA CR 165705 (April 

1981). This report is not available through the NTRS, but Maglieri’s 

compilation, 21–22, summarizes its abstract.
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33. F.L. Beissner, W.A. Lovell, A. Warner Robins, and E.E. Swanson, 

“Effects of Advanced Technology and a Fuel-Efficient Engine on a 

Supersonic-Cruise Executive Jet with a Small Cabin,” NASA CR 

172190 (August 1983).

34. F.L. Beissner, W.A. Lovell, A. Warner Robins, and E.E. Swanson, 

“Application of Near-Term Technology to a Mach 2.0 Variable 

Sweep Wing Supersonic Cruise Executive Jet,” NASA CR 172321 

(March 1984).

35. F.L. Beissner, W.A. Lovell, A. Warner Robins, and E.E. Swanson, 

“Effects of Emerging Technology on a Convertible, Business/

Interceptor, Supersonic Cruise Jet,” NASA CR 178097 (May 1986).

36. Graham Warwick, “Sonic Dreams,” Flight International (May 6, 

2003): 34–36. 

37. John M. Morgenstern, low sonic boom shock control/alleviation 

surface. US Patent 5,740,984, filed September 22, 1994, and issued 

April 21, 1998. Accessed November 12, 2011, http://www.patents.

com/us-5740984.html.

38. Univ. of Colorado, Biography of A. Richard Seebass, accessed April 

27, 2011, http://www.colorado.edu/aerospace/ARichardSeebass.html. 

Seebass, who had stepped down from being dean of the University 

of Colorado’s College of Engineering and Applied Sciences to 

become chair of the Department of Aerospace Engineering Sciences 

in 1995, had created a Lockheed Martin Engineering Management 

Program there. 

39. Bill Sweetman, “Whooshhh!” Popular Science, posted July 

30, 2004, accessed February 20, 2009, http://www.popsci.com/

military-aviation-space/article/2004-07/whooshhh.

40. “The History of Gulfstream, 1958–2008,” accessed November 13, 

2011, http://www.gulfstream.com/history/.

41. Richard Aboulafia, “The Business Case for Higher Speed,” Aerospace 

America Online, accessed July 8, 2010, http://www.aiaa.org/aerospace/

Article.cfm?issuetocid=ArchiveIssueID=16.

42. National Research Council, Commercial Supersonic Technology: The 

Way Ahead (Washington, DC: National Academies Press, 2001), 10.

43. John Tirpak, “The Bomber Roadmap,” Air Force Magazine 82, no. 6 

(June 1999): 30–36.

44. “Department of Defense FY 2001 Budget Estimates: Research, 

Development, Test and Evaluation Defense-Wide,” 1, Defense 

Advanced Research Projects Agency, February 2000, Program 

Element 0602702E, 87–88, 107–109. (Page 88 notes that it was a 

“congressional add.”)
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45. Guy Norris, “Back to the Future,” Flight International (December 

18, 2001), accessed November 13, 2011, http://www.flightglobal.com/

articles/2001/12/18/140226/back-to-the-future.html.

46. Bill Sweetman, “Back to the Bomber,” Jane’s International Defence 

Review 37, no. 6 (June 2004): 55.

47. Department of Defense Appropriations Act 2001, Pub. L. No. 106-

259, 114 Stat. 656 (August 9, 2001), accessed November 13, 2011, 

http://www.gpo.gov/fdsys/pkg/PLAW-106publ259/content-detail.html.

48. Sweetman, “Back to the Bomber,” 54–59.

49. Department of Defense FY 2002 Amended Budget Submission: 

Research, Development, Test, and Evaluation Defense-Wide, 1, 

Defense Advanced Projects Agency, June 2001, 132.

50. Biography, Rich Wlezien, accessed ca. April 15, 2011, http://www.

richwelzein.com/Personal/Wlezien.html.

51. DARPA Special Notice 00-17, “Advanced Supersonic Program—

Industry Day,” March 28, 2000, Alexandria, VA (February 29, 

2000).

52. Chambers, Innovations in Flight, NASA SP-2005-4539, 65.

53. D.J. Maglieri, P.J. Bobbitt, and H.R. Henderson, “Proposed Flight 

Test Program to Demonstrate Persistence of Shaped Sonic Booms 

Signatures Using BQM 34E RPV,” Eagle Aeronautics response to 

DARPA RFI-Advanced Supersonic Program, April 19, 2000, cited 

in Joseph W. Pawlowski, David H. Graham, Charles H. Boccadoro, 

Peter G. Coen, and Domenic J. Maglieri, “Origins and Overview of 

the Shaped Sonic Boom Demonstration Program,” AIAA paper no. 

2005-5, 6, 14.

54. Domenic J. Maglieri and Percy J. Bobbitt, “History of Sonic Boom 

Technology Including Minimization,” Eagle Aeronautics, Hampton, 

VA, November 1, 2001. This comprehensive study totaled 373 

pages.

55. “Quiet Supersonic Platform (QSP) Systems Studies and Technology 

Integration,” Commerce Business Daily, SOL RA 00-48, posted on 

CBDNet, August 16, 2000, accessed August 18, 2011, http://www.

fedmine.us/freedownload/CBD/CBD-2000/CBD-2000-18au00.html.

56. Richard Wlezien (DARPA) and Lisa Veitch (IDA), “Quiet 

Supersonic Platform Program,” AIAA paper no. 2002-0143, 40th 

Aerospace Sciences Meeting, Reno, NV, January 14–17, 2002, 4. 

IDA is the acronym for Institute for Defense Analysis.

57. Robert Wall, “DARPA Envisions New Supersonic Designs,” Aviation 

Week (August 28, 2000), 47.

58. Wlezien and Veitch, “Quiet Supersonic Platform Program,” 5–6.
144

Quieting the Boom

59. Graham Warwick, “Supersonic and Silent,” Flight International

(December 9, 2000), accessed November 13, 2011, http://www.

flightglobal.com/articles/2000/09/12/120156/supersonic-and-silent.

html.

60. Ibid.

61. Cited in Warrick, “Cutting to the Bone,” Flight International (July 

17, 2001), accessed November 13, 2011, http://www.flightglobal.com/

articles/2001/07/17/134122/cutting-to-the-bone.html.

62. Pennington Way, “Northrop Grumman Awarded First Contract 

to Study Quiet Supersonic Platform,” Defense Daily (November 

14, 2000), http://findarticles.com/p/articles/mi_6712/is_30_208/

ai_n28800344/.

63. Robert Wall and William Scott, “Northrop Grumman Gets Quiet 

Supersonic Work,” Aviation Week (November 13, 2000): 32.

64. Telephone interview of Charles H. Boccadoro by Lawrence Benson, 

August 20, 2011.

65. Ibid.; Joseph Pawlowski to Lawrence Benson, “Re: More SSBD 

Questions,” e-mail message, August 17, 2011. Also representing 

Northrop Grumman at the industry day were Tony Springs, Rob 

Chapman, and Jay Trott.

66. Biography of Charles Boccadoro, in Decadal Survey of Civil 

Aeronautics: Foundation for the Future (Washington, DC: The 

National Academies Press, 2006), 179. ISS headquarters was in 

Dallas.

67. Pawlowski to Benson, “Re: More SSBD Questions,” August 17, 

2011.

68. Benson/Boccadoro interview, August 20, 2011. The comprehensive 

NGC plan had eight sections on the various aspects it envisioned for 

the program.

69. In 2007, Raytheon sold its aircraft company to outside investors, 

who renamed their new entity Hawker Beechcraft Corporation.

70. Wall and Scott, “Northrop Grumman Gets Quiet Supersonic 

Work,” 32.

71. Way, “Northrop Grumman Awarded First Contract.”

72. Wall and Scott, “Northrop Grumman Gets Quiet Supersonic 

Work,” 32.

73. Robert Wall, “New Technologies in Quest of Quiet Flight,” Aviation 

Week (January 8, 2001): 61–62; Graham Warwick, “DARPA Cash 

to Fund Studies into Sonic Boom Reduction,” Flight International

(January 9, 2001): 17.
145

The Quiet Supersonic Platform

74. NASA Dryden, “Extensive Supersonic Laminar Flow Attained 

Passively in Flight,” News Release 00-13, January 26, 2000.

75. Wall, “New Technologies in Quest of Quiet Flight,” 61–62; 

Warwick, “DARPA Cash to Fund Studies”; Warwick, “Supersonic 

and Silent.”

76. University of Colorado, News Center, “Former Dean of 

Engineering Richard Seebass Dies Tuesday,” November 14, 

2000, accessed ca. July 15, 2011, http://www.colorado.edu/news/

r/4c5668f27e7454651c98568ed3ae0f5.html.

77. Warwick, “Supersonic and Silent.”

78. Pawlowski et al., “Origins and Overview of SSBD Program,” 4.

79. Wlezien and Veitch, “Quiet Supersonic Platform Program,” 7.

80. Ibid.

81. Bill Sweetman, “Quiet Supersonics in Sight: Technology Currently 

Under Development Could Form the Basis for Bizjet, Strike/

Reconnaissance Aircraft,” at Interavia Business & Technology

(November 1, 2001): accessed ca. July 20, 2011, http://www. 

highbeam.com/doc/1G1-80743274.html.

82. National Research Council, Commercial Supersonic Technology: The 

Way Ahead (Washington, DC: National Academy Press, 2001), recommendation number 2, 42, which references conducting a “technology demonstration” as defined on page 7.

83. Pawlowski et al, “Origins and Overview of SSBD Program,” 5; 

Benson/Boccadoro interview, August 20, 2011.

84. Source for figure 5-2: Peter G. Coen, David H. Graham, Domenic 

J. Maglieri, and Joseph W. Pawlowski, “QSP Shaped Sonic Boom 

Demo,” PowerPoint presentation, 43rd AIAA Aerospace Sciences 

Meeting, Reno, NV, January 10, 2005, slide 3.

85. Guy Norris, “Preferred Concepts Unveiled for Strike and Business 

QSP Versions,” Flight International (October 1, 2002), 4, quoting 

Charles Boccadoro.

86. Graham Warwick, “Super Striker,” Flight International (January 

15, 2002), accessed November 13, 2011, http://flightglobal.com/

articles/2002/01/15/141264/super-striker.html.

87. Ibid.

88. Ibid.

89. Guy Norris, “Overwing Engine Placing Shows Low Boom Promise,” 

Flight International (January 29, 2002): 29.

90. As quoted in Warwick, “Super Striker.”

91. Guy Norris, “Manufacturers Unveil Dual Relevant QSP 

Configuration,” Flight International (January 21, 2002): 6. No AIAA 
146

Quieting the Boom

papers were published on the QSP information revealed at this 

meeting.

92. Paul Lowe, “Answers Sought for SSBJ Questions,” Aviation 

International News (June 2002), accessed ca. July 20, 2011, http://www.

ainonline.com/aviation-news/aviation-international-news/2007-10-03/

answers-sought-ssbj-questions. 

93. Ibid.

94. Northrop Grumman, “Quiet Supersonic Platform (QSP) Shaped 

Sonic Boom Demonstrator (SSBD) Program,” presentation, 

Washington Press Club, September 3, 2003, slide 3.

95. “DARPA Selects Two To Develop Supersonic Aircraft,” Jane’s Defence 

Weekly (March 8, 2002), accessed ca. July 30, 2011, http://www.

articles.janes/Janes-Defence-Weekly-2002/DARPA.

96. Warwick, “Super Striker.” For a description of Boeing’s design 

effort by leaders of its QSP team, see Peter M. Hartwich, Billy 

A. Burroughs, James S. Herzberg, and Curtiss D. Wiler, “Design 

Development Strategies and Technology Integration for Supersonic 

Aircraft of Low Perceived Sonic Boom,” AIAA paper no. 2003-0556, 

41st Aerospace Sciences Meeting, Reno, NV, January 6–9, 2003. 

Neither of the other two system integrators published similar reports 

on their design process.

97. Northrop Grumman, “Northrop Grumman Awarded Additional 

Contracts To Continue Work on Quiet Supersonic Platform,” news 

release, May 14, 2002.

98. Robert Wall, “Bomber Becomes Focus of Quiet Aircraft Effort, 

Aviation Week (May 6, 2002): 28.

99. Northrop Grumman, “Northrop Grumman Unveils Concept for 

Quiet Supersonic Aircraft,” news release, September 26, 2002, 

with the illustration used in front of this chapter, accessed ca. July 

30, 2011, http://www.irconnect.com/noc/press/pages/news_releases.

html?d=32118; Sweetman, “Back to the Bomber,” 56; “Northrop 

Grumman Unveils Concept for Quiet Supersonic Flight,” Space 

Daily (October 2, 2002, accessed ca. July 30, 2011, http://www.

spacedaily.com/new/plane-sonic-02b.html.

100. Robert Wall, “Noise Control,” Aviation Week (August 4, 2003): 

23–24.

101. Benson-Boccadoro interview, August 20, 2011.

102. Biography, Rich Wlezien; U.S. Air Force Biography of Dr. Steven H. 

Walker, accessed November 13, 2011, http://www.af.mil/information/

bios/bio.asp?bioID=13291.
147

The Quiet Supersonic Platform

103. Laura M. Colarusso, “Fly Fast With No Boom,” Air Force Times, 

September 22, 2003, accessed ca. August 5, http://www.airforcetimes.

com/legacy/new/0-AirPaper-2209084.php.

104. Department of Defense, “Fiscal Year (FY) 2004/FY 2005 Biennial 

Budget Estimates, Research, Development, Test, and Evaluation 

Defense-Wide, 1—Defense Advanced Research Projects Agency,” 

February 2003, 248.

105. Colarusso, “Fly Fast With No Boom”; Benson-Boccadoro interview, 

August 20, 2011. NGC’s QSP II report and related data was submitted on a DVD.

106. Bill Sweetman, “Back to the Bomber,” Jane’s International Defence 

Review 37, no. 6 (June 2004): 54–59; Adam J. Herbert, “LongRange Strike in a Hurry,” Air Force Magazine 87, no. 11 (November 

2004): 27–31.

107. Benson-Boccadoro interview, August 20, 2011. The Switchblade 

project is summarized in chapter 9.
148

Navy F-5E Tiger II fighters off the California coast. (NGC)
149

CHAPTER 6

Planning and Starting 

the SSBD Project

With most of the Quiet Supersonic Platform program consisting of engineering studies, computer models, and laboratory experiments, its most tangible 

legacy became the Shaped Sonic Boom Demonstration (SSBD). This innovative project used an actual airplane—the Shaped Sonic Boom Demonstrator 

(also SSBD)—to finally put theory into practice. Yet despite all the confidence 

that decades of peer-reviewed articles, wind tunnel experiments, and computational fluid dynamics had conferred on the basic principles of the SeebassGeorge-Darden sonic boom minimization theory, showing that it would 

actually work with a real airplane in the real atmosphere was anything but easy.

Selecting a Demonstrator

In June 2001, Charles Boccadoro picked Joseph W. Pawlowski, who was 

in charge of systems engineering for the QSP effort, to manage Northrop 

Grumman’s sonic boom demonstration proposal.1 Pawlowski was a versatile 

engineer who had worked on a wide variety of systems since being hired by 

Northrop in 1973. He and another veteran engineer, aerodynamicist David H. 

Graham from NGC’s Advanced Air Vehicle Design office, had gone on factfinding trips in late summer of 2000 to garner some of the latest information on 

sonic boom mitigation. Helping the pair bond for the challenging project that 

lay ahead, on their first flight Graham offered the much taller Pawlowski his 

first-class seat, which had been reserved using frequent flyer miles. In Hampton, 

VA, they, along with Charles Boccadoro and Steve Komadina, visited Eagle 

Aeronautics, where Domenic Maglieri described his ideas for a low-cost sonic 

boom demonstrator. Later, while at the Georgia Institute of Technology in 

Atlanta, Pawlowski and Graham met Wyle Laboratory’s sonic boom specialist 

Ken Plotkin (there on a visit from his office in Arlington, VA). Plotkin went 

over some of his thoughts on sonic boom minimization with the two NGC 

engineers. The conversation continued when Plotkin gave Pawlowski a ride 
150

Quieting the Boom

to the airport. Northrop Grumman engaged both Eagle and Wyle to become 

members of its QSP team in August 2000.2

Although DARPA had not planned for the sonic boom demonstration to 

be an initial part of the QSP program, Boccadoro’s QSP team was interested 

almost from the beginning in Maglieri’s long-standing proposal to use a supersonic Ryan BQM-34E remotely piloted vehicle as a relatively low-cost sonic 

boom demonstrator (described in chapter 4). The Firebee’s modular construction, performance characteristics, and interchangeable components as well as 

previous wind tunnel data continued to make it an attractive option, at least 

in theory. Northrop Grumman’s recent purchase of Teledyne Ryan perhaps 

added to the team’s incentive to explore this opportunity. In anticipation of 

a future sonic boom demonstration contract, Northrop Grumman acquired 

all of the Navy’s usable BQM-43E components except for engines that were 

still being used in subsonic models of the Firebee. The airframes and spare 

parts were trucked from the Naval Air Weapons Station at Point Mugu, CA, 

to one of NGC’s facilities along Aviation Boulevard in El Segundo.3

By early 2001, the Northrop Grumman QSP team began to reconsider its 

concept for the demonstration. Analysis by NASA indicated that the Firebee’s 

airframe might not have been long enough to demonstrate a definitive shaped 

boom signature. CFD modeling also raised concern about effects of the shock 

waves from the jet-engine inlet located under the airframe. Furthermore, NGC 

technicians had found that the Firebee fuselages and parts obtained at Point 

Mugu, where they had been stored outdoors in the salty air, had deteriorated 

significantly since the mid-1990s. So the team decided to put the Firebee 

option on the back burner.4

As a possible long-shot alternative, David Graham pointed out that 

Northrop Grumman’s own F-5E fighter had two variations: the two-seat F-5F 

trainer and the RF-5E reconnaissance version with noses up to 42.5 inches 

longer and of different shapes than the basic F-5E (figure 6-1). Perhaps flying 

each of these aircraft supersonically at short intervals over an array of pressure 

sensors under the right conditions could show enough difference in their sonic 

booms to demonstrate the effect of airframe shaping—all at very little cost. 

However, some preliminary analysis in February 2001 by Graham and NGC 

colleague Hideo Ikawa and more detailed sonic boom modeling by Eagle 

Aeronautics revealed that all the signatures would still be typical N-waves. This 

had been predicted 2 months earlier by Domenic Maglieri, who determined 

that the longer noses did not have the smooth equivalent area distribution 

needed to produce a flattop or ramp-type signature. As a potential solution, 

Maglieri thought the F-5 would be an excellent candidate for using a new, 

properly designed nose extension to reshape its initial pressure rise into a flattop signature—something like what had been proposed for the Firebee.5

 Of all 
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Planning and Starting the SSBD Project

Figure 6-1. Profile comparison of F-5 Tiger II variants. (NGC)

the supersonic fighters in the U.S. inventory, the F-5E was uniquely suitable 

for such a modification.6

The Northrop F-5 Story

Back in 1954, when the United States Air Force and Navy were seeking supersonic combat aircraft of increasing size and sophistication, a U.S. Government 

study warned that many of America’s Cold War allies needed smaller and 

simpler yet high-performance fighters. Thomas Jones and others at Northrop 

Corporation immediately saw the potential export market in being able to 

offer a fast but economical jet fighter. Jones, a chief engineer who succeeded 

founder Jack Northrop as company president in 1959, wanted a plane that 

was not only a relative bargain to buy but one that would also be cost effective 

throughout its life cycle.7

This approach featured lots of doors and removable panels for ready access 

by maintenance personnel and easily replaceable components. With that 

in mind, Northrop’s design team came up with a concept designated the 

N-102. Helped by General Electric’s development of the small but powerful J85 turbojet, the design evolved by 1955 into the N-156, a lightweight 

aircraft, which Northrop hoped might also be suitable for the U.S. Navy’s 

small escort-type aircraft carriers. The Navy soon announced the retirement of these ships, but the Air Force released a requirement in 1955 for a 

supersonic trainer. Applying the area rule to its current design to improve 

transonic acceleration, Northrop created the TZ-156, which began flight 

tests at Edwards AFB in April 1959 as the YT-38. These tests went so well 

that the Air Force placed its first order for 50 T-38 Talons in October—the 

start of a production run of almost 1,200 aircraft lasting until 1972. The 

sleek T-38, easily capable of speeds up to about 820 mph, remains in use for 

undergraduate pilot training, introduction to fighter fundamentals, and a 

variety of special purposes, including some by NASA.8
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Quieting the Boom

Encouraged by progress with the TZ-156, Northrop’s design team continued working on its N-156F lightweight fighter version, using corporate funds 

to build the first prototype in early 1958. The Air Force soon agreed to buy 

two more prototypes, the first of which made its maiden flight at Edwards 

AFB on July 30, 1959—going supersonic without its engine yet having an 

afterburner. The early flight tests went so well that the Air Force stopped work 

on the third N-156F, which was eventually completed as an Air Force YF-5A 

that first flew in May 1963. While retaining as many T-38 structures as possible, Northrop spent the next few years weaponizing its NF-156F design with 

internal guns, bomb racks, missile pylons, fuel tanks, and other features needed 

in a rugged combat aircraft. The result was the F-5A and the two-seat F-5B. 

After the Air Force awarded its first F-5 production contracts in October 1962, 

Northrop built them alongside T-38s on its highly efficient assembly line in 

Hawthorne, CA. The F-5B entered operational service as a trainer with the 

Air Force in April 1964, followed 4 months later by the F-5A.9

 In view of the 

F-5’s intended international role during the Cold War, the Air Force named 

it the Freedom Fighter.

In October 1965, the Air Force deployed a unit of 12 F-5As, modified 

for aerial refueling and armored against small-caliber antiaircraft weapons, to 

South Vietnam for a 6-month combat evaluation code named Skoshi Tiger 

(Little Tiger). Although the F-5As did not fly enough missions over North 

Vietnam among their 2,664 sorties to test their air-to-air capabilities, they 

acquitted themselves well in air-to-ground operations considering their limited 

range and payload compared to the F-4 Phantom II and even the older F-100 

Super Sabre. Maintenance personnel hours per flying hour were slightly better 

than with the F-100 and much better than with the big, complicated F-4. After 

completion of Skoshi Tiger, the F-5As were used to help form a commando 

fighter squadron and later transferred to South Vietnam’s Air Force in 1967.

By 1972, 15 nations had received F-5As, F-5Bs, and RF-5As under the U.S. 

Government’s military assistance program or foreign military sales program 

while others were built under license in Canada and Spain.10

Based on the Vietnam deployment and feedback from other nations using 

the initial models of the F-5 Freedom Fighter, Northrop began testing an 

improved version, the F-5-21, which could better engage the latest models of 

the MiG-21.11 Rather than accept Northrop’s unsolicited bid for this to become 

the F-5A/B’s replacement, the Air Force decided to sponsor what it called the 

International Fighter Aircraft competition. Lockheed, McDonnell Douglas, 

and Ling-Temco-Vought submitted modified versions of existing fighters as 

other candidates. In November 1970, the Air Force declared Northrop’s entry 

the winner, with an initial contact for 340 aircraft. One month later, the Air 

Force gave it the designations F-5E and (for the two-seat version) F-5F. The 
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Planning and Starting the SSBD Project

Air Force also tried to bestow the generic name International Fighter Aircraft 

on the F-5E/F but eventually renamed it the Tiger II, an informal nickname 

it had picked up largely in memory of Skoshi Tiger. The RF-5E reconnaissance version was later called the Tigereye. The maiden flights of the F-5E and 

F-5F were in August 1972 and September 1974 respectively. In June 1973, 

an F-5E put on a spectacular display of its agility for potential customers at 

the Paris Air Show.12 Later in the 1970s, Northrop developed the RF-5E at 

its own expense, using three interchangeable nose pallets for various camera 

systems. (Joe Pawlowski spent the first 10 years of his career at NGC working 

on the F-5E and RF-5E, so he was already intimately familiar with the aircraft 

chosen for the SSBD project.) Northrop’s Hawthorne facility would eventually 

build 792 F-5Es and 140 F-5Fs plus 12 RF-5Es while factories in Switzerland, 

Korea, and Taiwan would build more than 500 additional variants of these 

aircraft under license.13

Compared to the F-5A, the F-5E incorporated GE’s more powerful J85-21 

engines with 20 percent higher thrust, 9 percent more wing area, maneuvering flaps, bigger leading edge extensions that extended all the way to the wing 

roots, a larger fuselage with more internal fuel storage, and a two-stage nose 

gear strut that can be raised almost 12 inches for a better angle of attack during 

takeoff. As regards military utility, the biggest improvement over its predecessor (basically a day fighter) was the installation of an Emerson AN/APQ-153 

radar as part of an integrated fire control system with a computing gunsight, a 

missile-launch computer, air-data inputs, and a gyroscopic platform. The F-5E 

has a maximum takeoff weight of 25,350 pounds, a takeoff run of 5,100 feet 

at that weight, a combat ceiling of 52,000 feet, and a ferry range (with three 

external tanks) of over 1,550 miles. Mach 1.64 is generally listed as the plane’s 

maximum speed at 36,000 feet above sea level.14 (This is where the coldest 

temperatures of the tropopause generally begin—allowing supersonic aircraft 

to achieve their highest Mach numbers.)

The relatively heavy losses suffered by large U.S. fighter-bombers from the 

hit-and-run tactics of smaller North Vietnamese MiG-17 and MiG-21 interceptors led to more realistic combat training of American aircrews. In 1969, 

the Navy’s Fighter Weapons School at Naval Air Station (NAS) Miramar, 

near San Diego, CA, began a training regimen known as Top Gun. A key 

aspect of Top Gun was flying small and agile aircraft, such as the Douglas A-4 

Skyhawk, against larger fighters, a practice known as Dissimilar Air Combat 

Tactics (DACT). The Navy’s success eventually prompted the USAF Tactical 

Air Command to form an adversary training squadron to provide DACT to Air 

Force aircrews. Because Air Force fighter wings in the early 1970s were mostly 

equipped with F-4s, the proponents of DACT wanted the new squadron to 

fly Northrop F-5s since its size, performance, and smokeless jet engines were a 
154

Quieting the Boom

close match to the MiG-21. Unfortunately, the Air Force owned no F-5s when 

its 64th Aggressor Squadron was being formed at Nellis AFB, NV, in 1972, 

but its Air Training Command had plenty of Northrop T-38s. Equipped with 

some of these Talons, the squadron soon proved its value in training “road 

shows” to other fighter bases.15

Although the T-38s proved to be a worthy adversary, they had not been 

designed or built for such strenuous maneuvers and began to suffer premature 

wear and tear. Fate intervened with the sudden North Vietnamese conquest 

of Saigon in May 1975. Seventy brand new F-5Es earmarked for the South 

Vietnamese Air Force suddenly became available to equip the 64th and two 

new aggressor squadrons in Nevada and England with a fourth soon activated 

in the Philippines.16 These F-5Es (painted in a wide variety of camouflage 

schemes) helped hone the skills of USAF aircrews for the rest of the Cold 

War—skills that were demonstrated during Desert Storm air operations in 

early 1991. By then, the Air Force had inactivated its aggressor squadrons 

because of force reductions in Europe and the Pacific, the aging of their F-5Es, 

and the option of flying F-16s (which more closely emulated some current 

Russian-built fighters) against larger F-4s, F-15s, and F-111s for DACT training. During the 1970s and 1980s, the U.S. Navy had supplemented and eventually replaced its A-4s with F-5Es, surplus Air Force F-16As (refurbished as 

F-16Ns), and Israeli Kfir C.1 fighters (redesignated as F-21s) for Navy and 

Marine Corps aggressor squadrons.17 The Navy and Marines have continued 

to use F-5Es well into the 21st century.

In 1996, the Navy moved its Top Gun program from NAS Miramar to the 

Naval Strike and Air Warfare Center at NAS Fallon in northwestern Nevada. 

As part of this realignment, Composite Fighter Squadron Thirteen (VFC-13), 

a Naval Reserve unit recently equipped with F/A-18 Hornets, converted to 

F-5E Tiger IIs to help provide adversary training at Fallon.18 The Marine Corps 

had a similar unit, Marine Fighter Training Squadron (VMFT) 401, stationed 

since 1987 at its Marine Corps Air Station (MCAS) in Yuma, AZ.19 As was the 

case with the Air Force, however, the Navy and Marine F-5Es began showing 

their age after years of hard use. To help keep them flying as long as possible, 

the Navy contracted with Northrop Grumman in 1999 to perform phased 

depot-level maintenance on its F-5s at the NGC East Coast manufacturing 

center in St. Augustine, FL. Northrop Grumman and selected subcontractors 

also continued to provide maintenance support, spares, and modifications for 

the F-5s still being flown by foreign nations, many of them increasingly being 

used as a lead-in jet trainer rather than a frontline combat aircraft.20

Besides its supersonic speed, the F-5E has many features that made it an 

attractive choice for serving as a sonic boom demonstrator. These included 

its light weight, a high fineness ratio, a blended canopy, and a relatively long 
155

Planning and Starting the SSBD Project

forebody with engine inlets located farther back than most other fighter aircraft—all of which could help diminish the contributions of secondary shock 

waves to the planned demonstrator’s bow shock. Northrop Grumman’s experience in producing larger F-5F and RF-5E versions by simply adding forebody 

extensions, and the extensive analytical and flight-test data collected when 

doing so, also boded well for the planned sonic boom modifications. From 

a financial standpoint, the costs of operating an F-5 were relatively low.21

Ironically, however, Northrop Grumman had no F-5s of its own to modify.

Forming the SSBD Working Group

On March 12, 2001, key members of NGC’s QSP team, including Domenic 

Maglieri and Percy Bobbitt, gave Richard Wlezien the pros and cons of three 

options for demonstrating the persistence of a shaped sonic boom signature 

through the atmosphere. The options were (1) flying two F/A-18s in close 

over-and-under formations to generate a flattop signature, which would follow 

up on a flight test performed by NASA Dryden in 1994 (described in chapter 

4); (2) testing Eagle Aeronautics’s longstanding idea of comparing results from 

a modified and unmodified Firebee; and (3) comparing the signatures of a 

baseline and specially modified F-5E.22 Except for the cost, the third option 

was obviously the preferred alternative.

Some members of Northrop Grumman’s QSP team were already making 

plans for the demonstration. Joe Pawlowski, who had become Northrop 

Grumman’s systems engineer for the QSP, had been appointed as project manager for the demonstration. David Graham was selected as its chief aerodynamicist. His expertise in dealing with wave drag on the company’s supersonic 

and stealthy YF-23 advanced tactical fighter prototype afforded him good 

experience for dealing with the shock waves that cause sonic booms. From 

outside the company, Ken Plotkin and Juliet Page of Wyle Laboratories as well 

as Domenic Maglieri and Bud Bobbitt of Eagle Aeronautics offered many years 

of expertise in sonic boom research. These and several other NGC personnel 

became core members of what would be become known at first as the Shaped 

Boom Demonstration (SBD) Working Group.

One of the key participants in planning for the demonstration was M.L. 

“Roy” Martin, chief test pilot at the Integrated Systems Sector’s Western Region. 

Martin was a veteran of more than 200 F-4 combat missions in Vietnam, a 

distinguished graduate of the USAF Test Pilot School, and a holder of a master 

of science degree in aeronautics and astronautics from Stanford. During his 

time with the Air Force, Air Force Reserve, and (starting in 1980) Northrop, 

he had flown several dozen types of aircraft, logging 6,000 flight hours in the 
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Quieting the Boom

T-38/F-5 family and with what Northrop had hoped would be its high performance offspring, the single-engine F-20 Tigershark. Most recently, he had 

flown a series of high-stress flight tests of the F-5 for the Navy in 2000. He also 

had many contacts throughout the civilian and military test pilot community 

that would be helpful in arranging support for the project.23

In what would prove to be an advantageous move, Charles Boccadoro 

got Roy Martin involved early in the QSP program. In the summer of 2000, 

Boccadoro called him into his office along with David Graham to talk about 

the possible options for a sonic boom demonstration. Martin was less than 

enthusiastic about the proposal to use Firebee RPVs. When Graham asked 

about modifying an F-5, Martin thought that might be a good solution and 

said he was scheduled to go up to NAS Fallon for a safety day and would begin 

checking on the availability of Navy F-5Es stationed there. While at Fallon, 

Martin ate lunch with Mike Ingalls, a manager at the NGC facility in St. 

Augustine that performed depot maintenance for the Navy, including that for 

F-5s. He informed Martin that the Navy was reviving a previous proposal for 

the U.S. Government to buy back surplus Swiss F-5Es with low flying hours 

to replace its stable of heavily used F-5Es. Once the Navy got congressional 

approval and funding for the deal, obtaining and modifying one of its tired 

Tiger IIs presumably would not be too difficult.24

In April 2001, DARPA released its formal solicitation for proposals from 

all three systems integrators on how best to show the persistence of a shaped 

sonic boom. DARPA added an unusual twist to this QSP minicompetition. 

The winner would not only have to propose the best plan in terms of technology and cost but would also have to propose the best plan for incorporating 

design reviews by the other two systems integrators and for sharing data collected among all QSP participants.25 Northrop Grumman quickly responded 

that same month with a proposal structured as a cooperative effort involving 

other companies and Government agencies. As for the vehicle to be used, 

the company submitted its preliminary design for modifying an F-5E with 

a specially shaped nose extension (shown in the next chapter). The cover 

of its proposal featured a CFD-generated image showing the modified aircraft’s hoped-for shock wave pattern.26 Because of the Dryden Flight Research 

Center’s sonic boom experience, resources, and credibility, NGC proposed 

making NASA responsible for data collection. Based on a comparison of this 

and the other proposals, DARPA awarded a $3.4 million contract (MDA 

972-01-2-0017) to the NGC Integrated Systems Sector in late July 2001 to 

begin preparing its flight demonstration of a shaped sonic boom signature 

using F-5Es.27 Northrop Grumman officially came under contract in midAugust when it received the first payment.28
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Planning and Starting the SSBD Project

Several weeks before the contract award, DARPA invited attendees from 

Northrop Grumman, the other two system integrators, NASA, the Air Force, 

and some of the other contractors and universities to a shaped sonic boom 

workshop on July 10, 2001, in Valencia, CA (just north of Santa Clarita).29

Consistent with DARPA’s rule that anyone who participates in the demonstration would share in the data, the workshop examined how the various 

attendees and their organizations could help in the project. Some of the invitees who soon became key members of Northrop Grumman’s Sonic Boom 

Demonstration Working Group (SBDWG) included Peter Coen of NASA 

Langley, Edward Haering of NASA Dryden, Mark Gustafson of the Air Force 

Research Laboratory (representing DARPA as its technical agent), and John 

Morgenstern, Lockheed Martin’s veteran sonic boom specialist. The working 

group also included the sonic boom experts from Wyle and Eagle who were 

already part of the QSP team.

Right after the contract award was announced, Joe Pawlowski began formally 

establishing the SBDWG. Because the working group’s members were located 

all across the United States, and getting them all together at one time and place 

would be difficult, he set up a special Web site for sharing information and 

ideas.30 (Later, this information was also posted on the DARPA Web site for 

access by Government participants.) As the weeks went by, additional experts 

from NASA Langley, NASA Dryden, Boeing, Lockheed Martin, Gulfstream, and 

Raytheon joined the working group.31 Eventually, more than 30 people served as 

members, with 9 of them composing the SSBD’s program management team: 

Richard Wlezien and then Steven Walker of DARPA, Charles Boccadoro and Joe 

Pawlowski of Northrop Grumman, Mark Gustafson of the AFRL, Peter Coen 

of NASA Langley, and Ed Haering and David Richwine of NASA Dryden.32

At first, Northrop Grumman optimistically predicted being able to conduct the flight tests—projected to require about 18 sorties—at Edwards AFB 

in the summer of 2002.33 But finding an F-5E to modify was only one of 

the many challenges confronting the SBD project. Before DARPA would let 

Northrop Grumman obtain an aircraft to modify, the company would have 

to complete an approved design. And to do this meant overcoming some 

unanticipated technical obstacles. One of the first to be identified was the 

need to better understand the effects of shock waves generated in front of 

jet-engine inlets.

NASA sonic boom specialist Ed Haering, who had gained valuable experience from NASA Dryden’s supersonic probing and measurement of shock 

waves during flight experiments in the 1990s (described in chapter 4), became 

involved in the project when he was invited to the Valencia workshop. He 

introduced himself in advance to David Graham by alerting him to the GPS, 
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Quieting the Boom

telemetry, recording, and other equipment that would need to be installed in 

the participating F-5Es to ensure the collection of accurate data—the topic 

of a presentation he later made at the workshop. He wrote that he was also 

“concerned that inlet-wing shocks will be different than predicted, adversely 

affecting the signature.”34

Following up on his presentation at the QSP workshop, Haering provided 

more details about his proposal to conduct a preliminary F-5E flight test to 

accurately measure the shock waves and expansions (regions of decreasing 

pressure) as they came off the various body parts of an F-5E, especially the 

shock waves that tended to spill out from around its engine inlets. He proposed 

using one of Dryden’s F-15s or F/A-18s as a probe aircraft, perhaps as early as 

December.35 These secondary shock waves coalesced through the atmosphere 

to merge with and reinforce the strength of the front and rear shock wave of 

the typical sonic boom. As the first prerequisite for conducting this test, Roy 

Martin went to NAS Fallon in mid-August to begin arranging for VFC-13 to 

deploy one of its F-5Es to Edwards, hopefully in January if not December.36

He also continued investigating ways to obtain F-5Es later for the shaped sonic 

boom demonstration itself.

The first meeting of the SBDWG was held at the NGC Advanced Systems 

Development Center in El Segundo on August 22, 2001. Those who could 

not attend in person participated via the new Web site and special telephone 

connections. The initial intent was to meet for approximately 2 hours every 

other Thursday, but with scheduling conflicts and other events, the working 

group would normally hold these meetings somewhat less often. Joe Pawlowski 

described the SBDWG ground rules as follows: “Remember that this is a 

working group meeting and that team interaction and brainstorming are the 

desired products. Your ideas and support are appreciated. As stated at the 

Boom Workshop in Valencia, our goal is to reach technical consensus among 

team members in the formulation and execution of the SBD Program. The 

working group meetings are [also] designed to support critical decisions at the 

scheduled milestone reviews.”37 After implementation of the DARPA contract 

and establishment of the SBDWG, work to design the most effective possible 

F-5 modifications (described in chapter 7) greatly accelerated.

By February 2002, some of the members began brainstorming a new name 

and acronym for the working group as well as the SBD project itself, which 

occasionally was referred to in jest as “silent but deadly.”38 Among the more 

creative suggestions were Boom Shaping Technology (BooST) and the Boom 

Aerodynamic and Atmospheric Attenuation Demonstration (BAAAD).39 The 

final choice was less colorful but very descriptive: the Shaped Sonic Boom 

Demonstration (SSBD).40 (The abbreviation of the working group thus 

became SSBDWG.)
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Planning and Starting the SSBD Project

The First Flight Test: 

Inlet Spillage Shock Measurements

One of the early priorities of the SBDWG was to begin planning the in-flight 

shock wave measurements of a standard F-5E recommended by Ed Haering. 

The main purpose of this probing, which Haering gave the name Inlet Spillage 

Shock Measurement (ISSM), was to collect data that could be incorporated 

into the CFD models needed to fully design the modifications for the shaped 

boom demonstrator.41 To help prepare for the ISSM probes and check on 

some preliminary CFD modeling by the NGC design team, Haering had 

Dana Purifoy, a Dryden test pilot who did the in-flight measurements of the 

SR-71 with an F-16XL in the 1990s, use an F-15B to probe the shock waves 

from a Dryden F/A-18 flown by fellow NASA test pilot Jim Smolka in late 

September 2001.42

Some of the issues examined by various working group members—especially Ed Haering, Dave Graham, and Roy Martin—involved the attributes of 

the Navy’s F-5E aggressor configuration, such as the effects that its permanently 

installed wingtip missile-launch rails and the normally carried Tactical Air 

Combat Training System (TACTS) telemetry pod might have on the ISSM 

test.43 Such details could potentially affect the propagation of pressure waves. 

Another seemingly simple requirement illustrates just how complicated test 

planning could become. This involved the installation of some special telemetry equipment in the F-5E’s cockpit—a GPS antenna, receiver, modem, and 

transmitter—that would be needed to obtain useful data.44 As Ed Haering 

explained, “Measuring the sonic boom signature is comprised of two parts, the 

measured pressure, and the relative position of the two aircraft.”45 A discrepancy of several inches could make a difference when measuring the behavior 

of shock waves, so the more accurate the GPS units, the better. Even Edwards 

AFB’s sophisticated radars could not be depended on to track aircraft locations 

to within 20 feet. During the F-16XL-SR-71 tests (which relied heavily on 

recently available differential GPS equipment), anomalies in the radar returns 

sometimes resulted in errors of 1,000 feet for the location of the F-16XL when 

the two planes were actually flying in close formation.46

Martin and Haering spent much of their time over the next month researching and testing GPS units and associated equipment that would be accurate 

enough for data collection yet small enough to be carried in the cockpit, especially without interfering with the ejection sequence—a major safety issue.47

They eventually determined that the preferred GPS unit, an Ashtech Z-12 

with an ultrahigh frequency (UHF) modem and power supply, would fit in the 

right-hand console of an F-5E with some adjustments, including the removal of 

a duplicate radio and use of a slightly larger map case to be built by Northrop 
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Quieting the Boom

Grumman technicians.48 When Martin took the proposed changes to VFC13, officers in the echelon above the squadron recommended a “top-down” 

approval process to get clearance.49 As a result, the proposal was elevated to 

Naval Air Systems Command (NAVAIR) at NAS Patuxent River in Maryland, 

where specialists gave the proposed cockpit installation a thorough review.50

Northrop Grumman’s Electrical and Data Systems Design office responded 

to NAVAIR’s concerns with a detailed layout for the GPS and modem setup, 

including its wiring, that was delivered to NAVAIR as part of a data package 

on December 21, 2001.51

While awaiting Navy approval for the F-5 deployment, Ed Haering 

planned the routes and profiles that the F-5E and F-15B would need to follow 

during the in-flight measurements as well as location of the ground sensors. 

He worked closely with David Richwine, Dryden’s F-15B manager, and Tim 

Moes, the F-15B chief engineer. Other members of the SBDWG helped in 

planning for optimal data collection, but Dave Graham alluded to Haering’s 

key role as follows: “If in doubt use Ed’s values. This is his test; we are all just 

very interested observers.”52 A flight safety specialist at Fallon thought the 

basic flight plan looked acceptable,53 and VFC-13’s operations officer assured 

Roy Martin on the qualifications of its pilots for the test. “They are all second 

tour, fleet fighter pilots who are highly experienced in formation flying and 

multi-plane operations.”54

Early in January, scheduling conflicts involving Dryden’s three F-15B pilots 

and other factors caused the test to be postponed until mid-February, which 

also allowed more time to get the Navy’s approval.55 On January 23, having 

done a fit test of the custom-built map case with an F-5E at Fallon, Martin 

delivered the GPS and associated equipment from Dryden to El Segundo 

for installation into the custom-built map case. After sending an apparent 

approval for the installation of the GPS equipment on January 30, a NAVAIR 

official apologetically informed Joe Pawlowski that the command still needed 

to check its electrical connections and possible effects on instrumentation.56

With Pawlowski having key Northrop Grumman employees who worked at 

Patuxent River help to expedite the process,57 NAVAIR’s final clearance for the 

cockpit equipment came through on February 8.58

This approval came just in time to conduct the ISSM tests the following 

week. NASA Dryden activated a previously planned schedule of events. Dana 

Purifoy, its F-15B probe pilot, flew Northrop technicians and Ed Haering up 

to Fallon in one of Dryden’s small passenger planes on Monday, February 11. 

Purifoy briefed VFC-13’s chosen pilot, Lt. Commander Edgar “Sting” Higgins, 

on operating procedures at Edwards while the GPS equipment was being 

installed. Navy technicians then checked the equipment for any electromagnetic interference.59 Haering used a receiving radio modem to ensure the GPS 
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Planning and Starting the SSBD Project

NASA F-15B and Navy F-5E during Inlet Spillage Shock Measurement Test, February 2002. (NASA)

package was transmitting data properly. He and Purifoy also asked that the 

F-5E’s centerline tank be removed since its shock waves would be incompatible 

with the design of the SSBD.60

Higgins flew the F-5E down to Edwards the following morning. As he 

entered the base’s airspace, Purifoy met him in an F/A-18 to familiarize Higgins 

with the test area and for the Dryden control room to check data reception 

from the F-5E’s GPS equipment. After landing for fuel, Higgins’s F-5E and 

Purifoy’s accompanying F-15B took off for the first of two flight tests on 

February 12, 2002, flying at about Mach 1.4 in both directions through the 

Edwards supersonic corridor. The pair completed two more similar test sorties 

on February 13, with Higgins returning the F-5E to Fallon later in the day.61

The F-15B, using its special nose boom with sensitive pressure instrumentation, gathered 56 supersonic shock wave signatures from the F-5B at distances 

from 60 feet to 1,355 feet while various sensors on the ground collected plentiful data in their sonic boom carpets.62

After the first sorties on February 12, Ed Haering immediately sent members of the working group some encouraging preliminary data just in time 

for a previously scheduled Interim Design Review (IDR) the next day in El 

Segundo. He also passed along an intriguing atmospheric phenomenon. A 
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Quieting the Boom

NASA employee at one of the sensor sites “could see the shock waves in the 

clouds for one pass. The shocks hit a sundog, increasing the brightness about 

ten times, and this lasted for 5–10 seconds, then started to fade. He is guessing 

the shocks may have crystallized the water vapor, or melted the ice crystals, or 

something. Of course he did not have a camera.”63

In accordance with earlier arrangements, Northrop Grumman reimbursed 

VFC-13 for its expenses and Peter Coen arranged for Dryden to get some 

special NASA supersonic research funding to help cover its portion of the 

test.64 In expressing NGC’s and its partners’ gratitude for the Navy’s support, 

Joe Pawlowski acknowledged that “it took a series of small miracles to pull this 

off, and I want to thank everyone involved for their support.”65 The precedents 

set in working with the Navy boded well for having VFC-13 deploy an F-5E 

again in the future. In fact, the entire ISSM flight-test project served as an 

“excellent dry run” for the Shaped Sonic Boom Demonstration.66

Integrating Flight Data with 

Computational Fluid Dynamics

After refinement and validation of the flight-test data, including rectifying 

some rather inexact GPS readings, the working group’s engineers and scientists 

went to work analyzing the data and applying it to CFD models. The major 

participants in this effort were Northrop Grumman’s David Graham, Keith 

B. Meredith (CFD lead), John A. Dahlin (deputy program manager), and 

Michael Malone (CFD specialist); Juliet Page and Ken Plotkin of Wyle Labs; 

and Ed Haering of NASA Dryden. Ultimately, they selected four pressure 

signatures for CFD validation based on those probes that had the smallest and 

most stable vertical separation distances 

(ranging from 77 feet to 105 feet), the 

straightest flight paths, and the steadiest speeds (ranging from Mach 1.396 to 

Mach 1.448). They then used Northrop 

Grumman’s Generalized Compressible 

Navier-Stokes Finite Volume (GCNSfv) 

CFD program, a structured implicit 

finite volume code (derived from the 

Ames Research Center’s ARC3D code). 

It was first applied in an inviscid mode, 

since viscous effects from the F-5E’s surfaces were assumed to be negligible at the 

Figure 6-2. Near-field (inner box) and 

midfield CFD grids used for post-ISSM 

analysis of shock wave signatures. (NGC)
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Planning and Starting the SSBD Project

distances measured. Later CFD analyses of midfield pressure signatures using 

both inviscid and viscous modes did verify negligible differences. The GCNSfv 

program included an extensive number of boundary conditions useful for 

measuring inlet flows. Its grid originally contained 8 million data points in 

the near field (within 0.5 body lengths of the aircraft) and another 4 million 

out to the midfield (3.0 body lengths).67

The analysts did repeated calculations and adjustments of GCNSfv’s predictions based on the actual ISSM probing data (which varied in the number of 

usable data points collected). By repeatedly refining the results and increasing 

the number of grid points to 14.2 million, concentrated mostly along the 

angle followed by the shock waves under the aircraft (shown in figure 6-2), 

the analysts were eventually able to validate the accuracy of the CFD solutions 

out to three body lengths.68

The analysts also developed a process “to interpolate the CFD solutions onto 

the actual relative flight paths between the F-5E and the F-15B during each 

probing to accurately simulate the pressure measurement signature.”69 Among 

the lessons learned, they found that determining the two aircraft’s relative 

speeds and flight paths, both vertically and horizontally, was critical for accurate 

correlations. Even knowing the exact location of the F-5E’s GPS antenna down 

to almost the centimeter and the plane’s precise angles of attack with decreasing 

fuel levels was important.70 Taking all these data into account, the CFD code’s 

postprocessed pressure signatures compared very well with those collected 

during the in-flight probes. “The comparison between the final CFD computed 

pressure signatures and the four selected flight test measurement[s] provided 

excellent correlation.”71 Figure 6-3 shows the close correlation of the pressure 

readings collected by the F-15B on February 13 during its 47th probe from 

about 94 feet beneath the F-5E 

compared with the postprocessed CFD prediction using 

the same flight conditions.72

For continuing design work 

on the modified F-5E, ISSM 

results found that the CFD estimates of F-5E inlet performance 

were acceptable. “Indeed, the 

entire process of the ISSM 

flight test and CFD correlation 

was successful, providing all the 

necessary procedures and confidence in predictive tools needed 

for the SSBD program.”73

Figure 6-3. F-5E pressure signature prediction using the 

Euler-based CFD code (solid line) compared to in-flight 

measurements (line with dots) by F-15B. (NGC)
164

Quieting the Boom

Endnotes

1. With the participants being organized as an integrated product team 

(IPT), his formal title became QSP Shaped Sonic Boom Demo IPT 

Lead.

2. Interview of Joseph W. Pawlowski and David H. Graham by 

Lawrence R. Benson, Northrop Grumman Space Park, Redondo 

Beach, CA, April 12, 2011; Biographical Sketch and Resume, 

Joseph W. Pawlowski, as of April 2011; David Graham to Lawrence 

Benson, “Biographical Information,” e-mail, April 28, 2011; Joseph 

Pawlowski to Lawrence Benson, e-mail, August 17, 2011.

3. Joseph W. Pawlowski, David H. Graham, Charles H. Boccadoro, 

Peter G. Coen, and Domenic J. Maglieri, “Origins and Overview 

of the SSBD Program,” Aerospace Sciences Meeting, Reno, NV, 

Jan 10-13, 2005, AIAA paper no. 2005-5, 4, 6, (also published 

with briefing slides by the Air Force Research Laboratory as AFRLVA-WP-2005-300 [January 2005]).

4. Pawlowski et al., “Origins and Overview of the SSBD Program,” 

AIAA paper no. 2005-5, 6.

5. Ibid., 7; Benson, Pawlowski/Graham interview, April 12, 2011; 

Domenic J. Maglieri by Lawrence R. Benson, telephone interview, 

March 18, 2009; David Graham to Lawrence Benson, “SSBD 

Design Questions,” August 4, 2011.

6. Source for figure 6-1: David Graham and Roy Martin, 

“Aerodynamic Design and Validation of SSBD Aircraft,” Northrop 

Grumman PowerPoint presentation, August 17, 2004, slide no. 3.

7. Marcelle S. Knaack, Office of Air Force History, Post–World War 

II Fighters, 1945–1973 (Washington, DC: GPO, 1986), 287; 

Frederick A. Johnsen, Northrop F-5/F-20/T-38, 44, Warbird Tech 

Series (North Branch, MN: Specialty Press, 2006), 5–6; William G. 

Stuart, Northrop F-5 Case Study in Aircraft Design (AIAA, September 

1978), 5-9. Stuart provides an engineer’s perspectives on the design 

process.

8. Johnsen, Northrop F-5/F-20/T-38, 7-8, 53–56; “2011 USAF 

Almanac: T-38 Talon,” Air Force Magazine 94, no. 5 (May 2011): 

93–94. 

9. Knaack, Post–World War II Fighters, 288–290; Johnsen, F-5/F20/T-38, 8–22.

10. Johnsen, F-5/F-20/T-38, 39-51, 91; Knaack, Post–World War II 

Fighters, 288-289.

11. Johnsen, F-5/F-20/T-38, 62–64, 71–76. 
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Planning and Starting the SSBD Project

12. John L. McLucas with Kenneth J. Alnwick and Lawrence R. Benson, 

Reflections of a Technocrat: Managing Defense, Air, and Space Programs 

During the Cold War (Montgomery, AL: Air University Press, 2006), 

127–128. McLucas was Acting Secretary of the Air Force at the time.

13. Knaack, Post–World War II Fighters, 292; “Northrop F-5,” 

Wikipedia, accessed July 18, 2011, at http://en.wikipedia.org/wiki/

Northrop_F-5. This article is particularly well-sourced. 

14. Knaack, Post–World War II Fighters, 297; Johnsen, F-5/F-20/T-38, 

71–90, 99. For design of each component of the fire control and avionics systems, see Stuart, “Northrop F-5 Case Study,” 171–202.

15. C.R. Anderegg, Sierra Hotel: Flying Air Force Fighters in the Decade 

After Vietnam (Washington, DC: Air Force History and Museums 

Program, 2001), 72–78.

16. McLucas, Reflections of a Technocrat, 128–129. 

17. Johnsen, F-5/T-38/F-20, 90-91; “Aggressor Squadron,” Wikipedia, 

accessed July 18, 2011, http://en.wikipedia.org/wiki/Aggressor_squadron. 

The Kfir was derived from the Dassault Mirage III. Enzo Angelucci, The 

Rand McNally Encyclopedia of Military Aircraft, 1914–1980 (New 

York: The Military Press, 1983), 440.

18. “Naval Air Station Fallon,” accessed July 11, 2011, http://www.cnic.

navy.mil/Fallon/About/index.htm; Fred Krause, “Naval Air Station 

Fallon Adversaries, Part One: VFC-13 Saints,” accessed July 21, 

2011, http://modelingmadness.com/scotts/features/krausevfc13g.htm.

19. “Marine Fighter Training Squadron 401,” accessed July 21, 2011, 

http://www.yuma.usmc.mil/tenantcommands/vmft401.html.

20. Northrop Grumman, “F-5 Tiger,” accessed July 18, 2011, http://

www.as.northropgrumman.com/products/f5tiger/index.html.

21. Pawlowski et al., “Origins and Overview of the SSBD Program,” 

AIAA paper no. 2005-5, 7.

22. D.J. Maglieri and P.J. Bobbitt, “Overview of Flight Demonstrations 

to Demonstrate Persistence of Shaped Sonic Boom Signatures,” presentation by Eagle Aeronautics to Dr. Richard Wlezien for Northrop 

Grumman, March 12, 2001, cited in Ibid., 7–8, 14.

23. Biographical Sketch, M.L. “Roy” Martin, Northrop Grumman 

Aerospace Systems, undated; Interview of Roy Martin by Lawrence 

R. Benson, Lancaster, CA, April 7, 2011.

24. Benson, Martin interview, April 7, 2011.

25. Pawlowski et al., “Origins and Overview of the SSBD Program,” 

AIAA paper no. 2005-5, 5.

26. Northrop Grumman, “Demonstration of the Persistence of Shaped 

Booms Using a Modified F-5E Aircraft,” April 2001, cited in 
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Quieting the Boom

Ibid., 8, 14; David Graham to Lawrence Benson, “SSBD Design 

Questions,” e-mail, August 4, 2011.

27. Northrop Grumman, “Northrop Grumman Awarded Contract To 

Demonstrate Less Intense Sonic Boom,” news release, Aug. 3, 2001, 

accessed ca. July 15, 2011, http://www.irconnect.com/noc/press/pages/

news_releases.html?d=19142.

28. Joe Pawlowski to Peter G. Coen et al., “QSP SBDWG Meeting 

Agenda,” e-mail, August 16, 2001.

29. Andrea Brda to C.M. Darden and 28 others, “Quiet Supersonic 

Platform (QSP) Shaped Sonic Boom Workshop Announcement,” 

e-mail, June 20, 2001; Charles Alcorn to C.M. Darden et al., 

“Shaped Boom Workshop,” e-mail, July 3, 2001.

30. Joe Pawlowski to Peter G. Coen et al., “QSP Shaped Boom Demo 

Program Status,” e-mail, August 1, 2001.

31. Joe Pawlowski to Peter Coen et al., SSBDWG meeting announcements, e-mail messages, August 16, 2001–April 9, 2002.

32. For a complete list of the SSBD Working Group, see Appendix A.

33. Pawlowski to Coen et al., “QSP SBD Program Status,” August 

1, 2001; Bruce Smith, “US Eyes Design to Lessen Sonic Boom, 

Aviation Week (August 13, 2001): 26; Guy Norris, “Quiet 

Supersonic Tests Set for 2002,” Flight International (August 14, 

2001), accessed ca. July 15, 2011, http://www.flightglobal.com/

articles/2001/08/14/134686/quiet-supersonic-tests-set-for-2002/html.

34. Ed Haering to David H. Graham, cc: to Joseph Pawlowski et al., 

“F-5E QSP Data Needs and Accuracies,” e-mail, June 28, 2001.

35. Interview, Edward A. Haering by Lawrence R. Benson, Dryden 

Flight Research Center, Edwards AFB, California, April 5, 2011; Ed 

Haering to David H. Graham et al., “Supersonic Probing of F-5E in 

2001,” e-mail, July 13, 2001.

36. M.L. “Roy” Martin (hereinafter, Roy Martin) to Ed Haering, “Re: 

Supersonic Probing of F-5E in 2001,” e-mail, July 24, 2001; Roy 

Martin to Ed Haering, “Re: Supersonic Probing of F-5E in 2001,” 

e-mail, August 17, 2001.

37. Joe Pawlowski to Peter G. Coen et al., “QSP SBDWG Meeting 

Agenda,” e-mail, August 16, 2001.

38. Benson, Pawlowski/Graham interview, April 12, 2011.

39. Ed Haering to Joe Pawlowski et al., “New SBD name?,” e-mail, 

February 22, 2002; Roy Martin to Ed Haering et al., “Re: New SBD 

name?,” e-mail, February 22, 2002.

40. Joe Pawlowski to Peter Coen et al., “SSBDWG Meeting Reminder - 

2/28/02,” e-mail, February 22, 2002.
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Planning and Starting the SSBD Project

41. Benson, Pawlowski/Graham interview, April 12, 2011; Keith B. 

Meredith, John A. Dahlin, David H. Graham, Edward A. Haering, 

Juliet A. Page, and Kenneth J. Plotkin, “Computational Fluid 

Dynamic Comparison and Flight Test Measurement of F-5E OffBody Pressures,” 43rd AIAA Aerospace Sciences Meeting, Reno, NV, 

January 10–13, AIAA paper no. 2005-6, 2005, 2.

42. David Graham to Ed Haering, “F-5 Off-Body Pressures,” e-mail, 

October 1, 2001; Ed Haering to David Graham, “Re: F-5 Off-Body 

Pressures,” e-mail, October 5, 2001; Interview of Dana Purifoy by 

Lawrence Benson, Dryden Flight Research Center, April 8, 2011.

43. Ed Haering to David Graham, “Re: F-5E QSP Data Needs and 

Accuracies,” e-mail, September 20, 2001; David Graham to Ed 

Haering, cc: Joe Pawlowski, “Re: F-5E QSP Data Needs and 

Accuracies,” e-mail, September 20, 2001.

44. Ed Haering to Roy Martin, “Re: F-5E QSP Data Needs and 

Accuracies,” e-mail, September 21, 2001.

45. Ed Haering to Roy Martin, “Re: F-5 flight and F-15B flight,” 

e-mail, October 10, 2001.

46. Ed Haering to Roy Martin, “Re: F-5 Off-Body Pressures,” e-mail, 

October 10, 2001.

47. Numerous e-mail messages between Roy Martin and Ed Haering et 

al., October 10–November 7, 2001.

48. Roy Martin to Ed Haering and Joe Pawlowski, “Re: Backup GPS,” 

e-mail, November 12, 2001. 

49. LCDR Darren Grove to Ed Haering et al., “Re: FW: F-5 GPS installation,” e-mail, November 15, 2001.

50. Roy Martin to Jeff Ysells (NAVAIR) et al., “F-5E SBD Close 

Aboard Test Update,” e-mail, November 21, 2001; Tommy White 

(NAVAIR) to Jeff Ysells, “F-5E SBD Close Aboard Test Update,” 

e-mail, December 4, 2001.

51. Mark Wang to Ed Haering et al., “GPS Instrumentation Schematic,” 

e-mail, December 18, 2001; Roy Martin to Ed Haering et al., “Re: 

F-5E drawing numbers,” e-mail, December 21, 2001.

52. David Graham to Juliet Page, “Flightpath for F-5E ISSM,” e-mail, 

February 9, 2002.

53. Ed Haering to David H. Graham, “Re: Urgent, F-5E probing priority,” e-mail, January 2, 2002.

54. Roy Martin to Ed Haering, “Re: F-15B/QSP Review Kick-off,” 

e-mail, January 2, 2002.

55. Ed Haering to Joe Pawlowski et al., “Re: F-5E status importance,” 

e-mail, January 7, 2001.
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Quieting the Boom

56. Tommy White to Jeff Ysells et al., “Re: Flight Clearance Request, 

e-mail message,” January 30, 2002; Scott White (NAVAIR) to Joe 

Pawlowski, “Re: Flight Clearance Request,” e-mail, February 1, 

2001.

57. Joe Pawlowski to Roy Martin et al., “FW: QSP Flight Clearance,” 

e-mail, February 4, 2001.

58. Jeff Ysells to Joe Pawlowski et al., “Re: QSP Flight Clearance,” 

e-mail, February 8, 2002; COMNAVAIRSYSCOM to 

COMAIRESFOR, “Interim Flight Clearance for F-5 Aircraft 

with Flight Test Instrumentation Installed...,” teletype message, 

0820006Z, February 2002.

59. Roy Martin to Jeff Ysells, “Re: QSP Mapcase,” e-mail, January 23, 

2002.

60. Edward A. Haering to Lawrence Benson, “Quick SSBD Question,” 

e-mail, August 29, 2011.

61. Joe Pawlowski to John Cole et al., “F-5E Flight Test at NASA,” 

e-mail, February 14, 2002.

62. Meredith et al., “CFD and Flight Test Measurement of F-5E,” AIAA 

paper no. 2005-6 (January 2005), 3.

63. Ed Haering to Joe Pawlowski et al., “VERY preliminary ISSM data,” 

e-mail, February 12, 2002.

64. Peter Coen to Dan Banks et al., “DFRC Funding Summary,” e-mail, 

January 10, 2002; Peter Coen to Ed Haering et al., “Re: Telecon for 

Tuesday,” e-mail, February 19, 2002.

65. Pawlowski to Cole et al., “F-5E Flight Test at NASA,” e-mail, 

February 14, 2002.

66. Meredith et al., “CFD and Flight Test Measurement of F-5E,” AIAA 

paper no. 2005-6 (January 2005), 1.

67. Ibid., 3–5.

68. Ibid., 5–9, David Graham and Roy Martin, “Aerodynamic Design 

and Validation of SSBD Aircraft,” Northrop Grumman, PowerPoint 

briefing, August 17, 2004, slides 12–16. Figure 6-2 is copied from 

slide 14.

69. Meredith et al., “CFD and Flight Test Measurement of F-5E,” AIAA 

paper no. 2005-6 (January 2005), 10.

70. David Graham to Ed Haering et al., “Re: GPS Antenna Position,” 

e-mail, February 20, 2002, with previous message traffic; Roy 

Martin to Joe Pawlowski et al., “Time and Fuel Line,” e-mail, 

February 22, 2002.

71. Ibid.
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Planning and Starting the SSBD Project

72. Graham and Martin, “Aerodynamic Design and Validation,” slide 

no. 15.

73. Meredith et al., “CFD and Flight Test Measurement of F-5E,” AIAA 

paper no. 2005-6, 10.
170

Improved SSBD wind tunnel model and mounting mechanism, May 2002. (NGC)
171

CHAPTER 7

Creating the Shaped Sonic 

Boom Demonstrator

In February 2001, 3 months after the QSP Phase I contract awards, some of 

the members of Northrop Grumman’s integrated product team (IPT) for the 

Quiet Supersonic Platform—in collaboration with Eagle Aeronautics’s sonic 

boom experts—began preliminary work on a new F-5E nose modification that 

would lower the strength of its sonic boom. As described in previous chapters, 

the basic principles and theories for reducing the pressure rise in the front half 

of an N-wave signature were fairly well understood. Even so, designing the 

exact geometrical contours (known aerodynamically as the loft) that would be 

certain to accomplish this goal while still retaining acceptable performance and 

handling qualities became a highly iterative process. Using a building block 

approach, the designers would eventually draw up almost two dozen basic 

configurations. The differences from one to the next were usually quite subtle, 

but the final configuration looked quite different than the original concept.

This design process combined high-order computational fluid dynamics, 

linear sonic boom–prediction models, wind tunnel evaluations, and some preliminary flight testing (the inlet spillage and shock measurements described in 

the previous chapter). The computer-generated image of F-5E shock waves in 

figure 7-1 hints at the value of continued advances in CFD to this endeavor 

not only for its powerful numbers-crunching and airflow-prediction capabilities but also for visualizing the nonlinear propagation of shock waves near 

an aircraft.1

 As implied by the experience described in this chapter, successfully creating an aerodynamically efficient low-boom aircraft would have been 

unlikely if not impossible before the advent of advanced CFD capabilities.

An Evolutionary Design Process

At the beginning of the SSBD project, the involved members of Northrop 

Grumman’s QSP integrated product team assumed that almost all of the 

required geometrical changes to the F-5E would be limited to its nose assembly. 
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Quieting the Boom

Figure 7-1. CFD-generated image 

of F-5E shock waves with pressure 

contours and expansion fields. (NGC)

They began by using relatively simple and 

speedy linear analysis tools to propose 

changes to the shape and volume of the nose 

that would achieve the desired pressure patterns for sonic boom reduction based on areadistribution principles.2

 Additional analyses 

refined the preliminary concept significantly. 

Using Euler codes, Eagle Aeronautics’s Percy 

Bobbitt completed a detailed study in early 

March 2001 defining the shape of the equivalent area distribution for modifying the front 

portion of an F-5E (while staying within the 

overall length and width of an F-5F’s forebody). CFD analysis indicated this 

loft would generate a flattop signature from 30,000 feet at Mach 1.4.3

Different flight conditions were also examined. Hideo Ikawa of NGC used 

a design optimization tool based on Christine Darden’s computer program for 

the minimization of sonic boom parameters (which she had named SEEB in 

recognition of its descent from the minimization theories of Richard Seebass.)4

Ikawa used this to calculate an area distribution that would create a flattop sonic 

boom at Mach 1.55. David Graham converted the results to a Mach 1.0 area 

distribution, which the NGC’s configuration specialist, Jay Vadnais, adapted 

to create the initial geometry for the proposed shaped boom demonstrator. 

Graham ran this design through Peter Coen’s PBOOM suite of linear tools 

to confirm it would generate a basically flattop sonic boom signature.5

 Keith 

Meredith of Northrop Grumman’s Advanced Flight Sciences CFD group completed verification of the near-field effects of this design using Euler codes on 

April 18, 2001. The NGC team submitted its proposal to demonstrate sonic 

boom shaping using this F-5E modification to DARPA a couple of days later. 

The initial configuration with this nose glove (which included an underbody 

extension known as a fairing) was later designated SBD-01 (figure 7-2).6

After DARPA awarded the Shaped Sonic Boom Demonstration contract to 

Northrop Grumman Integrated Systems Sector based on this proposal in July 

2001 and then provided funding in August, the design process resumed in earnest. SBD-02 was completed that same month, and SBD-04 was completed in 

September. Formation of the Sonic Boom Demonstration Working Group in 

August brought in more outside experts to help in the design process and evaluate the configurations. The steps required for each design iteration included (1) 

specifying an area distribution, (2) drawing up the aircraft lines, (3) projecting 

these surfaces onto a computational grid, (4) calculating a CFD solution, (5) 

validating the CFD solution, (6) evaluating its sonic boom signature based upon 

the shock wave pattern, and (7) correcting the area distribution based on these 
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Creating the Shaped Sonic Boom Demonstrator

Figure 7-2. Preliminary SSBD configurations. (NGC)

SBD-01

SBD-03

SBD-04

SBD-05

SBD-06

SBD-07

SBD-08

SBD-11

SBD-12

SBD-14

SBD-15

SBD-16

SBD-17

SBD-18

SBD-19

evaluations. Initially, this cycle took about 2 weeks, but as the participants gained 

experience, they were consistently able to do this in about 3 days.7

Even so, the design process took considerably longer than initially expected. 

At first, the team expected that only about 6 major design iterations would be 

needed to reach a suitable configuration, but in the end they created 23 major 

configurations (most of which are shown in figures 7-2 and 7-3). Counting 

minor variations in many of these, the designers produced a total of 60 configurations.8

 From an aerodynamics perspective, it probably would have been 

easier to design a completely new forebody from scratch.9

The design team used a variety of linear methods, especially during the early 

months when assuring that the configurations would generate the properly 

shaped sonic boom signature was the primary concern. These included the 

aforementioned SEEB and PBOOM, both of which were developed at NASA 

Langley in the early 1990s, and VORLAX, a generalized vortex lattice methodology first developed for NASA Langley in 1977 to help determine both 

subsonic and supersonic airflows.10 Other linear models included Wyle Lab’s 

latest version of PCBoom11 and NFBoom, a propagation code developed by 

Donald A. Durston of NASA Ames.12 Darden’s SEEB code was used throughout the design process, either directly or incorporated with other methods.13

As illustrated by figure 7-3, later configurations took on the characteristic pelican shape as the nose glove increased in size while the fairing under the fuselage 

grew longer and deeper.14 This fairing created an area of expansion under the engine 

inlets, lowering the pressure of a shock wave that would normally coalesce with 
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Quieting the Boom

that from the bow.15

Concerns about shock 

waves from the wings’ 

leading edges and inlet 

spillage, which led to the

ISSM tests, drove some of the 

design changes.16 In its later configurations, the combined structure 

had doubled in size. Many of the 

changes reflected the increased application of the NGC’s high-order GCNSfv 

computational fluid dynamics code (introduced in chapter 6).17 CFD specialists led by Keith Meredith used GCNSfv to 

account for nonlinear near-field and, later, mid-field shock and expansion effects. 

Previously, the GCNS code had normally been used to analyze onbody pressures, so it had to be revised to predict the offbody pressures as required for sonic 

boom purposes. Completing a single CFD prediction took 10 to 12 hours even 

on the powerful Silicon Graphics computer used for analyzing SSBD configurations. Fortunately, Northrop Grumman’s CFD laboratory had quite a bit of spare 

computer time available during the SSBD design effort, and the project received 

management’s support.18

The main purpose of the later design changes was to improve the aerodynamic performance and handling qualities of the modified F-5E while 

still maintaining its boom-shaping capability. Some configurations had to be 

rejected for not doing the latter. Regarding the predicted sonic boom signatures 

of the various configurations, “Everyone trusted Ken Plotkin’s judgment.”19

Roy Martin played a similar role on the F-5E’s aerodynamic performance. 

Early on, he recommended not making the nose glove any longer than the 

nose of a standard F-5F to avoid excessive lateral instability and being sure the 

width of the nose glove did not interfere with a smooth airflow into the engine 

inlets.20 He also advised configuring the nose glove for optimum performance 

at 32,000 feet rather than the 30,000 feet used in some of the early models. In 

addition to allowing a higher Mach number because of lower temperatures, 

this would permit the chase plane probing the demonstrator’s shock waves to 

also stay above 30,000 feet, which was the minimum height for Edwards AFB’s 

high-altitude supersonic corridor.21

Continual feedback from other members of the SSBDWG, including parallel CFD analyses by Boeing and Lockheed Martin using their own proprietary 

codes, was also part of the process.22 John Morgenstern and Tony Pilon of 

Lockheed Martin and Todd Magee of Boeing provided constructive help and 

advice. Morgenstern, for example, suggested a way to improve the NGC’s 

SBD-20

SBD-21

SBD-22

SBD-23

SBD-24

SBD-25

Figure 7-3. Later SSBD configurations. (NGC)
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Creating the Shaped Sonic Boom Demonstrator

method of calculating corrections to the area distributions that significantly 

reduced the turnaround time for design iterations. To help interpret inconsistencies in the CFD evaluations of the configurations by the three companies’ 

computer codes, Juliet Page of Wyle Labs devised an easy and consistent format 

for comparing their data.23 In addition, a recently developed three-dimensional 

propagation code by Eagle’s Percy Bobbitt, with programming support from 

Old Dominion University’s aerospace engineering department, was used to 

verify the results of these analyses.24

The SSBDWG’s second Interim Design Review, the purpose of which was 

to present the working group’s consensus on a technical solution to DARPA, 

was held on February 13, 2002—the day after the first ISSM flight tests at 

Edwards AFB (described in chapter 6). An e-mail sent that evening by Ed 

Haering at NASA Dryden to IDR attendees tentatively confirmed a positive 

correlation between near-field flight-test probe data and CFD predictions.25

The working group was thus able to show DARPA that it was closing in on 

a design that could more accurately account for the effects of inlet spillage 

and associated shocks as well as the F-5E’s less-than-ideal wing sweep. The 

configuration approved at the IDR had been designated SBD-24b (a minor 

alteration of SBD-24, shown in figure 7-3), the design of which initially was 

completed in January 2002.26

Wind Tunnel Testing at NASA’s Glenn Research Center

The next big challenge was to confirm the pressure signatures of the approved 

configuration with wind tunnel testing, scheduled for March 2002 in the 8-footby-6-foot supersonic section of the Glenn Research Center’s wind tunnel complex in Ohio. As described in chapter 4, computational fluid dynamics had 

become essential in designing aircraft, but wind tunnel testing was still required 

to help physically validate what the computer models predicted. So at the same 

time as the working group was planning, conducting, and analyzing the ISSM 

flight tests, it was also planning a wind tunnel experiment for the same basic 

purpose. After the successful correlation of February’s ISSM flight-test data with 

CFD predictions, members of the group were hoping for a similar validation 

in the wind tunnel. However, when Keith Meredith sent the latest CFD results 

for the wind tunnel model to David Graham, who was already at Glenn, it was 

obvious that the model’s support system would cause interference problems.27

The F-5E model chosen for the wind tunnel test was a 5-percent scale model 

(about 21⁄2 feet long), which had been built in the 1970s (but apparently never 

used) for weapons integration and separation testing. The loft of configuration 

SBD-24b was scaled down to make a miniature nose glove that could easily 
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Quieting the Boom

Figure 7-4. SSBD model in Glenn wind tunnel, March 2002. (NGC)

be exchanged with the model’s regular nose. Because of the model’s original 

purpose, it had a wind tunnel mounting strut where the tail section would 

have been. The goal of the SSBD was to modify only the shock waves affecting 

the front end of the sonic boom signature, so the lack of shock waves from tail 

surfaces was not critical to its design. The shock waves created by the mounting 

device, however, would cause problems.28

The model had several other limitations that would soon become painfully 

apparent. It had no internal-force balance, and its flow-through inlets lacked 

internal ducting, so the airflow passed straight through the internal cavity and 

exited in an uncontrolled manner. Because of the concerns about inlet spillage, a 

mass flow plug was placed just behind the model, connected by a fiberglass flow 

adaptor duct that covered the aft portion of the model’s fuselage. This allowed 

inlet spillage to be controlled so that the testers could assess the effects of the 

airflow. To change the model’s angle of attack (AOA), which was necessary for 

experimenting with different flight conditions, someone had to enter the tunnel 

and manually adjust the mounting bracket. This meant turning off and then 

restarting the 87,000-horsepower motors that drive the tunnel’s high-speed compressor. Figure 7-4 shows the SSBD model’s installation in the wind tunnel.29

The tunnel test plan called for examining the model in both its baseline 

and modified configurations at speeds of Mach 1.30, Mach 1.35, and Mach 

1.40 using three angles of attack. In addition to sensors in the mass flow plug, 

there were survey probes at numerous stations along the tunnel walls to collect offbody pressure measurements. The test required use of the Glenn Wind 
177

Creating the Shaped Sonic Boom Demonstrator

Tunnel for 80 hours; 20 of those with the air flowing. As these hours passed, 

the problems became ever more evident. To quote the definitive technical 

account of the test, “results were disappointing for both the baseline F-5E and 

the SSBD-24b configuration.”30

The offbody pressures from the baseline F-5E showed unexplained and 

unrealistic sensitivities to the Mach numbers as well as significant changes 

in forebody, inlet, and wing shocks when only small changes in the latter 

two shocks were expected. The model’s azimuth (directional) angles not only 

affected the wing shock as expected but also appeared to affect the pressure 

readings from the forebody. There were further discrepancies between baseline 

CFD predictions and wind tunnel data. Results with the SBD-24b configuration were somewhat different but no less troubling. For example, at both Mach 

1.30 and Mach 1.40, there were unexpected pressure changes in the shocks 

from the modified forebody, which affected the plateau region of the pressure 

signature that would be critical for generating a flattop sonic boom N-wave.

Even allowing for expected interference from the model’s support structure, 

the testers observed significant differences in shock location and strength from 

the CFD predictions. Figure 7-5 is an example of some of these discrepancies. 

Figure 7-5. Wind tunnel data (dotted line) versus CFD prediction (solid line) at Mach 1.40, March 

2002. (NGC) Key: h/L = height-to-length ratio; Φ = azimuth angle; MFR = inlet mass flow ratio; 

Δp = pressure increase in pounds per square foot; WTM = CFD wind tunnel model.
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Quieting the Boom

In this case, the wind tunnel data from the nose area matched CFD predictions fairly well (left third of the chart), departed from CFD predictions in 

the inlet and wing area (middle third), and failed as expected to provide any 

data from the rear of the model (right third). Even where the results followed 

anticipated trends, the data points were scattered and often not repeatable. 

Problems involving the wind tunnel itself included static pressure variations, 

off-centerline data, and questionable Mach and flow-angle calibrations.31 “In 

conclusion,” the results at Glenn “did not verify the shaped sonic boom design 

methodology; the near-field pressure did not support the CFD predicted signature, and significant model & tunnel data quality issues were identified.”32

As would be expected, the Glenn wind tunnel test was a major topic at the 

next SSBDWG meeting on March 21, 2002. This was followed by the SSBD 

Preliminary Design Review (PDR) on March 26.33 Disappointed but determined to overcome this serious setback, SSBD program management decided 

to attempt another wind tunnel test after correcting as many of the problems 

as possible.34 (As discussed later in this chapter, this PDR also featured some 

good news about the availability of a Navy F-5E for the future demonstration.) 

Because of recent events and the need for more testing and CFD work, the 

critical design review (CDR), scheduled for mid-May, was postponed until 

the discrepancies could be resolved. As explained to the SSBDWG by Joe 

Pawlowski, “We are still in the process of understanding the issues with the 

previous test and will be generating additional test plans. NASA Glenn is 

investigating the data issues....”35

In preparation for this second try, Northrop Grumman specialists improved 

the model by adding an internal six-component force-and-moment balance to 

directly measure lift and other forces acting upon it. (In this context, “moment” 

refers to the torque that would tend to twist or pitch an airframe up or down.36) 

They also removed the mass flow plug to reduce the interference from extraneous shock waves. To help compensate for its absence, they inserted wedges in 

the duct and pressure instrumentation (known as rakes) at the aft exit to control 

mass flow. To move the model farther from the strut and its shock waves, they 

mounted it on a short sting. As shown in the accompanying photograph, the 

strut itself was reduced in size to alleviate blockage and lower the strength of the 

shocks it produced. After troubleshooting the problems encountered at Glenn, 

the project’s CFD experts carefully analyzed the effects of proposed configuration changes prior to fabrication of the new model components. Meanwhile, 

specialists at Glenn conducted a flow survey and examined ways to improve 

the collection and validity of SSBD data in the wind tunnel.37

During this same period, the design team was making subtle revisions to 

SBD-24b. Based on continued analyses, the team digitally sculpted the aft 

section of the under-fuselage fairing to a narrower and more tapered shape 
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Creating the Shaped Sonic Boom Demonstrator

to improve airflow and thereby reduce 

the possibility of viscous separation. 

Additionally, the design team realigned 

the angle of the nose assembly to minimize 

trim drag. CFD modeling assured that 

these changes did not adversely affect the 

desired sonic boom pressure distribution. 

This latest (and final) configuration was 

designated SSBD-24b4. Figure 7-6 shows 

the shape of its nose glove and fairing from 

the side, in cross sections, and under the 

fuselage (including two additional small 

fairings extending back from the engine inlets). Although considerably higher 

and deeper than the nose of a standard F-5F, the SSBD nose glove matched 

its length and width. The additional weight of the added components, including flight-test instrumentation, would be more than offset by the absence of 

the F-5E’s two 20 millimeter (mm) cannons, ammunition, radar, and other 

equipment. Extra ballast would therefore be required to keep its center of 

gravity within the limits of a normal F-5E or F-5F.38

With the 5-percent F-5E model’s new mounting system and loft revised to 

match that of SSBD-24b4, the retest in the Glenn Center’s 8-foot-by-6-foot 

wind tunnel section took place during the last week of May 2002. The tunnel was 

operated at Mach 1.367, which was as close as could be precisely calibrated to the 

Mach 1.40 speed planned for the eventual flight demonstration. Only 40 hours 

of tunnel time were required compared to 80 hours in March with 20 of the 40 

hours being actual air-on time. This time, the results were encouraging. “Wind 

tunnel and CFD pressure distributions for the SSBD configuration showed a 

good correlation over most of the length of the model.... Wing shock strength 

and location were correctly predicted when matched with normal force.”39

The results verified the ability of Northrop Grumman’s GCNS code to predict offbody pressures of the SSBD configuration to at least 1.5 body lengths 

from both configurations of the model as well as sensitivity to lift, Mach 

number, and mass flow changes.40 The data also confirmed CFD predictions 

that making moderate changes to Mach number, lift coefficient, and inlet 

mass flow did not significantly change near-field, offbody pressures. The only 

correlation that had fallen off since the March test involved pressure measurements near the inlet, which was not unexpected because of the removal of the 

well-instrumented mass flow plug. Although the specialists at the Glenn Center 

went out of their way to improve test procedures, there was some continued 

data scattering. Even so, “Results of the second test were significantly better 

than the first in nearly every way.”41

Figure 7-6. Final SSBD configuration 

24b4 compared with other F-5s and 

showing its new underbody fairings. (NGC)
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Quieting the Boom

The experience gained at NASA Glenn offered two major lessons learned 

for conducting sonic boom wind tunnel experiments. Because of the wellknown influence of an airplane’s lift coefficient on sonic boom overpressures, 

any models used need to be equipped to directly measure the forces acting 

upon them. And because sonic boom testing is less forgiving than regular 

aerodynamic testing for measuring onbody and offbody pressures, the wind 

tunnel used should be thoroughly analyzed in advance of model fabrication 

for characteristics such as the model-mounting arrangements, inlet-flow fields, 

Reynolds number, and test section flow characteristics.42

After a careful analysis of data from the successful second test, the Critical 

Design Review for the SSBD was held in El Segundo on July 18, 2002. Most 

importantly, the meeting approved the latest configuration and allowed 

Northrop Grumman to begin physical fabrication of the new nose and fairing.43

Although having encountered some unexpected challenges, the design process owed its ultimate success to several factors (some that could be considered lessons learned for similar projects in the future). Getting early test pilot 

involvement “proved invaluable for maximizing the use of similarity to previous aircraft modifications and for understanding the many capabilities and 

few important limitations of the F-5 aircraft.”44 The working group structure 

encouraged prompt contributions from a wide range of participants, which 

was especially useful in areas like sonic boom and wind tunnel testing, where 

NGC personnel had less experience. The relatively small design and analysis 

team dedicated to the project was able to react quickly to each new CFD result 

while QSP-SSBD program management assured access to the needed computer 

resources. Northrop Grumman’s extensive database of past F-5 configurations, 

both produced and proposed, and its existing 6-DOF simulation that could 

be quickly modified, provided valuable data and saved time.45

Initial Fabrication and Final Wind Tunnel Testing

To prepare to manufacture the parts that would compose the nose glove and 

fairings, a 15-person vehicle-design team under Keith Applewhite used a computer-aided design (CAD) system to render the shape of the 24b4’s surfaces 

into the tooling and precise specifications needed to make its outer panels and 

inner structures. The panels would be made from composite materials, while 

aluminum would be used for frames and stringers. One of the first steps for the 

CAD program was to smooth out minor imperfections in the fit and finish of 

the original CFD-generated loft for unobstructed airflow at supersonic speeds.

In coordination with the aerodynamic design team, other relatively minor 

tweaks continued during the coming months. CFD was used to investigate the 
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Creating the Shaped Sonic Boom Demonstrator

offbody pressures of certain individual components (such as the nose-mounted 

pitot probe that measures airspeed), spillage from an inlet to the aircraft’s environmental control system (ECS), wing lift, and horizontal tail angles. Some 

of the seemingly mundane but essential features that also required additional 

design work were nose-gear doors (which later proved problematic), arrangements for drainage, and exhaust ducting for the ECS. The functioning of this 

exhaust system would be critical because the fairing would be covered with a 

composite carbon-fiber skin known as LTM-45EL. This was a cost-effective 

material for making prototype and low-volume items partly because its resin 

was preimpregnated into the fabric and did not need curing at high temperatures and pressures.46 One drawback, however, was that it would not tolerate 

direct heating of more than 250 °F. Dave Graham was more worried about this 

issue than the effects of the SSBD modifications on the F-5E’s stability and 

control. The design teams devised a stainless steel ECS exhaust system to ensure 

dissipation of any heat buildup by using CFD to model its geometry, surface 

flow, and cooling capacity. They also decided to install thermal switches inside 

the fairing to alert the pilot in case of a dangerous hot-air leak.47

Even as some design work continued, a team of skilled craftsmen 

at Northrop Grumman’s Advanced 

Composites Manufacturing Center 

in El Segundo were preparing to 

make the nose glove and fairing.48

Leading this team was Mark Smith, 

a manufacturing engineer who had 

begun his career with Northrop 

in 1973 working on the F-5. To 

accomplish the fabrication as efficiently as possible, they followed 

rapid prototype procedures, which 

NGC had used when making small 

new vehicles in the past. The initial 

fabrication process began during 

July 2002 in NGC’s Building 905. 

As shown in the two accompanying photos, some of the first steps 

were to create the foam tooling that 

served as templates for laminating 

(laying up) the surfaces to be used 

for shaping the outer skin panels. 

A total of 33 precisely engineered 

Preparing tooling (top) to form the outer mold line 

of the nose glove (bottom) in August 2002. (NGC)
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Quieting the Boom

panels of various sizes eventually would be needed to cover the exterior of 

the nose glove, including the fairing extending under the fuselage. As with 

the aerodynamic design process, making all the required parts became more 

complicated (and time consuming) than originally planned.49

Although there was now confidence that SSBD configuration 24b4 could 

indeed lower the initial overpressure of its sonic boom signature, more testing 

and analysis were needed to verify its stability and control qualities. The value 

of CFD continued to be evident in this effort. Because of the small size of the 

high-speed wind tunnel model and its uncalibrated ducts, only CFD could be 

used to show the supersonic trimmed-drag effects of the nose glove.50

The CFD analyses indicated that the aerodynamics of SSBD-24b4 were 

within Northrop Grumman’s existing (and very extensive) F-5 database but 

just barely for angles of attack at high speeds.51 They also predicted it could 

meet the desired speed of Mach 1.4 at 32,000 feet on a standard day (i.e., one 

with the normal range of temperatures for that altitude) and would be statically stable about all its axes.52 Even though preliminary CFD predictions of 

the aerodynamic coefficients showed acceptable handling qualities, two more 

wind tunnel tests were needed to validate the offbody pressures of the SSBD 

design and to update 6 degrees of freedom (6-DOF) motions used in computer 

simulations for the standard F-5E’s flight maneuvers. These tests would help 

verify the plane’s handling qualities for flight-readiness reviews to be conducted 

by both Northrop Grumman and the Navy. Fortunately, the SSBD F-5 would 

be flying mostly straight and level with relatively gradual turns, which did not 

require validating the entire F-5E flight envelope.

Wind tunnel testing of the SSBD 24b4’s low-speed handling qualities 

required a model at least twice as large as the 5 percent scale model used 

for high-speed testing, one with both vertical and horizontal tail surfaces.53

The SSBDWG originally had assumed that they could modify a legacy F-5E 

model from the 1970s, but despite inquiries both within and outside the 

company, David Graham was unable to locate one. So Northrop Grumman 

fabricated a 10-percent scale model using stereolithography, the CAD technique in which an ultraviolet laser device printed the three-dimensional loft of 

the model one layer at a time using a special resin-like material.54 After getting 

an aluminum skin, the resulting 5-foot-long model (shown in the accompanying photograph) was tested in Northrop Grumman’s 7-foot-by-10-foot 

low-speed wind tunnel for 251⁄2 hours in August 2002 to validate CFD predictions for stability and control, including force-and-moment measurements 

throughout its reduced flight envelope. The existing 5-percent model was then 

tested for the same factors in a 4-foot supersonic wind tunnel section at the 

Air Force’s Arnold Engineering Development Center (AEDC) in Tennessee 

during October 2002. Both tests started with the models having the standard 
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Creating the Shaped Sonic Boom Demonstrator

F-5E nose to establish a direct link to 

the existing database before moving on 

to the SSBD configuration. All the data 

collected were postprocessed to build 

increments between the standard and 

modified configurations for the stability and control analysis.55

These two final wind tunnel tests 

revealed no significant changes in 

SSBD-24b4’s longitudinal responses—

except for the need to add 2 degrees 

of horizontal tail trim at most Mach 

numbers to compensate for a change 

in its pitching-moment coefficient. The lateral (directional) responses were 

comparable to that of a standard F-5E except for some reductions in yaw and 

roll stability. This made its handling qualities very comparable to an F-5F (with 

its longer forebody) when carrying a 275-gallon centerline fuel tank (which 

produced effects much like the underbody fairing). The controls worked well, 

with no significant change in power by the ailerons or horizontal tail surfaces 

and only a slight reduction in rudder power at high deflections and angles of 

attack. Previous concerns about sideslip effects on control power were deemed 

insignificant. Further aerodynamic and engineering analyses found that the 

effects of the SSBD modification on stability and control matched CFD predictions and would be suitable within its restricted flight envelope. In conclusion, 

both the subsonic and supersonic handling qualities of the modified aircraft 

were found to be satisfactory and not too different from other F-5 configurations with stability augmentation engaged.56

With the completion of wind tunnel testing and additional design refinements, the final configuration was confirmed at a DARPA-sponsored meeting in Huntington Beach, CA, in December 2002. Before the parts could be 

completed and installed, however, the Navy would have to approve this radical 

remodeling of one of its Tiger IIs and place it on loan to Northrop Grumman.

Ten percent model of SSBD in Northrop 

Grumman’s low-speed wind tunnel, October 

2002. (NGC)

Obtaining the F-5E

The eventual modification of a stock F-5E would have to be done at a suitable 

facility with an adjacent runway, preferably located within easy flying distance 

to an FAA-approved supersonic corridor. Some members of the Northrop 

Grumman’s QSP IPT gave some early consideration to doing it in Southern 

California at the Scaled Composites complex or another available facility at 
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Quieting the Boom

the Mojave Airport, in one of Dryden’s hangars at nearby Edwards AFB, or 

in an NGC building at Air Force Plant 42 in Palmdale. Although these locations would be close to the manufacturing facilities in El Segundo and the test 

range at Edwards, they selected Northrop Grumman’s maintenance depot in 

St. Augustine, FL (abbreviated as the NGSA), which is located at the St. Johns 

County Airport, as the most logical choice. The technicians and mechanics 

at the NGSA had unequalled experience in breaking down, refurbishing, and 

returning to flight status various Navy aircraft including F-5s. Doing the SSBD 

modifications would be similar to this work. Roy Martin later determined, 

however, that the 8,000-foot St. Johns runway, although suitable for a normal 

F-5, would not provide enough of a safety margin for the modified F-5E. As 

a solution, John Nevadomsky, the NGSA operations and safety officer, suggested flying all but the first Florida flight out of the nearby Cecil Commerce 

Center, which had been built up around a former military base named Cecil 

Field with a 12,500-foot runway. An Army reserve unit there later agreed to 

host the modified F-5 and its chase plane.57

Now all that was needed was to obtain a suitable aircraft. While hoping 

the Navy would agree to provide one of theirs, Northrop Grumman explored 

several other options. These included leasing an F-5E from the Swiss Air Force 

or from a couple of private companies that were considering the purchase of 

F-5Es from Switzerland or Taiwan.58

As explained in chapter 6, arranging for the U.S. Navy’s aggressor squadron 

at NAS Fallon in Nevada to deploy one of its F-5Es to Edwards AFB for the 

2-day ISSM flight tests had not been a simple matter. Even so, Roy Martin was 

happy to report from Fallon in late October 2001 that the staff of VFC-13, 

including its soon-to-be commander, W.J. Cole, had agreed to support the 

future SSBD (pending the approval of higher headquarters) with another similar deployment. Of course, they expected reimbursement by either NGC or 

NASA. Martin also informed fellow SSBD team members that VFC-13 would 

try to accommodate all the needed special equipment in the F-5E’s cockpit.59

Getting the Navy’s approval for a long-term loan of one of its F-5Es, which 

would have to be demilitarized and partially rebuilt into the SSBD configuration, 

was more complicated. The instrument for arranging this would be a Cooperative 

Research and Development Agreement (CRADA), which is basically a contract 

between a Federal and a non-Federal entity to facilitate joint R&D projects. As 

with the ISSM test, Mike Ingalls, NGSA’s aircraft overhaul program manager 

who had excellent relationships with many Navy officials, was largely responsible 

for obtaining the F-5E. In January 2002, he informally approached Naval Air 

Systems Command officials about allowing Northrop Grumman to borrow and 

modify one for the SSBD. Receiving a favorable response, Joe Pawlowski drafted 

a formal request cosigned by Steven R. Briggs, a retired rear admiral who was 
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Creating the Shaped Sonic Boom Demonstrator

vice president of the NGC Air Combat Systems division. Ingalls delivered this 

request to the NAVAIR program management office for multimission aircraft 

(code PMA-225) in late January while stopping at Patuxent River on his way to 

Switzerland with NAVAIR representatives.60 There they discussed the purchase of 

surplus F-5s from the Swiss Air Force, which would be a key factor for obtaining 

use of one of the Navy’s existing F-5Es.

In March 2002, after Joe Pawlowski had explained more about the program to Rear Adm. Timothy Heely of the Naval Air Warfare Center’s Aircraft 

Division, Jim Sandberg, a former test pilot who was one of NGC’s onsite 

personnel at Patuxent River, set up a full-scale briefing for Vice Adm. Joseph 

Dyer, NAVAIR commander. Dyer was very knowledgeable on the technical 

and safety aspects of experimental projects like the SSBD, having formerly been 

the Navy’s chief test pilot and chief aviation engineer.61 Attendees at this meeting, held on March 22, included Lisa Veitch representing DARPA; Peter Coen 

from NASA; and Charles Boccadoro, Steven Briggs, and Joe Pawlowski from 

NGC. After Veitch gave an introduction to the QSP program, Pawlowski gave 

a short briefing on the planned Shaped Sonic Boom Demonstration. Admiral 

Dyer responded favorably pending three conditions: having a Navy test pilot fly 

some of the sorties, meeting all Navy flight clearance criteria, and being given 

more involvement in the QSP program, especially if there was a follow-on to 

Phase II. The Navy’s tentative approval to provide an aircraft allowed DARPA’s 

Richard Wlezien to make a favorable go, no-go decision on the SSBD at the 

Preliminary Design Review held on March 26.62

Even with NAVAIR’s tentative approval, negotiating terms of the CRADA 

became a drawn-out process that included coordination with the Navy’s Type 

Command (TYCOM) in New Orleans, which was responsible for operating 

F-5 type aircraft. Because the planned purchase of the surplus F-5Es from 

Switzerland was not yet final, the Navy at first wanted the modified F-5E 

restored to its original condition after the demonstration. Negotiating terms 

of the CRADA required frequent discussions and exchanges of information 

with NAVAIR. Joe Pawlowski and other NGC personnel made three more trips 

to Patuxent River to negotiate terms of the CRADA and work with NAVAIR 

specialists regarding the flight clearance process.63

On December 10, 2002, 1 day after Admirals Dyer and Heely and Barbara 

Olsen from NGC’s subcontracts office signed the CRADA, Pawlowski reported 

the “good news” to the membership of the SSBDWG. “The Navy has finally 

signed the CRADA and released the F-5E aircraft! We are now getting it ready 

to fly a baseline functional check flight next week to assess aircraft performance 

prior to modification.”64 The F-5E chosen for the modification, identified as 

BUNO 74-1519, came from the U.S. Marine Corps aggressor squadron at 

Yuma, AZ. (In Navy parlance, BUNO is an abbreviation for Bureau Number.) 
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Quieting the Boom

As indicated by the first two digits of this number (inherited from the original 

Air Force–allocated tail number), it had been built in 1974. The plane was in 

need of a major overhaul, but NAVAIR authorized a lifetime extension of 50 

flight hours given that the planned demo would put only minimal stresses on 

the airframe.

Roy Martin put the old F-5 through its paces during functional check flights 

(FCFs) on December 17 and December 18. The first flight revealed some 

minor handling abnormalities, but after the NGSA mechanics replaced some 

parts, he was able to make several runs along the supersonic corridor off the 

Florida coast. Instead of the expected Mach 1.55, however, the plane was able 

to achieve only Mach 1.4 at 32,000 feet. The temperature there was measured 

at –41 °F compared to –48 °F on a standard day. In view of the abnormally 

high temperature and having the option of using a pushover maneuver from 

a higher altitude to gain speed, Martin and Graham still hoped to be able to 

achieve the planned Mach 1.4 during the planned tests at Edwards despite the 

extra drag that the modification would impose. After further analyses, it was 

concluded that “a max Mach number of only 1.4 for the unmodified aircraft 

on a hotter than standard day is not a show stopper. There is no reason to 

delay installing the SSBD modifications to the...aircraft.”65 To begin preparing 

the Marine fighter plane for this work, it was towed into NGSA’s Hangar 40 

on January 9, 2003.66 Much to the delight of all involved, in early February, 

NAVAIR notified Joe Pawlowski that the last of four congressional committees 

had approved the Navy’s purchase of Swiss F-5s. This meant that after having 

disassembled and modified BUNO 74-1529, the NGSA would not have to 

restore the plane to its original condition after the demonstration as had been 

required in the CRADA.67

Final Fabrications and Modification

The modification team in St. Augustine, led by Dale Brownlow, began preparing the F-5E for its transformation during the second part of January by 

removing its existing nose section. At the same time, across the country in 

El Segundo, Mark Smith and his fabrication team began putting together 

the subassemblies. This work included constructing aluminum bulkheads and 

internal braces and aligning them in a nose-assembly tool, which (as shown 

in an accompanying photograph) served as a template. The final step was to 

attach the carefully shaped outer mold line (OML) composite skin panels to 

the nose-glove framework. The LTM45EL carbon fiber used for the panels was 

the same material to be used on Scaled Composites’ SpaceShipOne that won 

the X-Prize for achieving the first private-sector suborbital flights in 2004.68
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Creating the Shaped Sonic Boom Demonstrator

Nose bulkheads and framework being assembled and later crated for shipment with skin panels 

attached. (NGC)

The new nose and other recently delivered parts in a hangar at St. Augustine on April 3, 2003. (NGC)

Fabrication of the nose section was completed in mid-March, when it was carefully packaged as shown in the next photograph. The fairing was also completed 

for shipment to St. Augustine on March 17. As an extra precaution because 

of the skin’s susceptibility to overheating, the designers provided a number of 

temperature-indicating tabs to be applied to the fairing’s outer skin near the 

ECS exhaust outlet. During the future test program, postflight inspections of 

these “tell-tales” (which would change color if exposed to high temperatures) 

revealed no such problems.69

The next photograph shows the new nose being aligned with the strippeddown F-5E fuselage shortly after its arrival at NGSA Hangar 40 along with 

boxes and crates holding other components. To some extent, the rebirth 

of the Marine fighter as the F-5 SSBD was equivalent to handcrafting a 

new prototype. To help in this process, the NGSA workforce was augmented by Mark Smith and three technicians from El Segundo. Reflecting 
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Quieting the Boom

the high-level interest in completing the project, Charles Boccadoro and 

Joe Pawlowski spent the next several months taking turns overseeing the 

work in St. Augustine. As might be expected when putting a one-of-a-kind 

structure together for the first time, the modification team began encountering some problems.70

One of the more tedious issues involved securely mating the nose glove 

and fairing to the existing framework of the old F-5. A complex arrangement of bulkheads and aluminum stringers (shown in figure 7-7) served as 

a skeleton for the modified exterior. Based on NGC’s file of F-5E plans and 

specifications, the fabrication design team had configured this aluminum 

framework for easy attachment to a production F-5E’s existing structure—

or so it was hoped. Unfortunately, over the past quarter century BUNO 

74-1529 had undergone a lot of field maintenance and some overhauls with 

many minor changes not documented in available maintenance records. 

Because of these nonstandard specifications, about 90 percent of the shims 

and spacers shipped from El Segundo did not quite line up in the exact places 

they were supposed to. As a result, the NGSA technicians had to improvise 

and hand-fit new connectors.71

Not all of the project’s troubles involved work on the aircraft. One late 

evening in April 2003, Charles Boccadoro was returning to his hotel on a 

narrow country road when he swerved to avoid a drunk driver in a black 

pickup truck. His rental car crashed into a drainage ditch, and when he 

regained consciousness, the engine compartment was on fire. Despite a badly 

injured kneecap, he was able to pull himself out the window and, with the 

help of some good Samaritans who came on the scene, get away before the 

passenger compartment was engulfed in flames. When emergency personnel 

arrived, his biggest concern was retrieving his laptop computer. Fortunately, 

a very good doctor in Jacksonville helped him begin rehabilitation from his 

injury, and even the data stored on the hard drive of his charred computer 

was recoverable. The accident may also have garnered him some sympathy 

at corporate headquarters, where unhappiness about the SSBD’s delays and 

cost overruns had been mounting. In that regard, the SSBD project was 

fortunate to have continued receiving strong support from Scott Seymour, 

Boccadoro’s superior at the Integrated Systems Sector.72

Figure 7-7. Framework for the SSBD nose glove and fairing. (NGC)
189

Creating the Shaped Sonic Boom Demonstrator

In addition to the F-5 SSBD’s external shape being modified, much of its 

internal equipment was replaced. In effect, the former fighter plane was transformed into a flight--research platform. First, the NGSA team had removed 

the radar antenna, both 20 mm guns and ammunition boxes, the lead computing optical sight system, and the fire control computer. They also installed 

a sophisticated pitot static probe on the point of the new nose and relocated 

the battery, tactical air control antenna, and UHF identification friend or foe 

(IFF) antenna to other parts of the aircraft.73

Ed Haering and colleagues at NASA Dryden planned and obtained the 

special flight-test instrumentation needed in the SSBD. As during the ISSM 

test in February 2002, one of the key components was an Ashtech Z-12 carrierphase differential GPS receiver.74 In addition to recording data in its internal 

memory, it had a UHF modem for transmitting data to others. Once again, the 

NGC specialists in El Segundo integrated the receiver into a package that fit 

in the map case on the right side of the cockpit as shown in an accompanying 

photo. The GPS unit would determine the plane’s exact position relative to 

the similarly equipped F-15B probe aircraft, the standard F-5E, and the array 

of microphones on the ground.75

Precisely measuring speed, acceleration heading, pitch, roll, yaw, and other 

aerodynamic factors required a suite of sensitive air-data acquisition instruments. 

This specialized equipment consisted of a calibrated Mach meter; temperaturecontrolled air-data transducers; an unheated outside air temperature probe with a 

signal conditioner and power supply to gauge true airspeed; a three-axis rate gyroscope; sensitive accelerometers; a signal-conditioning, power control module; an 

S-band telemetry transmitter; an Inter-Range Instrumentation Group (IRIG) 

format B time code generator; and three time recorders. To record pilot comments and the readings of cockpit instruments—such as air speed, altitude, 

and trim—two small “lipstick” video cameras were connected to a three-deck 8 

mm airborne video and voice recorder mounted in the right-side gun bay. The 

telemetry system would allow realtime monitoring and recordings 

on the ground, while the onboard 

data-recording system would provide redundancy. Using UHF, 

the GPS data would be transmitted separately from the telemetry 

data stream on the S-band.76 The 

accompanying photograph shows 

some of the GPS equipment and 

one of the little video cameras 

inside the cockpit. “Lipstick” camera and GPS unit in cockpit. (NGC)
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Quieting the Boom

Since Northrop Grumman’s St. Augustine facility conducted only routine 

flights of the aircraft it overhauled, it did not have the antennas or instrumentation needed to receive and record flight-test telemetry from the F-5 SSBD, 

as the former F-5E would be redesignated. To obtain these data during the 

required local check and envelope-expansion flights, Northrop Grumman had 

to install a special ground telemetry station as well as arrange advance clearances 

from the Federal Communications Commission (FCC) for the frequencies that 

would be used.77 The equipment included a microwave antenna mounted on 

the roof of the NGSA hangar and an S-band telemetry receiver with related 

processors, displays, recorders, and printers.78 Most of the instrumentation was 

installed and wired by late April.

On April 28, the modified F-5 with a big new olive drab nose and offwhite underbody fairing attached to its original gray airframe was towed to 

the NGSA painting facility. One week later, it emerged having a bright white 

exterior with the sides of the fuselage featuring a red pinstripe shaped like a 

typical N-wave sonic boom signature and a parallel blue pinstripe representing 

the predicted flattop signature.79 This clever design was the inspiration of a 

Northrop Grumman engineer named Joan Yazejian.80 The transformation of 

the old F-5E fighter jet into the F-5 SSBD appeared to be complete.

All seemed to be going well until June 8, during preparations for the first 

high-speed taxi test scheduled for the following day. The inspectors noticed some 

unacceptable free play with the front doors for the nose landing gear. Unlike the 

aft portion, which was replaced with a newly designed wider door, the existing 

clamshell doors had been integrated into the new fairing using the same hinges 

and an extended actuation arm. This 

seemingly simple mechanical problem 

took the rest of the month to solve. Mark 

Smith, who was now leading the modification team in St. Augustine following 

Dale Brownlow’s retirement in May, 

brought in three of the technicians who 

had fabricated the nose in El Segundo to 

help make the necessary fixes and get the 

landing gear flight worthy. As shown in 

figure 7-8, one of their ingenious solutions was securing the clamshell doors 

with segments of a piano hinge.81

The delay this caused in starting flight operations almost made for an 

awkward situation with the Boeing Company. Regarding a chase plane and 

escort for the long cross-country flight to California, Roy Martin’s preference had been to use another F-5-type aircraft, such as a T-38, which had 

piano hinge

forward door

metal strap

metal strap

Figure 7-8. Changes made to nose gear door 

components. (NGC)
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Creating the Shaped Sonic Boom Demonstrator

the same basic performance. Charles Boccadoro had therefore arranged for 

Boeing to provide a T-38 chase plane as part of the arrangement for sharing 

in the SSBD’s data. Martin went to Seattle in early June to help Boeing test 

pilot Mike Bryan bring the T-38 to Florida. (As practice for later flying the 

F-5 SSBD with its long nose, Martin frequently controlled the T-38 from 

the back seat on the flight to St. Augustine.) When it became obvious that 

the nose gear door would not soon be fixed, the time came to notify Boeing 

of the embarrassing delay. Just before that, however, Bryan told his hosts 

that his office at Boeing had just called to inform him that his T-38 was, in 

any case, needed back in Seattle.82 He would return a month later when the 

F-5 SSBD was ready to fly.

Test Plan Approval and Flight Clearance

Planning for flight operations continued in parallel with the fabrication and 

modification work. These would begin with functional check flights and subsonic envelope-expansion maneuvers in Florida followed by a cross-country 

ferry flight to California, where additional FCFs and supersonic envelopeexpansion profiles would be conducted in preparation for the actual sonic 

boom flight tests. Reflecting the plane’s ownership, the Navy was responsible 

for flight safety, which helped assure that the planning process was very systematic and rigorous. In all, more than 50 NAVAIR specialists and officials would 

be involved in reviewing and supporting the SSBD project.83

Northrop Grumman’s flight-test engineer for the SSBD was Steve Madison. 

With inputs from members of the working group and others involved in the 

project, he pulled together all the requirements needed to prepare for and 

conduct the Shaped Sonic Boom Demonstration. Briefings on these preparations were regularly presented, updated, and reviewed during 2002 and early 

2003—both internally and by NAVAIR, which also assessed a detailed design 

analysis of the SSBD modification. This feedback helped in the drafting of a 

test plan, an early version of which was first posted on the SSBD Web site in 

October 2002. The briefings and planning documents covered a wide range of 

topics, including governing directives, inspection procedures, quality-assurance 

criteria, certification standards, personnel qualifications, and SSBD instrumentation. They also specified the sequence of actions to be followed for the 

aircraft’s ground checks, envelope-expansion flights, functional check flights, 

and, finally, the sonic boom data-collection flights.84 The process culminated 

in formal SSBD test plans for the data-collection flights as well as the preceding envelope-expansion flights. NASA Dryden published a related planning 

document to cover the in-flight near-field probes.85
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Quieting the Boom

Roy Martin getting into “the Pelican” for a ground test on July 23, 2003, just before its first 

flight. (NGC)

In preparing fight profiles, the planners followed a “predict, test, analyze”86 procedure. They used data collected from the Northrop Grumman 

subsonic and AEDC supersonic wind tunnel tests combined with the existing 

F-5 performance database and CFD analyses to assure the modified F-5E 

would have enough stability (especially specific damping ratios) and other 

handling qualities in all of the planned flight conditions. Military Standard 

(MIL-STD) 1797, “Flying Qualities of Piloted Aircraft,” defined these and 

other criteria in great detail. As chief SSBD test pilot, Roy Martin approved 

each of the planned maneuvers.87

Northrop Grumman conducted a series of flight-readiness reviews (FRRs). 

These covered the statuses of the aircraft configuration, engineering analysis, 

test plan, completion of modifications, safety-hazard analysis, and other readiness factors. On June 9, 2003, having been reassured by these reviews that the 

modified F-5 would be safe to fly, NAVAIR formally transmitted its eagerly 

awaited initial flight clearance (first announced on June 6), which closely followed the thresholds in NGC’s previously published test plan. For the record, 

the message listed the various conditions and constraints that the aircraft 

would comply with, such as flying only in visual meteorological conditions, 

not exceeding Mach 1.45, keeping the most strenuous of several approved 
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Creating the Shaped Sonic Boom Demonstrator

maneuvers under 3.0 equivalent gravitational forces (g’s), turning with bank 

angles of no more than 60 degrees, and making no abrupt changes in pitch, 

roll, or yaw.88

Two days after the Navy’s initial flight clearance notification, the nose gear 

problem was discovered.89 Since the loose door would not affect nonflying 

activity, Roy Martin was able to take the F-5 SSBD out on the St. Johns 

runway for the first ground test as scheduled on June 9.90 Keeping below the 

F-5’s takeoff speed of 150 knots, this and two subsequent acceleration tests on 

July 23 were part of a systematic series of ground checkouts of all the aircraft’s 

systems, including the revised environmental controls. The taxi runs tested the 

plane’s brakes at various speeds and distances. On one run, the drag chute was 

deployed to simulate an abort at 130 knots. These operations also previewed 

functioning of the air-data instrumentation system, the Ashtech Z-12, and the 

telemetry equipment that would be so important in recording and transmitting 

results of the flight tests.91

After resolving the landing-gear problem and receiving another NAVAIR 

flight clearance on July 3,92 the final flight-readiness reviews for the planned 

activities could begin. These were conducted in front of a nine-person board 

cochaired by representatives from NGC and NAVAIR. By late July, the final 

FRR for the envelope-expansion and ferry flights had assured NAVAIR that all 

pertinent quality assurance and safety issues for the new F-5 SSBD had been 

addressed successfully.93 After a final ground test on July 23, the time had come 

to check it out in the air.
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Quieting the Boom

Endnotes

1. Source for figure 7-1: Peter G. Coen and Roy Martin, “Fixing the 

Sound Barrier: The DARPA/NASA/Northrop Grumman Shaped 

Sonic Boom Flight Demonstration,” PowerPoint presentation, 

Experimental Aircraft Assoc. (EAA) Air Venture, Oshkosh, WI, 

July 2004, slide no. 4.

2. David H. Graham, John A. Dahlin, Keith B. Meredith, and 

Jay L. Vadnais, “Aerodynamic Design of Shaped Sonic Boom 

Demonstration Aircraft,” 43rd AIAA Aerospace Sciences Meeting, 

Reno, NV, January 10–13, 2005, AIAA paper no. 2005-8, 3.

3. Domenic Maglieri to Lawrence Benson, “Comments on Chapter 

7,” e-mail, September 19, 2011.

4. C.M. Darden, “SEEB-Minimization of Sonic-Boom Parameters 

in Real and Isothermal Atmospheres,” LAR-1179 (January 1994), 

NTRS abstract.

5. Peter G. Coen, “Development of a Computer Technique for 

Prediction of Transport Aircraft Flight Profile Sonic Boom 

Signatures,” NASA CR 188117 (March 1991).

6. David Graham to Lawrence Benson, “SSBD Design Questions,” 

e-mail, August 4, 2011. Figure 7-3 copied from Graham and 

Martin, “Aerodynamic Design and Validation of SSBD,” slide 

no. 4.

7. Graham to Benson, August 4, 2011.

8. Robert Wall, “Noise Control,” Aviation Week (August 4, 2003): 

23–24, citing interview with Charles Boccadoro; John Croft, 

“Engineering through the Sound Barrier,” Aerospace America 42, 

no. 9 (September 2004): 29. Figures 7-2 and 7-3 extracted from 

Graham and Martin, “Aerodynamic Design and Validation of 

SSBD,” slide no. 4.

9. Croft, “Engineering through the Sound Barrier,” 29, citing 

interview with Charles Boccadoro.

10. L.R. Miranda, R.D. Elliott, and W.M. Baker, “A Generalized 

Vortex Lattice Method for Subsonic and Supersonic Flow 

Applications,” NASA CR 2895 (December 1977).

11. Kenneth J. Plotkin and Fabio Grandi, “Computer Models 

for Sonic Boom Analysis: PCBoom4, CABoom, BooMap, 

CORBoom,” Wyle Report WR-02-11 (June 2002).
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Creating the Shaped Sonic Boom Demonstrator

12. Graham and Martin, “Aerodynamic Design and Validation of 

SSBD” (August 17, 2004), slide no. 8. Daniel A. Durston’s 

“NFBOOM User’s Guide, Sonic Boom Extrapolation and 

Sound-Level Prediction,” NASA Ames Research Center, was 

an unpublished document. His November 2000 edition is 

cited in Charles L. Carr et al., “Minimization of Sonic Boom 

on Supersonic Aircraft Using an Evolutionary Algorithm,” 

2003, accessed August 14, 2011, http://portal.acm.org/citation.

cfm?id=1756700.

13. Graham to Benson, August 4, 2011.

14. Figure 7-3 copied from Graham and Martin, “Aerodynamic Design 

and Validation of SSBD,” slide no. 6.

15. Michael Dornheim, “Will Low-Boom Fly?” Aviation Week

(November 7, 2005): 69.

16. Ibid.; Graham et al., “Aerodynamic Design of SSBD,” AIAA paper 

no. 2005-8, 3.

17. Meredith, “CFD Comparison and Flight Test Measurement,” 

AIAA paper no. 2005-6, 5. Based on the Ames Research Center 

3-Dimensional (ARC3D) code, GCNSfv was a multiple-block 

code that allowed both arbitrary face-matching and overlapping 

block interfaces. It used nodal finite volume and a diagonal 

beam-warming algorithm with viscous modifications. NGC 

had developed an extensive compilation of boundary conditions 

from various airframe components to use in airflow predictions. 

Boundary conditions and parametric linear interpolations were 

computed on multiple grids and a sequence of coarse and fine 

meshes using various techniques.

18. Benson, Pawlowski/Graham interview, April 12, 2011; Wall, 

“Noise Control,” 24.

19. Benson, Pawlowski/Graham interview, April 12, 2011.

20. Interview of Roy Martin by Lawrence Benson, Lancaster, CA, 

April 7, 2011.

21. David Graham to Ed Haering et al., “FW: Release of F-5SBD 

Loft,” e-mail, October 4, 2001.

22. Lockheed Martin’s analysis in early 2002 used its SPLTFLOW-3D 

code. See John F. Morgenstern, Alan Arsian, Victor Lyman, 

and Joseph Vadyak, “F-5 Shaped Sonic Boom Demonstrator’s 

Persistence of Boom Shaping Reduction through Turbulence,” 
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Quieting the Boom

AIAA paper no. 2005-12, 43rd Aerospace Sciences Meeting, Reno, 

NV, January 10–13, 2005, 3–4.

23. Joe Pawlowski to Peter Coen et al., “SBDWG Meeting Reminder,” 

e-mail, January 8, 2002; “CFD Used in Sonic Boom Test 

Program,” CFD Review (September 23, 2003), accessed ca. August 

30, 2011, http://www.cfdreview.com/application/03/09/23/1327257.

shtml.

24. Osama A. Kandil, Z. Yang, and P.J. Bobbitt, “Prediction of Sonic 

Boom Signature Using Euler-Full-Potential CFD with Grid 

Adaptation and Shock Fitting,” AIAA paper no. 2002-2543 (June 

2002), cited in Pawlowski et al., “Origins and Overview of the 

SSBD,” AIAA paper no. 2005-5, 8, 14. Kandil was a professor and 

Yang a research assistant.

25. Ed Haering to Joe Pawlowski et al., “VERY preliminary ISSM 

data,” e-mail, February 12, 2002.

26. Joe Pawlowski to Peter Coen et al., “SBDWG Meeting Reminder,” 

e-mail, January 22, 2002; Joe Pawlowski to Peter Coen et al., “ 

IDR Rescheduled for Wednesday 2/13/02,” e-mail, February 4, 

2002; Graham to Benson, “SSBD Design Questions,” August 4, 

2011.

27. Graham to Benson, August 4, 2011.

28. The vertical tail surface of a typical fighter aircraft configuration 

such as the F-5 serves as a horizontal stabilizer and rudder. The 

horizontal surfaces serve as vertical stabilizers as well as elevators 

for climbing or descending. All of these components can create 

shock waves during transonic and supersonic flight.

29. David H. Graham, John A. Dahlin, Judith A. Page, Kenneth J. 

Plotkin, and Peter G. Coen, “Wind Tunnel Validation of Shaped 

Sonic Boom Demonstration Aircraft Design,” 43rd Aerospace 

Sciences Meeting, Reno, NV, January 10–13, 2005, AIAA paper 

no. 2005-7, 2–3; Graham and Martin, “Aerodynamic Design and 

Validation of SSBD,” slides nos. 17–19, with figure 7-4 copied 

from slide no. 20.

30. Graham et al., “Wind Tunnel Validation of SSBD,” AIAA paper 

no. 2005-7, 3.

31. David Graham, “Wind Tunnel Boom Test,” PowerPoint 

presentation, July 18, 2002, with figure 7-5 copied from slide 

no. 7.
197

Creating the Shaped Sonic Boom Demonstrator

32. Graham et al., “Wind Tunnel Validation of SSBD,” AIAA paper 

no. 2005-7, 4.

33. Joe Pawlowski to Peter Coen et al., “SSBDWG Meeting 

Reminder,” e-mail, March 19, 2002; Joe Pawlowski to Richard 

Wlezien et al., “SSBD PDR 3/26/0,” e-mail, March 20, 2002.

34. Joe Pawlowski to Peter Coen et al., “SSBDWG Meeting - 

4/18/02!!,” e-mail, April 9, 2002.

35. Joe Pawlowski to Peter Coen et al., “SSBD CDR Status,” e-mail, 

May 1, 2002.

36. Steven A. Brandt et al., Introduction to Aeronautics: A Design 

Perspective (Reston, VA: AIAA, 2004), 87–88.

37. Graham et al., “Wind Tunnel Validation of SSBD,” 4–5; Graham, 

“Wind Tunnel Boom Test,” July 18, 2002.

38. Graham and Martin, “Aerodynamic Design and Validation of 

SSBD,” figure 7-6 extracted from slide no. 5.

39. AIAA paper no. 2005-7, 5.

40. Graham and Martin, “Aerodynamic Design and Validation of 

SSBD,” slide no. 26.

41. Graham et al., “Wind Tunnel Validation of SSBD,” AIAA 

2005-7, 6.

42. Ibid.

43. Joe Pawlowski to Peter Coen et al., “SSBD CDR Postponed,” 

e-mail, June 17, 2002; Joe Pawlowski to Lisa Veitch, “Re: SSBD 

CDR Meeting Reminder - 7/18/02,” e-mail, July 17, 2002; Peter 

Coen to Ed Haering, “SSBD Status,” e-mail, August 7, 2002.

44. Graham et al., “Aerodynamic Design of SSBD,” AIAA paper no. 

2005-8, 6.

45. Ibid., 6–7.

46. R. Francombe, “LTM—A Flexible Processing Technology for 

Polymer Composite Structures,” paper presented at NATO 

Research and Technology Organization (RTO) Applied Vehicle 

Technology (AVT) specialists meeting on low-cost composite 

structures, Loen, Norway, May 7–11, 2001, accessed August 28, 

2011, http://ftp.rta.nato.int/public//PubFullText/RTO/MP/RTO-MP069-II///MP-069(II)-$$TOC.pdf.

47. Benson, Pawlowski-Graham interview, April 12, 2011; Graham et 

al., “Aerodynamic Design of SSBD,” AIAA paper no. 2005-8, 3–4.

48. Joe Pawlowski to Lawrence Benson, “EXT: Re: More SSBD 

Questions,” e-mail, August 17, 2011.
198

Quieting the Boom

49. Benson, Graham-Pawlowski interview, April 12, 2011; Croft, 

“Engineering through the Sound Barrier,” 30.

50. Benson, Pawlowski-Graham interview, April 12, 2001; Graham et 

al., “Aerodynamic Design of SSBD,” AIAA paper no. 2005-8, 3–4.

51. Graham and Martin, “Aerodynamic Design and Validation of 

SSBD,” slide no. 28.

52. Ibid., slide no. 11.

53. The latter, which serve as both a stabilizer and elevator, is 

sometimes referred to as a stabilator.

54. Graham et al., “Aerodynamic Design of SSBD,” AIAA paper no. 

2005-8, 5; Marshall Brain, “How Stereolithography 3-D Layering 

Works,” accessed July 30, 2011, http://computer.howstuffworks.com/

stereolith.htm.

55. Graham to Benson, “SSBD Design Question,” April 4, 2011.

56. Graham and Martin, “Aerodynamic Design and Validation of 

SSBD,” slide nos. 31–33.

57. Benson, Martin Interview, April 7, 2011; Roy Martin to G. Allen 

West, “Preliminary QSP SOW Definition,” e-mail, June 25, 2001; 

Roy Martin to Joe Pawlowski, “Factors to be resolved concerning 

F-5E mod for QSP,” e-mail, March 29, 2002.

58. Benson, Martin Interview, April 7, 2011; Martin to West, June 25, 

2001.

59. Roy Martin to Joe Pawlowski et al., “Trip Report Fallon NAS,” 

e-mail, October 26, 2001.

60. Benson, Graham-Pawlowski interview, April 12, 2011; Pawlowski 

to Benson, “Re: More SSBD Questions,” e-mail, August 31, 2011.

61. Biography of Joseph Dyer (who later became an executive at 

IRobot Corp. and chair of NASA’s Aerospace Safety Advisory 

Panel), accessed July 16, 2011, http://investor.irobot.com/phoenix.

zhtml?c=193096&p=irol-govBio&ID=195535.

62. Pawlowski to Benson, August 31, 2011; Pawlowski to Peter Coen, 

“Presentation Material for SSBD PDR,” e-mail, March 25, 2011.

63. Benson, Pawlowski-Graham interview, April 12, 2001; Pawlowski 

to Benson, August 31, 2011.

64. Joe Pawlowski to Peter Coen et al., “ Good News! & SSBDWG 

Meeting Notice,” e-mail, December 10, 2001.

65. David Graham to Peter Coen et al., “Baseline F-5E Supersonic 

Functional Check Flight,” e-mail, January 23, 2002, quoted; 
199

Creating the Shaped Sonic Boom Demonstrator

Roy Martin to Ed Haering et al., “ Florida Temperature,” e-mail, 

January 24, 2002.

66. Northrop Grumman, “SSBD Aircraft Assembly Photo-Log,” April 

17, 2003, slide no. 9.

67. Pawlowski to Benson, “Re: EXT: More SSBD Questions,” e-mail, 

September 3, 2011.

68. Advanced Composites Group, “SpaceShipOne Makes Historic 

Space Fight,” news release, October 2004, accessed ca. August 10, 

2011, http://www.advanced-composites.co.uk/aerospace_archived_

news_index_pre2007.html.

69. Joe Pawlowski to Lawrence Benson, “Re: SSBD Chapter 7 for 

Review,” e-mail, September 29, 2011.

70. Benson, Graham-Pawlowski interview, April 12, 2011; Benson, 

Boccadoro interview, August 12, 2011. The three aircraft 

mechanics from El Segundo were Malcolm Croxton, Jack Allan, 

and Darrell Norwood: Boccadoro to Benson, e-mail, “Names,” 

August 20, 2011.

71. Benson, Graham-Pawlowski interview, April 12, 2011. Source for 

figure 7-7: Northrop Grumman, “F-5 SSBD Aircraft Description,” 

September 2, 2004, slide no. 4.

72. Benson, Boccadoro interview, August 20, 2011.

73. Steve Madison, Ken Ferguson, and Roy Martin, “Test Plan: Quiet 

Supersonic Platform Shaped Sonic Boom Demonstrator Data 

Collection,” Revision A, March 31, 2003, Appendix C, confirmed 

during review of this chapter.

74. Founded in 1987 in Santa Clara, CA, Ashtech in 1997 became 

part of Magellan Corp., which was in turn a subsidiary of Orbital 

Sciences Corp. In 2001, Magellan Corp. was acquired by the 

Thales Group, which later sold its GPS business to an investment 

company that renamed it Magellan Navigation—with the Ashtech 

brand continuing to focus on high-precision global satellite 

navigation system equipment.

75. Edward A. Haering, James E. Murray, Dana D. Purifoy, David 

H. Graham, Keith B. Meredith, Christopher E. Asburn, and Lt. 

Col. Mark Stucky, “Airborne Shaped Sonic Boom Demonstration 

Pressure Measurements with Computational Fluid Dynamics,” 

43rd AIAA Aerospace Sciences Meeting, Reno, NV, January 

10–13, 2005, AIAA paper no. 2005-9, 5. 
200

Quieting the Boom

76. Madison et al., “Test Plan: QSP SSBD,” 5–6, Appendices B and 

C; Haering et al., “Airborne Sonic Boom Demonstration Pressure 

Measurements,” AIAA paper no. 2005-9, 5; Haering to Benson, 

“Re: Quick SSBD Question,” e-mail, August 29, 2011.

77. Benson, Pawlowski-Graham interview; Bruce King to Ed Haering 

et al., “Re: Urgent? Florida TM freq scheduling,” e-mail, March 

12, 2003, with previous message traffic inserted.

78. Steve Madison, “Shaped Sonic Boom Demo (SSBD) Test Plan 

Review,” PowerPoint presentation, as of February 2011, slide no. 

37.

79. Date stamps on digital photos showing the work at NGSA.

80. Pawlowski to Benson, e-mail, August 31, 2011.

81. Benson, Graham-Pawlowski interview, April 12, 2011; Benson, 

Boccadoro interview, August 20, 2011. Source for figure 7-8: 

“Shaped Sonic Boom Demonstration Overview,” AIAA Southern 

California Aerospace Systems and Technology Conference, Buena 

Park, CA, May 21, 2005, slide no. 12.

82. Statement of Work, “Boeing T-38 Chase Aircraft Support for 

F-5SSBD Flight Test Program,” April 17, 2003; Benson, Martin 

interview, April 7, 2011.

83. Northrop Grumman Integrated Systems, “SSBD/SSBE Team 

Roster,” September 16, 2004, slide nos. 13 and 14.

84. Joe Pawlowski to Peter Coen et al., “Draft SSBD Test Plan 

Available for Review,” e-mail, October 15, 2002; Madison, “SSBD 

Test Plan Review.”

85. Steve Madison, Ken Ferguson, and Roy Martin, “Test Plan: Quiet 

Supersonic Platform Shaped Sonic Boom Demonstrator Data 

Collection,” Revision A, March 31, 2003; Steve Madison, Roy 

Martin, Keith Applewhite, and Eric Vartio, “Test Plan: Quiet 

Supersonic Program Flight Envelope Clearance,” Revision 6, May 

5, 2003.

86. Benson-Martin interview; MIL-STD-1797A, “Flying Qualities 

of Piloted Aircraft,” December 19, 1997, accessed ca. September 

1, 2011, http://www.mechanics.iei.liu.se/edu_ug/tmme50/MILHDBK-1797.PDF. (The next edition, MIL-STD-1797B, was 

issued on February 15, 2006.)

87. Ibid.

88. COMNAVAIRSYSCOM Patuxent River MD/4.OP, to 

AIRTEVRON Three One China Lake CA et al., “F-5 
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Creating the Shaped Sonic Boom Demonstrator

Interim Flight Clearance for TYCOM Designated Aircraft,” 

teletype message, 162007Z, July 2003, referencing 

COMNAVAIRSYSCOM 092003Z, June 2003, which was the 

initial flight clearance.

89. Pawlowski to Benson, e-mail, August 31, 2011.

90. Coen and Martin, “Fixing the Sound Barrier,” slide no. 14.

91. Northrop Grumman, “F-5 SSBD Test Plan Review,” undated, slide 

nos. 7–9.

92. Pawlowski to Benson, e-mail, August 31, 2011.

93. Madison, “SSBD Test Plan Review,” slide no. 18; Pawlowski et al., 

“Origins and Overview of the SSBD,” AIAA 2005-5, 10.
202

The Navy’s F-5E, Northrop Grumman’s F-5 SSBD, and Dryden’s F-15B on August 29, 2003. (NASA)
203

CHAPTER 8

Proof at Last

Making and Measuring Softer Sonic Booms

The weather appeared favorable in the Jacksonville area on the morning of 

July 24, 2003, as the Northrop Grumman team prepared for the maiden 

flight of the F-5 SSBD. The former F-5E had not flown since the previous December, before its transformation into a sonic boom test bed. 

Temperatures were in the 70s, climbing toward a high in the upper 80s. 

Relative humidity hovered at almost 100 percent as the day began, but visibility was satisfactory, and seasonal thunderstorms were not forecast until 

the afternoon.1

 Before beginning this flight (and all subsequent flights), the 

pilot and ground personnel complied with a safety checklist and stringent 

“go, no-go” criteria based on an extensive hazard analysis.2

 With everything 

in order, the time had finally arrived for the rebuilt F-5, now unofficially 

nicknamed the Pelican, to take to the air.

Functional Check Flights

Roy Martin climbed into the F-5 SSBD’s cockpit and gave a thumbs up 

to Charles Boccadoro as his unique aircraft began its taxi from Northrop 

Grumman’s St. Augustine facility. With many of his colleagues watching 

intently, Martin’s modified F-5 soon cleared the St. Johns County Airport’s 

8,000-foot runway. Serving as a chase plane, Mike Bryan’s T-38 accompanied it into the air, with John Nevadomsky in the back seat. After a busy but 

uneventful functional check flight into a restricted flying area (W-158A) off 

the Atlantic coast, both planes flew inland to the western edge of Jacksonville’s 

extended city limits. There they landed on the 12,500-foot runway of Cecil 

Field, which would serve as their temporary base of operations for the next 

several days. As predicted by the preflight simulations and analyses, the F-5 

SSBD displayed slightly reduced directional stability but nothing unexpected. 

From Cecil Field they flew an additional FCF and envelope expansion on July 

27 and another on the morning of July 28.3 For record-keeping purposes, 
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Quieting the Boom

Flying over Air Force Plant 42, showing Northrop Grumman’s Site 3, with arrow pointed toward 

Building 307, and Site 4, with Building 401 in lower right corner. (NASA)

these and all subsequent flight checks and flight tests by the F-5 SSBD were 

assigned a sequential number starting with QSP-1. (See appendix B for a table 

listing all the flights.)

As with all the future flight tests, the three local sorties lasted less than an 

hour. The main purpose of the Florida FCFs was to confirm the plane’s subsonic 

airworthiness, the calibration of its air-data measurements, the telemetry from its 

new instruments to the temporary ground station during orbits over St. Augustine, 

and that all systems were working properly for the upcoming cross-country trip to 

California. Martin also verified that the modified F-5 could still exceed the speed 

of sound despite the drag of its larger body by pushing it to Mach 1.1.4

 On July 

28, having successfully completed the final local sortie earlier in the morning, the 

two planes headed west on the long ferry flight to Palmdale, CA, making four stops 

along their way (a journey described previously in the Introduction).5

Avoiding a rare summer thunderstorm building over Lancaster, the two aircraft gracefully touched down on the runway at Air Force Plant 42 in Palmdale 

on Tuesday afternoon, July 29. Belying its name, Plant 42 is more than a single 

facility; it is actually a 5,800-acre installation offering spacious and secure 

locations for a number of separate hangars, industrial facilities, shops, offices, 
205

Proof at Last

and miscellaneous buildings used by Northrop Grumman, Lockheed Martin 

(including its Skunk Works), Boeing, and other aerospace companies and 

Government organizations. Northrop Grumman occupied facilities in Sites 3 

and 4 (shown in the accompanying photo). The latter includes Building 401, 

the huge structure where Northrop had completed assembling its B-2 stealth 

bombers—originally, in total secrecy. The SSBD team would operate out of a 

section of Building 307 in Site 3.6

After landing, the F-5 SSBD and its T-38 escort taxied to Site 3, where 

they were welcomed by a maintenance crew as well as some of the Northrop 

Grumman engineers from El Segundo who had designed the plane and were 

anxious to see the finished product. Because of the threatening weather, the F-5 

was quickly moved into the shelter of Building 307; Section 4 of which was 

reserved for the SSBD team. When Roy Martin got back to his home in Lancaster 

that evening, he found that the storm had uprooted large trees onto two of his 

nearby neighbors’ homes. Such unseasonal storms were not much of a concern for 

the Shaped Sonic Boom Demonstration but the unusually warm summer was. 

Weather balloons had been measuring much higher-than-normal atmospheric 

temperatures, which, because of the Mach number parameters used in designing 

the F-5 modifications, could pose a serious threat to the SSBD’s success.

Functional flight checks resumed on Saturday, August 2, with two FCFs 

(QSP-4 and QSP-5) flown mainly over Edwards AFB’s restricted airspace. 

For the remainder of the SSBD, Roy Martin and Cmdr. Darryl “Spike” Long, 

the Navy’s chief test pilot at Naval Air Weapons Station (NAWS) China Lake, 

CA, alternated as pilots of the F-5 SSBD. With Mike Bryan having taken 

Boeing’s T-38 back to Seattle, a NASA Dryden F/A-18 piloted by Jim Smolka 

flew chase. The focus of the Palmdale functional check flights was supersonic 

envelope expansion. Another sortie was conducted on August 4, and after a 

long hiatus to address the performance problems described below, the final 

FCF was flown on August 15.7

The subsonic and supersonic envelope expansions in Florida and California 

validated handling qualities for 15 flight conditions with a series of exercises 

called maneuver blocks. Each maneuver block included pitch stick and rudder 

doublets (two opposing movements of the controls in quick succession), 

30-degree bank-to-bank rolls, steady heading sideslips, and close-loop turns. 

The subsonic maneuver blocks were flown both with and without the stability 

augmentation system, which automatically positions the horizontal tail and 

rudder to dampen pitch and yaw oscillations. The system was always turned 

on during the supersonic maneuver blocks.8

In addition to their intended purpose, these flights had other benefits. As 

pointed out in the published summary of the SSBD, “Although the supersonic 

envelope expansion flights were not designed to support shaped sonic boom 
Quieting the Boom

206

data collection, they proved to be invaluable as trial runs for the flight crews, 

the flight test ground controllers, and for the ground data crews.”9 (As described 

below, the sensors and other data-collection equipment were already in place.)

Unfortunately, however, concerns expressed earlier about having to delay 

the flight testing until summer proved well-founded. Continuing weather balloon measurements, including those from GPS radiosondes, showed ambient 

temperatures at the planned flight-test altitude to be about 17 °C (30.6 °F) 

higher than the standard atmosphere temperature for which the demonstration 

had been planned. (The standard temperature at 32,000 feet is about –55 °C 

or –48.5 °F.) The high temperature would not only hamper the F-5’s ability to 

reach the Mach number of 1.4 for which its modifications had been designed, 

but it would limit its endurance as well.10 Indeed, Roy Martin could only get 

the F-5 SSBD up to about Mach 1.2 on his first supersonic envelope-expansion 

flight on August 2.11

Because of this unfortunate weather pattern, members of the SSBD Working 

Group and others involved in the project recommended postponing the flight 

tests until November, when upper atmosphere temperatures would surely be 

more favorable. Although this made sense from a purely technical standpoint, 

Charles Boccadoro had to consider other issues, such as the response of corporate management. So he vetoed any further delay, telling team members, 

“Time is our enemy.” As he later explained to the author, “To be behind schedule and over budget is true hell for a program manager.”12 In a bold move to 

allow the demonstration to proceed, he reached out to NAVAIR’s propulsion 

directorate and General Electric Aviation’s engine maintenance division to get 

permission for Northrop Grumman technicians—led by NGSA’s flight-test 

engineer, William “W.D.” Thorne—to do a compressor wash and uptrim the 

F-5 SSBD’s jet engines for maximum thrust.13

Finally, at 1030 Pacific daylight time (PDT) on the morning of August 

25, 2003, with no wind and the surface temperature already at 91 °F, Spike 

Long entered the cockpit of the Northrop Grumman F-5 SSBD for its first 

sonic boom flight test (QSP-8). Turning on only the left engine to conserve 

fuel, he taxied to Runway 25. After about two minutes of GPS data logging to 

acquire and confirm satellite signals, he turned on the right engine and took 

off at 1102. After reaching 4,400 feet, he pushed the engines into military 

power (maximum thrust without the use of afterburners) and quickly climbed 

to 25,000 feet. On the way, he was joined by NASA F/A-18B number 846 

piloted by Jim Smolka as a photo chase aircraft and NASA F-15B number 836 

piloted by Dana Purifoy, who was there to perform the first in-flight probes of 

the F-5 SSBD’s shock waves.14 Mike Thomson was in the back seat.15 NASA 

Dryden had improved the F-15B’s nose boom since the ISSM tests, when its 

Sonix digital absolute pressure transducer (which converted physical shock 
207

Proof at Last

wave measurements to electrical signals) could take only 17 samples per second. 

For the SSBD, NASA Dryden added a Druck analog differential transducer 

that was capable of 400 samples per second.16

After finishing the photo opportunity, the tuneup of the F-5’s engines soon 

proved to have been successful. Lighting his afterburners, Long climbed to 

47,000 feet and, closely followed by Purifoy’s F-15B, turned toward the supersonic corridor. Nine miles west of Mojave, the F-5 SSBD began accelerating 

in a 12-degree dive, reaching a gravity-assisted maximum speed of Mach 1.41 

before leveling off at 31,500 feet. It led the F-15B through the probing run 

at Mach 1.38 despite an outside air temperature of only –38.2 °F (–39 °C).17

This speed was within the margins required for adequate flight tests. Charles 

Boccadoro was in an office with Tom Weir, NGC’s director of advanced design, 

when they received word that the plane had “hit its mark.”18 He immediately 

called Steve Walker at DARPA to report the good news.

The high-fidelity Ashtech GPS tracking system also proved its capabilities 

during the flight test with relative positioning between the F-5 and the F-15 

being displayed to within mere centimeters both in the two aircraft and down 

at the Dryden control room. Long’s postflight report commented somewhat 

sardonically that “the painfully precise NASA engineers did request several 

redo’s. I figure Dana was off by a foot or two from time to time.”19 Sixty-five 

minutes after climbing into the cockpit, Spike Long’s feet were back on the 

ground. Later in the day another Navy pilot, Lt. Cmdr. Dwight “Tricky” Dick 

of Composite Fighter Squadron (VFC)-13, arrived at Palmdale from NAS 

Fallon with his camouflaged F-5E. All was in place for SSBD’s next flight 

test—the one that would compare the two F-5s’ sonic booms as they reached 

the ground.

Preparations at Edwards Air Force Base 

During the months that Northrop Grumman was fabricating the new parts 

in El Segundo, then modifying and preparing the Shaped Sonic Boom 

Demonstrator in St. Augustine, members of the working group and additional specialists at NASA’s Dryden and Langley Centers were planning and 

preparing for the Shaped Sonic Boom Demonstration at Edwards AFB. The 

basic plan was to measure the sonic boom of the standard F-5E from Fallon 

followed less than a minute thereafter by that from the F-5 SSBD to compare 

the initial overpressures and loudness of the two sonic booms in the same 

basic atmospheric conditions. Since this would be the first ever opportunity 

to show the effects of sonic boom shaping, the participants wanted to employ 

the latest in pressure measuring and acoustic recording technology both on 
208

Quieting the Boom

the ground and in the air. To take full advantage of the opportunity presented 

by the demonstration flights, NASA’s Dryden and Langley Centers as well as 

Wyle Laboratories made plans for an extensive number of ground sensors.20

Implementing this proved significantly more complicated than simply going 

out into the desert and setting up the equipment.

With Ed Haering as the lead planner, the working group’s sonic boom specialists determined the best area under the Edwards high-altitude supersonic 

corridor to place the array of sensors. This would in turn determine the exact 

route to be flown by the aircraft. They chose to use Cords Road, which ran 

east to west under the base’s R-2515 restricted airspace, as the centerline for 

the aircraft’s flightpath (shown in figure 8-1).21 The land along Cords Road is 

divided into a checkerboard pattern, either under the jurisdiction of the Bureau 

of Land Management (BLM) or privately owned. Because the private owners 

were difficult to contact, the planners limited their sensor sites to BLM sections. 

Based on maps and aerial photographs, they selected the specific locations on 

which to distribute sensors in the desired configuration while keeping them 

within a reasonable walking distance of existing roads. The sites selected were 

on either side of a 6-mile stretch of Cords Road just north of Harper Dry 

Lake, which is located about 30 miles north of California Highway 58 between 

Barstow and Boron.22 It was expected that this road, the lakebed, and other 

local landmarks would be readily visible to the pilots flying 32,000 feet above.23

Arranging to use the area for the SSBD proved to be a long and complicated 

coordination process for Ed Haering and some colleagues at NASA Dryden. 

Mostly unoccupied by humans, the area is the habitat of several threatened or 

endangered species, most notably the desert tortoise and Mojave ground squirrel. Starting in the fall of 2002, Haering and Mike Beck, the environmental 

specialist at NASA Dryden, spent a great deal of time working with the BLM 

office in Barstow and the Edwards AFB environmental management division 

to get permits and meet other requirements to use the land. For example, they 

had to arrange tortoise protection training for all the 

personnel who would be 

working on the sensor array, 

which was eventually accomplished with the help of a 

video recording of the training. A BLM-approved biologist (paid for out of project 

funds) was required to oversee the site selections as well 

as the setup and removal of 

Edwards AFB

Supersonic Corridor

Figure 8-1. Map of SSBD flight plan. (NASA)
209

Proof at Last

equipment. Vehicles were prohibited from driving off the existing dirt roads, and 

when desert tortoises were encountered on the roads (as happened on several 

occasions), they could not be picked up and moved out of the way.24

To provide spatial sampling along the center of the flightpath, plus bracketing to the side, the SSBD ground sensor team set up their equipment in and 

around three major sites adjacent to Cords Road—designated West, Center, 

and East—and at Sites North and South, 2 and 3 miles from the road. The 

sensors around the central site were arranged in a cruciform pattern. To gain an 

extra boost in speed from prevailing winds and avoid having the sonic booms 

reach Boron and communities along U.S. Highway 395, the working group 

chose to have the planes fly from west to east for the measurements.25 (This is 

the reverse of the direction flown on a similar route by Chuck Yeager during 

the XS-1’s first supersonic flight.)

In addition to the pressure sensors, microphones, and associated electronic 

devices, the equipment positioned out in the desert included specially equipped 

vehicles, generators, battery packs, cables, and portable toilets. Since these 

items would be left unattended in the isolated area for much of the time, the 

testers had to hire armed guards to watch over them. As NASA Dryden’s security contractor explained, “equipment left alone for a few days would probably 

be stripped clean.”26

By the time the F-5 SSBD landed at Palmdale, the ground array had been 

laid out and its equipment made ready for use. NASA Langley had deployed an 

acoustic instrumentation van with ultrasensitive Brül and Kjaer (B&K) 4193 

low-frequency condenser microphones and supporting equipment. Among the 

personnel from Langley was Christine Darden, whose minimization research 

had helped pave the way for designing the SSBD. Wyle Labs provided similar 

sensor capabilities using identical microphones feeding into advanced TEAC 

and National Instruments recording systems. NASA Dryden contributed two 

Boom Amplitude and Direction Sensor (BADS) systems and other instruments. Designed by James Murray, David Berger, and Ed Haering, each BADS 

system (shown in an accompanying photo) included six Sensym differential 

pressure transducers attached about 6 feet apart to an octahedron-shaped 

framework. The separation of the sensors would help determine the angles 

of incoming acoustic rays. With its sophisticated pneumatic and electronic 

instrumentation, the BADS system could measure pressure changes to within 

plus or minus .003 psf at more than 8,000 times per second.27

In addition to the members of the three organizations mentioned above, 

Northrop Grumman, Lockheed Martin, Boeing, and Gulfstream personnel 

also helped set up and monitor the stations. Because of the delayed start of the 

demonstration and another commitment, the Langley Acoustics Division’s van 

had to depart after the initial flight test of August 25, which left Site North 
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Quieting the Boom

Boom Amplitude and Direction Sensor near Cords Road, August 2003. (NASA)

unused for the remainder of the SSBD.28 Other than that, the ground array 

network functioned largely as planned for the rest of the flight tests.

The same cannot be said for another highly anticipated means of measuring 

the shock waves. In addition to the near-field probing by the F-15B and the 

far-field measurements by the ground sensors, the SSBD test plan called for 

two midfield probes. To expand on prior in-flight sonic boom experiments, Ed 

Haering had got the working group to include provisions for recording the F-5 

SSBD’s shock wave signature as it evolved through the atmosphere. In August 

2002, he began working with Gulfstream and Raytheon to obtain executive-type 

jets for this purpose.29 The companies agreed to supply a Gulfstream G-V and 

Raytheon Premier I. NASA Dryden equipped each of them with one of its Small 

Airborne Boom Event Recorder (SABER) devices, which involved installation 

of two static pressure ports on top of their fuselages. Dryden would also loan an 

Ashtech Z-12 to Raytheon to provide the Premier I with accurate position and 

velocity data. (The Gulfstream G-V was already equipped with this GPS system.)

Including these two civilian aircraft in the SSBD flight tests required many 

months of coordination and logistical preparations. The test plan called for each 

jet to fly below the F-5 SSBD at subsonic speeds, one at levels between 3,000 

feet and 10,000 feet and the other at levels between 15,000 feet and 12,000 feet. 

Unfortunately, acoustic analyses eventually confirmed that aerodynamic noise 

from the two planes could adversely affect the microphones. Problems were also 

encountered with mounting the instrumentation. As a result, participation by 

the two corporate jets had to be canceled before the demonstration.30
211

Proof at Last

Making Aviation History

After Spike Long’s successful probing flight on August 25, the SSBD team 

was anxious to make the long-awaited ground measurements of the shaped 

and unshaped sonic booms, but the potential for thunderstorms on August 26 

forced postponement of the flight. The weather forecast was better for the next 

day, so in the wee hours of August 27, the members of the ground recording 

team made their way through the desert to the remote equipment sites north of 

Harper Dry Lake.31 With only the Milky Way lighting the dark sky overhead, 

the ground crews looked for their headlights to illuminate reflectors on sticks 

marking sensor locations and watched out for any desert tortoises on the roads. 

David Graham and three passengers had to stop and wait patiently for about 

15 minutes until a tortoise got out of their way.32 The crews needed to set up 

and check their equipment before dawn, since the flight test was scheduled 

to occur shortly thereafter when the layer of air over the desert floor was usually at its calmest. In the NGC control center at Plant 42, Ken Plotkin was 

examining the latest readings from weather balloons and reports from the field. 

When he was sure that atmospheric conditions were acceptable for undistorted 

sonic boom signatures to reach the sensors—with no turbulence and a slight 

thermal inversion near the surface and acceptable winds aloft—Plotkin gave 

the go-ahead for the launch.33 At Edwards AFB, the NASA Dryden control 

room got ready to monitor the flights.

At 0626 local time, just as the Sun was rising above the distant horizon,34

Roy Martin in the F-5 SSBD (call sign Leahi 05) and Lt. Cmdr. Dick in the 

Navy F-5E (Leahi 06) took off from the long runway of Air Force Plant 42 

on flight number QSP-9. They flew into a clear sky with only a few clouds at 

12,000 feet and compared the readings on their altimeters and Mach meters 

as they flew north. Twenty minutes later, when they reached 45,000 feet, Dick 

did a gradual S maneuver to get the required 45 seconds behind Martin for the 

sonic boom run. The original test plan had called for the F-5 SSBD to follow 

the standard F-5B, but because of the difficulty the enlarged F-5 could have 

in keeping up with the sleeker F-5E in the higher-than-normal temperatures, 

their places had been reversed.35 Cruising at Mach 0.9 over the Mojave Airport 

at 0644, Martin lit his afterburners, began a 12-degree dive, and accelerated 

to a maximum speed of Mach 1.38. Because a thick surface haze prevented 

Martin from seeing Cords Road or other landmarks while flying into the 

rising sun, he had to rely on his hand-held GPS unit to navigate through the 

supersonic corridor on the prescribed course. After leveling off at 32,000 feet, 

the F-5 SSBD was able to maintain a steady Mach 1.36 (about 920 mph) from 

14 miles west of the recording array until after passing over it at about 0646. 

Flying at the same speed, Dick followed by the desired 45 seconds. Returning 
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Quieting the Boom

Figure 8-2. F-5E and F-5 SSBD sonic boom 

signatures. (NASA)

to Palmdale, Martin touched down 

on Plant 42’s runway at 0703 and 

Dick 1 minute later. After taxiing 

back to NGC Site 3 and shutting 

down their engines at 0722, the two 

pilots joined other team personnel 

to learn more about the measurements of their sonic booms.36

Working at one of the sensor 

sites, David Graham thought the 

second boom sounded distinctly 

louder than the first.37 Data displayed on the screen of a laptop 

computer quickly confirmed the 

difference. It showed the sonic boom generated by Dick’s standard F-5E had 

an initial pressure rise of 1.2 psf while that from Martin’s modified aircraft registered only 0.82 psf. Of equal significance, a blue line plotting the F-5 SSBD’s 

pressure measurements showed that its signature reached the ground with the 

predicted flattened shape. Overlaying the blue line was a red one showing the 

F-5E’s typical N-wave. These lines closely matched the red and blue pinstripes 

that so hopefully decorated the Pelican’s fuselage. Although reproduced in only 

black and white on the printed page, figure 8-2 shows this historic sonic boom 

exactly as recorded by the BADS unit at Site West—the first sensor ever to 

measure a shaped sonic boom.38

When these results reached the control center at Plant 42, Ken Plotkin 

did a little victory dance. He then called Albert George at Cornell University, 

interrupting a counseling session with one his students, to inform him that 

the flight test had finally confirmed his and Seebass’s theory beyond all doubt. 

“I knew it would,” the professor replied. When the image had been received 

at the NASA Dryden control room, Peter Coen jumped up from his seat and 

announced, “It’s a classic flattop!”39

The original SSBD test plan had called for eight sonic boom data-collection 

sorties with a break for in-depth data analysis after the first four.40 The delays 

in starting the flight tests, the cancellation of the Gulfstream and Raytheon 

probe missions, deteriorating weather conditions, and other factors reduced 

the number of data-collection flights to five. After a quick turnaround of the 

F-5 SSBD, Spike Long took off on the third of these (QSP-10) at 0905 PDT 

along with Tricky Dick in the F-5E. After reaching the vicinity of Lake Isabella, 

Long climbed to 47,000 feet while Dick, reaching 45,000 feet, maneuvered his 

plane to follow by the required interval. Long hit a maximum speed of Mach 

1.41 as he descended through a milky haze into the flightpath—the fastest 
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Proof at Last

flight yet. He was able to maintain a steady Mach 1.38 at 31,800 feet for the 

sonic boom run at 0930. Although he flew about one-half mile north of Cords 

Road because of overcorrecting for high-altitude crosswinds, the sensor array 

recorded the sonic booms satisfactorily. Surface winds, however, were now too 

high for signatures as good as on the early morning flight. Dick’s F-5E followed 

by 45 seconds with similar results. Long landed at Plant 42 at 0946, 2 minutes 

before Dick touched down. In his postflight report, Long wrote that “Tricky 

from VFC-13 has been an excellent addition to the test team” and that “we 

should make this guy a test pilot now!”41

Roy Martin and Dwight Dick flew a very similar sortie (QSP-11) from 0620 

to 0653 on the following morning, which provided the ground observers with 

more sonic boom data.42 The plots of the sonic boom signatures remained fairly 

consistent, confirming that the first recordings on the morning of August 27 

were no fluke. However, the quality of the ground data continued to decline 

after that flight because of less favorable atmospheric conditions.43

The last data-collection flight on August 29 (QSP-12) focused on in-flight 

probing combined with more ground data collection. Spike Long in the F-5 

SSBD and Tricky Dick in the F-5E took off from Palmdale shortly after 0830 

local time. They joined up with Dana Purifoy and Mike Thomson in NASA 

F-15B number 836 and NASA F/A-18B number 846 piloted by Dick Ewers. As 

the aircraft climbed to altitude, Carla Thomas in the back seat of the F/A-18B 

took photos of the other three flying in formation (including the one in front 

of this chapter). Dick’s F-5E then broke away and headed home to Fallon while 

Long and Purifoy got into position northeast of Lake Isabella before turning 

and descending for their second near-field probing run through the supersonic 

corridor. Because the temperature at 32,000 feet was even 10 degrees warmer 

(at –29 °F) than earlier in the week, Long could reach only Mach 1.38 during 

his shallow dive. He had to keep gradually descending just to maintain Mach 

1.34 during the rest of the more than 80-mile probing run, which included 

the segment over the ground array. After completing his mission at 0920, Long 

reiterated one of the major lessons learned during the flight tests: “The sun 

angle was the biggest detriment during data collection and course management 

was more luck than skill. If future events are planned we will reverse the run-in 

course to avoid this scenario.”44 After Long’s departure for Palmdale, Ewers’s 

F/A-18B rejoined Purifoy’s F-15B in the supersonic corridor for some NASA 

Dryden midfield probing unrelated to the SSBD project. Because of the lessthan-favorable weather, QSP-12 was the final SSBD flight test.

After Northrop Grumman posted a combined news release with DARPA 

and NASA on August 28 announcing the previous day’s successful demonstration, what had once been a rather obscure project, mainly of interest to 

those involved in aeronautics or the aviation industry, quickly received wider 
Quieting the Boom

214

publicity.45 On September 3, the NGC, DARPA, and NASA officials hosted 

a briefing at the National Press Club in Washington, DC, with representatives from the general media as well as the aviation press attending.46 Charles 

Boccadoro presented a graphically rich slide show on Northrop Grumman’s 

participation in the QSP and the SSBD.47 He also relayed an anecdote about 

first learning of the result. “About 20 minutes [after takeoff], we were all listening 

to our chief test pilot Roy Martin over the radio when the guys in the desert...

called back and said they could hear the difference. We weren’t expecting that. 

We knew we had something at that point.”48 With the attendees having seen 

the graphic depiction of the sonic boom signatures in Boccadoro’s presentation, 

Richard Wlezien, now NASA’s vehicle systems program manager in the Office of 

Aerospace Technology, stated that “the results were about as unambiguous as you 

could get.”49 Added Peter Coen: “The team was confident that the SSBD design 

would work, but field measurements of sonic booms are notoriously difficult.... 

[So] we were all blown away by the clarity of what we measured.” To put the 

achievement in its historical context, Wlezien also noted, “This demonstration 

is the culmination of 40 years of work by visionary engineers.”50

In addition to numerous accounts of the achievement in aeronautics and 

aviation publications, a flurry of articles and reports began appearing in the 

general media, ranging from a short wire story by the Associated Press published 

in newspapers nationwide to two televised reports several minutes in length 

on CNBC showing video of the aircraft interspersed with interviews of Roy 

Martin, David Graham, and Joe Pawlowski.51 Northrop Grumman was now 

reaping a harvest of favorable publicity as an intangible return on its investment 

in sonic boom research. Some of the corporation’s major contributors to the 

SSBD are shown in the accompanying photo, taken during a company party 

in El Segundo on October 14, 2003, while celebrating the project’s success.

The timing of the SSBD project’s success was fortuitous. In May 2003, the 

FAA—citing the findings by the National Research Council that there were 

no insurmountable obstacles to building a quiet small supersonic aircraft—

had begun seeking comments on its noise standards in advance of a technical 

workshop on the issue.52 The noise standards included Part 91 of Title 14 of the 

Code of Federal Regulations (CFR), which prohibited supersonic flight over 

the United States. On November 30, 2003, in Arlington, VA, the FAA held 

the Civil Supersonic Aircraft Technical Workshop. It allowed subject matter 

experts to submit comments on recent supersonic research data and present 

their findings on the mitigation of environmental impacts, as well as to inform 

the public. In response, the Aerospace Industries Association, the General 

Aviation Manufactures Association, and most aircraft companies reported that 

the FAA’s sonic boom prohibition was still the most serious impediment to 

creating the market for a supersonic business jet.53
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Proof at Last

Key members of Northrop Grumman’s QSP/SSBD team. Front row: Charles Boccadoro, Joe 

Pawlowski, David Graham, and Roy Martin. Rear row: Steve Komadina, Mark Smith, and Paul 

Meyer, who was vice president of advanced systems at the time. (NGC)

The major aircraft and engine companies participating in the QSP all made 

presentations on addressing the sonic boom and jet-noise problems. Among 

them, Steve Komadina and David Graham discussed the promising results of 

their QSP research and SSBD flight tests.54 Complementing cases made by 

Gulfstream and other manufacturers for a supersonic business jet, Richard G. 

Smith III of Berkshire Hathaway’s NetJets provided an analysis of the potential 

SSBJ market and suggested the need for a comprehensive public-private risksharing consortium.55 On the all-important issue of human response to sonic 

booms, Peter Coen and Brenda Sullivan updated attendees on NASA Langley’s 

latest analyses and its reconditioned boom-simulator booth. Building on the 

recent progress in taming the sonic boom, Coen outlined planned initiatives 

in NASA’s Supersonic Vehicles Technology program. In addition to leveraging 

the results of QSP research, NASA hoped to engage industry partners in planning follow-on projects involving critical supersonic technologies. Of special 

relevance to the FAA workshop, NASA was actively considering options for 

an experimental low-boom aircraft that could fly over populated areas for the 

sake of definitive surveys on the public’s response to reduced sonic signatures 

both outside and indoors.56 Meanwhile, NASA was preparing to use the only 

existing reduced-boom airplane for more research into the physics of sonic 

booms and how to control them.
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Quieting the Boom

Preparing for the Shaped Sonic Boom Experiment

Although the Shaped Sonic Boom Demonstration had been extremely successful as a proof of concept—more than meeting the objectives of DARPA’s 

contract with Northrop Grumman—the unfavorable high-altitude temperatures, limited number and scope of the flight tests, relatively quiet conditions in the lower atmosphere, and less-than-ideal functioning of some of 

the instrumentation left many of the participants hungry for more sorties 

and more data. Systematically gathering and analyzing flight-test data had 

always been a hallmark of NASA’s aeronautics mission and, before that, of the 

NACA’s. Among an extensive list of SSBD lessons learned compiled by one 

of the NASA researchers was this rather tongue-in-cheek entry: “If at first you 

succeed (8/27/03), you might be cancelled. Hide your success until you get a 

reasonable amount of data.”57

Another lesson learned from the SSBD is that a new technology program 

“will cost twice your initial estimate.”58 With the SSBD venture having lasted 

almost a year longer than first anticipated and the QSP program having cost 

Northrop Grumman more than $4 million in discretionary funds, its corporate 

management was not eager to spend even more money to extend the project 

purely for the sake of scientific research.59 And although the modified F-5E was 

a unique platform for performing such research, it was existing on borrowed 

time because of the requirement to return the plane to the Navy. So even as the 

demonstration was underway, Peter Coen was working to get NASA to sponsor 

about 20 more flight tests in cooler weather, when the F-5 SSBD could reach 

Mach 1.4 and stronger surface winds would be likely for gathering a wider 

range of data.60 He was successful in obtaining approximately $1 million from 

NASA Aeronautics’s Vehicle Systems Division to reimburse contractors (especially Northrop Grumman) and cover some additional expenses for a follow-on 

test program. Using NASA funding, the Air Force Research Laboratory managed an Air Vehicles Technology Integration Program (AVTIP) contract with 

Northrop Grumman to conduct SSBE flight operations. Meanwhile, NAVAIR 

agreed to amend the CRADA to allow the additional flight tests and extend its 

loan of the F-5 SSBD to Northrop Grumman until the end of January 2004.61

To reflect the follow-on testing’s scientific purpose while indicating continuity with the SSBD, NASA named it the Shaped Sonic Boom Experiment. NASA 

also continued the Government-industry management structure successfully 

used for the SSBD by retaining most of its working group. The 26 members 

of the SSBE Working Group (listed in appendix A) included representatives 

from the Langley and Dryden Centers, the AFRL, Northrop Grumman, Wyle 

Laboratories, Eagle Aeronautics, Gulfstream Aerospace, Raytheon Aircraft, 

Boeing, and Lockheed Martin. As SSBE program manager, Peter Coen served 
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Proof at Last

as the group’s chairman, with Joe Pawlowski managing Northrop Grumman’s 

lead role in the flight operations.62

The SSBE working group convened in person in Arlington, VA, on 

November 13, 2003—just after the FAA civil supersonic workshop earlier in 

the day—to establish data requirements and review a preliminary test plan. 

Once again, it called for back-to-back flights with the F-5 SSBD and a standard 

F-5E as well as near-field probing by the F-15B. Based on lessons learned in 

the previous tests and the desire for more data, the planners also made several 

changes. In view of the poor visibility experienced by the pilots in August, the 

primary flightpath in the new test plan would run from east to west—away 

from the morning Sun. In addition to measuring signatures at the SSBD’s 

original design speed of Mach 1.4 at 32,000 feet above sea level, the 20 planned 

flight tests afforded the opportunity to fly some of the missions at both higher 

and lower speeds and altitudes for evaluating sonic boom characteristics under 

off-design conditions. The planners added two entirely new flight-test profiles 

to the schedule: having the F-5 SSBD generate a focused boom and allowing 

the two F-5s to fly over the ground array in close formation. In case of poor 

weather or unforeseen problems, the working group ranked the 20 planned 

data missions in their order of priority in case some of them had to be canceled 

because of weather or other problems. Yet for some missions, the planners 

hoped to measure the effects of turbulence on the sonic boom signatures.63

Reflecting other lessons learned, there were also some major changes in datacollection arrangements and capabilities. Because of the long drives required 

for the ground crews to reach the area near Harper Lake and the need to guard 

the equipment left there during off-duty hours, the working group agreed 

to set up ground instrumentation at a less remote location. They decided to 

use a quiet section within the perimeter of Edwards AFB known as North 

Base—located across Rogers Dry Lake from the major Air Force and NASA 

facilities—where security would not be a significant issue. Based on findings 

during the SSBD in August, the planners also agreed to concentrate most of 

the monitoring equipment into a smaller area. And to compensate for the 

inability to use corporate jets for in-flight measurements, the working group 

approved a Dryden proposal to have a Czech-made Blanik sailplane from the 

USAF Test Pilot School (TPS)—an almost perfectly quiet aircraft—measure 

midfield shock waves above the ground turbulence level.64 Its role would be 

similar to that of the YO-3A light aircraft used during the SR-71’s probing by 

the F-16XL in 1995 (described in chapter 4) and the Goodyear blimp during 

the National Sonic Boom Evaluation in 1966 and 1967 (chapter 1).

Preparations to implement this ambitious agenda continued at a fast pace 

during the remainder of 2003, with NAVAIR reviewing the test plan (including the new pushover maneuver needed to focus a sonic boom) and VFC-13 
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Quieting the Boom

formally agreeing to once again deploy one of its F-5Es to Palmdale if at 

all possible. Representatives from NASA Dryden, Northrop Grumman, and 

Lockheed Martin conducted an initial flight-readiness review on December 

6. Because the F-5 SSBD had not flown since August, Northrop Grumman 

technicians had to perform multiple inspections and maintenance actions 

to make sure it would be ready for another round of flight tests. By Friday, 

January 9, 2004, preparations were complete—with the test plan having been 

approved, the F-5 SSBD certified for flight, the ground array being put in 

place, and recording instrumentation installed on the glider. The 20 planned 

flight tests would need to be conducted within the next 2 weeks to allow time 

for flying the F-5 back to St. Augustine and preparing it for return to the Navy 

by January 31.65

As shown in figure 8-3, the ground recording array included 26 sites (conveniently designated Alpha through Zulu) placed 500 feet apart in a straight line 

through desert terrain paralleling the North Base runway at a heading of 240 

degrees magnetic. Two supplemental sites (M2 and Q2) were located 100 feet from 

Sites Mike and Quebec for fine-scale sampling, and two lateral sites (Mike Left and 

Mike Right) were placed 500 feet on either side of Mike to ensure the measurement of maximum overpressures in 

case the aircraft flew slightly off track. 

There were also Far North and Far 

South sites equipped with automatic 

sensors 2 miles from the main array 

to determine whether the F-5 SSBD’s 

flattop signature would also persist 

off to the sides of the sonic boom 

carpet. To monitor surface conditions, a portable weather station was 

deployed between sites M and M2.66

With the approval of the Edwards AFB Environmental Management 

Division, the ground crew set up a total of 42 different sensors under and 

to the side of the designated flightpath. Using postprocessed carrier-phase 

Differential GPS (DGPS) measurements, the sensor location for each site was 

surveyed to within just 0.03 meters.67 Sites I through X, ML, MR, and Q2 

were equipped with B&K Type 4193 low-frequency condenser microphones 

and associated amplification, power supplies, and processing equipment. On 

sites I through L, the microphones fed into a TEAC RD-145T digital audio 

tape (DAT) recorder. On sites M, ML, MR, and N, the microphones were connected to a laptop computer, with a special National Instruments data acquisition (DAQ) card installed, which offered immediate viewing of sonic boom 

signatures. The microphones on sites O through X used two DAT PC208AX 

Figure 8-3. SSBE ground array (NASA). Key: 

MR=Mike Right, ML=Mike Left, FN=Far North, 

FS=Far South.
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Proof at Last

B&K microphone and recording equipment. (NASA)

DAT recorders. (A microphone and recording equipment are shown in accompanying photos.)68

The sites at either end of the array (A through H and Y through Z) as well 

as M2, FN, and FS were equipped with Dryden-built automatic sonic boom 

recording systems. These consisted of the previously described BADS used in 

the SSBD, the SABER system designed for mounting on aircraft, and another 

Dryden device called the Boom Amplitude and Shape Sensor (the BASSo-matic), a completely autonomous single-transducer version of the BADS. 

Dryden produced 10 of the latter just in time for the SSBE. All three systems 

used Sensym SCXL004DN pressure sensors as their basic transducer element 

with those for the smaller BASS and SABER systems affixed to a flat plate 

placed on the ground. After processing with filters, preamplifiers, buffers, and 

computer software, the data collected was saved on flash memory cards. The 

three NASA systems tagged the exact times of the sonic boom measurements 

with built-in GPS receivers, which were later used to interpolate the exact 

times of the data captured by the B&K microphones in the TEAC, Sony, and 

National Instruments recordings.69

Personnel from NASA Dryden, NASA Langley, Northrop Grumman, 

Wyle Labs, Eagle Aeronautics, Gulfstream Aerospace, Boeing, and the FAA 

(all with desert tortoise protection training) set up and operated the ground 

array. Although its location was more convenient than the remote array along 

Cords Road, the ground crews once again had to arrive before dawn to set up 

and check out the equipment for morning flights. They then monitored radio 

communications from the approaching aircraft to learn when the supersonic 

sprints toward their ground array would start.

NASA Dryden contracted with the USAF Test Pilot School to install B&K 

4193 microphones and a SABER recording system on the two-seat L-23 Super 

Blanik sailplane (shown in an accompanying photo) and make midfield measurements of the sonic booms over the ground array as the F-5s flew overhead. They fastened the microphone on the left wingtip with a bullet-nose 
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Quieting the Boom

Blanik L-23 sailplane with microphone on left wingtip and installed recording equipment. (NASA)

attachment and windscreen to minimize wind noise during flight. A B&K 

Nexus amplifier raised the voltage level to improve the signal-to-noise ratio for 

recording on the SABER, which automatically sensed the arrival of the shock 

waves. The testers also installed a Thales Navigation Z-Xtreme carrier-phase 

differential GPS receiver for position and velocity data. A handheld GPS unit 

with a moving map display was also provided to help the pilot fly a precise 

route under the F-5s’ flightpath.70

The in-flight probing system on NASA F-15B Number 836 (depicted in 

figure 8-4) was further improved from that used during the SSBD in August. 

NASA Dryden installed a new data recorder that lowered transducer noise and 

more than doubled the analog data-sampling rate to 977 times per second. 

The pneumatic reference tank (also called a lag tank), which was part of a 

complicated system used to ensure the accuracy of the pressure measurements 

made by the nose boom, was also replaced. During the SSBD, Dryden had 

Figure 8-4. Schematic of F-15B nose boom probing system. (NASA)
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Proof at Last

relied on a spare 252-cubic-inch SR-71 nitrogen tank to perform this function. However, when the F-15B dived from over 45,000 feet down to below 

32,000 feet for the supersonic runs, the reference tank saturated the analog 

differential transducer readings for almost all the probes. This left only the 

digital transducer at 17 samples per second to provide good data. To correct 

this deficiency, Dryden technicians fabricated a new 100-cubic-inch reference 

tank, which would work very well during the SSBE.71

Conducting the SSBE: Twenty-One Flights in 10 Days

With all preparations in place and everyone involved eager for the tests to 

get under way, flight operations began on Monday morning, January 12, 

2004. As during the SSBD, Cmdr. Darryl “Spike” Long from China Lake 

had been scheduled to alternate with NGC’s Roy Martin as the F-5 SSBD’s 

pilot. Unfortunately, Long came down with a stubborn head cold just before 

test start and had to remove himself from flight status for the entire span of 

the SSBE. This meant Martin would get in a lot of flying time during the next 

2 weeks, performing all 21 SSBE missions plus 4 more sorties to return the 

plane to St. Augustine. Once again, Lt. Cmdr. Dwight “Tricky” Dick from 

Fallon would fly the baseline F-5E, completing eight missions from January 

13 to January 15 during its deployment to Palmdale. Dana Purifoy would 

pilot NASA F-15B number 836, performing four successful probe missions 

on January 21 and January 22. Jim Smolka and Dick Ewers would fly chase in 

NASA F/A-18 number 846 during three missions on January 12 and January 

14. The Blanik L-23 sailplane would be flown by three Air Force officers 

from the USAF Test Pilot School: Lt. Col. Mark “Forger” Stucky, Lt. Col. 

Robert “Critter” Malacrida, and Maj. Vince “Opus” Sei. Civilian employee 

Gary Aldrich towed them to altitude in a Pawnee Pa-25, releasing the glider 

at about 10,000 feet. The two TPS aircraft flew on each of the first 11 SSBE 

missions from January 12 to January 16 and three more times on January 19.72

To obtain the best possible data, they would need to launch and navigate the 

glider to be over the ground array and under the sonic boom shock waves at 

just the right times and locations.

After getting into the F-5 SSBD’s cockpit at 0900 Pacific Standard Time 

(PST) on January 12 and carrying out all the preflight chores, Roy Martin 

(still using the call sign Leahi 05) took off 40 minutes later. On this and most 

subsequent SSBE missions, Martin flew a fairly standard route and profile 

to get to the ground array. He went north through Edwards AFB restricted 

airspace to the vicinity of Koehn Lake and then far enough east (often near 

Goldstone on later missions) to make a right turn toward the southwest and 
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Quieting the Boom

descend from 40,000 feet to begin a run through the supersonic corridor about 

20 miles north of Barstow. He continued supersonically on a west-southwest 

heading over Edwards North Base and the northern edge of Rogers Dry Lake 

then slowed to a subsonic speed before reaching Mojave.73

Although the initial sortie’s primary purpose was to serve as a functional 

check flight, it began with NASA F/A-18 number 846 joining up with the 

F-5 SSBD at 1055 for an attempt to take some schlieren photography of 

its shock waves during the supersonic segment of the flight test. As Martin’s 

F-5 approached the ground array after reaching the desired Mach 1.4 speed 

at 32,000 feet, he did a 0.5-g pushover maneuver for 3 seconds to practice 

creating a focused sonic boom before recovering at 30,800 feet and Mach 

1.38. Meanwhile, the L-23 (call sign Cobra 77) glided quietly below. After 

passing over Mojave, Martin turned back toward Edwards and did a lowspeed run by its control tower at only 100 above ground level to help confirm the accuracy of the F-5 SSBD’s air-data system. Proceeding south, the 

Pelican was back on the runway at Palmdale at 1031 local time after a busy 

50 minutes in the air.

Wasting no time, Martin was back in the F-5’s cockpit at 1230 local time 

to begin preparing for the next sortie, which was supposed to include inflight probing by the NASA F-15B 836. After waiting for the launch of Dana 

Purifoy’s F-15 and an airborne pickup (establishing the communications link 

between the two aircraft) at 1316, Martin took off to join up with the F-15. 

Just as the two aircraft began their supersonic run toward the ground array at 

1331 PST, one of the F-15’s engines suffered a compressor stall, and Purifoy 

had to drop out of the formation. Martin continued over the ground array at 

Mach 1.4 and 32,000 feet with the L-23 again on station below. He then began 

a subsonic descent over California City, followed by another low-level flyby 

of the Edwards tower to check air-data calibrations. Meanwhile, Purifoy had 

seen indications of a landing gear problem with his F-15B, so Martin—with 

sufficient jet fuel still remaining—flew around to perform a visual inspection to 

ensure its wheels were down. After the F-15 was safely on the ground, Martin 

returned to Palmdale, landing at 1401 PST.74 Fortunately, the SSBE’s schedule afforded plenty of opportunities to perform in-flight probing toward the 

end of the flight-test schedule, and the old F-15’s engines would be in better 

condition by then.

The ambitious schedule for January 13 called for three flight tests (QSP15–17). With Lt. Cmdr. Dwight Dick having arrived from Fallon on the previous day, all of them featured back-to-back sonic boom measurements of the 

F-5 SSBD and standard F-5E (Leahi-06) at Mach 1.4 and 32,000 feet. He and 

Roy Martin took off on the day’s first flight test at 0656 PST, just as the Sun 

was rising. All went according to plan as they flew over the ground array and 
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Proof at Last

the glider 45 seconds apart. After landing at Palmdale at 0730, however, they 

learned that field personnel had reported a malfunction in Martin’s GPS telemetry. At 0930, after the Ashtech Z-12’s software had been rebooted, Martin 

got back in the cockpit for another sonic boom run with Dick. They flew this 

one almost identically with the previous test with the L-23 again participating. This time Martin’s GPS transmissions seemed okay, but those from Dick’s 

F-5E had experienced the same problem as the F-5 SSBD’s signals had on the 

previous flight, and therefore, it too had to be reprogrammed. The third flight 

test of the day, which lasted from 1300 to 1333, flew the same scenario as the 

first two, except this time both GPS systems behaved themselves, much to the 

relief of the data collectors.75

The same pilots flew the same basic course twice again on January 14 (QSP18 and 19), but this time to generate sonic booms at off-design speeds for 

data-analysis purposes. After a 0957 takeoff on the first flight, they entered 

the supersonic corridor from 45,000 feet and accelerated to Mach 1.43 for a 

data-collection run at 32,000 feet over the ground array and the glider. The 

day’s second flight, which began at 1327, followed the same profile but crossed 

the ground array at only Mach 1.35. Both planes were back on the Palmdale 

runway by 1400.76

To take full advantage of the F-5E’s final day at Palmdale, the F-5 SSBD 

flew three more back-to-back missions with it on January 15. Martin and Dick 

took off on the first flight at 0655. At 0709, just 2 minutes before beginning 

the pushover from 45,000 feet toward the ground array, the control center 

informed Martin that his GPS modem was once again failing to transmit. He 

continued on the flightpath, crossing over the ground array and the glider, 

flying Mach 1.43 at 32,000 feet. He was followed by Dick’s F-5E maintaining 

the same speed, with both planes back on Plant 43’s runway by 0727. The 

Ashtech Z-12 was reprogrammed in time for the next flight, which took off at 

0957. Martin and Dick flew almost the same profile as during the early morning flight except for doing the sonic boom run at only Mach 1.35.77

A published paper on the SSBE later commented, “While onboardrecorded data tends to be cleaner than telemetered data, failure in the onboard 

recording system could result in loss of mission. Having both onboard and 

telemetered data gives redundancy for data collection, which saved several 

flights in this program.”78

The test scenario for QSP-22, which took off at 1257 on the afternoon of 

January 15, was quite different from any of the previous missions involving 

both F-5s. The primary purpose of this test was to eliminate any effects of 

changing winds during the interval between the two signatures by measuring 

them almost simultaneously. To do this, the F-5E was supposed to fly in the 

F-5 SSBD’s Mach cone, within 580 feet behind and about 19 degrees below, 
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Quieting the Boom

as they passed over the ground array at Mach 1.35 and 32,000 feet. When the 

pilots returned to Palmdale at 1329, they learned that the F-5E’s GPS modem 

stopped transmitting from the time it began its pushover until just after passing 

Site Mike.79 In this case, the Z-12’s internal memory preserved the GPS data. 

The sonic boom measurements on the ground (described in the next section) 

would prove to be somewhat disappointing for another reason. The F-5E had 

arrived with its centerline pylon still attached. Because of the extra drag, Dick’s 

airplane was out-accelerated by the F-5 SSBD at the start of the supersonic run 

and was unable to catch up and follow as closely as planned.80

With the F-5E having returned home to Fallon, flight-test operations on 

January 16 were the lightest of the SSBE with only one sortie in the afternoon. 

After a low-speed taxi to make sure that a problem discovered with the nosewheel actuator had been fixed, Roy Martin took off in the F-5 SSBD at 1503. 

He then made an uneventful solo run at Mach 1.35 and 32,000 feet over the 

ground array and the glider, landing back at Palmdale at 1538. Although this 

was Friday, the test team would not be taking the weekend off.

Roy Martin took off in the F-5 SSBD three times on Saturday morning, 

January 17, at 0703, 0945, and 1138. All of these were solo supersonic runs 

planned to measure sonic booms generated at off-design flight conditions. On 

the first mission, Martin did a pushover maneuver from 32,000 feet and Mach 

1.375 to create a focused sonic boom. On the second mission, he flew over the 

ground array at a steady-state speed of Mach 1.375 but this time at 36,000 

feet. He also flew at 36,000 feet on the third mission (after noting turbulence 

at between 30,000 feet and 32,500 feet), but this time he sped overhead at 

Mach 1.45—the highest speed permitted by the NAVAIR flight clearance.81

The fast pace of flight tests resumed on Monday, January 19, with three 

more solo sorties by Roy Martin.82 Taking off at 0659, he performed a 3-second 

0.1-g pushover down to 30,000 feet that focused a sonic boom toward the L-23 

then recovered at 31,000 feet to cross over the ground array at Mach 1.375. 

On all the remaining six flight tests, the F-5 SSBD would make passes over 

the ground array in both directions to get the most out of each sortie. Martin 

took off on the first of these at 0954. As on many of the previous flights, he 

made his first pass from east to west at Mach 1.375 and 32,000 feet with the 

L-23 again below. He then made a supersonic U-turn to the right and, still at 

32,000 feet, returned over the array from west to east at Mach 1.3. Even with 

the extra afterburner time, the F-5 SSBD still had 1,100 pounds of fuel left after 

landing at 1026. Following the postflight inspection and refueling, it was back 

in the air at 1159 for another dual run. This time Martin made the first pass 

at Mach 1.4 and 32,000 feet and the second at Mach 1.31 and 31,200 feet.83

This flight test (QSP-29) was the last in which the L-23 sailplane participated. During its 14 flights, Gary Aldrich took off in the Pawnee Pa-25 with the 
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Proof at Last

L-23 in tow about 15 to 20 minutes before the F-5 began its sonic boom run. 

The sailplane usually released at about 10,000 feet and glided over the ground 

array at between 6,000 feet and 8,000 feet.84 The lower altitudes helped it record 

the weak signatures of booms echoing off the ground.85 Skillful piloting and 

the plane’s slow speed kept it on station during the supersonic runs. The data 

recorded by the L-23 sailplane would help enable analysts to determine the 

distortions in sonic boom signatures caused by turbulence in the lower atmosphere and recorded by ground sensors. Approximately 16 seconds after each 

of the F-5s flew overhead, their sonic booms were heard by the L-23 pilot and 

automatically recorded by the SABER system. About 6 seconds later, it would 

record a second weaker boom that had been reflected off the ground.86 In this 

interval, the glider flew about 400 to 500 feet. Figure 8-5 depicts how one of the 

acoustic rays in a sonic boom 

would pass the L-23 on its way 

to the sensor at Site N as well 

as how a reflected ray from the 

sonic boom that had reached the

ground earlier would also cross 

its path.87

The last 2 days of the SSBE 

flight tests, January 21 and 

January 22, were devoted to 

near-field measurements of 

the F-5 SSBD’s shock wave patterns, while the ground array continued to 

collect far-field data. Dryden’s F-15B number 836 piloted by Dana Purifoy 

successfully performed probe after probe as Roy Martin flew the F-5 at several 

different speeds while maintaining the optimum attitude of 32,000 feet. On 

each flight, the two aircraft flew side-by-side in a close formation from Palmdale 

until reaching the start point for the supersonic runs. As Martin pushed over 

and accelerated, Purifoy slid his F-15 Eagle below and behind the F-5. When 

Martin leveled out at 32,000 feet and radioed that he had reached the desired 

Mach number, Purifoy pushed his left stick with the throttles forward just 

enough to move slowly through the F-5’s shock waves. He had to keep his eyes 

on the F-5 while also keeping a special vector symbol in his heads-up display 

(HUD) on the horizon to remain level. Since the pressure changes from F-5’s 

shock waves disrupted the altimeter, the crewmembers in the back seat helped 

provide situational awareness and relayed other instrument readings, such as 

the indicated Mach number. Engineers in Dryden’s control center—which 

had a precise display of the aircraft’s relative positions as well as telemetry of 

the nose boom’s pressure measurements showing when it had crossed the bow 

shock—advised Purifoy when to begin slowing down and back out of the 

Figure 8-5. Direct and reflected acoustic rays passing 

L-23 glider (GL) over the ground array. (NASA)
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Quieting the Boom

shock waves. Unless nearing the end of the supersonic run, the F-15 would 

then quickly follow up with another probe.88

On January 21, Martin took off for the first probing mission (QSP-30) at 

0702, joined up with Purifoy’s F-15B with Mike Thomson in the backseat, 

and led them on a westbound Mach 1.4 run over the ground array. After 

beginning a right turn over Site Mike, they did an eastbound run at Mach 

1.35. During these first two runs, the 

F-15 completed 12 successful probes. 

The pressure signature recorded on 

the sixth of these (identified as probe 

30-6) is depicted in figure 8-6. Both 

planes were turned around in time 

for Martin to make a 1124 takeoff for 

another similar mission. This time, 

they made both their supersonic runs 

at Mach 1.375, completing 10 successful probes.89

The last day of SSBE testing on Thursday, January 22, provided six more 

two-way supersonic probing runs. Roy Martin’s F-5 SSBD took off at 1124 on 

its first sortie, 1342 on its second, and 1534 on its third with Dana Purifoy’s 

F-15B already in the air before each launch. Craig Bomben flew in the back 

seat of the F-15 on the first and third of these flights and Frank Batteas sat in 

for the second flight. The F-5 flew at 32,000 feet for all of the probing runs 

but at various speeds: twice at Mach 1.375 on the first flight; at Mach 1.4 and 

Mach 1.35 on the second flight; and at Mach 1.375 and Mach 1.4 on the third 

and last of the flight tests (QSP-33). The two pilots conducted 45 successful 

near-field probes during the four missions.90

In all, the F-15B completed 68 near-field probes at distances of 60 to 720 

feet from the F-5 SSBD. The majority of probes were made directly below at 

an average distance of about 100 feet, but others were flown off to one side 

or the other. Although all the probes provided valuable shock wave measurements, there were some lessons learned. The F-15 collected the most detailed 

data when it moved through the shock wave pattern at the slowest possible 

speed relative to the F-5.91 It was also noted that the F-15 tended to be pushed 

around more by the shock waves when probing off to the side than when 

directly under the F-5.92

In planning the SSBE, historical January weather statistics for the area 

around Edwards AFB had indicated that only early morning flights would 

meet the stringent atmospheric criteria required to collect useful sonic boom 

data.93 As it turned out, nearly perfect weather conditions as well as the overall 

reliability of the participating aircraft allowed the functional check flight and 

Figure 8-6. Illustration of F-15B probing F-5 

SSBD shock waves. (NASA)
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Proof at Last

all 20 planned flight tests to be completed in only 11 days. The SSBD project 

had gone through its share of problems and delays over the past 21⁄2 years, but 

as Joe Pawlowski remarked when looking back years later, it also experienced 

“a lot of small miracles.”94

Even though the flight tests ended in what seemed like plenty of time to 

return the F-5 SSBD to the Navy, Roy Martin did not get much rest after his 

final postflight debriefing. He was back at Northrop Site 3 the next day to fly the 

F-5 back to St. Augustine, this time accompanied by an F/A-18 from Air Test 

and Evaluation Squadron 31 (VX-31) at China Lake. On the third leg of their 

journey, the F/A-18 had an in-flight emergency and had to divert to Memphis, 

TN, while Martin landed at Birmingham, AL. He was stuck there for 3 nights 

awaiting another escort and sitting out inclement weather in Alabama and northern Florida. On Tuesday, January 27, accompanied by a Northrop Grumman 

Citation XL corporate jet, Martin finally made it to the St. Johns County Airport, 

where the Pelican’s journey had begun 6 months before.95

Collecting and Analyzing the Data

The ground array crews recorded an abundance of sonic boom data from 

the 21 SSBE flights. NASA Dryden provided the sensors (BADS, BASS, and 

SABER) for 13 of the sites: A through H, M2, Y through Z, F through N, 

and F through S (see figure 8-3). Wyle Laboratories equipped Sites I through 

L and along with Langley provided the equipment for Sites M, MR, ML, and 

N. Gulfstream Aerospace, supported by Northrop Grumman, equipped the 

remaining 11 locations—sites O through X. FAA personnel from the U.S. 

Department of Transportation’s John Volpe Center in Cambridge, MA, also 

helped. As shown in an accompanying photograph taken on January 13, some 

of the men and women manning the SSBE ground array (whose names also 

appear in several previous chapters) had been involved in sonic boom research 

for many years. Every morning in advance of the first flight, team members 

would set out much of the recording equipment and check the settings of the 

B&K 4231 systems with sound calibrators. Monitoring radio calls from the 

aircraft, they would turn on the recorders when the F-5 SSBD began accelerating toward the array and turn them off about 30 seconds after the final boom. 

Dryden’s BADS, BASS, and SABER systems activated automatically upon 

sensing the pressure waves. Immediately after each flight, personnel at Sites 

M, ML, MR, and N would review data on the quick-look DAQ card systems 

positioned in the center of the array, so as to make any adjustments for the 

next flight. Personnel at the BADS and BASS sites could also review their data 

before the next flight.96
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Quieting the Boom

Fourteen members of the SSBE’s data-collection team. Front row, left to right: Edward Haering 

(Dryden), Brenda Sullivan (Langley), David Graham and David Schein (NGC), James Murray 

(Dryden), Mark Stucky (USAF TPS, in flight suit), Domenic Maglieri (Eagle), and Gary Aldrich (USAF 

TPS, in flight suit). Rear row: Kenneth Plotkin (Wyle), David Read and Judy Rochat (FAA), Peter 

Coen (Langley), John Swain (Wyle, without hat), and Joe Salamone (Gulfstream). (Photo by Plotkin)

The ground array sensors made over 1,300 sonic boom recordings, the 

F-15B captured near-field shock wave signatures on 45 probes, and the L-23 

recorded 29 midfield signatures plus secondary booms reflected off the desert 

floor. All of this data was supplemented by records of atmospheric conditions, 

including the weather balloons launched at Edwards AFB, Vandenberg AFB 

(CA), China Lake, and other military installations in the region.97

The redundancy of recordings and the analysts’ ability to cross-reference 

and interpolate data from the various sources helped compensate for certain 

equipment limitations. For example, the atmospheric measurements made by 

highly accurate DGPS rawinsonde-equipped weather balloons was used to 

compensate for pneumatic lag and related inaccuracies in the F-5 SSBD’s pitotstatic air-data system, which was later discovered to have a small leak in the 

plumbing used to apply pressure to the nose boom. The SSBE’s comprehensive 

data-collection strategy also helped compensate for a few major malfunctions. 

For example, on six flights, the raw GPS data from the F-5 SSBD or baseline 

F-5E were lost when being downloaded, but their previous GPS transmissions 

to the ground array had been saved. A record of GPS readings is essential for 

precise Mach number calibration and sonic boom data reduction. Fortunately, 

SSBE analysts were able to correlate the somewhat less accurate data from the 
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Proof at Last

ground instruments with those recorded from other flights by both the onboard 

and ground equipment. This allowed them to recalibrate time and position data 

for the signatures on the six affected flights for greater precision.98

Almost as soon as the flight tests had been completed, sonic boom researchers began the task of cleaning, processing, organizing, analyzing, comparing, 

and interpreting the vast amount of data collected. Over the next several 

months, key participants also presented briefings on the SSBD and SSBE 

at conferences and symposiums from coast to coast.99 On August 17, 2004, 

NASA’s Langley Research Center hosted a review of preliminary findings at a 

Shaped Sonic Boom Experiment Closeout Workshop. Members of the SSBE 

Working Group presented a number of reports followed by panel discussions 

on the significance of the results, issues raised, and next steps. One of the 

next steps was to prepare and publish a series of formal scientific and technical papers on most aspects of the SSBD and SSBE.100 The first of these had 

been presented at a joint conference of the American Institute of Aeronautics 

and Astronautics and the Council of European Aerospace Societies (CEAS) 

in Manchester, England, in May 2004. The AIAA then devoted an entire session to the SSBD-SSBE at its 43rd Aerospace Sciences Meeting and Exhibit 

in Reno, NV, held from January 10 through January 13, 2005. An additional 

paper on the SSBE was presented at the 26th AIAA Aeroacoustics Conference 

in Monterey, CA, May 23 through May 25, 2005.(See appendix D for a list 

of these reports.)

The more than 1,300 sonic boom measurements made by the 42 ground 

sensors displayed variations caused by their location along the array, changing 

atmospheric conditions, differences in aircraft speed and altitude, and some 

random anomalies. The lines plotted for the signatures from the F-5 SSBD usually had a jagged shape at the plateau region of its flattop signatures presumably 

caused by intrusions from wing and inlet shock waves as well as atmospheric 

turbulence. Even so, reviews of the signatures confirmed consistently lower 

overpressure in the flattop signatures of the F-5 SSBD versus the stronger 

N-wave signatures of the standard F-5E. The SSBD’s signatures also appeared 

to be consistently shorter than those of the F-5E.101

One of NASA’s reasons for sponsoring the SSBE was the desire to learn 

about the effects of turbulence on shaped sonic boom signatures. In this regard, 

the January weather and numerous flights later in the day, although not distorting the sonic boom signatures as much as expected, did not disappoint 

the analysts. In general, however, the data recorded proved the persistence of 

the shaped sonic boom signature through turbulence.102 An analysis by John 

Morgenstern and colleagues at Lockheed Martin using CFD modeling confirmed a consistent 18-percent reduction in the initial pressure impulse as well 

as a reduction in perceived loudness of 6.4 decibels in the F-5 SSBD’s sonic 
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Quieting the Boom

Figure 8-7. One shaped sonic boom signature as measured by Site B (top left), the 

L-23 glider (bottom left), Site E (top right), 

and after being reflected back to the glider 

(bottom left), all within 1.3 seconds. (NASA)

booms as compared to those from the 

standard F-5E.103

The data collected by the Air Force 

L-23 sailplane allowed analysts to compare the sonic boom signatures recorded 

at ground level with clean signatures 

measured above by the L-23 and signatures from the shock waves reflected 

back into the atmosphere. At first, the 

L-23’s flight plan called for it to be 

directly over the center of the ground 

array (near Site M) when the sonic 

boom arrived, but soon the researchers 

had it begin up boom of the center point 

so that the shock waves measured along the ground array could literally travel 

past the L-23. Approximately 6 seconds after each of the F-5s flew overhead, 

the sonic boom was heard by the L-23 pilot and automatically recorded by its 

SABER system.104

Ken Plotkin, Ed Haering, Domenic Maglieri, Brenda Sullivan, and 

Gulfstream’s Joseph Salamone used these data to determine exactly how the 

surface signatures were distorted by boundary-layer conditions. Figure 8-7, for 

example, shows how one of the sonic booms generated by the F-5 SSBD on 

January 15 (QSP-21) was affected by atmospheric conditions. The four graphs 

plot the signatures of one sonic boom captured by B&K 4193 microphones 

as it evolved behind and through the L-23 glider to ground sensors and again 

back up to the glider—all within about 1.2 seconds.105

Using such comparative data, the researchers were able to develop a turbulencesubtraction algorithm. Because turbulence causes almost identical perturbations in 

the pressure patterns of both the front and rear shocks, a mathematical template 

based on the rear shock distortion pattern could be used to subtract the effects of 

turbulence and smooth out the front of the signature to show what it would be in 

a standard atmosphere with minimal surface winds—in the case of the two F-5s, 

cleaner N-waves or flattops. Figure 8-8 shows the application of this technique to 

the SSBD signatures recorded at several sites during the same Mach 1.35 

flyover (QSP-21) on January 15.106

Although the rapid changes 

in atmospheric pressure were the 

most common metric used for 

measuring the strength of sonic 

booms, how loud these abrupt 

Figure 8-8. Removal of effects of turbulence from 

five signatures. (NASA)
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Proof at Last

changes sounded to human ears would be a key factor in determining what 

might be acceptable to the public. Brenda Sullivan of Langley’s Structural 

Acoustics Branch found that the shaped sonic booms were even quieter than 

their reduced pressure rise would indicate. The reduction of average overpressure from 1.2 psf in the sonic booms of the F-5E to 0.9 psf in those from the 

F-5 SSBD would equate to an expected reduction of 2.5 decibels in perceived 

loudness. Based on an advanced acoustical analysis of 132 booms recorded by 

19 microphones on seven of the flight tests, she found the sonic booms made 

by the F-5 SSBD actually averaged 4.7 decibels quieter than those made by 

the F-5E. She concluded that the combined effects of both slower rise time 

and lower peak pressure of the shaped sonic boom signatures helped cause this 

result.107 This reduction in loudness was found to persist through turbulence.108

All previous flight tests measuring focused booms involved aircraft that normally generated N-wave signatures. The F-5 SSBD presented the first chance to 

do so from an aircraft designed to create shaped sonic booms. This opportunity 

especially interested Ken Plotkin and Domenic Maglieri, who had collected 

and analyzed focused boom data in the past and were currently doing related 

research for NASA.109 As discussed in earlier chapters, even a civil aircraft 

designed to generate an acceptably quiet sonic boom carpet when cruising 

supersonically could still create more powerful focused booms when accelerating, turning, or beginning to descend with a pushover maneuver. Based on 

the F-5 SSBD’s design parameters and performance limitations, such as not 

transitioning from subsonic to supersonic in level flight, it was decided to use 

a pushover maneuver for the Shaped Sonic Boom Experiment. The three pushovers flown by Martin on January 12, 

17, and 19 successfully placed focused 

booms on ground array sensors (Site 

Q on QSP-13 and Site E on QSP 

flights 24 and 27). On these sorties, 

Martin would quickly push his stick 

forward to attain unloaded forces of 

0.1 g to 0.5 g and hold the pushovers 

for about 3 seconds until making an 

approximate 1.75-g recovery into 

level flight. Figure 8-9 illustrates how 

this kind of maneuver projects multiple acoustic rays to form a caustic (the 

dark curved line) that intersects the surface with a narrow sonic footprint.110

The coverage of the focused boom footprints, projected forward more than 

6 miles from the start of the pushover maneuver, closely matched that predicted 

using PCBoom4. The actual focused boom signatures, however, revealed new 

data. On January 17, for example, the signature of the focused boom was 

Figure 8-9. Diagram of acoustic rays during 

a pushover maneuver to create a focused 

(U-wave) sonic boom. (Wyle)
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Quieting the Boom

recorded at Site E as a sharp U-wave with an overpressure of 3 psf as predicted, 

and then it evolved into a shape corresponding to an N-wave as it crossed 

additional sensors while also being overlapped by the premaneuver flattop 

signatures. The focused boom weakened and eventually dissipated as it passed 

Site W. The signatures of the postfocus carpet boom, however, did not display 

the flattop shaping of the sonic booms created by the F-5 SSBD when flying 

straight and level. Instead, they were recorded as conventional N-waves. The 

researchers concluded that this resulted from a flight condition in which the 

lift load was only one quarter of that for which the F-5 SSBD was designed. 

“The focusing maneuver was successful, but a lesson learned was that a focusing 

maneuver will be at a flight condition that does not correspond to a minimum 

boom cruise condition.”111 This unexpected finding was “a useful result” that 

“led to a realization that a focus maneuver of a low-boom shaped aircraft will 

generally correspond to an off-design condition. That result can be exploited 

by making an off-design condition a complex wave whose focus factor is less 

than that of a simple boom with two shocks.”112

The only event that failed to provide hoped-for data was the close-behind 

flight of the two F-5s at Mach 1.35 on January 15 (QSP-22). Instead of the 

usual separation of 45 seconds (or about 63,000 feet), the F-5E was supposed to 

follow no more than 700 feet (or 0.3 seconds) behind and about 200 feet below 

the F-5 SSBD. This would subject their sonic boom signatures to the same 

amount of turbulence. Unfortunately (and somewhat ironically), the sleeker 

baseline F-5E could not quite keep up with the modified F-5, so its sonic boom 

signature arrived 2 seconds later. Because turbulence in the lower atmosphere 

was higher than during any of their other flights together, the effects of turbulence scatter on the sonic booms could not be precisely determined.113

The in-flight sonic boom measurements made during the F-15B probes, which 

measured the F-5 SSBD’s shock waves shortly after coming off its airframe, would 

be especially valuable for use in computational fluid dynamics. Figure 

8-10 depicts the near-field pressure 

signature as measured on the sixth 

probe made at Mach 1.414 during the 

early morning flight test on January 

21 (QSP-30).114

The superimposed photo of the 

F-5 SSBD clearly shows the propagation of its shock waves, starting 

with a strong bow shock. This prevents the next three forebody shocks 

from moving forward to reinforce 

Figure 8-10. Near-field probing data, with photo 

showing sources of shock waves. (NASA)
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Proof at Last

the bow shock farther down in the midfield and far field. After another strong 

shock from the wings and their leading edge extension (abbreviated as LEX 

on the chart), there is a strong expansion (a type of decompression) before 

another shock from the trailing edge of the wings and the horizontal stabilizer. 

After a final recompression shock wave, the pressure drops as the plume from 

the engines’ exhaust dissipates. The box on the lower left shows the movement 

of the probe relative to the angle of the shock cone, and the box at the lower 

right shows the orientation of the F-15B below the F-5. On some probes, it 

was learned that the bow shock could advance 10 feet or more from the ideal 

Mach cone.115

A technical paper published on the airborne portion of the SSBE emphasized the importance of precision in gathering this data; among the lessons 

learned: “For all measurements, accurate global positioning system–based 

timing is essential for data correlation with multiple aircraft.... Shock measuring plumbing design require[s] careful sizing.... [and] ....Real-time monitoring 

of measured shock waves is essential for efficient shock wave probing.”116 A 

delay in communications from the Dryden control room to the F-15B on the 

relative positions of the aircraft during probes allowed only gross corrections 

for the next probe. It would have been desirable to upgrade the F-15B’s cockpit 

instrumentation, especially with a relative position display, but the compressed 

schedule for completing the SSBE did not allow enough time.117

After applying various corrections, recalibrations, and adjustments to the raw 

data and inputting flight conditions (e.g., Mach number, lift coefficient, angle 

of attack), meteorological data, and other variables, the researchers were able to 

begin validation of computational fluid dynamics codes. At the Langley workshop in August 2004, NGC’s Keith Meredith showed how the data collected 

could be incorporated into CFD analyses. First, Ed Haering selected 6 of the 

68 probes based on such factors as the number of data points in each recorded 

signature, the constancy of the F-5 SSBD’s Mach numbers and flightpath angles 

(which implied the plane’s 

lift, AOA, and trim), and 

how close to exactly parallel it and the F-15B flew 

during the probes. He 

reprocessed the GPS flightpath data recorded during 

these probes in five ways to 

select the process that would 

provide the best CFD comparisons. Meredith then 

incorporated data from the 

Figure 8-11. A CFD image (left) and graph of the CFDgenerated shock wave signature, with the actual signature 

recorded during the flight test also shown on the graph. 

The squiggly horizontal line under the F-5 SSBD depicts 

the path flown by the F-15B during this probe. (NGC)
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Quieting the Boom

Figure 8-12. CFD comparison of normal F-5E (left) and F-5 SSBD (right) at Mach 1.4 with shock 

waves shown propagating from forebody and pressure contours from the engine inlet. (NGC)

six selected signatures with NGC’s GCNS model using the offset grid with 

14.2 million data points. Some of the CFD runs required minor adjustments to 

compensate for slight deviations in the probing measurements, but in general, 

the CFD results were in excellent agreement with the flight-test data. Figure 8-11 

depicts the second probe on January 22 (QSP-31) flying at Mach 1.38 with an 

overlay of the recorded and CFD-generated sonic boom signatures.118

A collaborative overview of the SSBD project prepared by Joe Pawlowski, 

David Graham, Charles Boccadoro, Peter Coen, and Domenic Maglieri 

assessed the significance of what the Shaped Sonic Boom Demonstration 

and Experiment had recorded. “The vast amount of data collected during 

these tests will be invaluable to future supersonic aircraft designs in that it 

will allow designers to go forward with confidence in the ability to predict, 

and thereby control, sonic booms.”119 Using computational fluid dynamics, 

the data revealed the effects of sonic boom shaping in practice as well as in 

theory. In what might seem counterintuitive to a layperson, the stronger bow 

shock generated by the F-5 SSBD’s nose glove actually resulted in a weaker and 

more slowly spiking bow wave in the far-field (e.g., on the ground) because 

trailing shock waves would be less prone to merge with it. Furthermore, the 

SSBD’s carefully designed underbody fairing produced an area of expansion 

(decompression) that decreased the shock wave from the engine inlets. What 

in decades past could only be imagined in the mind’s eye of sonic boom 

researchers could now be imaged in vivid colors based on real-world flighttest data. Figure 8-12 shows how the F-5 SSBD’s modifications changed the 

normal F-5E shock waves and pressure dips into a pattern that reduced the 

strength of its sonic boom. The pressure in the dark areas above both aircraft 

and below the F-5 SSBD equates to at least –75 psf (below ambient air pressure), while the stronger bow shock extending down from the front of the 
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Proof at Last

F-5 SSBD equates to more than 50 psf.120 Although the original colors are 

not reproduced on paper, the results are clearly evident even in tones of gray 

and black. 

The achievements of the Shaped Sonic Boom Demonstration and 

Experiment did not go unrecognized. Among the many tributes and honors 

given to the participants, Aviation Week and Space Technology bestowed one 

of its “Laurels” for 2003 on Charles Boccadoro, Richard Wlezien, and Steven 

Walker; the AIAA awarded its Aircraft Design Award for 2004 to Charles 

Boccadoro, Joseph Pawlowski, and David Graham; and NASA recognized 

the entire SSBD team with a 2004 Turning Goals into Reality Partnership 

Award.121 The Navy, which had previously planned to use Bureau Number 

(BUNO) 74-1519 for spare parts, recognized the significance of this old but 

now unique F-5 by allowing it to be preserved. The disassembled aircraft was 

delivered in August 2004 to the Valiant Air Command Museum in Titusville, 

FL, where, after being reassembled and restored by volunteers (as shown in a 

photo at the end of the last chapter), the Pelican has been on display with the 

museum’s collection of “warbirds” since June 2006.122
236

Quieting the Boom

Endnotes

1. Weather Warehouse, “Jacksonville Cecil Field Airport, 7/24/03,” 

accessed August 11, 2011, https://weather-warehouse.com/WxHubP/

WxSPM531874661_174.28.158.213/1_Jacksonville.

2. Steve Madison, Roy Martin, Keith Applewhite, and Eric Vario, 

“Test Plan: Quiet Supersonic Program Flight Envelope Clearance,” 

Appendices H and I, Revision 6 (May 5, 2003).

3. Benson-Martin interview, April 7, 2011; Peter G. Coen, David H. 

Graham, Domenic J. Maglieri, and Joseph W. Pawlowski, “Origins 

and Overview of the Demonstration Program,” PowerPoint presentation, January 10, 2005, slide no. 17, SSBD Flight Test Summary; 

Northrop Grumman, “Northrop Grumman F-5E Modified for 

Sonic Boom Demonstration Completes First Flight,” news release, 

July 29, 2003.

4. Steve Madison, Roy Martin, Keith Applewhite, and Eric Vario, 

“Test Plan: Quiet Supersonic Program Flight Envelope Clearance,” 

Appendices H and I, Revision 6 (May 5, 2003); Graham et al., 

“Aerodynamic Design of SSBD,” AIAA paper no. 2005-8, 6; 

Northrop Grumman, “Shaped Sonic Boom Demonstration Program 

Overview,” undated, 5.

5. The Introduction provides a detailed description of the cross-country 

ferry flight, based primarily on a telephone interview of Roy Martin 

by Lawrence Benson, May 31, 2011.

6. “Air Force Plant 42,” accessed August 10, 2011, http://www. 

dreamlandresort.com/black_projects/plant42.htm; Madison, “SSBD 

Test Plan Review,” slide no. 51.

7. Northrop Grumman, “Shaped Sonic Boom Demo Flight Test 

Program,” PowerPoint presentation, August 17, 2004, slide no. 5, 

“SSBD/SSBE Team Roster: Test Pilots (SSBD).”

8. Graham et al., “Aerodynamic Design of SSBD,” AIAA paper no. 

2005-8, 5.

9. Pawlowski et al., “Overview of the SSBD,” AIAA paper no. 

2005-5, 10.

10. Ibid., 12. Source for temperatures at 32,000 feet: Aerographer/

Meteorology, Table 1-6, U.S. Standard Atmosphere Heights and 

Temperatures, accessed August 27, 2011, http://www.tpub.com/ 

content/aerographer/14269/css/14269_75.htm.

11. Benson-Martin interview, May 31, 2011.

12. Benson-Boccadoro interview, August 12, 2011.

13. Ibid.; Croft, “Engineering through the Sound Barrier,” 30.
237

Proof at Last

14. NGC, Flight Report, QSP-8, August 25, 2003, with attached pilot 

report by Cmdr. “Spike” Long.

15. Dana D. Purifoy to Lawrence Benson, “Re: Name(s) of F-15B 

Backseater during SSBD/SSBE,” e-mail, October 6, 2011.

16. Edward A. Haering and James E. Murray, “Shaped Sonic Boom 

Demonstration/Experiment Airborne Data SSBD Final Review,” 

PowerPoint briefing, August 17, 2004, slide no. 27; Edward A 

Haering, James E. Murray, Dana D. Purifoy, David H. Graham, 

Keith B. Meredith, Christopher E. Ashburn, and Lt. Col. 

Mark Stucky, “Airborne Shaped Sonic Boom Demonstration 

Measurements with Computational Fluid Dynamics Comparisons,” 

AIAA paper no. 2005-9, 43rd Aerospace Sciences Meeting, Reno, 

NV, January 10–13, 2005, 6.

17. NGC, Flight Report, QSP-8, August 25, 2003.

18. Benson-Boccadoro interview, August 12, 2011.

19. Cmdr. “Spike” Long, QSP Pilot Report, August 25, 2003.

20. Madison et al., “Test Plan QSP SSBD Data Collection,” 11–12.

21. Source for figure 8-1: Coen and Martin, “Fixing the Sound Barrier,” 

slide no. 19.

22. The lake used to have year-round water and still has a marsh with a 

wildlife viewing area. Bureau of Land Management, “Harper Dry 

Lake,” accessed August 20, 2011, http://www.blm.gov/ca/st/en/ 

fo/barstow/harper.html, as of August 2011.

23. Kenneth J. Plotkin, Edward A. Haering, Domenic J. Maglieri, 

Joseph Salamone, and Brenda M. Sullivan, “Ground Data 

Collection of Shaped Sonic Boom Experiment Aircraft Pressure 

Signatures,” AIAA paper no. 2005-10, 43rd Aerospace Sciences 

Meeting, Reno, NV, January 10–13, 2005, 2.

24. Ibid., 3; Numerous e-mail messages from and to Ed Haering and 

Mike Beck on meeting desert tortoise protection and other land-use 

requirements.

25. Madison et al., “Test Plan QSP SSBD Data Collection,” 2, 11–12; 

Plotkin et al., “Ground Data Collection of SSBE,” AIAA paper no. 

2005-10, 2–3.

26. Ed Haering to David McCurdy, “Security and toilets,” e- mail, 

January 16, 2003. As it turned out, many of the sticks at Harper 

Lake used to position the sensors and all but one of the reflector 

stakes used to find locations in the dark were ripped up or stolen. Ed 

Haering, “Draft SSBD Lessons Learned,” June 6, 2004, 5.

27. Ken Plotkin, “SSBD Ground Boom Data Wyle and Northrop,” 

PowerPoint briefing, September 19, 2003, slide nos. 2–4; Plotkin et 
238

Quieting the Boom

al., “Ground Data Collection of SSBE,” AIAA paper no. 2005-10, 

2–5; Ed Haering to Lawrence Benson, “Re: SSBD Chapter 8 for 

Review,” e-mail, October 26, 2011.

28. Plotkin, “SSBD Ground Boom Data,” September 19, 2003, slide 

nos. 2–4; Plotkin et al., “Ground Data Collection of SSBE,” AIAA 

paper no. 2005-10, 2.

29. Ed Haering to Joe Pawlowski et al., “Re: SSBDWG Meeting Notice 

- Flight Test Planning,” e-mail, August 19, 2002.

30. Madison et al., “Test Plan: QSP SSBD Data Collection,” as of 

April 17, 2003, 10; Benson-Haering interview, April 5, 2011; 

Graham Warwick, “F-5E Shapes up to Change Sonic Boom,” Flight 

International, August 5, 2003, 30.

31. Sweetman, “Whooshhh!” Popular Science (July 2004); Croft, 

“Engineering through the Sound Barrier,” Aerospace America

(September 2004): 30. 

32. Sweetman, article cited above. A new Moon had set the previous 

evening and would not rise until after 0600: Time&Date.com, 

“Moonrise and Moonset in Los Angeles,” August 2003, accessed 

August 26, 2011, http://www.timeanddate.com/worldclock/astronomy.

html?n=137&month=8&year=2003&obj=moon&afl=-11&day=1.

33. “CFD Used in Sonic Boom Test Program,” CFD Review, September 

3, 2003; Kenneth Plotkin et al., “Ground Measurements of a 

Shaped Sonic Boom,” AIAA paper no. 2004-2923 (May 2004), 3–4.

34. Time&Date.com, “Sunrise and Sunset in Los Angeles.”

35. Croft, “Engineering through the Sound Barrier,” 30.

36. NGC, Flight Report, QSP-9, August 27, 2003.

37. As quoted by Sweetman in “Whooshh!” http://www.popsci.com.

38. Figure 8-2 copied from Coen and Martin, “Fixing the Sound 

Barrier,” slide 21.

39. Benson-Plotkin interview, May 2, 2011; Croft, “Engineering 

through the Sound Barrier,” 24, 31.

40. Madison et al., “Test Plan QSP SSBD Data Collection,” as of April 

17, 2003, 9–10.

41. NGC, Flight Report, QSP-10, August 27, 2003, with attached 

pilot report by Cmdr. Spike Long attached; Plotkin et al., “Ground 

Measurements,” AIAA paper no. 2004-2923, 4.

42. NGC, Flight Report, QSP-11, August 28, 2003.

43. Plotkin, “SSBD Ground Boom Data,” slide no. 7.

44. NGC, Flight Report, QSP-12, August 29, 2003, with attached 

pilot report by Cmdr. Spike Long (quoted); Plotkin et al., “Ground 

Measurements,” AIAA paper no. 2004-2923, 4.
239

Proof at Last

45. Jim Hart (NGC), Jan Walker (DARPA), Kathy Barnstorff (NASA 

Langley), and Gray Creech (NASA Dryden), “Northrop Grumman/

Government Team Shapes Aviation History with Sonic Boom Tests,” 

news release, August 28, 2003, accessed ca. September 1, 2011, 

http://www.irconnect.com/noc/press/pages/news_releases.html?d=44396.

46. Science Blog, news advisory, “DARPA, Northrop Grumman, NASA 

to Brief Media on Results Achieved in Supersonic Boom Reduction 

Demo,” August 28, 2003, accessed August 23, 2011, http://www.

scienceblog.com/community/older/archives/K/1/pub1157.html.

47. Northrop Grumman, “Quiet Supersonic Platform (QSP) Shaped 

Sonic Boom Demonstrator (SSBD) Program,” PowerPoint presentation, Washington Press Club, September 3, 2003.

48. “NG, NASA, DARPA Announce Successful Sonic Boom 

Reduction,” Aerospace Daily (September 4, 2003): 6.

49. Ibid.

50. Kathy Barnstorff, Jan Walker, and Jim Hart, “NASA Opens New 

Chapter in Supersonic Flight,” news release, September 4, 2003, 

accessed ca. September 1, 2011, http://www.nasa.gov/centers/langley/

news/releases/2003/03-060.html; “F-5SSBD Press Conference,” http://

sonicbooms.org/News/F5SSBD_PressConf.html.

51. Andrew Bridges (AP Science Writer), “Changing Jet’s Shape Takes 

the Bang out of Sonic Booms” (September 4, 2004); Videos of 

CNBC’s Tech Watch with Jane Wells, September 10, 2003, provided 

to author by Joe Pawlowski.

52. National Research Council, Commercial Supersonic Technology: The 

Way Ahead (Washington, DC: National Academies Press, 2001), 

41–43.

53. James R. Asker, “FAA Seeks Information on Sonic Boom Research,” 

Aviation Week (June 2, 2003): 21; David Bond, “The Time is Right,” 

Aviation Week (October 20, 2003): 57–58.

54. Steve Komadina, “Quiet Supersonic Platform (QSP),” PowerPoint 

presentation, FAA Civil Supersonic Aircraft Technical Workshop, 

Arlington, VA, November 13, 2003; David Graham, “Shaped Sonic 

Boom Demonstrator Program,” same venue, November 13, 2003. 

Presentations accessed September 5, 2011, http://www.faa.gov/about/

office_org/headquarters_offices/apl/noise_emissions/supersonic_aircraft_

noise/. Spokespersons for Boeing, Lockheed Martin, Gulfstream, 

Raytheon, General Electric, and Pratt & Whitney also made one or 

more presentations.
240

Quieting the Boom

55. Richard G. Smith III, “NETJETS,” PowerPoint presentation, FAA 

Civil Supersonic Aircraft Technical Workshop, Arlington, VA, 

November 13, 2003.

56. Peter G. Coen (for Kevin P. Shepherd), “Human Response to Sonic 

Booms” (November 13, 2003); Brenda M. Sullivan, “Metrics for 

Human Response to Sonic Booms” (November. 13, 2003); Peter G. 

Coen, “Supersonic Vehicles Technology: Sonic Boom Technology 

Development and Demonstration” November 13, 2003 (all presented at FAA Civil Supersonic Aircraft Workshop, November 

13, 2003); Aimee Cunningham, “Sonic Booms and Human Ears: 

How Much Can the Public Tolerate,” Popular Science (July 30, 

2004) accessed ca. September 10, 2011, http://www.popsci.com/

military-aviation-space/article/2004-07/sonic-booms-and-human-ears.

57. Haering, Draft SSBD Lessons Learned, 10.

58. Martin and Coen, “Fixing the Sound Barrier,” slide no. 22, “Lessons 

Learned from Initial Tests.”

59. Benson-Boccadoro interview, August 20, 2011.

60. Irene Mona Klotz, “Test Shows Shape Sheds Sonic Boom’s Bang” 

(September 26, 2003), accessed ca. September 10, 2011, http://www.

upi.com/Science_News/203/09/26/UPI-32491064603528/.

61. NGC-NASA, “Shaped Sonic Boom Experiment Program Overview,” 

ca. September 2004, 1.

62. SSBD/SSBE Team Roster.

63. SSBE Overview, 1–2; “Shaped Sonic Boom Demonstrator Data 

Collection Test Plan Addendum, Quiet Supersonic Platform Shaped 

Sonic Boom Experiment” (ca. December 2003), 3–5, 7.

64. SSBE Overview, 1–2; Test Plan Addendum SSBE, 5–6.

65. SSBE Overview, 3; Tom McCoy, “Flight Readiness Review for 

Shaped Sonic Boom Experiment” (January 6, 2004).

66. SSBE Overview, 5; Plotkin et al., “Ground Data Collection SSBD,” 

AIAA paper no. 2005-10, 3–4; Edward A. Haering, James E. 

Murray, Kenneth J. Plotkin, and Brenda Sullivan, “NASA Shaped 

Sonic Boom Experiment, Ground Sensors and Data Final Data 

Review,” PowerPoint presentation, August 17, 2004, figure 8-3 copied from slide no. 9.

67. Haering et al., “NASA SSBE Ground Sensors,” slide nos. 10–11.

68. Plotkin et al., “Ground Data Collection of SSBE,” AIAA paper no. 

2005-10, 4–5; Haering et al., “NASA SSBE Ground Sensors,” slide 

nos. 15–17.

69. Haering et al., “NASA SSBE Ground Sensors,” slide nos. 10–14.
241

Proof at Last

70. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 7; Haering and Murray, “SSBD/E Airborne 

Data,” slide nos. 15–16.

71. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 6; Haering and Murray, “SSBD/E Airborne 

Data,” slide nos. 15–16. 

72. Benson-Martin interview, April 7, 2011; Benson-Purifoy interview, 

April 8, 2011; QSP Flight Reports, January 12–22, 2004; “SSBD/

SSBE Team Roster,” slide no. 6, “Test Pilots (SSBE).”

73. Martin and Coen, “Fixing the Sound Barrier,” slide no. 25, “Revised 

Ground Track”; Author’s review of Flight Reports QSP-13 through 

QSP-33, January 12–22, 2004.

74. NGC, Flight Report, QSP-14, January 12, 2004.

75. NGC, Flight Reports, QSP-15, QSP-16, and QSP-17, January 13, 

2004.

76. NGC, Flight Reports, QSP 18 and QSP 19, January 14, 2004.

77. NGC, Flight Reports, QSP 20 and QSP 21, January 15, 2004.

78. Haering et al., Airborne SSBD Pressure Measurements,” AIAA paper 

no. 2005-9, 33.

79. NGC, Flight Report QSP 21, January 15, 2004.

80. NASA-NGC, “SSBD Program Overview,” 5.

81. NGC, Flight Reports, QSP-24, 25, and 26, January 17, 2004. The 

last report noted that the data run was made at Mach 1.43, but 

the speed was later revised to Mach 1.45 in the SSBE Flight Test 

Summary matrix used in NGC-NASA briefings during 2004. This 

would equate to a true airspeed of over 950 mph, based on http://

www.hochwarth.com/misc/AviationCalculator.html.

82. As this was the Martin Luther King Federal holiday, the team had to 

get special permission to conduct operations.

83. NGC, Flight Reports, QSP-27, 28, and 29, January 19, 2001.

84. Plotkin et al., Ground Data Collection of SSBE,” AIAA paper no. 

2005-10, 5; Haering et al., “NASA SSBD Ground Sensors,” August 

17, 2004, slide 84.

85. Haering, Draft SSBD Lessons Learned, 3.

86. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 13.

87. Haering et al., “NASA SSBE Ground Sensors,” August 17, 2004, 

slide no. 87 used for figure 8-5.

88. Edward A. Haering, James E. Murray, Dana Purifoy, David H. 

Graham, Keith B. Meredith, Christopher E. Ashburn, and Lt. 

Col. Mark Stucky, “Airborne Shaped Sonic Boom Demonstration 
242

Quieting the Boom

Pressure Measurements with Computational Fluid Dynamics 

Comparisons,” AIAA paper no. 2005-9, 43rd Aerospace Sciences 

Meeting, Reno, NV, January 10–13, 2005, 10–11 (also source for 

figure 8-6).

89. NGC Flight Reports, QSP-30 and 31, January 21, 2001; SSBE 

Flight Test Summary.

90. NGC Flight Reports, QSP-32 and 33, January 22, 2001; SSBE 

Flight Test Summary; Purifoy to Benson, October 6, 2011.

91. Haering et al., Airborne SSBD Pressure Measurements with CFD,” 

AIAA paper no. 2005-9, 3, 15.

92. Haering, Draft SSBD Lessons Learned, 1.

93. NASA/NGC, “SSBE Program Overview

94. Benson-Graham-Pawlowski interview, April 12, 2011.

95. SSBE Flight Test Summary; NASA-NGC, “SSBE Program 

Overview,” 5; Benson-Martin interview, April 7, 2011.

96. Plotkin et al., Ground Data Collection of SSBE,” AIAA paper no. 

2005-10, 5.

97. NASA-NGC, “SSBE Program Overview,” 3; Haering et al., 

“Airborne SSBD Pressure Measurements,” AIAA paper no. 2005-9, 

14–15.

98. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 8–10.

99. These included the University of Southern California on March 

17; the Society of Experimental Test Pilots (SETP) in San Diego, 

CA, on March 26; the Society of Automotive Engineers in Wichita, 

KS, on April 21; the SETP in Annapolis, MD, on April 22; the 

Confederation of European Aerospace Societies in Manchester, 

England, on May 11; and the Experimental Aircraft Association in 

Oshkosh, WI, in July.

100. Agenda, “Shaped Sonic Boom Experiment Closeout Workshop,” 

Pearl Young Theater, NASA Langley Research Center, Hampton, 

VA, August 17, 2004. As evident in the footnotes, briefings from 

this workshop and the papers published by the AIAA have been 

essential sources for writing this and the three previous chapters.

101. Haering et al., “NASA SSBE Ground Sensors” (August 17, 2004), 

slide nos. 25–56; Plotkin et al., Ground Data Collection of SSBE,” 

AIAA paper no. 2005-10, 1, 5, 8.

102. Plotkin et al., “Ground Data Collection of SSBE,” AIAA paper no. 

2005-10, 5, 8–9; Haering et al., “NASA SSBE Ground Sensors” 

(August 17, 2004), slide nos. 88–89. 
243

Proof at Last

103. John M. Morgenstern, Alan Arslan, Victor Lyman, and Joseph 

Vadyak, “F-5 Shaped Sonic Boom Demonstrator’s Persistence of 

Boom Shaping Reduction Through Turbulence,” AIAA paper no. 

2005-12, 43rd Aerospace Sciences Meeting, Reno, NV, January 

10–13, 2005, 1, 7–9, 14.

104. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 13.

105. Plotkin et al., “Ground Data Collection of SSBE,” AIAA paper 

no. 205-10, 5–10; Haering et al., “NASA SSBE Ground Sensors” 

(August 17, 2004), slide nos. 58–89, with figure 8-7 copied from 

slide no. 88. 

106. Kenneth J. Plotkin, Domenic J. Maglieri, and Brenda M. Sullivan, 

“Measured Effects of Turbulence on the Loudness and Waveforms 

of Conventional and Shaped Minimized Sonic Booms,” AIAA paper 

no. 2005-2949, 26th AIAA Aeroacoustics Conference, Monterey, 

CA, May 23–25, 2005, 5–6. Figure 8-8 copied from Haering et al., 

“NASA SSBE Ground Sensors” (August 17, 2004), slide nos. 76 

and 77.

107. Brenda M. Sullivan, “Sonic Boom Loudness Results for Shaped 

Sonic Boom Experiment,” SSBE Closeout Workshop, August 17, 

2004.

108. Plotkin, Maglieri, and Sullivan, “Measured Effects of Turbulence on 

Loudness,” AIAA paper no. 2005-2949, 7-8.

109. Domenic Maglieri to Lawrence Benson, “Re: SSBD Chapter 8 for 

Review,” e-mail, October 16, 2011.

110. Kenneth J. Plotkin and Roy Martin, “NASA Shaped Sonic Boom 

Experiment: Pushover Focus Maneuver, Final Data Review,” 

PowerPoint presentation, NASA Langley Research Center, 

Hampton, VA, August 17, 2004, with figure 8-9 copied from 

slide no. 6; Kenneth J. Plotkin, Roy Martin, Domenic J. Maglieri, 

Edward A. Haering, and James E. Murray, “Pushover Focus Booms 

from the Shaped Sonic Boom Demonstrator,” AIAA paper no. 

2005-11, 43rd Aerospace Sciences Meeting, Reno, NV, January 

10–13, 2005, 1–3.

111. Plotkin et al., “Pushover Focus Booms from the SSBD,” AIAA paper 

no. 2005-11, 4–14, 4–5 quoted.

112. Ibid.

113. Morgenstern et al, “F-5 SSBD’s Persistence Through Turbulence,” 

AIAA paper no. 2005-12, 10–11.

114. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, figure 8-10 extracted from 16.
244

Quieting the Boom

115. Ibid.; Haering, Draft SSBD Lessons Learned, 1.

116. Haering et al., “Airborne SSBD Pressure Measurements,” AIAA 

paper no. 2005-9, 33 quoted.

117. Haering, Draft SSBD Lessons Learned, 2.

118. Keith Meredith, “SSBE—Flight Test to CFD Comparison,” 

PowerPoint presentation, Langley Research Center, Hampton, VA, 

August 17, 2004, figure 8-11 extracted from slide nos. 14 and 16.

119. Pawlowski et al., “Overview of the SSBD Program,” AIAA paper no. 

2005-5, 13.

120. Meredith, “SSBE—CFD Comparison,” slide no. 9 used for figure 

8-12.

121. “2004 Aircraft Design Award,” Aviation Week (October 4, 2004): 11; 

NASA Turning Goals into Reality 2004 Awards, accessed August 25, 

2011, http://www.aeronautics.nasa.gov/events/tgir/2004/2004_award_

winners.pdf.

122. Valiant Air Command Warbird Museum, Unscramble [bulletin], 

August/September 2004 and July 2006; Museum Gallery, accessed 

October 18, 2011, http://www.vacwarbirds.org/.
.
246

F/A-18B no. 852, used to perfect Low Boom/No Boom flight maneuvers. (NASA)
247

CHAPTER 9

Continuing Research; 

Postponing Development

Exactly 2 weeks after the Federal Aviation Administration held its civil supersonic technical workshop in Arlington, a Concorde airliner flew for the last 

time. It touched down in Bristol, England, on November 26, 2003—3 weeks 

before the 100th anniversary of the Wright brothers’ first flight.1 The Concorde’s 

retirement after more than 30 years of Mach 2 service marked the first time in 

modern history that the trend toward ever-faster modes of transportation had 

gone into reverse. Although the causes of the Concorde’s demise were primarily economic, its inherently loud sonic boom was the main reason it had been 

unable to offer airlines a suitable route structure. Its absence now left the market 

for high-speed travel open solely to smaller and intrinsically quieter supersonic 

business jets for the foreseeable future.

Losing the Momentum for a Low-Boom Demonstrator

After the generally promising studies on the feasibility of a Quiet Supersonic 

Platform and the success of the Shaped Sonic Boom Demonstrator, the stars 

seemed to be aligning in favor of taking the next steps toward developing a 

small supersonic civilian airplane. Various market analyses projected a viable 

market for supersonic business jets, with the most optimistic predicting the 

potential for up to 500 SSBJs over a 20-year period. In a colorful portrayal of 

the aviation industry’s growing interest, a June 2004 article in Fortune magazine stated that companies “are starting to get excited about a new generation 

of hot little jets that would warp the very fabric of space-time while meeting 

noise and environmental regulations.”2

During the next several years, major American and European aircraft manufacturers and a few individual investors pursued assorted SSBJ concepts with 

varying degrees of cooperation, competition, and commitment. Some of these 

and other aviation-related companies also worked together on supersonic strategies through two major consortiums: Europe’s High-Speed Aircraft Industrial 
248

Quieting the Boom

Project (known by its French acronym, HISAC)—comprised of more than 30 

companies such as EADS (parent company of Airbus), Dassault, and Sukhoi as 

well as universities and other organizations; and the Supersonic Cruise Industry 

Alliance (SCIA)—referred to as the Super Ten. The SCIA included airframe 

manufacturers Boeing, Cessna, Gulfstream, Lockheed Martin, Northrop 

Grumman, and Raytheon; engine builders Rolls-Royce, GE, and Pratt & 

Whitney; and the fractional ownership company NetJets. This group’s ambitious goal was supersonic civilian flight within 10 years.3

 To make this possible, 

the SCIA told NASA that its top priority was to solve the issue of sonic boom 

noise over populated areas as soon as possible, something that would almost 

certainly require flight tests with an experimental low-boom aircraft.4

Meanwhile, acoustics specialists at NASA Langley including Kevin Shepherd 

and Brenda Sullivan had resumed an active program of studies and experiments 

on the human response to sonic booms. They upgraded the HSR-era simulator 

booth with an improved computer-controlled playback system, new loudspeakers, and other equipment to more accurately replicate the sound of various boom 

signatures, such as those recorded at Edwards (described later in this chapter). 

In 2005, they also added predicted boom shapes from several low-boom aircraft 

designs.5 At the same time, Gulfstream was creating its own new mobile sonic 

boom simulator to help demonstrate the difference between traditional and 

shaped sonic booms to a wider audience. Although Gulfstream’s folded-horn 

design could not reproduce the extremely low frequencies of Langley’s simulator 

booth (with its rack of large subwoofers), it created a “traveling” pressure wave 

that moved past the listener and resonated with postboom noises, features that 

were judged more realistic than other simulators.6

In September 2003, 2 months before holding its civil supersonics workshop, the FAA had started the Partnership for Air Transportation Noise and 

Emissions Reduction (PARTNER) Center of Excellence along with NASA 

and a number of universities. One of the center’s purposes was to conduct and 

share research into sonic boom acceptability. After having begun the process 

for considering a new American metric on acceptable sonic booms, the FAA 

then helped prompt the International Civil Aviation Organization (ICAO) and 

its Committee for Aviation Environmental Protection to put the issue on its 

agenda in the interest of global consistency. Addressing existing SST-era noise 

restrictions for a new generation of smaller supersonic airplanes would require 

international agreements and probable action by the U.S. Congress. Doing 

this would necessarily be time consuming. Carl Burleson, the director of the 

FAA’s Office of Environment and Energy, warned, “It’s one thing to develop a 

new scientific metric. It’s another to develop a public consensus.”7

In addition to the major aircraft companies, sometimes referred to as original equipment manufacturers (OEMs), two new privately held companies 
249

Continuing Research; Postponing Development

were also making significant progress on SSBJ designs. These were Supersonic 

Aerospace International (SAI), led by J. Michael Paulson, son of Gulfstream 

founder Allen E. Paulson, and Aerion Corporation, led by former Learjet 

President Brian Barents and chaired by its chief benefactor, billionaire investor 

Robert M. Bass. In October 2004, both companies revealed their SSBJ concepts at a conference of the National Business Aviation Association (NBAA).8

 In 2000, just before his death, Allen Paulson bequeathed $25 million to his 

son to form SAI and contract with Lockheed Martin’s Skunk Works to design 

a low-boom SSBJ. The resulting design, refined over the next several years, was 

a 132-foot-long, two-engine, 12-passenger aircraft featuring canards and an 

inverted V-tail capable of flying up to Mach 1.8. SAI called it the Quiet Small 

Supersonic Transport (QSST). Based on extensive CFD and wind tunnel testing, its sonic boom was estimated to be only 1 percent as loud as the Concorde’s.9

Aerion Corporation was formed in 2002. Its 8-to-12-passenger design, 

which the company continued to refine in future years, featured a 136-foot 

fuselage and tapered biconvex wings (similar to those of the F-104 fighter) with 

natural laminar flow. Richard Tracy, the company’s chief technology officer, 

had owned Reno Aeronautical, which worked on the wing’s design as one of 

DARPA’s contractors during the QSP. Not being a low-boom concept, Aerion’s 

SSBJ was optimized for cruising both supersonically at about Mach 1.6 and 

transonically at up to Mach 1.15.10 Because of the Mach cutoff effect, the latter 

option was intended to allow it to fly as fast as possible over land while costing 

less than competing designs.11 Although flying at transonic speeds might be 

permitted under the ICAO’s rule, which prohibits “the creation of a disturbing sonic boom,”12 the FAA’s blanket ban on civilian aircraft flying more than 

Mach 1 would still have to be relaxed to meet this goal.

Despite their progress in sonic boom research and efficient low-boom 

designs, both SAI and Aerion would have to negotiate joint ventures with 

major aircraft corporations before they could begin any serious development 

work. On their part, the OEMs—some of which were pursuing their own 

SSBJ design efforts—continued to await the kind of sonic boom research and 

testing by NASA that would lead to relaxation of the onerous national and 

international noise regulations. They wanted such assurance before making 

the multibillion dollar commitment needed to develop and produce an SSBJ.

In this context of both renewed enthusiasm and continued uncertainty 

within the aviation industry, as well as finite Government funding, NASA’s 

aeronautics organizations hoped to sustain the momentum in developing supersonic technologies fostered by DARPA’s Quiet Supersonic Platform program 

and the SSBD-SSBE. The next step most desired by both the aviation industry 

and NASA proponents was an X-plane, preferably one designed from nose to 

tail for generating sonic booms quiet enough to satisfy the public and thereby 
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help lead to changes in the Federal Aviation Administration’s supersonic rule. 

Despite a reduction in overall aeronautical research, NASA’s FY 2006 budget 

included projects in four areas that focused narrowly on breakthrough technology demonstrations of benefit to the public, including sonic boom mitigation. 

NASA Vehicle Systems Program Manager Richard Wlezien (referring to the 

SSBD) explained the objective as follows: “The F-5 boom was shaped, but not 

mitigated.... The next step is to show [an] acceptable sonic boom.”13

Although it was a relatively modest proposal compared to many NASA 

programs, sustaining funds would not be easy. The Agency’s budget requests 

for aeronautics declined steadily: $959 million for FY 2004, $919 million for 

FY 2005, and $852 million for FY 2006.14 The aeronautics budget request was 

only $593.8 million for FY 2007, but this largely reflected a change in accounting procedures for operations at NASA’s research centers.15 Based perhaps on 

only the raw data, an article in Aviation Week & Space Technology lamented that 

“NASA is attempting to absorb a 40% cut in its aircraft technology development programs without a clear national aeronautics policy to guide it.”16 In 

any case, it was clear that new programs needed to pursue President George 

W. Bush’s goal of establishing a lunar base as a stair step for an eventual piloted 

mission to Mars, in addition to the ongoing demands of the Space Shuttle program and International Space Station, were forcing NASA to make some hard 

choices. Even so, the prospects for pursuing a new sonic boom demonstrator 

continued to move forward during the first half of 2005 with strong backing 

from the Supersonic Cruise Industry Alliance.17

In July 2005, NASA announced the Sonic Boom Mitigation Project. It 

inherited recently awarded contracts of approximately $1 million each for 

5-month concept explorations on the feasibility of either modifying another 

existing aircraft or (more likely) designing a new demonstrator. The participating companies were Boeing Phantom Works, Raytheon Aircraft, Northrop 

Grumman teamed with Gulfstream, and Lockheed Martin teamed with Cessna. 

The best of the concepts would provide the basis for the experimental low-boom 

aircraft that, if successful, could be used for human response surveys. Robert 

E. Meyer, Dryden’s associate director for programs, was named as mitigation 

project manager.18 As summarized by Peter Coen, NASA’s supersonic vehicle 

sector manager, “these studies will determine whether a low sonic boom demonstrator can be built at an affordable cost in a reasonable amount of time.”19

With the support of most of the aerospace industry, the Sonic Boom 

Mitigation Project appeared to be on a fast track. NASA specialists were already 

reviewing the companies’ existing research to help draft an RFP for building the 

demonstrator. Preston “Pres” Henne, a Gulfstream senior vice president who 

had long been a strong SSBJ advocate, expected a selection to be made by early 

2006 and the experimental airplane to be flying before the end of 2008.20 His 
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Continuing Research; Postponing Development

forecast was corroborated by Dryden’s Robert Meyer. “It will probably be an 

X-plane, although we don’t have a designation for it yet.... We’re approaching 

this fairly aggressively. We hope to award the contract to the winning company 

early next year and perform flight tests in 2008.”21

These predictions soon proved to be premature. On August 30, 2005, 

Lisa Porter, NASA’s newly appointed associate administrator for aeronautics, 

informed participants that NASA could no longer fund the new demonstrator. 

After less than 2 months of gestation, the Sonic Boom Mitigation Project was 

terminated while still in its first trimester.22 In retrospect, just as the technological capabilities and business case for an experimental low-boom airplane 

seemed to be reaching a critical mass, its cancellation postponed any chance 

of resolving the ban on civilian supersonic flight for at least another decade. 

Although NASA would explore cheaper alternatives while continuing other 

avenues of sonic boom research, the demise of the mitigation project marked 

a major detour in the quest for quiet supersonic flight.

Despite this setback, there was still one significant boom-lowering experiment in the making. Gulfstream Aerospace Corporation, which had been 

teamed with Northrop-Grumman in one of the stillborn mitigation studies, 

had already patented a new sonic boom mitigation technique.23 Testing this 

invention—a retractable lance-shaped device to extend the effective length of 

an aircraft’s nose section—would be the next major sonic boom flight demonstration at Edwards AFB.

Inventing the Low Boom/No Boom Maneuver

In the meantime, NASA Dryden was doing some relatively modest (i.e., low 

cost) but very innovative sonic boom flight experimentation intended mainly 

to improve low-boom simulation capabilities. In a joint project with the FAA 

and Transport Canada in July 2005, researchers from Pennsylvania State 

University (a key contributor to the PARTNER Center of Excellence’s noisereduction effort) strung an array of advanced microphones at Edwards AFB 

to record sonic booms created by Dryden F/A-18s far above and miles away. 

Eighteen volunteers, who sat on lawn chairs alongside the row of microphones 

during the flyovers to experience the real thing, later gauged the fidelity of 

the recordings. These could then be used to help improve the accuracy of the 

booms replicated in simulators, such as the advanced mobile simulation system 

developed by Gulfstream.24

This experiment (and more to come in future years) was made possible by a 

clever new flight profile, featuring an inverted push-over maneuver, called “Low 

Boom/No Boom.” The initial inspiration for developing this technique was the 
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measurement of a low sonic boom from a sounding rocket returning to Earth at a 

steep angle and low Mach number. NASA Dryden’s Ed Haering used PCBoom4 

to model a flight profile that could emulate this result with an F/A-18 Hornet. In 

essence, the profile applied Frank Walkden’s 1958 theory on how an airplane’s lift 

affects the strength of its sonic boom, which had first been measured by NASA’s 

in-flight probes made above and below a B-58 in 1963 (figure 1-4). This meant 

that the weaker shock waves from an aircraft’s upper surfaces could propagate a 

quieter sonic boom signature when flying upside down.

Jim Smolka, applying his piloting skills, then refined Haering’s modeling into a flyable maneuver in a series of flight tests using NASA F/A-18B 

number 852 equipped with an Ashtech Z-12 differential GPS unit and a 

Research Quick Data System (RQDS) that converted normal air data into 

pulse-code modulated data for transmission to the ground stations. With its 

precise telemetry and an extensive ground array of BASS and BADS pressure 

sensors and microphones, these flight tests were able to determine exactly 

how to create controlled sonic booms. The new technique allowed F/A-18s to 

generate shaped (“low boom”) signatures. It also could produce the evanescent 

sound waves (“no boom”) that remain after the refraction and absorption of 

shock waves generated at low Mach speeds before they reach the surface.25

The basic Low Boom/No Boom technique (depicted later in figure 9-6) 

involves cruising just below Mach 1 at about 50,000 feet, rolling into an 

inverted position, diving at a 53-degree angle, keeping the aircraft’s speed at 

Mach 1.1 during a portion of the dive, and pulling out to recover at about 

32,000 feet. This flight profile took advantage of four attributes that contribute to reduced overpressures: a long propagation distance (the relatively high 

altitude of the dive), the weaker shock waves generated from the upper surfaces 

of an aircraft (by beginning the dive while inverted), low airframe weight and 

volume (the relatively small size of an F/A-18), and a low Mach number. This 

technique allowed Dryden’s F/A-18s, which normally generate overpressures 

of 1.5 psf in level flight, to produce overpressures under 0.1 psf. Using these 

maneuvers, Dryden’s test pilots could place these focused quiet booms precisely 

on specific locations, such as those with observers and sensors. Not only were 

their overpressures low, but they also had a longer rise time than the typical 

N-shaped signature. High-fidelity recordings of these reduced booms would 

be used in the new generation of acoustic simulators.26

Silencing the Bow Shock with Quiet Spike

Quiet Spike was the name that Gulfstream gave to the telescoping nose-boom 

concept, which it began developing in 2001. Based on CFD modeling and 
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Continuing Research; Postponing Development

results from Langley’s 4-foot-by4-foot supersonic wind tunnel 

in 2002, company experts were 

convinced that its patented 

Quiet Spike device could mitigate a sonic boom greatly by creating only mild nose shock from 

its narrow tip followed by weak 

shocks from the cross-section 

transitions between adjacent 

telescoping sections, asymmetrically shaped to propagate less powerful pressure waves in parallel to the 

ground.27 However, the company needed a way to test the structural and 

aerodynamic suitability of the device and also obtain supersonic flight data 

on its shock-scattering abilities.

NASA’s Dryden Flight Research Center had all the capabilities to accomplish these tasks. Under this latest public-private partnership, Gulfstream 

fabricated a telescoping 470-pound nose boom (made of molded graphite 

epoxy over an aluminum frame) to attach to the radar bulkhead of Dryden’s 

frequently modified F-15B number 836. As shown in figure 9-1, a motorized 

cable and pulley system could extend the spike up to 24 feet and retract it 

back to 14 feet. After extensive static testing at Gulfstream’s Savannah, GA, 

facility, Gulfstream and NASA technicians at Dryden attached the specially 

instrumented spike to the radar bulkhead of the F-15B in April 2006 and began 

conducting further ground tests (see photo). Michael Toberman was Dryden’s 

project manager. Key engineers included Dryden’s Leslie Molzahn and Thomas 

Grindle and Gulfstream’s Frank Simmons III, Donald D. Freund, and Robert 

A. “Robbie” Cowart.28

After safety reviews, aerodynamic assessments, and six baseline flights to 

measure the F-15B’s flight data with its standard air-data nose boom, Dryden 

conducted 32 Quiet Spike flight tests from August 10, 2006, to February 

14, 2007.29 After carefully verifying the Quiet Spike’s behavior during several subsonic envelope-expansion flights completed on October 3, veteran 

NASA test pilot Jim Smolka took it to Mach 1.2 on October 20 to begin 

incrementally expanding its supersonic flight envelope up to Mach 1.4 and 

45,000 feet. On December 13, NASA Dryden’s F-15B number 837 began inflight pressure-measurement probes of its spike-equipped counterpart. Aerial 

refueling by AFFTC’s KC-135 Stratotanker—with the Quiet Spike fully 

extended—allowed a longer mission within the R2508 restricted area and 

along an extended high-altitude supersonic corridor in coordination with the 

FAA’s Los Angeles Center. The chase F-15B, flown by Thomas Hill of AFFTC’s 

Figure 9-1. Specifications of Quiet Spike F-15 nose 

extension. (Gulfstream)
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Quieting the Boom

F-15B no. 836 during vibration testing of Gulfstream’s Quiet Spike at the Dryden Flight Research 

Center. (NASA)

F-15B number 836 in flight with Quiet Spike, September 2006. (NASA)
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Continuing Research; Postponing Development

46th Test Group, collected data at distances of 100 feet to 700 feet from the 

Quiet Spike during 31 successful probes at Mach 1.4. On January 19, 2007, 

Smolka finished expanding the Quiet Spike’s supersonic envelope by testing it 

at Mach 1.8. Except during supersonic sideslip maneuvers, the only discrepancy between the F-15B with and without Quiet Spike was reduced directional 

stability at speeds above Mach 1.4. The spike itself proved to be structurally 

sound in all flight conditions, and it even went beyond expectations by being 

extended to its full length while flying supersonically.30

It was known from the outset that the weak shock waves generated by 

the Quiet Spike would rather quickly coalesce with the more powerful shock 

waves generated farther back on the F-15’s unmodified high-boom airframe. 

Therefore, the in-flight probes collected pressure signatures from less than 

1,000 feet away using similar techniques as during the SSBD-SSBE tests. 

Figure 9-2 shows one of these signatures, made from 95 feet directly below 

the Quiet Spike F-15B flying at Mach 1.4, compared with a CFD prediction. 

The flight test confirmed the Quiet 

Spike’s ability to generate a relatively 

weak saw-tooth pattern. Also as anticipated, the powerful fifth shock wave 

(generated from the F-15B’s inlets 

and wings) resulted in a sonic boom 

at ground level similar to that from a 

standard F-15B.31 As Pres Henne put 

it, “Frankly, the F-15, compared to 

what we would have in [our] airplane, 

is a flying brick. It has strong shocks 

coming off of it, and there is no way 

we can stay ahead of that.”32 Analyses, 

however, indicated that by themselves, 

the weak shock waves from the front of 

the aircraft would not have coalesced, and only a muffled sonic boom would 

have been heard from them on the ground. As with the SSBE, the data collected from the Quiet Spike tests would be of continuing value for developing 

and refining CFD capabilities.33

On February 13 and February 14, 2007, with all the major test objectives 

having been accomplished, the Quiet Spike F-15B flew to the former Kelly 

AFB, TX, and then on to Savannah, where Gulfstream and NASA technicians 

restored the aircraft to its normal configuration. A report to the Society of 

Experimental Test Pilots in September, prepared by 10 of the NASA Dryden 

and AFFTC personnel involved in the project as well as Gulfstream’s Cowart, 

concluded, “The Gulfstream and NASA experience working on [this] joint 

Figure 9-2. CFD prediction and in-flight 

pressure measurement with shock waves 

from Quiet Spike nose boom and F-15B 

radome circled. (NASA)
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Quieting the Boom

flight research project was very good. The project took longer than expected, but 

once the flying started, it progressed rapidly and achieved all test objectives.”34

For this successful test of an innovative design concept for a future SSBJ, 

James Smolka and Leslie Molzahn of NASA Dryden and Robbie Cowart, 

Donald Howe, and Frank Simmons of Gulfstream subsequently received 

Aviation Week & Space Technology’s Laureate Award in Aeronautics and 

Propulsion in March 2008. (Just 1 month after celebrating this honor, both 

Gulfstream and Dryden were saddened by the death in an aircraft accident of 

Gerard Schkolnik, Gulfstream’s director of supersonic technology programs 

since 2006, who before that had been a Dryden engineer for 15 years.)35

Focusing on Fundamentals: The Supersonics Project

In January 2006, after several months of internal deliberations, Headquarters 

NASA announced its restructured Aeronautics Research Mission Directorate 

(ARMD) and a new aeronautics strategy. As explained by Lisa Porter, the 

associate administrator for the ARMD, “NASA is returning to long-term 

investments in cutting-edge fundamental research in traditional aeronautical 

disciplines...appropriate to NASA’s unique capabilities.”36 One of ARMD’s 

four new program areas was Fundamental Aeronautics with Rich Wlezien as 

program director. Likewise, Fundamental Aeronautics had four research areas: 

rotary wing, subsonic fixed wing, supersonics, and hypersonics.

In May 2006, NASA released more information on Fundamental 

Aeronautics, including a detailed 5-year plan for what was named the 

Supersonics Project with Peter Coen as its principal investigator. No longer 

calling for any single objective as tangible (or costly) as a low-boom demonstrator, NASA confirmed the benefits of sustaining research into sonic boom 

reduction technology as one of its goals. “[I]t is only through NASA investment in new technologies and improved design methods that the benefits 

of increased cruise speed will become a reality for the general public. These 

benefits include...reduced travel time for business and pleasure, rapid delivery 

of high value cargo including time critical medical items, and rapid response 

of disaster first responders” as well as potential military missions.37

The 60th anniversary, on October 14, 2007, of the XS-1 breaking the sound 

barrier brought renewed attention to the era of supersonic flight, including 

the continued barriers to developing any more civilian aircraft that could do 

the same.38 At the end of the month, NASA convened its first conference on 

Fundamental Aeronautics in New Orleans with more than 400 specialists 

from the aviation industry, universities, and Government agencies attending.39

The session on the Supersonics Project covered numerous challenges requiring 
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Continuing Research; Postponing Development

innovative multidiscipline solutions within the areas of efficiency, performance, 

systems integration, and environmental impact—including the sonic boom. 

Milestones in each area were projected over 5 years. To serve as longer range 

goals on which to focus this research, the Supersonics Project projected capabilities for the next three generations of supersonic civil aircraft. The first was 

an SSBJ (designated N+1) that could carry 6 to 20 passengers 4,000 nautical 

miles at Mach 1.6—Mach 1.8 by 2015. The next generation, projected for 

2020, was a small airliner (N+2) that could carry up to 70 passengers at the 

same speed and range. Furthest in the future, between 2030 and 2035, was an 

efficient multi-Mach aircraft that could carry 100 to 200 passengers 6,000 nm 

at Mach 1.6 with an acceptable boom, and at Mach 2.0 without sonic boom 

restrictions. The acceptable sonic boom metric for all three aircraft was a noise 

that measured less than 70 PLdB.40

In December 2007, the White House released the first National Plan for 

Aeronautics Research and Development. It implemented Executive Order 13419 

of December 20, 2006, and an accompanying National Aeronautics Research 

and Development Policy released with the Executive order. Among various 

future aircraft capabilities, “economically viable aircraft capable of supersonic speeds over land (with an acceptable sonic boom impact) are also 

envisioned.”41 Apparently, however, this was not an explicitly stated objective. In addressing R&D for the near term (less than 5 years), midterm 

(5 to 10 years), and far-term (more than 10 years), the interagency plan 

listed specific goals for improving supersonic cruise efficiency, reducing 

high-altitude emissions, and lowering supersonic jet noise, but as regards 

sonic boom, it called for reductions only “as regards military aircraft.”42

This, however, did not preclude NASA’s Supersonics Project from actively 

continuing research for the eventual design of low-boom civilian aircraft.

One of the Supersonics Project’s major technical challenges was to accurately model the propagation of sonic booms all the way from an aircraft 

to the ground incorporating all relevant physical phenomena and all flight 

conditions. These included realistic atmospheric conditions, especially 

turbulence, during which “the resultant variability in ground signatures is 

profound and important to the quantification of boom impact.”43 Another 

challenging goal was to model the effects of acoustic vibrations on structures 

and the people inside (an issue for which military firing ranges and the use 

of explosives had been the focus of most recent research). Developing these 

models would require continued advances in CFD capabilities, wind tunnel 

improvements, exploitation of existing databases, and additional flight tests.44

The ARMD solicited proposals on meeting the goals of the Fundamental 

Aeronautics Program from both industry and academia.45 Meanwhile, an 

extensive in-house study by experts at the Langley and Ames Centers on the 
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potential of CFD tools (which to date had been mainly developed for aerodynamic efficiency purposes) to make better sonic boom simulations would 

find reasons for optimism. “Given the encouraging nature of the preliminary 

results...it is reasonable to expect the expeditious development of an efficient 

sonic boom prediction methodology that will eventually become compatible 

with a [shaped boom] optimization environment.”46

During this period, NASA’s aeronautics budget continued to contract 

with requested funding dropping from $511.7 million for FY 2008 to 

$446 million for FY 2009. The bulk of this 13-percent reduction was 

for Aerospace Systems, down $26 million, and Fundamental Aeronautics, 

down $34 million.47

Meanwhile, the Fundamental Aeronautics Program actively continued 

to establish collaborative projects with the private sector, academia, and 

other Federal agencies. Many of these were through partnerships established 

in response to NASA Research Announcements (NRAs) under its Research 

Opportunities in Aviation (ROA) program.48 In support of this outreach, 

the ARMD hosted 600 attendees at the second meeting on Fundamental 

Aeronautics in Atlanta from October 7 to October 9, 2008, timed to precede the 61st anniversary of Chuck Yeager’s historic flight. Jaiwon Shin, 

associate administrator for aeronautics since January, emphasized how 

the program was benefiting from innovative precompetitive research with 

approximately 100 industry and academic partners working on 219 studies 

and projects. The meeting included more than a dozen reports on sonic 

boom experimentation and modeling, most of them by experts from the 

Langley and Ames Centers.49

The Supersonics Project’s many activities included continued research on 

ways to assess human responses to sonic booms.50 Based on multiple studies that had long cited the more bothersome effects of booms experienced 

indoors, Langley began in the summer of 2008 to build one of the most 

sophisticated sonic boom simulation systems yet. Completed in 2009, it 

consisted of a carefully constructed 12-foot-by-14-foot room with sound 

and pressure systems that would replicate all the noises and vibrations 

caused by various levels and types of sonic booms.51 Such studies would be 

vital if most concepts for supersonic business jets were ever to be realized.

During the same month as the second Fundamental Aeronautics conference in Atlanta, NASA awarded advanced study contracts for the N+2 

and N+3 quiet supersonic airplane concepts, each worth about $2 million, to teams led by Boeing and Lockheed Martin. It also began working 

with Japan’s Aerospace Exploration Agency (JAXA) on supersonic research, 

including sonic boom modeling.52 Although not yet resurrecting any firm 

plans for a new low-boom supersonic research airplane, NASA supported 
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Continuing Research; Postponing Development

an application to the Air Force by its research partner Gulfstream that 

reserved the designation X-54A for when this might be done in the future.53

Reflecting Gulfstream’s progress toward a low-boom design, the company 

also trademarked “The Whisper” as a name for a future SSBJ. Despite its 

progress on controlling the sonic boom, Gulfstream’s management did 

not believe there would be a business case for proceeding with an SSBJ 

until FAA and ICAO regulations were relaxed. Some of the other aircraft 

manufacturers, as well as Aerion and SAI, continued to work on their SSBJ 

concepts during 2008, but none were yet willing or able to invest the funding necessary to move beyond research and design activities.54

One of the most unusual and challenging concept explorations completed at this time (not part of the Supersonics Project) was a DARPA program, nicknamed Switchblade, to determine the feasibility of a supersonic 

oblique flying wing. Although the potential advantages of such a configuration were primarily military—the ability to loiter at slow speeds but fly 

efficiently at supersonic speeds by changing its angle—an oblique wing 

might also propagate a weaker-than-normal sonic boom carpet, projecting 

its strongest signature off to one side of its flightpath.55 In March 2006, 

DARPA awarded $10.3 million to Northrop Grumman Integrated Systems 

for a Phase 1 preliminary design review, which the company hoped would 

lead to an experimental unpiloted technology demonstrator during Phase 

2.56 Controlling a tailless flying wing, with its engine pods kept pointing 

straight ahead as the rest of the airplane swiveled above, would have been 

one of an oblique flying wing’s most difficult challenges.57 Having to absorb 

cuts to its FY 2009 budget, DARPA decided not to continue Switchblade 

beyond the first phase, which by October 2008 had included more than 

1,000 subsonic and supersonic wind tunnel runs.58

Shortly after the October 2008 Fundamental Aeronautics conference, 

the FAA—citing continued inquiries from the aircraft manufacturers and 

designers—slightly updated its policy on certification standards for supersonic aircraft noise. Although still putting off any changes to the supersonic 

prohibition pending future research and public participation, the FAA clarified that future supersonic aircraft flying at subsonic speeds would have to 

meet the same noise restrictions (Stage 4) as subsonic aircraft.59

Unfortunately for the near-term prospects of civilian supersonic flight, 

the autumn of 2008 also brought the near collapse of the American financial system, leading into a global recession followed by years of economic 

and fiscal problems in the United States and Europe. These developments 

negatively affected many industries not the least being air carriers and 

aircraft manufacturers. The impact on those recently thriving companies 

making business jets was aggravated by a populist and political backlash at 
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Quieting the Boom

American corporate executives, some of them subsidized temporarily by the 

Federal Government, for their continued use of company jets. Lamenting 

this unsought negative publicity, Aviation Week & Space Technology examined the plight of the small-jet manufacturers in a story with this descriptive 

subheading: “As if the economy were not enough, business aviation becomes 

a scapegoat for executive excess.”60 Ironically, one early consequence of the 

recession was $150 million in stimulus funding added to NASA’s FY 2009 

aeronautics budget as an element in the Obama administration’s American 

Recovery and Reinvestment Act.61

NASA’s Fundamental Aeronautics Program kept its primary focus on the 

more distant future. Almost 600 people attended its third conference, held 

again in Atlanta from September 29 to October 1, 2009. The Supersonics 

Project had by now awarded more than $43 million in contracts to 68 commercial and educational partners for a wide variety of research projects. In the 

next year, the Supersonics Project planned to focus on several areas: designing 

simultaneously for both low boom and low drag; doing more flight testing and 

modeling of boom impacts on structures and people, especially for developing 

modeling capabilities; working with the FAA, ICAO, and other organizations on a roadmap for sonic boom acceptability; and continuing to explore 

approaches for large-scale sonic boom testing.62

As regards the latter possibility, Boeing—under a Supersonics Project contract—studied low-boom modifications for one of NASA’s F-16XL aircraft 

(being kept in storage at Dryden) as a possible way to obtain a reduced-boom 

demonstrator. This relatively low-cost idea had been one of the options being 

considered during NASA’s short-lived Sonic Boom Mitigation Project in 2005. 

In the case of the F-16XL, the modifications proposed by Boeing included an 

extended nose glove (reminiscent of the SSBD), lateral chines that blend into 

the wings (as with the SR-71), a sharpened V-shaped front canopy (like those of 

the F-106 and SR-71), an expanded nozzle for its jet engine (similar to those of 

F-15B number 837 described below), and a dorsal extension (called a “stinger”) 

to lengthen the rear of the airplane. Although such add-ons would not offer 

the low-drag characteristics also desired in a demonstrator, Boeing felt that its 

“initial design studies have been encouraging 

with respect to shock mitigation of the forebody, canopy, inlet, wing leading edge, and 

aft lift/volume distribution features.”63

Additional design work refined this 

concept with more extensive modifications, including a large horizontal stabilizer 

(shown in figure 9-3) to achieve the desired 

results.64 The study did much to advance the 

Figure 9-3. Proposed low-boom 

modifications to an F-16XL. (NASA)
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Continuing Research; Postponing Development

F-15B number 836 flying with F-15B number 837 in January 2009. (NASA)

application of CFD and geometry shape optimization for a low-boom design, 

which in this case was achieved at a slightly higher undertrack noise level than 

desired. NASA deemed the extent of the required modifications (of which the 

H-tail was one option) to be too complex, expensive, and taxing on the flight 

control system of the F-16XL to pursue beyond the initial study.65

Measuring Tail Shocks: The LaNCETS Tests

Meanwhile, NASA already had another unique aircraft available to perform an 

innovative sonic boom experiment under the aegis of the Supersonics Project. 

NASA Dryden named this experiment the Lift and Nozzle Change Effects 

on Tail Shocks (LaNCETS). Both the SSBD and Quiet Spike experiments 

had involved only the shock waves generated from the front of an aircraft. Yet 

those from the rear of an aircraft as well as its jet-engine exhaust plumes also 

contribute to sonic booms—especially the strong recompression spike of the 

typical N-wave signature. These rear shocks had long been more difficult to 

analyze and control than those from the front of an aircraft. NASA initiated 

the LaNCETS experiment to address this issue.66
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NASA Dryden had just the airplane with which to do this: the F-15B 

number 837. Originally built in 1973 as the Air Force’s first preproduction 

TF-15A two-seat trainer (soon redesignated F-15B), it had been extensively 

modified for various experiments over its long lifespan. These included the Short 

Takeoff and Landing (STOL) Maneuvering Technology Demonstration, the 

High-Stability Engine Control project, the Advanced Control for Integrated 

Vehicles Experiment (ACTIVE), and the Intelligent Flight Control Systems 

(IFCS). This unique F-15 Eagle had the following special features: digital flyby-wire controls, canards on the forebody (that could be used for adjusting 

longitudinal lift distribution), and thrust-vectoring variable area-ratio nozzles 

on its twin jet engines to change the pitch and yaw of the exhaust flow (that 

could also be used to constrict and expand plumes).67 Researchers planned to 

use these capabilities for validating computational tools developed at Langley, 

Ames, and Dryden to predict the interactions between shocks from the tail 

and exhaust under various lift and plume conditions.

Tim Moes, one of the Supersonics Project’s associate managers, was the 

LaNCETS project manager at Dryden. Jim Smolka, who had flown most of 

F-15B number 837’s previous missions at Dryden, was its test pilot. He and Nils 

Larson in F-15B number 836 conducted Phase 1 of the test program with three 

missions from June 17 to June 19, 2008. They gathered high-quality baseline 

measurements with 29 probes, all at 

40,000 feet and speeds of Mach 1.2, 

1.4, and 1.6.68 Figure 9-4 shows the 

shock wave pattern measured by one 

of these probes in relation to the tested 

F-15’s modified airframe.69

Phase 2 of the project began on 

November 24, 2008. The LaNCETS 

team flew nine flight tests by 

December 11 before being interrupted 

by a freak snowstorm during the third 

week of December and then having 

to break for the holiday season.70 The 

LaNCETS team completed the project with flight tests on January 12, 15, and 30, 2009. In all, Jim Smolka and 

flight engineer Mike Thomson flew a total of 13 missions in F-15B number 

837, 11 of which included in-flight shock wave measurements by number 836 

at distances of 100 feet to 500 feet. Nils Larson piloted the probing flights 

with Jason Cudnik or Carrie Rhoades in the back seat. The aircrews tested the 

effects of positive and negative canard trim at Mach 1.2, Mach 1.4, and Mach 

1.6 as well as thrust vectoring at Mach 1.2 and Mach 1.4. They also gathered 

Figure 9-4. Shock wave signature of the 

highly modified F-15B number 837. (NASA)
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Continuing Research; Postponing Development

Test pilot James Smolka, flight engineers Mike Thomson and Jason Cudnik, and test pilot Nils 

Larson in front of F-15Bs used for LaNCETS project. (NASA)

supersonic data on plume effects with different nozzle areas and exit-pressure 

ratios. Once again, Dryden’s sophisticated GPS equipment recorded the exact 

locations of the two aircraft for each of the datasets.71 On January 30, 2009, 

with Jim Smolka at the controls one more time, number 837 made its 251st 

NASA flight, the last before a well-earned retirement among the other historic 

aircraft on display at Dryden.72

In addition to its own researchers at the Langley, Ames, and Dryden Centers, 

NASA also made the large amount of data collected available to industry and 

academia as part of the Supersonics Project. For the first time, analysts and 

engineers would be able to use actual flight-test results to validate and improve 

CFD models on tail shocks and exhaust plumes—taking another important 

step toward the design of a truly low-boom supersonic airplane.73

Simulated, Softened, and Super Booms

Although the LaNCETS project was the most prominent of NASA’s sonic 

boom tests during the last several years of the 21st century’s first decade, Dryden 

continued adapting its Low Boom/No Boom aerial technique for testing the 

effects of reduced booms on people and buildings as well as for gathering data 

and sound recordings that could be used with sonic boom simulators. In June 

2006, researchers installed 288 various accelerometers and microphones all over 
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Quieting the Boom

Figure 9-5. Some of the sensors in one room of the 

house used for sonic boom testing at Edwards AFB 

in 2006. (NASA)

and around a ranch-style house 

built at Edwards AFB in about 

1960 and slated for demolition. 

As indicated by figure 9-5, the 

instrumentation installed inside 

the house was very extensive (as 

was that outdoors). During 6 

days between June 13 and June 

22, Dryden F/A-18Bs conducted 

19 flight tests (with two aircraft 

flying on each mission) to produce a total of 98 low-amplitude (0.05 psf to 0.8 psf) and 14 louder (0.84 psf to 

1.8 psf) sonic booms. The flights resulted in the collection of a vast amount of 

detailed structural data as well as recordings for sonic boom simulations.74 The 

researchers also recruited 77 volunteer listeners (divided into groups of about 

20 per day) for a human-response survey. With two F/A-18s in the air at once, 

they were able to deliver a sonic boom every 3 minutes to help the volunteers 

compare one to another. By contrast to similar surveys in the past, immediately 

after listening to the sonic booms, the volunteers tended to give comparable 

annoyance ratings whether they were seated in the living room or outdoors in 

the backyard. When filling out questionnaires at the end of each day’s tests, 

however, 63 percent of the volunteers concluded that the booms experienced 

inside the house, which was in rather poor repair, were more annoying.75

NASA and other participating researchers learned how sonic booms of 

varying intensity affected a more substantial home in a similar experiment, 

during July 2007, given the nickname House Variable Intensity Boom Effect 

on Structures (House VIBES). Acoustics specialists from Langley installed 112 

sensors (again, a mix of accelerometers and microphones) inside the unoccupied half of a modern (late 1990s) duplex house. Other sensors were placed 

on and around the house and up a nearby 35-foot tower. These measured 

pressures and vibrations from 12 normal-intensity N-shaped booms (up to 

2.2 psf) created by F/A-18s in steady and level flight at Mach 1.25 and 32,000 

feet as well as 31 shaped booms (registering 0.08 psf to 0.7 psf) from F/A-18s 

using the Low Boom/No Boom flight profile (illustrated in figure 9-6 with a 

photograph showing one of their contrails).76

The quieter booms were similar to those that would be expected from 

an acceptable supersonic business jet. The specially instrumented F/A-18B 

number 852, with the RQDS air-data transmission system, performed six of 

the flights and an F/A-18A made one. As during the SSBE, an instrumented 

L-23 sailplane from the Air Force Test Pilot School recorded shock waves at precise locations in the path of the focused booms above the surface boundary layer 
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Continuing Research; Postponing Development

to account for atmospheric 

effects. The data from the 

indoor sensors confirmed 

considerably lower vibrations and noise levels in the 

modern house than had been 

the case with the older house. 

At the same time, data gathered by the outdoor sensors 

added significantly to NASA’s 

variable-intensity sonic boom 

database. This would help to 

program and validate sonic boom propagation codes for years to come, including more advanced three-dimensional versions of PCBoom.77

In 2009, NASA Dryden began a series of analogous tests in an experiment 

called Sonic Booms on Big Structures (SonicBOBS), the purpose of which 

was clearly indicated by its name. Sponsored by NASA’s Supersonics Project, 

participants included Gulfstream Aerospace, Penn State University, and the 

Air Force Flight Test Center. The first phase, conducted on June 11, consisted 

of flights to calibrate a variety of sensors installed in and around the Air Force 

Flight Test Museum, which offered a large volume of interior space. As in previous testing, two F/A-18s flew both straight and level flights and looping Low 

Boom/No Boom profiles to create nine normal and nine quiet sonic booms.78

These profiles were repeated with similar flights on September 9 and September 

12 for Phase I of SonicBOBS. NASA Dryden, NASA Langley, and Gulfstream 

provided a variety of sensors, including special microphones placed inside mannequin heads to better mimic what a person would hear. As a follow-on to House 

VIBES, the first day’s experiment gathered data from an unoccupied residence 

in the base housing area. The second day focused on measurements at the Base 

Consolidated Support Facility, the Environmental Services office, and the Flight 

Test Museum.79 Dryden later made the data recorded by its microphones and 

pressure sensors available to other researchers on a DVD. (This database also 

included a coincidental recording of the sonic boom from Discovery on its 

approach to Edwards AFB for the 48th and last Space Shuttle landing there.)80

Of special significance during the flight tests on September 9, the differences 

between normal and quiet sonic booms were experienced by a large delegation 

from the ICAO’s Committee on Aviation Environmental Protection, including 

its Aircraft Noise Working Group and Supersonic Task Group. Peter Coen, who 

was there for the tests, thought “the visit was immensely successful.... From the 

perspective of sonic boom research and the prospect of potentially establishing a 

noise-based rule for supersonic overland flight, the visit was a major milestone.”81

Figure 9-6. Flight profile used to deliver reduced sonic 

booms. (NASA)
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Quieting the Boom

The Center resumed Sonic BOBS testing on October 14 and October 16, 

2010, with the first day’s flights being conducted on the 63rd anniversary of 

the XS-1 breaking the sound barrier. This time, the sensors were installed only 

in and near the base’s consolidated support building. Although analysis of the 

data would require some time, what was being learned from the all these tests 

and other research led Peter Coen to observe, “I’m more convinced our big 

issue will be disturbances in large structures rather than houses.”82

NASA Dryden continued to perform a variety of tests and experiments 

related to sonic booms into the century’s second decade. In January 2011, 

the Center was involved in an unusual sonic boom research project: the Sonic 

Boom Resistant Earthquake Warning System (SonicBREWS). In anticipation 

of the installation of advanced seismic monitors called QuakeGuard, made by 

Seismic Warning Systems, Inc., in the Lancaster-Palmdale area, NASA Dryden 

installed some of the monitors in its main office building. This would help 

determine whether or not these ultrasensitive monitors would be able to filter 

out vibrations from the frequent sonic booms produced at Edwards AFB.83

The technology for in-flight measurements of shock waves also continued 

to advance. In February 2011, for example, NASA Dryden began flight testing 

two sophisticated prototype probe devices attached to the centerline pylon of an 

F-15B. Designed by Eagle Aeronautics and built by Triumph Aerospace Systems 

as part of the NASA Supersonics Project, one of the probes was conical for 

mounting on the nose of the trailing aircraft and the other was wedge-shaped for 

mounting on the generating aircraft. Combined with high-response transducers 

that could nearly instantaneously measure shock waves from the probed aircraft, 

the new devices could also monitor flight conditions such as Mach number, angle 

of attack, sideslip angle, temperature, and pressure without the lag time and other 

discrepancies encountered during existing probing missions.84

In a twist from the low-boom testing of recent years, in May 2011, Dryden 

began a major new flight test that could create louder than normal booms. 

Sponsored by the Supersonics Project, it was named the Superboom Caustic 

Analysis and Measurement Program (SCAMP). Its main purpose was to examine 

the critical transition from subsonic to supersonic speeds, which could create a 

focused boom two to five times louder than when cruising. A recently completed 

study of maneuver effects on a generic low-boom SSBJ using the latest computational and modeling techniques “found that the focus boom can be minimized by 

initiating transition and higher altitude and increasing climb angle. Acceleration 

rates have been found to have little influence.”85 More still needed to be learned 

about how to predict focused boom signatures and their locations and then 

design ways that quiet supersonic aircraft of the future could avoid them.

The SCAMP testing provided empirical data on this phenomenon. 

Researchers strung out an array of 81 microphones to record 70 localized sonic 
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Continuing Research; Postponing Development

booms from 13 flights by an accelerating F/A-18B flown by Nils Larsen in the 

remote Black Mountain supersonic corridor north of Boron. As in other recent 

flight tests at Edwards, additional measurements were made above the ground—

this time by a motorized glider flying at 4,000 feet to 10,000 feet and a 35-foot 

blimp tethered at 3,500 feet. The project involved a large team that included 

members from NASA Langley, Wyle Labs, Eagle, Boeing, Northrop Grumman, 

Gulfstream, Cessna, Penn State, Central Washington University, MetroLaser 

Inc., and Seismic Warning Systems. In some ways, the SCAMP was reminiscent of the SSBD and SSBE projects—and it certainly benefited from lessons 

learned then. According to Thomas Jones, Dryden’s SCAMP manager, “It was 

operationally complex, given the number of team members, and logistically 

complicated, given the remote location of the microphone array, the unpaved 

roads leading to the site, and the communications between all the players, assets, 

and the control room at Dryden.... However, given the challenges, the SCAMP 

team worked together to gather one of the most interesting sets of supersonic 

flight research data...in some time.”86 Future analysis of this data could assist 

in the development of CFD codes for helping develop flight profiles and refine 

low-boom aircraft designs for mitigating transition focused booms.87

It was clear that, even without any immediate prospects for development of 

a new low-boom test bed, NASA’s Supersonics Project was sustaining research 

on the acceptability of sonic booms. For example, in the fall of 2011, Dryden 

hosted a project dubbed Waveforms and Sonic Boom Perception and Response 

(WSPR) in conjunction with Langley, Wyle Labs, Gulfstream, Penn State, 

Fidell Associates, and Tetra Tech. Dryden’s Larry Cliatt was the principal investigator. The WSPR project’s primary purpose was developing data-collection 

methods and test protocols for future public perception studies in other communities where (unlike at Edwards) the residents were not used to hearing 

sonic booms. With data being recorded by 13 sensors in the base housing area, 

Dryden’s F/A-18s flew 22 specified profiles from November 4 to November 18, 

generating 82 reduced and 5 normal sonic booms ranging from 0.08 psf up 

to 1.4 psf. Using a standard questionnaire, more than 100 volunteer residents 

reported their responses upon hearing these sonic booms on paper forms, at 

a Web site, or from smartphones using a special “app” supplied by Dryden.88

Keeping Focused on the Future

Although the manufacturers of large passenger aircraft were doing well in the 

first years of the 21st century’s second decade, the business jet market remained 

mired in economic doldrums.89 Even so, some companies still had supersonic 

aspirations, albeit at a very slow pace. The HISAC alliance in Europe was no 
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Quieting the Boom

longer active, but a few of its original members such as Sukhoi and Dassault 

continued some research on potential designs and discussions on joint developmental arrangements.90 The Japan Aerospace Exploration Agency, a collaborator with NASA in sonic boom acceptability research, was also working 

on its own supersonic transport concept and an unpiloted sonic boom demonstrator.91 In the United States, Gulfstream remained one of NASA’s most 

active partners in the Supersonics Project while keeping its SSBJ design on the 

drawing board. As explained by Gulfstream’s president, Joe Lombardo, “We 

believe we have the technology to limit the boom to a non-discernable level, 

but you will still have to change regulations that prohibit supersonic flight over 

land.”92 Boeing, although it had no announced plans for an SSBJ, continued 

to be interested in technology breakthroughs that might pave the way for a 

future SST.93 Aerion, with its SSBJ designed for transonic cruise over land, was 

continuing research and seeking a manufacturing partner, but the company 

also began promoting its expertise in subsonic laminar flow technology.94

NASA held its fourth Fundamental Aeronautics meeting in Cleveland from 

March 15 to March 17, 2011.95 Over the past 5 years, the Supersonics Project 

had supported a wide range of analysis capabilities and technologies. In addition 

to sonic boom research, these included advances in the following areas: aerodynamic design tools for more efficient supersonic cruise, powerful yet fuel-efficient 

engine technologies that addressed high-altitude emissions while making less 

noise around airports, advanced lightweight materials for innovative airframe 

construction, improved multidiscipline system-level design techniques, and (if 

the sonic boom issue could be solved) the integration of future supersonic airplanes into the FAA’s next-generation (NextGen) air traffic control system.96 As 

regards findings about how to achieve a truly quiet sonic boom signature, Peter 

Coen disclosed one preliminary result when interviewed for an article published 

the same month as the conference. “We’re coming to the conclusion that the 

best thing to do is really try not to get that completely smooth pressure rise on 

the back end, but break the shock on the back end into several pieces so you can 

get the attenuation without the coalescing.”97 NASA and its Supersonics Project 

partners were also making significant progress in designing high-speed propulsion systems for both lower boom and quieter engines.98

As mentioned above, the Supersonics Project’s sonic boom research had been 

a beneficiary of the portion of supplemental FY 2009 funds from the American 

Recovery and Reinvestment Act that went to Fundamental Aeronautics. These 

funds helped support sonic boom design validations by teams led by Boeing 

and Lockheed Martin, additional wind tunnel testing, focused boom research, 

and a new community-response pilot project. A number of previous projects recently had been completed, including the N+2 system-level study for a 

small supersonic airliner by 2020–2025. Boeing, in partnership with Pratt & 
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Continuing Research; Postponing Development

Figure 9-7. Some of the concepts for the Supersonics Project’s N+1 SSBJ, N+2 small supersonic airliner, and N+3 supersonic transport. (NASA)

Whitney, Rolls-Royce, and Georgia Tech, had come up with two promising 

if still-conceptual configurations: a 100-passenger design optimized for cruise 

efficiency and a more extensively studied 30-passenger design optimized for a 

quieter sonic boom (65 PLdB to 70 PLdB).99

The system-level studies by Boeing and Lockheed Martin for the N+3 supersonic transport were perhaps the most futuristic of all the research sponsored 

by the Supersonics Project. By the targeted timeframe of 2030 to 2035 (three 

decades after the retirement of the Concorde), the companies thought both the 

necessary technologies and the air travel market could be ready for a new and 

economically supportable SST. Building upon their work during the QSP program and progress since then, both companies came up with interesting Mach 

1.8 design concepts featuring long streamlined airframes with special sonic boom 

shaping, advanced materials, laminar flow, variable-cycle engines, and bleedless 

inlets. Boeing designed its more conventional configuration to carry 120 passengers. It included small canards, swept wings in the rear, a large upright V-tail, 

and two top-mounted engines.100 Lockheed Martin’s concept for carrying 100 

passengers had larger canards and an inverted V-tail joined to swept wings, with 

four engines mounted below.101 Although the shaped sonic booms from both 

were predicted to be at least 30 dB quieter than those from the similarly sized 

Concorde, neither would be as quiet as called for in NASA’s N+3 goals.102

Size still mattered when it came to sonic boom signatures, but by 2012, 

continuing advances in CFD began showing great promise for designing N+2-

size supersonic airliners able to carry 30 to 80 passengers while generating a 

sonic boom level of only 70 PLdB.103 A briefing by the Supersonics Program 

manager highlighted this achievement as follows:

Breakthrough Knowledge Advancement: Methodologies for the 

development of aircraft with shaped sonic boom signatures, particularly in the aft end of the vehicle where complex interaction 

between lift and volume effects takes place, have been applied to 

integrated systems level designs and validated through wind tunnel 

testing. Low boom targets for N+2 configurations have been met; 

methods are applicable to N+1 and N+3 vehicles as well.104
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Although not yet budgeted, NASA had begun planning to have a low-boom 

experimental vehicle (LBEV) that would be available for flight testing by the 

end of FY 2018.105 The successful wind tunnel validations of the latest design 

concepts increased interest in moving ahead with this aircraft, which, as mentioned previously, would be designated the X-54.106 A study by the National 

Research Council that was completed in early 2012 strongly recommended 

that NASA resume focusing much of its diminished aeronautics budget on the 

development of X-planes, such as the sonic boom demonstrator.107 Meanwhile, 

no matter how many advances some of the Nation’s best aeronautical engineers 

were making on designing supersonic aircraft with quieter booms, the most 

immediate issues remained public acceptance and related national and international aviation regulations.

Here too, there had been some signs of progress, if still very tentative. 

The Federal Aviation Administration, with the support of NASA and other 

members of the Partnership for Air Transportation Noise and Emissions 

Reduction, held its first formal public forum on supersonic noise restrictions 

on October 24, 2008, in Chicago during a symposium on aircraft noise at 

O’Hare International Airport. Subsequently, the FAA held “Public Meetings 

on Advanced Technologies and Supersonics” in each of the next 3 years: on 

March 1, 2009, in Palm Springs, CA, along with an annual University of 

California symposium on aviation noise and air quality issues; on April 21, 

2010, as part of an Acoustical Society of America conference in Baltimore; 

and on July 14, 2011, at DOT headquarters in Washington, DC.108 These 

meetings, attended by professionals and anyone else who was interested in the 

issues, included presentations by experts from NASA, Penn State (representing the PARTNER Center), and four prospective supersonic manufacturers: 

Gulfstream, Aerion, Lockheed Martin, and Boeing. In addition to briefings 

on the recent progress in sonic boom research and discussions on the need for 

quality data with reliable evidence of acceptable sonic boom mitigation levels 

to justify amending the rules to allow the development of any future supersonic aircraft, the meetings featured realistic demonstrations of various types 

and amplitudes of sonic booms in Gulfstream’s latest mobile audio booth, the 

Supersonic Acoustics Signature Simulator II (SASSII).109

At the meeting in July 2011, Lourdes Maurice of the FAA emphasized how 

the FAA, NASA, and the ICAO had initiated the development of a roadmap 

for researching public response to sonic booms. Her presentation defined key 

steps needed to assure a firm technical basis and noise standards for determining sonic boom acceptability.110 Aerion and Gulfstream representatives gave 

details on their progress in researching and designing a quiet SSBJ, much of 

it in partnership with NASA, with the sonic boom “whisper” expected from 

Gulfstream’s design demonstrated in the SASSII parked outside.111 The NASA 
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Continuing Research; Postponing Development

presentation on advancements being 

made in sonic boom research showed 

how recent designs could exponentially 

lower the perceived sound of sonic 

booms (figure 9-8), hopefully making 

them acceptable to the public.112

Until a truly low-boom experimental airplane became available to give 

live demonstrations of the progress 

that designers had been making for 

the past decade, gaining this acceptance from the public would be difficult. 

In a recent article, Peter Coen summed up the impasse. “It’s a real challenge 

for us moving forward to clearly identify and explain to the public that the 

sonic boom we’re talking about now is completely different from what has 

ever been heard in the past.”113

An environment of anemic economic activity and unstable financial markets continued to threaten much of the aerospace industry, including the business jet sector.114 And with the Federal Government facing a looming fiscal 

crisis in a period of political deadlock in Washington, NASA’s future budgets remained under threat.115 Nevertheless, understandably cautious aircraft 

companies and a financially constrained NASA kept pressing on toward the 

ultimate goal of supersonic civilian flight. It was clear that the more than six 

decades of discoveries about sonic booms and the lessons learned on how to 

control them had begun to pay real dividends. Meanwhile, supersonic specialists in NASA and the private sector remained patiently committed to finding a 

way to follow up on Northrop Grumman’s Shaped Sonic Boom Demonstrator 

with an airplane that could demonstrate the quietness of a carefully shaped 

and mitigated sonic boom.

Figure 9-8. Effects of sonic boom shaping 

and pressure rise on sound levels. (NASA)

As documented by this book, past expectations for a civilian supersonic airplane with an acceptable sonic boom to fly over populated areas have repeatedly run up against scientific, technical, economic, and political hurdles too 

high to overcome. That is why such an airplane has yet to fly almost three 

quarters of a century into the jet age. Yet the knowledge gained and lessons 

learned from each attempt attest to the value of persistence in pursuing both 

basic and applied research. Recent progress in controlling sonic booms builds 

upon the meticulous research, careful testing, and inventive experimentation 

by NASA and its partners in Government, industry, and academia over more 
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Quieting the Boom

The F-5 Shaped Sonic Boom Demonstrator on display at the Valiant Air Command Museum in 

Titusville, FL. (Photo courtesy of the museum)

than six decades; the data and documentation preserved through NASA’s scientific and technical information program; and the special facilities and test 

resources maintained and operated by NASA’s research Centers. This book 

has emphasized one of the most important milestones on this long journey: 

Northrop Grumman’s F-5 Shaped Sonic Boom Demonstrator. The success 

of the DARPA-sponsored Shaped Sonic Boom Demonstration and NASA’s 

follow-on Shaped Sonic Boom Experiment exemplifies how a truly cooperative effort among Government agencies, private corporations, and academic 

institutions can produce noteworthy results in a short time at a reasonable cost.

Since the dawn of civilization, conquering the twin tyrannies of time and 

distance has been a powerful human aspiration, one that served as a catalyst for 

many technological innovations. It seems reasonable to assume that this need for 

speed may eventually break down the barriers in the way of practical supersonic 

transportation to include solving the problem of the sonic boom. If that time 

finally does come, a worn out former fighter plane, with the front of its fuselage 

modified to resemble a long pelican’s beak, will have helped lead the way.
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Continuing Research; Postponing Development

Endnotes

1. For a compendium of articles, photos, and videos in commemoration of the Concorde’s last flights, see the British Broadcasting 

Corporation’s (BBC’s) “In Depth Farewell to Concorde,” last 

updated August 15, 2007, accessed September 21, 2011, http://news.

bbc.co.uk/1/hi/in_depth/uk/2003/concorde_retirement/default.stm.

2. Stuart F. Brown and Edward H. Phillips, “Mine’s Faster than 

Yours,” Fortune (June 28, 2004), accessed ca. September 

1, 2011, http://money.cnn.com/magazines/fortune/fortune_

archive/2004/06/28/374394/index.htm. For other examples, see 

Graham Warwick, “Quiet Progress: Aircraft Designers Believe 

They Can Take the Loud Boom Out of Supersonic Travel,” Flight 

International (October 20, 2004): 32–33; Edward H. Phillips, 

“Boom Could Doom: Debate Over Hybrid SSBJ Versus Pure 

Supersonic is Heating Up,” Aviation Week (June 13, 2005): 84–85; 

Francis Fiorino, “Lowering the Boom,” Aviation Week (November 

7, 2005): 72; “Supersonic Private Jets in Development,” Business 

Travel News Online (October 26, 2006); John Wiley, “The SuperSlow Emergence of Supersonic,” Business and Commercial Aviation 

(September 1, 2007): 48–50; Edward H. Phillips, “Shock Wave: 

Flying Faster Than Sound is The Holy Grail of Business Aviation,” 

Aviation Week (October 8, 2007): 50–51.

3. Mark Huber, “Mach 1 for Millionaires,” Air & Space Magazine

(March–April 2006), accessed February 20, 2009, http://www. 

airspacemag.com/flight-today/millionaire.html.

4. David Collogan, “Manufacturers, NASA Working on Bizjet Sonic 

Boom Project,” The Weekly of Business Aviation, July 18, 2005, 21.

5. Brenda M. Sullivan, “Research on Subjective Response to Simulated 

Sonic Booms at NASA Langley Research Center,” paper presented 

at International Sonic Boom Forum, State College, PA, July 21–22, 

2005.

6. Brenda M. Sullivan, Patricia Davis, Kathleen Hodgdon, Joseph A. 

Salamone, and Anthony Pilon, “Realism Assessment of Sonic Boom 

Simulators,” CASI document no. 200800022677, January 2008.

7. Graham Warwick, “Quiet Progress: Aircraft Designers Believe 

They Can Take the Loud Boom Out...but Can They Convince 

Regulators?” Flight International (October 12, 2004): 32; Frances 

Fiorino, “Lowering the ‘Boom’,” Aviation Week (November 7, 

2005): 72.
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Quieting the Boom

8. “Fast Money: Concepts Unveiled at...NBAA,” Flight International

(October 19, 2004): 3; David Collogan, “Two Groups Vie To 

Develop Supersonic Business Jets,” Aviation Week (October 18, 

2004), accessed November 18, 2008, http://www.aviationweek.

com/aw/generic/story_generic.jsp?channel=businessweekly&id=news/

SUPER10184.xml.

9. Eric Hagerman, “All Sonic, No Boom,” Popular Science (March 

2007), accessed July 8, 2011, http://www.popsci.com/militaryaviation-space/article/2007-03/all-sonic-no-boom; Huber, “Mach 1 for 

Millionaires”; Supersonic Business Jet (Web site), “Quiet Supersonic 

Transport (QSST),” accessed October 10, 2011, http://www. 

supersonic-business-jet.com/prototypes/quiet_supersonic_transport.php. 

SAI’s own Web site apparently went offline before mid-2011. 

10. Edward H. Phillips, “Revised Design: Aerion Aims for 

Improvements in Aerodynamics and Cabin Comfort,” Aviation Week

(November 7, 2005): 70; Huber, “Mach 1 for Millionaires”; “Aerion 

Refines Business Case for Supersonic Jet,” Flight International

(August 1, 2006): 19; Aerion Corporation, accessed October 22, 

2011, http://aerioncorp.com/; Supersonic Business Jet (Web site), 

“Aerion SBJ,” accessed October 22, 2011, http://www.supersonicbusiness-jet.com/prototypes/quiet_supersonic_transport.php.

11. See Kenneth J. Plotkin, Jason R. Matisheck, and Richard R. 

Tracy, “Sonic Boom Cutoff Across the United States,” AIAA paper 

no. 2008-3033, 14th AIAA/CEAS Aeroacoustics Conference, 

Vancouver, B.C., May 5–7, 2008.

12. Peter Coen to Lawrence Benson, “Re: Chapter 9 of SSBD Book,” 

e-mail, November 8, 2011.

13. Jefferson Morris, “NASA Budget Boosts Space Exploration, 

Cuts Aeronautics,” Aviation Week (February 8, 2005), accessed 

ca. October 15, 2011, http://www.aviationweek.com/aw =news/

NASABUDGET02085.xml (site discontinued); Graham Warwick, 

“NASA Narrows R&D Agenda,” Flight International (February 15, 

2005): 28.

14. NASA Budget Request Summaries, FYs 2004–2007, accessed 

October 25, 2011, http://www.nasa.gov/news/budget/index.html. 

Congressional appropriations usually added funding to these 

requests.

15. Coen to Benson, November 8, 2011.

16. Frank Morring, “Rudderless: NASA Aeronautics Chief Hopes 

New Administrator Will Push for Clear Policy To Guide Facility 

Closings,” Aviation Week (March 7, 2005): 38.
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Continuing Research; Postponing Development

17. Collogan, “Manufacturers, NASA Working on Bizjet Sonic Boom 

Project,” 21. 

18. Ellen H. Thompson (NASA HQ), Gary Creech (Dryden), and 

Kathy Barnstorff (Langley), “NASA Funds Studies for Quieter 

Supersonic Boom,” NASA news release 05-176, July 8, 2005; 

Biography, Robert E. Meyer Jr., accessed October 22, 2011, http://

www.nasa.gov/centers/dryden/news/Biographies/Management/meyer.

html; “Northrop Grumman to Help NASA Define Requirements for 

Quiet Sonic Boom Research Aircraft,” Northrop Grumman news 

release, July 12, 2005.

19. Collogan, “Manufacturers, NASA Working on Bizjet Sonic Boom 

Project,” 21.

20. Ibid. For Gulfstream’s analysis of SSBJ prospects at the time, see 

Preston A. Henne, “Case for a Small Supersonic Civil Aircraft,” 

Journal of Aircraft 42, no. 3 (May–June 2005): 765–774.

21. T.A. Heppenheimer, “The Boom Stops Here,” Air & Space Magazine

(October–November 2005), accessed January 3, 2009, http://www.

airspacemag.com/flight-today/boom.html.

22. David Mould and Dean Acosta, “NASA Names New Associate 

Administrator,” NASA news release 05-348, October 24, 2005; 

Michael A. Dornheim, “Will Low Boom Fly? NASA Cutbacks 

Delay Flight Test of Shaped Demonstrator...,” Aviation Week

(November 7, 2005): 68–69. There were no NASA news releases on 

the cancellation of the Sonic Boom Mitigation Project.

23. Gulfstream Aerospace Corporation, supersonic aircraft with spike 

for controlling and reducing sonic boom. US Patent 6,698,684, 

issued March 2, 2004, http://www.patentstorm.us/patents/6698684/

description.html.

24. Jay Levine, “Lowering the Boom,” X-Press (July 29, 2005), accessed 

January 4, 2009, http://www.nasa.gov/centers/dryden/news/X-Press/

stories/2005/072905.

25. Edward A. Haering, James W. Smolka, James E. Murray, and 

Kenneth J. Plotkin, “Flight Demonstration of Low Overpressure 

N-Wave Sonic Booms and Evanescent Waves,” 17th International 

Symposium on Nonlinear Acoustics, International Sonic Boom 

Forum, State College, PA, July 21–22, 2005.

26. Ibid.; Jay Levine, “Lowering the Boom.”

27. US Patent 6,698,684 (previously cited); Graham Warwick, 

“Gulfstream Design Spikes Sonic Boom,” Flight International

(March 23, 2004): 32; Donald C. Howe et al., “Development of 

the Gulfstream Quiet Spike for Sonic Boom Minimization,” AIAA 
276

Quieting the Boom

paper no. 2008-124, presented at 46th Aerospace Sciences Meeting, 

Reno, NV, January 7–10, 2008.

28. “Gulfstream Aerospace to Test Patented Spike for Controlling and 

Reducing Sonic Boom on NASA F-15,” Gulfstream news release, 

July 17, 2006; Natalie D. Spivey et al., “Quiet Spike Build-up 

Ground Vibration Testing Approach,” NASA TN 2007-214625 

(November 2007); James W. Smolka, Robert A. Cowart, et al., 

“Flight Testing of the Gulfstream Quiet Spike on a NASA F-15B,” 

paper presented to the Society of Experimental Test Pilots, Anaheim, 

CA, September 27, 2007, 1–24 (unpaginated copy provided in 

December 2008 to the author, who added page numbers), figure 

9-1 extracted from 12; Stephen B. Cumming, Mark S. Smith, and 

Michael A. Frederick, “Aerodynamic Effects of a 24-foot Multisegmented Telescoping Nose Boom on an F-15B Airplane,” NASA 

TM 2008-214634 (April 2008).

29. The most critical flight safety concern was having to land with the 

spike fully extended.

30. “Gulfstream’s Initial Flight Tests Validate Structural Soundness 

of Sonic Boom Mitigator,” Gulfstream news release, October 16, 

2006; “Gulfstream Quiet Spike Goes Supersonic,” Gulfstream news 

release, October 23, 2006; Stephen B. Cummings, Mark S. Smith, 

and Michael A. Frederick, “Aerodynamic Effects of a 24-Foot Multisegmented Telescoping Nose Boom on an F-15B Airplane,” NASA 

TM 2008-214634 (April 2008); Jim Smolka, Leslie Molzahn, and 

Robbie Cowart, “Flight Testing of the Gulfstream Quiet Spike on a 

NASA F-15B,” PowerPoint presentation, printed out for the author 

on December 11, 2008, while at Dryden.

31. Smolka et al., “Flight Testing of the Quiet Spike,” 33-37, figure 9-2 

extracted from 36.

32. As quoted by J.B. Wilson in “Quiet Spike: Softening the Sonic 

Boom,” Aerospace America 45, no. 10 (October 2007): 39.

33. Edward A. Haering et al., “Preliminary Results from the Quiet 

Spike Flight Test,” PowerPoint presentation, NASA Fundamental 

Aeronautics Program meeting, New Orleans, October 30–November 

1, 2007.

34. Smolka et al, “Flight Testing of the Gulfstream Quiet Spike,” 38.

35. “Aeronautics/Propulsion Laureate,” Aviation Week (March 17, 2008): 

40; “Gulfstream appoints Gerard Schkolnik as Director, Supersonic 

Technology Programs,” Gulfstream news release, March 15, 2006; 

“Obituary: Gerard Schkolnik,” Aviation Week (April 21, 2008): 22; 
277

Continuing Research; Postponing Development

David Collogan, “Head of SST Research for Gulfstream killed in 

Crash,” Weekly of Business Aviation 86, no. 16 (April 21, 2008): 177.

36. Michael Braukus and Doc Mirleson, “NASA Restructures 

Aeronautics Research,” NASA news release 06-008, January 12, 

2006; Lisa Porter, “Reshaping NASA’s Aeronautics Program,” 

PowerPoint presentation, January 12, 2006, 3, accessed February 

2, 2009, http://www.nasa.gov/home/hqnews/2006/jan/HQ_06008_

ARMD_Restructuring.html.

37. Peter Coen, Mary Jo Long-Davis, and Louis Povinelli, 

“Fundamental Aeronautics Program Supersonics Project, Reference 

Document,” May 26, 2006, accessed January 5, 2009, http://www.

aeronautics.nasa.gov/fap/documents.html.

38. For example, several articles in the October 8, 2007, issue of 

Aviation Week, with “Supersonics: Boom or Bust?” as its cover title; 

John Wiley, “The Super-Slow Emergence of Supersonic, Sixty Years 

After Glamorous Glennis Made History,” Business and Commercial 

Aviation 101, no. 3 (September 2007): 48–50.

39. Lisa J. Porter, “NASA’s Aeronautics Program,” PowerPoint presentation, Fundamental Aeronautics Annual Meeting, New Orleans, LA, 

October 30, 2007, accessed January 5, 2009, http://www.aeronautics.

nasa.gov/fap/PowerPoints/ARMD&FA_Intro.pdf.

40. Peter Coen, Lou Povinelli, and Kaz Civinskas, “Supersonics Program 

Overview,” October 30, 2007, accessed January 5, 2009, http://www.

aeronautics.nasa.gov/fap/PowerPoints/SUP-Coen-final.pdf.

41. John H. Marburger, National Plan for Aeronautics Research and 

Development and Related Infrastructure (Washington, DC: National 

Science and Technology Council, December 2007), accessed 

February 2, 2009, http://www.whitehouse.gov/sites/default/files/ 

microsites/ostp/aero-natplan-2007.pdf, 16, 53.

42. Ibid., 53; Kristin Scuderi, “President Bush Approves National 

Plan for Aeronautics Research and Development and Related 

Infrastructure,” White House Office of Science and Technology 

news release, December 21, 2007.

43. Coen et al., “Supersonics Project, Reference Document,” 36.

44. Ibid., 19–22 and 42–49; NASA/ARMD, “Fundamental Aeronautics 

Reference Materials,” PowerPoint presentation, 45th annual AIAA 

Aerospace Sciences Meeting, Reno, NV, January 2007, http://www.

aeronautics.nasa.gov/fap/documents.html.

45. J.D. Harrington, “NASA Announces Aeronautic Research 

Opportunities,” NASA news release 07-18, January 30, 2007.
278

Quieting the Boom

46. J.H. Casper et al., “Assessment of Near-Field Sonic Boom 

Simulation Tools,” AIAA paper no. 2008-6592, 26th Applied 

Aerodynamics Conference, Honolulu, HI, August 18–21, 2008.

47. NASA Budget Request Summaries, FY 2008 and FY 2009, accessed 

October 29, 2011, http://www.nasa.gov/news/budget/index.html; 

Daniel Morgan and Carl E. Behrens, “National Aeronautics and 

Space Administration: Overview, FY2009 Budget, and Issues for 

Congress,” Congressional Research Service, February 26, 2008.

48. NASA/ARMD, “Fundamental Aeronautics Collaborative Research,” 

December 2007, accessed January 5, 2009, http://www.aeronautics.

nasa.gov/fap/partners.html; Jefferson Morris, “Quiet, Please: With 

More Emphasis on Partnering, NASA Continues Pursuit of Quieter 

Aircraft,” Aviation Week (June 25, 2007): 57–58.

49. “Fundamental Aeronautics Program Annual Meeting—October 

7–9, 2008,” accessed January 5, 2009, http://www.aeronautics.nasa.

gov/fap/meeting/agenda.html; Jaiwon Shin, “Opening Remarks, 

Fundamental Aeronautics Program 2008 Annual Meeting,” 

PowerPoint presentation, October 7, 2008; Peter Coen, Lou 

Povinelli, and Kas Civinskas, “Supersonics Program Overview,” 

PowerPoint presentation, same venue, October 7, 2008; “Marking 

61 Years of Supersonic Curiosity,” accessed January 5, 2009, http://

www.nasa.gov/topics/aeronautics/features/x1_supersonics_prt.htm.

50. Brenda M. Sullivan, “Sonic Boom Modeling Technical Challenges,” 

CASI document no. 200700363733, October 31, 2007.

51. Brenda M. Sullivan, “Design of an Indoor Sonic Boom Simulator 

at NASA Langley Research Center,” paper presented at NoiseCon 2008, Baltimore, MD, July 12–14, 2008, and “Research at 

NASA on Human Response to Sonic Booms,” paper presented 

at 5th International Conference on Flow Dynamics, Sendai, 

Japan, November 17–20, 2008; Coen et al., “Supersonics Project 

Overview,” October 7, 2008.

52. Beth Hickey, “NASA Awards Future Aircraft Research Contracts,” 

contract release C08-060, October 6, 2008; Graham Warwick, 

“Forward Pitch,” Aviation Week (October 20, 2008): 22–23; Beth 

Dickey, “NASA and JAXA To Conduct Joint Research on Sonic 

Boom Modeling,” NASA news release 09-117, May 8, 2008.

53. “X-54A Designation Issued as Placeholder for Future Boom 

Research Aircraft,” Aerospace Daily (July 21, 2008): 1.

54. John Croft, “Missing Ingredients Fail To Dent Enthusiasm,” 

Flight International (May 13, 2008), accessed ca. October 1, 2011, 

http://business.highbeam.com/411058/article-1G1-179313476/; 
Continuing Research; Postponing Development

279

Robert Wall, “Gulfstream Sees Need To Demonstrate Low-Noise 

Supersonic Flight before 2013,” Aviation Week (May 28, 2007): 

34; Graham Warwick, “Making Waves,” Aviation Week (June 30, 

2008): 44; “Supersonics Face Funding Barrier,” Flight International

(October 14, 2008), accessed ca. October 1, 2011, http://business.

highbeam.com/411058/article-1G1-186885117/.

55. For example: Ilan Kroo and Alex VanDerVelden, “The Sonic Boom 

of an Oblique Flying Wing,” AIAA paper no. 90-4002 (October 

1990), and “Sonic Boom of the Oblique Flying Wing,” Journal of 

Aircraft 31, no. 1 (January–February 1994): 19–25; Christopher A. 

Lee, “Design and Testing of Low Sonic Boom Configurations and 

an Oblique All-Wing Supersonic Transport,” NASA CR 197744 

(February 1995).

56. Jim Hart, “Northrop Grumman Selected...to Design First-Ever 

Supersonic ‘Oblique Flying Wing’ Aircraft,” Northrop Grumman 

news release, March 23, 2006.

57. Graham Warwick, “Flying Sideways,” Flight International (April 18, 

2006), accessed August 22, 2011, http://www.flightglobal.com/news/

articles/flying-sideways-206034/.

58. Graham Warwick, “DARPA Kills Oblique Flying Wing,” Aviation 

Week (October 1, 2008), accessed October 10, 2011, http://www.

aviationweek.com/aw/generic/story.jsp?id=news/OBLI10018c.xml.

59. “FAA Updates Policy on SST Noise Certification,” The Weekly of 

Business Aviation 87, no. 17 (October 27, 2008): 195.

60. Graham Warwick, “Open Season,” Aviation Week (March 2, 2009): 

20–21.

61. Peter Coen, “Fundamental Aeronautics Program Supersonics 

Project,” PowerPoint presentation, NASA Fundamental Aeronautics 

Technical Conference, Cleveland, OH, March 15–17, 2011, 

accessed October 23, 2011, http://www.aeronautics.nasa.gov/pdf/

supersonics.pdf, slide no. 21.

62. Peter Coen, “Fundamental Aeronautics Program Supersonics 

Project,” NASA Fundamental Aeronautics Program 2009 Annual 

Meeting, September 29, 2009, accessed October 22, 2011, http://

www.aeronautics.nasa.gov/fap/SUP-Atlanta-2009-v2.pdf, slide nos. 

10, 34–36.

63. Graham Warwick, “Beyond the N-Wave: Modifying NASA’s ArrowWing F-16XL Could Help Pave the Way for Low-Boom Supersonic 

Transports,” Aviation Week (March 23, 2009): 52.

64. Coen, “Supersonics Project,” September 29, 2009, slide no. 38 

(source for figure 9-3).
280

Quieting the Boom

65. Coen to Benson, November 8, 2011.

66. “Supersonics Project Reference Document,” 43. The acronym 

“LaNCETS” was devised by Ed Haering: Interview by Lawrence 

Benson, Dryden Flight Research Center, December 12, 2008.

67. Dryden Flight Research Center, “F-15B #837,” accessed February 

15, 2009, http://www.nasa.gov/centers/dryden/ aircraft/F-15B-837/

index.html.

68. Larry Cliatt et al., “Overview of the LaNCETS Flight Experiment 

and CFD Analysis,” PowerPoint presentation, Fundamental 

Aeronautics Annual Meeting, Atlanta, October 2, 2008.

69. Tim Moes, “Objectives and Flight Results of the Lift and Nozzle 

Change Effects on Tail Shock (LaNCETS) Project,” PowerPoint 

presentation, International Test & Evaluation Association, Antelope 

Valley Chapter, February 24, 2009, with figure 9-4 copied from slide 

no. 23.

70. Single sorties were flown on November 24 and 25 and December 

2, 3, 9, and 11. Three sorties were flown on December 4. Timothy 

Moes to Lawrence Benson, “Re: More Details on LaNCETS,” 

e-mail, March 11, 2009.

71. Guy Norris, “Sonic Solutions: NASA Uses Unique F-15B To 

Complete Design Tools for Quiet Supersonic Aircraft,” Aviation 

Week (January 5, 2009): 53; Gray Creech and Beth Dickey, “Lancets 

Flights Probe Supersonic Shockwaves,” Dryden news release 09-04, 

January 22, 2009; Moes, “Flight Results of LaNCETS Project,” 

February 24, 2009.

72. “NASA NF-15B Research Aircraft,” fact sheet, as of March 11, 

2009, accessed December 14, 2009, http://www.nasa.gov/centers/

dryden/news/FactSheets/FS-048-DFRC_prt.htm.

73. For an early analysis, see Trong T. Bui, “CFD Analysis of Nozzle Jet 

Plume Effects on Sonic Boom Signature,” AIAA paper no. 2009-

1054, 47th Aerospace Sciences Meeting, Orlando, FL, January 5–8, 

2009.

74. Jacob Klos and R.D. Bruel, “Vibro-Acoustical Response of Buildings 

Due to Sonic Boom Exposure: June 2006 Field Test,” NASA TM 

2007-214900 (September 2007), with figure 9-5 extracted from 309 

and 310; Denise M. Miller and Victor W. Sparrow, “Assessing Sonic 

Boom Responses to Changes in Listening Environment, Signature 

Type, and Testing Methodology,” JASA 127, issue 3 (2010): 1898.

75. Brenda Sullivan et al., “Human Response to Low-Intensity Sonic 

Booms Heard Indoors and Outdoors,” NASA TM 2010-216685 

(April 2010).
281

Continuing Research; Postponing Development

76. Figure 9-6 copied from Edward A. Haering et al., “Initial Results 

from the Variable Intensity Sonic Boom Propagation Database,” 

PowerPoint presentation, May 7, 2008, slide no. 4.

77. Gary Creech, “Sonic Boom Tests Scheduled,” Dryden news release 

07-38, July 5, 2007; Guy Norris, “Sonic Spike,” Aviation Week

(October 8, 2007): 52; Jacob Klos, “Vibro-Acoustic Response of 

Buildings Due to Sonic Boom Exposure: July 2007 Field Test,” 

NASA TM 2008-215349 (September 2008); Edward A. Haering 

et al., “Initial Results from the Variable Intensity Sonic Boom 

Propagation Database,” AIAA paper no. 2008-3034, presented at the 

14th AIAA/CEAS Aeroacoustics Conference, Vancouver, May 5–7, 

2008. Accompanied by a PowerPoint briefing with the same title.

78. Gray Creech, “Supersonic Diving: Quieting the Boom,” Dryden 

Web page feature, June 18, 2009, accessed January 22, 2011, http://

www.nasa.gov/centers/dryden/Features/sonicbobs.html.

79. Alan Brown, “NASA To Conduct Sonic Boom Research Over 

Edwards Next Week,” Dryden news release 09-54, September 4, 

2009.

80. Edward A. Haering and Sarah Renee Arnac, “Sonic Booms on Big 

Structures (SonicBOBS) Phase I Database,” DFRC-2020, CASI 

document no. 20100024301, March 2010; “Space Shuttle: End of 

Mission Landings,” accessed October 29, 2011, http://www.nasa.gov/

mission_pages/shuttle/launch/eomland.html.

81. Gray Creech, “ICAO Team Witnesses Sonic Boom Research 

Flights,” Dryden Web page feature, September 29, 2009, accessed 

October 21, 2011, http://www.nasa.gov/centers/dryden/Features/

icao_sonic_booms.html; Gray Creech, Dryden news release 09-75, 

“2009—Another Year of Accomplishments at NASA Dryden,” 

December 21, 2009.

82. “SonicBOBS: NASA Researching Reducing Intensity of Sonic 

Booms,” Dryden Web page feature, October 7, 2010, accessed 

January 22, 2011, http://www.nasa.gov/centers/dryden/Features/sonic_

bobs_tests.html; John Croft, “NASA Furthers Sonic Boom Irritation 

Studies,” Flight International (November 24, 2010), accessed 

October 22, 2011, http://www.flightglobal.com/news/articles/350137/.

83. Gray Creech, “SonicBREWS Brewing Up an Earthquake Warning 

System,” January 11, 2011, accessed October 22, 2011, http://www.

nasa.gov/centers/dryden/Features/SonicBREWS.html.

84. “NASA Dryden Flies New Supersonic Shockwave Probes,” Aerotech 

News and Review (February 25, 2011): 1, 11; Domenic Maglieri to 
282

Quieting the Boom

Lawrence Benson, “Comments on Chapter 9,” e-mail, October 31, 

2011. 

85. Domenic J. Maglieri, Percy J. Bobbitt, Steven J. Massey, Kenneth 

J. Plotkin, Osama A. Kandil, and Xudong Zheng, “Focused and 

Steady-State Characteristics of Shaped Sonic Boom Signatures: 

Prediction and Analysis,” NASA CR 2011-217156 (June 2011), 12.

86. Gray Creech, “Getting Loud Now: Enjoy Peace and Quiet Then,” 

May 27, 2011, accessed July 20, 2011, http://www.nasa.gov/centers/

dryden/Features/scamp.html.

87. Domenic Maglieri to Lawrence Benson, “Comments on Chap. 

9,” e-mail, October 31, 2011. Preliminary data indicated that the 

overpressure of the most powerful of the super booms was probably 11 psf: Kenneth Plotkin to Lawrence Benson, “Fw: AVTIP and 

SCAMP,” e-mail, October 30, 2011.

88. “Sonic Boom Research Study Recruitment Begins,” Dryden Web 

page feature, June 23, 2011, accessed July 26, 2011, http://www.

nasa.gov/centers/dryden/Features/sonic_boom_recruit_orig.html; “More 

Edwards Residents Needed for Sonic Boom Study,” Dryden Web 

page feature, August 4, 2011, accessed August 5, 2011, http://

www.nasa.gov/centers/dryden/Features/sonic_boom_recruit.html; Gray 

Creech, “NASA Quiet Sonic Boom Research Effort Ends with a 

Whisper,” December 1, 2011, Dryden Web page feature, http://

www.nasa.gov/centers/dryden/Features/WSPR_research_complete.html.

89. Deliveries had dropped from 1,139 in 2008 to 732 in 2010 with 

as few as 600 projected for 2011. Joseph C. Anselmo and William 

Garvey, “Prolonged Pain: Honeywell’s Bizjet Forecast Corks Any 

Premature Celebration,” Aviation Week (October 10, 2011): 54–55.

90. Graham Warwick, “Sonic Overture: European Researchers Test 

the Waters on International Supersonic Collaboration,” Aviation 

Week (July 13, 2009): 53–54; Bob Coppinger, “A Distant Boom,” 

Flight International (April 27, 2010), accessed ca. September 15, 

2011, http://www.flightglobal.com/news/articles/ebace-a-distantboom-340971/; Robert Wall and Guy Norris, “Filling A Gap: 

Interest Rises in High-Speed Premium Air Travel,” Aviation Week

(June 27, 2011): 38.

91. Giko Sehata and Yomiuri Shimbun, “Can SSTs Be Made Quieter?: 

JAXA Advancing in Development of High-Speed Commercial 

Aircraft,” Daily Yomiuri (Tokyo), May 9, 2010, 3; “Quiet Booms,” 

Aviation Week (May 23, 2011): 13.

92. “Turbulent Times: Face to Face—Joe Lombardo,” Aviation Week

(October 18, 2010): 61–62.
283

Continuing Research; Postponing Development

93. Warwick, “Sonic Overture,” 54; Graham Warwick, “Key 

Developments,” Aviation Week (January 25, 2010), 104.

94. Aerion, “Order Book at $4 Billion as Aerion Nears Decision on 

Manufacturing Partner,” news releases, June 15, 2009; “Aerion Taps 

SHS to Promote Development of New Supersonic Business Jet,” 

March 15, 2010; “Aerion Diversifies to Meet Demand for Subsonic 

Natural Laminar Flow,” May 16, 2011, http://aerioncorp.com/

media#press. During July and August 2010, one of NASA Dryden’s 

F-15Bs carried a scale model of Aerion’s latest supersonic laminar 

flow wing design under its centerline on five flights at speeds up to 

Mach 2. Aeron, “Aerion Announces Details of Recent Supersonic 

Flight Tests,” news release, October 18, 2011; Guy Norris, “Aerion 

Ambitions,” Aviation Week (October 18, 2010): 42; William Garvey, 

“Looking for a Home: A Fast Promise After a Slow Start,” Aviation 

Week (April 9, 2012): 16. By 2012, Aerion estimated that up to $3 

billion would be needed to develop and produce its SSBJ.

95. NASA, “2011 Fundamental Aeronautics Technical Conference 

Recap,” Cleveland, OH, March 15–17, 2011, accessed October 23, 

2011, http://www.aeronautics.nasa.gov/fap/meeting_recap_2011.html. 

Just under 400 people were in attendance.

96. Peter Coen, “Fundamental Aeronautics Program Supersonics 

Project,” 2011 Technical Conference, Cleveland, OH, March 

15–17, 2011, accessed October 23, 2011, http://www.aeronautics.

nasa.gov/pdf/supersonics.pdf.

97. Jim Banke, “Quieter Flight: A Balancing Act,” Aerospace America

(March 2011): 42–43.

98. Guy Norris and Graham Warwick, “Sound Barrier: Propulsion 

Integration Holds the Key to Low-Noise, Low-Boom Supersonic 

Transports,” Aviation Week (June 4/11, 2012): 50–53.

99. Coen, “Supersonics Project,” March 15, 2011; Harry R. Wedge 

et al., “N+2 Supersonic Concept Development and System 

Integration,” NASA CR 2010-216842 (August 2010).

100. Robert H. Wedge et al. (incl. Kenneth Plotkin and Juliet Page), 

“N Plus 3 Advanced Concept Studies for Supersonic Commercial 

Transport Aircraft Entering Service in the 2030–2035 Period,” 

NASA CR 2011-217084 (April 2011).

101. John Morgenstern, Nicole Norstrud, Marc Stelnack, and Craig 

Skoch, “Final Report for the Advanced Concept Studies for 

Supersonic Commercial Transports Entering Service in the 2030 to 

2035 Period, N+3 Supersonic Program,” NASA CR 2010-216796 

(October 25, 2010).
284

Quieting the Boom

102. Coen, “Supersonics Project,” March 15, 2011, figure 9-7 extracted 

from slide no. 9; Graham Warwick, “Mach Work: Advances in 

Aerodynamics, Structures, and Engines Hold Promise for Quiet, 

Efficient Supersonic Transports,” Aviation Week (May 17, 2010): 43.

103. By the spring of 2012, wind tunnel tests had verified the success of 

these improved CFD-aided designs. As explained by Peter Coen, 

“That was really a breakthrough for us. Not only that the tools 

worked, but that our tests show we could do even better in terms of 

reducing noise than we thought at the start of the effort.” Jim Banke, 

“Sonic Boom Heads for a Thump,” NASA Web Feature, May 8, 

2012, accessed May 11, 2112, http://www.nasa.gov/topics/aeronautics/

features/sonic_boom_thump.html.

104. Peter Coen, “Supersonics Project Overview,” PowerPoint 

Presentation, Fundamental Aeronautics Program 2012 Technical 

Conference, Cleveland, OH, March 13–15, 2012, accessed April 15, 

2012, http://www.aeronautics.nasa.gov/fap/2012-PRESENTATIONS/

SUP_2012_508.pdf, slide no. 15.

105. Graham Warwick, “Raise the Limit: Research to Define Acceptable 

Boom Limit Paces Return of Supersonic Travel,” Aviation Week (July 

18/25, 2011): 57.

106. Graham Warwick, “Boom Time: Demonstrator Needed To 

Convince Regulators Shaped Booms Allow Quiet Supersonic 

Flight,” Aviation Week (April 23/30, 2012): 54–55.

107. National Research Council, Recapturing NASA’s Aeronautics Flight 

Research Capabilities (Washington DC: the National Academies 

Press, 2012), 32–36, accessed May 11, 2012, http://www.nap.edu/

catalog.php?record_id=13384. As shown on page 9 of this report, 

NASA’s recent aeronautics budgets had been $512 million in FY 

2008, $500 million in FY 2009, $507 million in FY 2010, and 

$534 million in 2011.

108. FAA, “Supersonic Aircraft Noise,” accessed October 15, 2011, http://

www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/

supersonic_aircraft_noise/. This Web site has links to all the papers 

presented at the Civil Supersonic Aircraft Technical Workshop in 

2003 and the FAA Public Meetings on Advanced Technologies and 

Supersonics in October 2009, March 2010, and July 2011.

109. Ibid.; FAA, “Civil Supersonic Aircraft Panel Discussion,” Federal 

Register 76, no. 100 (May 24, 2011): 30231.

110. Lourdes Maurice, “Civil Supersonic Aircraft Advanced Noise 

Research,” PowerPoint presentation at FAA Public Meeting on 
285

Continuing Research; Postponing Development

Advanced Technologies and Supersonics, Washington, DC, July 14, 

2011.

111. Richard Tracy, “Aerion Supersonic Business Jet,” and Robbie 

Cowart, “Supersonic Technology Development,” PowerPoint presentations at FAA Public Meeting on Advanced Technologies and 

Supersonics, Washington, DC, July 14, 2011.

112. Peter Coen, “Fixing the Sound Barrier: Three Generations of U.S. 

Research into Sonic Boom Reduction...and What it Means to 

the Future,” PowerPoint presentation at FAA Public Meeting on 

Advanced Technologies and Supersonics, Washington, DC, July 14, 

2011, figure 9-8 copied from slide no. 18. The signature identified as 

a “ramp” can be described more completely as a “symmetrical initial 

shock ramp” and the “low boom” as a “symmetrical ramp.” Maglieri 

to Benson, October 31, 2011.

113. Banke, “Quieter Flight,” 42.

114. Joseph C. Anselmo and William Garvey, “Prolonged Pain: 

Honeywell’s Bizjet Forecast Corks any Premature Celebration,” 

Aviation Week (October 10, 2011): 54–55.

115. In response to these budgetary pressures, the Fundamental 

Aeronautics Program merged the air-breathing portion of the 

Hypersonics Project with the Supersonics Project while research on 

Entry, Landing, and Descent (EDL) vehicles was transferred to the 

Space Technology Program. See Jaiwon Shin, “NASA Aeronautics 

Fundamental Aeronautics Program Technical Conference,” 

PowerPoint presentation, 2012 Fundamental Aeronautics Technical 

Conference, Cleveland, OH, March 13–15, 2012, accessed April 

15, http://www.aeronautics.nasa.gov/fap/meeting_recap_2012.html; 

Graham Warwick, “Cut To the Bone: Aeronautics Research Funding 

Decline Makes It Harder To Take Technologies to the Next Level,” 

Aviation Week (February 27, 2012): 35.
286

A color-coded illustration of high-pressure shock waves and lower pressure expansions based 

on imagery that was generated by the Computational Fluid Dynamics (CFD) program used by 

its SSBD team in designing the F-5’s modifications. A photo of the modified aircraft in flight has 

been inserted to complete the illustration. (Illustration: NGC, Photo: NASA)
287

APPENDIX A

Key SSBD and SSBE Personnel

SSBD Management Team

Richard Wlezien DARPA QSP Program Manager (2000–2003)

Steven Walker DARPA QSP Program Manager (2003–2004)

Lisa Veitch IDA QSP Deputy Manager

Charles Boccadoro NGC NGC QSP Program Manager

Peter Coen NASA Langley DARPA Technical Agent

Mark Gustafson AFRL DARPA Technical Agent

Joseph Pawlowski NGC SSBD Project Manager

Edward Haering NASA Dryden Principal Investigator

David Richwine NASA Dryden F-15B Manager

SSBD Working Group

Richard Wlezien DARPA 

Steven Walker DARPA

Peter Coen 

Mark Gustafson 

Lisa Veitch 

NASA Langley

DARPA/AFRL

IDA

Sue Morris CENTRA*

Joe Pawlowski NGC

Rich Biegner 

Dave Graham 

NGC

NGC

Steve Madison NGC

Roy Martin 

Keith Meredith 

NGC

NGC

Ed Haering 

Dave Richwine 

David McCurdy 

David Hilliard 

Kevin Shepherd 

NASA Dryden

NASA Dryden

NASA Langley

NASA Langley

NASA Langley
288

Quieting the Boom

Domenic Maglieri Eagle Aeronautics

Percy Bobbitt Eagle Aeronautics

Ken Plotkin Wyle Laboratories

Juliet Page Wyle Laboratories

Todd Magee Boeing

Peter Hartwich Boeing

Tom Porter Gulfstream

Joe Salamone Gulfstream

Rob Wolz Gulfstream

Tony Pilon Lockheed Martin

John Morgenstern Lockheed Martin

Joe Vadyak Lockheed Martin

Sam Bruner Raytheon Aircraft

Cathy Downen Raytheon Aircraft

Kurt Schueler Raytheon Aircraft

James Poncer AFRL

*CENTRA Technology (a DARPA support contractor)

SSBE Program Management Team

Peter Coen NASA Langley SSBE Program Manager

Keith Numbers AFRL AVTIP Program Manager

Adam Harder AFRL AVTIP Contract Administrator

Charles Boccadoro NGC NGC QSP Program Manager

Joseph Pawlowski NGC NGC SSBE Project Manager

Edward Haering NASA Dryden Principal Investigator

Steven Corda NASA Dryden F-15B Manager

SSBE Working Group

Peter Coen 

Joe Pawlowski 

NASA Langley

NGC

Dave Graham NGC

Steve Madison NGC

Roy Martin 

Keith Meredith 

NGC

NGC

Dave Schein NGC

Ed Haering NASA Dryden
289

Key SSBD and SSBE Personnel

Gerard Schkolnik NASA Dryden

Dave McCurdy NASA Langley

Brenda Sullivan NASA Langley

David Hilliard NASA Langley

Kevin Shepherd NASA Langley

Domenic Maglieri Eagle Aeronautics

Percy Bobbitt Eagle Aeronautics

Ken Plotkin Wyle Laboratories

Juliet Page Wyle Laboratories

Todd Magee Boeing

Tom Porter Gulfstream

Joe Salamone Gulfstream

Rob Wolz Gulfstream

Victor Lyman Lockheed Martin

Tony Pilon Lockheed Martin

John Morgenstern Lockheed Martin

Joe Vadyak Lockheed Martin

Sam Bruner Raytheon Aircraft

Cathy Downen Raytheon Aircraft

Adam Harder AFRL

Keith Numbers AFRL

SSBD Test Pilots

Roy Martin Northrop Grumman F-5 SSBD

Darryl “Spike” Long NAWS China Lake F-5 SSBD

Dwight “Tricky” Dick NAS Fallon F-5E

Edgar “Sting” Higgins NAS Fallon F-5E (ISSM)

Mike Bryan Boeing T-38

Dana Purifoy NASA Dryden F-15B

Jim Smolka NASA Dryden F/A-18

SSBE Test Pilots

Roy Martin Northrop Grumman F-5 SSBD

Dwight “Tricky” Dick NAS Fallon F-5E

Dana Purifoy NASA Dryden F-15B

Jim Smolka NASA Dryden F/A-18

Richard Ewers NASA Dryden F/A-18
290

Quieting the Boom

Mark “Forger” Stucky USAF Test Pilot School Blanik L-23

Robert “Critter” Malacrida USAF Test Pilot School Blanik L-23

Vince “Opus” Sei USAF Test Pilot School Blanik L-23

Gary Aldrich USAF Test Pilot School Pawnee Pa-25

Northrop Grumman Vehicle Design Team

Keith Applewhite Team Lead; Loads

Terry Britt Dynamics

Dale Brownlow Modification Lead

John Corskery Mass Properties

Habeeb Hasseem Finite Element Model

Dick Hong Mass Properties

Joseph Lavoie Composite Structure

Andy Limon Structures Lead

Steve McCleskey Stress

Bob Parker Stress

Eddy Pedroza Avionics/Electrical 

Larry Roussel Configuration Mgt.

Mark Sherman Fairing Structure

Mark Smith Mfg. Engineering

Aziz Soltani Configuration Mgt.

Ron Srenco Materials & Processes

Jerry Stuart Nose Structure

Jim Ueda F-5 Design Manager

Chris Yasaki Nose Structure

Tom York Fairing Structure

NGC Flight Test Support: St. Augustine

Steve Madison Test Conductor

Keith Applewhite 

Eric Vartio 

Al Scholz 

Loads & Dynamics

Stability & Control

Instrumentation

Pat Foster Instrumentation

John Nevadomsky 

Dan Nehring 

Darren McPhillips 

Jim Fallica 

Operations Mgr.

Flt. Test Engineer

Crew Chief

Flt. Test Support
291

Key SSBD and SSBE Personnel

W.D. Thorne Flt. Test Support

Diane Barnes Quality Assurance

Nate McKendrick Flight Dispatch

Merv Burne Instrumentation

John Garry Instrumentation

Larry Stencel Instrumentation

NGC Flight Test Support: Palmdale

Steve Madison Test Conductor

Keith Applewhite Loads & Dynamics

Eric Vartio Stability & Control

Al Scholz Instrumentation

Pat Foster Instrumentation

Mike Foxgrover Crew Chief

Larry Baldini Test Support

Dennis Cruickshank Quality Assurance

Jim Difenderfer Test Support

W.D. Thorne Test Support

Mike Ingalls Test Support

Chuck Rider* F-5E Plane Capt.

* Sikorsky employee, NAS Fallon

NASA Dryden Flight Test Support: Edwards AFB

F-15B Operations:

Tim Moes Chief Engineer

Keith Krake Instrumentation

Martin Trout Backseat

Michael Thomson Backseat

Christine Visco Ops. Engineer

Mark Collard Ops. Engineer

John Spooner Instr. Technician.

Corry Rung Instr. Technician.

Perry Silva Crew Chief

Tim Cutler Ground Crew

Roger Lynn Ground Crew

Tom Wolfe Ground Crew
292

Quieting the Boom

Carl Booker Inspector

Other Support:

Patricia Kinn Acft. Scheduling

Nancy Wilcox Acft. Scheduling

Tracy Ackeret Range Control 

Kathleen Howell Control Room

Russell James Control Room

Rich Rood Frequency Mgt.

Carla Thomas Photography

Jim Ross Photography

Tony Landis Photography

Thomas Tschida Photography

SSBD Data Collection Team

Ed Haering NASA Dryden

Jim Murray NASA Dryden

David Berger NASA Dryden

Ellen Klingbeil NASA Dryden

James Parie NASA Dryden

Norma Campos NASA Dryden

Jack Ehernberger NASA Dryden

Ed Teets NASA Dryden

Chris Ashburn NASA Dryden

Peter Coen NASA Langley

Dave McCurdy NASA Langley

Ken Plotkin Wyle Labs

Tom Baxter Wyle Labs

John Swain Wyle Labs

Joe Salamone Gulfstream

Todd Magee Boeing

Dave Graham NGC

Dave Schein NGC

Jonathan King NGC

Steve Komadina NGC

John Mangus NGC

Andrew Maskiell NGC

Dustin Okada NGC

Anne Bender NGC
293

Key SSBD and SSBE Personnel

Robert Ganguin 

Leslie Smith 

NGC

NGC

Rich Wasson NGC

Bryan Westra 

Joan Yazejian 

Alan Arslan 

NGC

NGC

Lockheed Martin

Herb Kuntz Lockheed Martin

John Morgenstern 

Tony Pilon 

Lockheed Martin

Lockheed Martin

SSBE Data Collection Team

Ed Haering NASA Dryden

Jim Murray NASA Dryden

Gregory Noffz NASA Dryden

Chris Ashburn NASA Dryden

Peter Coen NASA Langley

Brenda Sullivan NASA Langley

Ken Plotkin Wyle Labs

Tom Baxter Wyle Labs

John Swain Wyle Labs

Domenic Maglieri Eagle Aeronautics

Joe Salamone Gulfstream

Dave Graham NGC

Dave Schein NGC

Greg Epke NGC

Joe Pawlowski NGC

Eric Adamson Boeing
294

Quieting the Boom

APPENDIX B

F-5 SSBD Flight Chronology

Flight Date (and Takeoff Capsule

Number Time if Flight Test) Summary

St. Augustine and Jacksonville, FL

Piloted by Roy Martin, NGC

QSP-1 July 24, 2003 Functional Check Flight (FCF), St. Johns Airport to 

Cecil Field, with Boeing T-38 chase plane.

QSP-2 July 27, 2003 FCF/envelope expansion, with T-38 chase.

QSP-3 July 28, 2003 FCF/envelope expansion, with T-38 chase.

Cross-Country to California 

Piloted by Roy Martin, NGC

Ferry 1 & 2 July 28, 2003 Cecil Field via Huntsville, AL, to Tinker AFB, OK, with T-38.

Ferry 3 & 4 July 29, 2003 Tinker AFB via Roswell, NM, to Palmdale, CA, with T-38.

Shaped Sonic Boom Demonstration

All flown from Air Force Plant 42, Palmdale, to Edwards AFB restricted areas

QSP-4 August 2, 2003 FCF/envelope expansion piloted by Martin, with NASA 

F/A-18 chase.

QSP-5 August 2, 2003 FCF/envelope expansion by Martin, with F/A-18 

chase; ground data measurements practice.

QSP-6 August 4, 2003 FCF/envelope expansion by Cmdr. Darryl Long, USN, 

with F/A-18 chase; ground data measurements 

practice.

QSP-7 August 15, 2003 FCF/envelope expansion by Martin, with F/A-18 

chase; ground data measurements practice.

QSP-8 August 25, 2003, First sonic boom flight test, flown by Long, with F/A1030 18 chase; practice NASA F-15B probe at Mach 1.38 

and ground data measurements.

QSP-9 August 27, 2003, Flown by Martin with Navy F-5E over ground array 

0626 at Mach 1.36 and 32,000 feet; historic first shaped 

sonic boom measurement.

QSP-10 August 27, 2003, Flown by Long with F-5E, sonic boom run at Mach 

0905 1.38 over ground array.
295

F-5 SSBD Flight Chronology

QSP-11 August 28, 2003, Flown by Martin with F-5E over ground array.

0620

QSP-12 August 29, 2003, Flown by Long with F-15B for in-flight probe at Mach 

0830 1.34; F-5E had departed for NAS Fallon after photos 

by F/A-18B chase.

Shaped Sonic Boom Experiment

All piloted by Roy Martin from Air Force Plant 42, Palmdale, to Edwards AFB restricted areas

All measured by ground sensor array

QSP-13 January 12, 

2004, 0940

FCF with F/A-18B chase and L-23 sailplane; included 

Mach 1.4 practice focus boom from 32,000 feet. 

QSP-14 January 12, 

2004, 1318

F/A-15B in-flight probe aborted; Mach 1.4 run at 

32,000 feet; Air Force L-23 below.

QSP-15 January 13, 

2004, 0656

Mach 1.4 run at 32,000 feet with F-5E; L-23 below.

QSP-16 January 13, 

2004, 1000

Mach 1.4 run at 32,000 feet with F-5E; L-23 below; 

F/A-18B chase.

QSP-17 January 13, 

2004, 1300

Mach 1.4 run at 32,000 feet with F-5E; L-23 below.

QSP-18 January 14, 

2004, 0957

Mach 1.43 run at 32,000 feet with F-5E; L-23 below.

QSP-19 January 14, 

2004, 1327

Mach 1.35 run with F-5E; L-23 below; F/A-18B chase

QSP-20 January 15, 

2004, 0655

Mach 1.43 run at 32,000 feet with F-5E, L-23 below.

QSP-21 January 15, 

2004, 0957

Mach 1.35 run at 32,000 feet with F-5E; L-23 below.

QSP-22 January 15, 

2004, 1257

Mach 1.35 close formation run at 32,000 feet with F-5E 

before it continued on to NAS Fallon; L-23 below.

QSP-23 January 16, 

2004, 1503

Solo run at Mach 1.375 and 32,000 feet; L-23 below.

QSP-24 January 17, 

2004, 0703

Solo run at Mach 1.375 and 32,000 feet to create 

focus boom.

QSP-25 January 17, 

2004, 0945

Solo run at Mach 1.375 and 36,000 feet.

QSP-26 January 17, 

2004, 1138

Solo run at Mach 1.45 and 36,000 feet.

QSP-27 January 19, 

2004, 0659

Solo run at Mach 1.375 and 32,000 feet to create 

focus boom; L-23 below.

QSP-28 January 19, 

2004, 0954

Two solo runs: Mach 1.375 and 32,000 feet; Mach 

1.33 and 31,000 feet; L-23 below.
296

Quieting the Boom

QSP-29 January 19,

2004, 1159

Two solo runs: Mach 1.40 and 32,000 feet; Mach 

1.31 and 32,000 feet; L-23 below.

QSP-30 January 21, 

2004, 0702

Two F-15B probing runs: Mach 1.4 and 32,000 feet; 

Mach 1.35 and 32,000 feet.

QSP-31 January 22, 

2004, 1124

Two F-15B probing runs: both at Mach 1.375 and 

32,000 feet.

QSP-32 January 22, 

2004, 1342

Two F-15B probing runs: Mach 1.4 and Mach 1.35, 

both at 32,000 feet.

QSP-33 January 22, 

2004, 1534

Two F-15B probing runs: Mach 1.375 and Mach 1.4, 

both at 32,000 feet.

Cross-Country to Florida

Piloted by Roy Martin

Ferry 5 January 23, From Palmdale via Albuquerque to Tinker AFB; 

& 6 2004 accompanied by F/A-18 from NAWS China Lake.

Ferry 7 January 24, From Tinker AFB to Birmingham; F/A-18 diverted to 

2004 Memphis for maintenance.

Ferry 8 January 27, From Birmingham to St. Augustine after weather delay; 

2004 accompanied by NGC Citation XL corporate jet.

Northrop Grumman SSBD/SSBE postflight reports; PowerPoint tables: “Shaped Sonic Boom 

Demo Flight Test Program,” and “Shaped Sonic Boom Flight Test Summary,” August 17, 2004; 

Telephonic interviews of Roy Martin by Lawrence Benson, May 31 and November 6, 2011.
297

APPENDIX C

F-5E SSBD Modifications 

and Specifications

Key F-5 SSBD Specifications:

length: 49.8 feet

height: 13.4 feet

wingspan: 26.7 feet

area: 186 square feet.

takeoff weight: ~15,000 lbs (internal fuel only)

maximum authorized speed 

with modifications: Mach 1.45
298

Initial Design of 

August 2001
299

Nearly Final Design 

of January 2002

Source of drawings: David Graham and Roy 

Martin, “Aerodynamic Design and Validation 

of SSBD Aircraft,” PowerPoint presentation, 

Shaped Sonic Boom Experiment Closeout 

Workshop, Langley Research Center, 

Hampton, VA, August 17, 2004.
300

Quieting the Boom

APPENDIX D

Key SSBD and SSBE Reports

Kenneth J. Plotkin, Juliet Page, David H. Graham, Joseph W. Pawlowski, 

David B. Schein, Peter G. Coen, David A. McGurdy, Edward A. 

Haering, James E. Murray, L.J. Ehernberger, Domenic J. Maglieri, Percy 

J. Bobbitt, Anthony Pilon, and Joe Salamone, “Ground Measurements of 

a Shaped Sonic Boom,” AIAA paper no. 2004-2923, 10th AIAA-CEAS 

Aeroacoustics Conference, Manchester, England, May 10–12, 2004.

Joseph W. Pawlowski, David H. Graham, Charles H. Boccadoro, Peter G. 

Coen, and Domenic J. Maglieri, “Origins and Overview of the Shaped 

Sonic Boom Demonstration Program,” AIAA paper no. 2005-5, 43rd 

Aerospace Sciences Meeting, Reno, NV, January 10–13, 2005.

Keith B. Meredith, John A. Dahlin, David H. Graham, Michael B. 

Malone, Edward A. Haering, Juliet A. Page, and Kenneth J. Plotkin, 

“Computational Fluid Dynamics Comparison and Flight Test 

Measurement of F-5E Off-Body Pressures,” AIAA paper no. 2005-6, 

43rd Aerospace Sciences Meeting, Reno, NV, January 10–13, 2005.

David H. Graham, John A. Dahlin, Juliet A. Page, Kenneth J. Plotkin, 

and Peter G. Coen, “Wind Tunnel Validation of Shaped Sonic Boom 

Demonstration Aircraft Design,” AIAA paper no. 2005-7, 43rd 

Aerospace Sciences Meeting, Reno, NV, January 10-13, 2005.

David H. Graham, John A. Dahlin, Keith B. Meredith, and Jay L. Vadnais, 

“Aerodynamic Design of Shaped Sonic Boom Demonstration Aircraft,” 

AIAA paper no. 2005-8, 43rd Aerospace Sciences Meeting, Reno, NV, 

January 10–13, 2005.

Edward A. Haering, James E. Murray, Dana D. Purifoy, David H. Graham, 

Keith B. Meredith, Christopher E. Ashburn, and Lt. Col. Mark Stucky, 

“Airborne Shaped Sonic Boom Demonstration Pressure Measurements 

with Computational Fluid Dynamics,” AIAA paper no. 2005-9, 43rd 

Aerospace Sciences Meeting, Reno, NV, January 10–13, 2005.
301

Key SSBD and SSBE Reports

Kenneth J. Plotkin, Edward A. Haering, James E. Murray, Domenic J. 

Maglieri, Joseph Salamone, Brenda M. Sullivan, and David Schein, 

“Ground Data Collection of Shaped Sonic Boom Experiment Aircraft 

Pressure Signatures,” AIAA paper no. 2005-10, 43rd Aerospace Sciences 

Meeting, Reno, NV, January 10–13, 2005.

Kenneth J. Plotkin, Roy Martin, Domenic J. Maglieri, Edward A. Haering, 

and James E. Murray, “Pushover Focus Booms from the Shaped Sonic 

Boom Demonstrator,” AIAA paper no. 2005-11, 43rd Aerospace 

Sciences Meeting, Reno, NV, January 10–13, 2005.

John M. Morgenstern, Alan Arslan, Victor Lyman, and Joseph Vadyak, “F-5 

Shaped Sonic Boom Persistence of Boom Shaping Reduction through 

the Atmosphere,” AIAA paper no. 2005-12, 43rd Aerospace Sciences 

Meeting, Reno, NV, January 10–13 2005.

Kenneth J. Plotkin, Domenic Maglieri, and Brenda M. Sullivan, “Measured 

Effects of Turbulence on the Loudness and Waveforms of Conventional 

and Shaped Minimized Sonic Booms,” AIAA paper no. 2005-2949, 11th 

AIAA/CEAS Aeroacoustics Conference, Monterey, CA, May 23–25, 2005.
302

Quieting the Boom

Selected Bibliography

Books, Monographs, and Conference Proceedings

Air Force Flight Test Center History Office. Ad Inexplorata: The Evolution of 

Flight Testing at Edwards Air Force Base. Edwards AFB: AFFTC, 1996.

Aircraft Engine Noise and Sonic Boom. Conference Proceedings (CP) no. 42. 

Presented at the North Atlantic Treaty Organization (NATO) Advisory 

Group for Aerospace Research and Development (AGARD), Neuilly sur 

Seine, France, 1969.

Anderegg, C.R. Sierra Hotel: Flying Air Force Fighters in the Decade after 

Vietnam. Washington, DC: Air Force History and Museums Program, 

2001.

Angelucci, Enzo. The Rand McNally Encyclopedia of Military Aircraft, 

1914–1980. New York: The Military Press, 1983.

Baals, Donald D., and William R. Corliss, Wind Tunnels of NASA. NASA 

SP-440. Washington, DC: NASA, 1981.

Baize, Daniel G., ed. 1995 NASA High-Speed Research Program Sonic Boom 

Workshop Held at Langley Research Center, Hampton, Virginia, September 

12–13, 1995 1. NASA CP-3335. Hampton, VA: Langley Research 

Center, July 1996. Configuration, Design, Analysis, and Testing 2. NASA 

CP-1999-209520. Hampton, VA: Langley Research Center, December 

1999.

Brandt, Steven A., John J. Bertin, Randall J. Stiles, and Ray Whitford. 

Introduction to Aeronautics: A Design Perspective. Reston, VA: AIAA, 

2004.

Chambers, Joseph R. Innovation in Flight; Research of the NASA Langley 

Research Center on Revolutionary Concepts for Aeronautics. NASA 

SP-2005-4539. Washington, DC: NASA, 2005.
303

Selected Bibliography

Conway, Erik M. High-Speed Dreams: NASA and the Technopolitics of 

Supersonic Transportation, 1945–1999. Baltimore: Johns Hopkins 

University Press, 2005.

Darden, Christine M., ed. High-Speed Research: Sonic Boom; Proceedings of a 

Conference Held at Langley Research Center, Hampton, Virginia, February 

25–27, 1992. 2 vols. NASA CP-3172 and CP-3173. Washington, DC: 

NASA, 1992.

Darden, Christine, Albert R. George, Wallace D. Hayes, Allan D. 

Pierce, and Clemans Powell. Status of Sonic Boom Methodology and 

Understanding; Proceedings of a Workshop Sponsored by the National 

Aeronautics and Space Administration and held at NASA Langley Research 

Center, Hampton, Virginia, January 19–20, 1988. NASA CP-3027. 

Washington, DC: NASA, 1989.

Darling, David. The Complete Book of Spaceflight: From Apollo 1 to Zero 

Gravity. Hoboken, NJ: John Wiley and Sons, 2003.

Dick, Steven J., ed. NASA’s First 50 Years: Historical Perspectives; NASA 50th 

Anniversary Proceedings. NASA SP-2010-4704. Washington, DC: NASA, 

2010.

Driver, Cornelius (conference chairman). Proceedings of the SCAR Conference 

Held at Langley Research Center, Hampton, Virginia, November 9–12, 

1976. Parts 1 and 2. NASA CP-001. Hampton, VA: Langley Research 

Center, 1976.

Driver, Cornelius, and Hal T. Barber (conference cochairmen). Supersonic 

Cruise Research ’79: Proceedings of a Conference Held at Langley Research 

Center, Hampton, VA, November 13–16, 1979. Parts 1 and 2. NASA 

CP-2108. Hampton, VA: Langley Research Center, 1980.

Edwards, Thomas A., ed. High-Speed Research: Sonic Boom; Proceedings of a 

Conference Held at Ames Research Center, Moffett Field, California, May 

12–14, 1993 1. NASA CP-10132. Moffett Field, CA: Ames Research 

Center, 1994. 

Gorn, Michael H. Expanding the Envelope: Flight Research at NACA and 

NASA. Lexington, KY: University of Kentucky Press, 2001.
304

Quieting the Boom

Hallion, Richard P. Supersonic Flight: Breaking the Sound Barrier and 

Beyond—The Story of the Bell X-1 and Douglas D-558. New York: The 

Macmillan Co. in association with the Smithsonian Institution National 

Air and Space Museum, 1972.

Hallion, Richard P., and Michael H. Gorn. On the Frontier: Experimental 

Flight at NASA Dryden. Washington, DC: Smithsonian Institution Press, 

2003.

Hallion, Richard P., ed. NASA’s Contributions to Aeronautics. 2 vols. NASA 

SP-2010-570. Washington, DC: NASA, 2010.

Horwitch, Mel. Clipped Wings: The American SST Conflict. Cambridge, MA: 

MIT Press, 1982.

Huebner, Lawrence D., Scott C. Asbury, John E. Lamar, Robert E. 

McKinley, Robert C. Scott, William J. Small, and Abel O. Torres (compilers). Transportation Beyond 2000: Technologies Needed for Engineering 

Design, Proceedings of a Workshop Held at Hampton, Virginia, September 

26–28, 1995. 2 parts. NASA CP-10184. February 1996.

James and Associates, ed. YF-12 Experiments Symposium: A Conference Held 

at Dryden Flight Research Center, Edwards, California, September 13–15, 

1978. NASA CP-2054. 1978.

Jenkins, Dennis R., and Tony R. Landis, Valkyrie: North America’s Mach 3 

Superbomber. North Branch, MN: Specialty Press, 2004.

Johnsen, Frederick A. Northrop F-5/F-20/T-38. Vol. 44, Warbird Tech Series. 

North Branch, MN: Specialty Press, 2006.

Kempel, Robert W. The Conquest of the Sound Barrier. Beirut: HPM 

Publications, 2007.

Kent, Richard J. Safe, Separated, and Soaring: A History of Civil Aviation 

Policy, 1961–1972. Washington, DC: FAA, 1980.

Knaack, Marcelle S. Post–World War II Bombers, 1945–1973 2, Encyclopedia 

of U.S. Air Force Aircraft and Missile Systems. Washington, DC: GPO for 

Office of Air Force History, 1988.
305

Selected Bibliography

Langley Research Center. Aerodynamic Analysis Requiring Advanced 

Computers. Parts 1 and 2 [conference proceedings]. NASA SP-347. 

Washington, DC: National Technical Information Service, 1975.

Marburger, John H., signatory. National Plan for Aeronautics Research and 

Development and Related Infrastructure. Washington, DC: National 

Science and Technology Council, December 2007. http://www.whitehouse.gov/sites/default/files/microsites/ostp/aero-natplan-2007.pdf.

McCurdy, David A., ed. High-Speed Research: 1994 Sonic Boom Workshop: 

Proceedings of a Workshop Held in Hampton, Virginia, June 1–3, 

1994 1, Atmospheric Propagation and Acceptability Studies. NASA 

CP-3279. Hampton, VA: Langley Research Center, October 1994. 2, 

Configuration, Design, Analysis, and Testing. NASA CP-1999-209699. 

Hampton, VA: Langley Research Center, December 1999.

McLean, F. Edward. Supersonic Cruise Technology. NASA SP-472. 

Washington, DC: NASA, 1985.

McLucas, John L., Kenneth J. Alnwick, and Lawrence R. Benson. Reflections 

of a Technocrat: Managing Defense, Air, and Space Programs During the 

Cold War. Montgomery, AL: Air University Press, 2006.

Merlin, Peter W. From Archangel to Senior Crown: Design and Development of 

the Blackbird. Reston, VA: AIAA, 2008.

National Research Council. Commercial Supersonic Technology: The Way 

Ahead. Washington, DC: National Academies Press, 2001.

National Research Council. Recapturing NASA’s Aeronautics Flight Research 

Capabilities. Washington, DC: National Academies Press, 2012.

National Research Council. U.S. Supersonic Aircraft: Assessing NASA’s HighSpeed Research Program. Washington, DC: National Academies Press, 

1997.

Neufeld, Michael J. Von Braun: Dreamer of Space, Engineer of War. New 

York: Alfred A. Knopf, 2007.

Rochester, Stuart I. Takeoff at Mid-Century: Federal Civil Aviation Policy in 

the Eisenhower Years, 1953–1961. Washington, DC: FAA, 1976.
306

Quieting the Boom

Rumerman, Judy A. NASA Historical Data Book Volume VI: NASA Space 

Applications, Aeronautics, Space Research and Technology, Tracking and 

Data Acquisition/Space Operations, Commercial Programs, and Resources, 

1979–1988. NASA SP-2000-4012. Washington, DC: NASA, 2000.

Schwartz, Ira R., ed. Second Conference on Sonic Boom Research: Proceedings 

of a Conference Held at the National Aeronautics and Space Administration, 

Washington, DC, May 9–10, 1968. NASA SP-180. Washington, DC: 

NASA, 1968.

Schwartz, Ira R., ed. Third Conference on Sonic Boom Research: Proceedings of 

a Conference Held at the National Aeronautics and Space Administration, 

Washington, DC, October 29–30, 1970. NASA SP-255. Washington, 

DC: NASA, 1971.

Seebass, A. Richard, ed. Sonic Boom Research: Proceedings of a Conference 

Held at the National Aeronautics and Space Administration, Washington, 

DC, April 12, 1967. NASA SP-147. Washington, DC: NASA, 1967.

Stillwell, Wendell H. X-15 Research Results. NASA SP-60. Washington, DC: 

NASA, 1965.

Wallace, Lane E. Flights of Discovery: Sixty Years of Flight Research at Dryden 

Flight Research Center. NASA SP-2006-4318. Washington, DC: NASA, 

2006.

Ward, Bob. Dr. Space: The Life of Wernher von Braun. Annapolis, MD: Naval 

Institute, 2005.

Whitehead, Allen H., ed. First Annual High-Speed Research Workshop; 

Proceedings of a Workshop Sponsored by the National Aeronautics and Space 

Administration, Washington, DC, and Held in Williamsburg, Virginia, 

May 14–16, 1991. 4 parts. NASA CP-10087. Hampton, VA: Langley 

Research Center, 1992.

Wolfe, Tom. The Right Stuff. New York: Bantam Books, 1980.

Yeager, Chuck, and Leo Janis. Yeager. New York: Bantam Books, 1985.
307

Selected Bibliography

Reports, Papers, Presentations, and Articles1

Aboulafia, Richard. “The Business Case for Higher Speed.” Aerospace 

America Online. Accessed July 8, 2011, http://www.aiaa.org/aerospace/

Article.cfm?issuetocid=ArchiveIssueID=16.

Alford, William J., and Cornelius Driver. “Recent Supersonic Transport 

Research.” Astronautics & Aeronautics 2, no. 9 (September 1964): 26–37.

Anderson, John D. “NASA and the Evolution of Computational Fluid 

Dynamics.” In Hallion, NASA’s Contributions to Aeronautics 1, 431–434.

Anderson, Robert E. “First Annual HSR Program Workshop: Headquarters 

Perspective.” In Whitehead, 1991 HSR Workshop, 3–24.

Andrews, William H. “Summary of Preliminary Data Derived from the 

XB-70 Airplanes.” NASA TM X-1240 (June 1966).

Anselmo, Joseph C., and William Garvey. “Prolonged Pain: Honeywell’s 

Bizjet Forecast Corks Any Premature Celebration.” Aviation Week, 

October 10, 2011, 54–55.

Bahm, Catherine M., and Edward A. Haering. “Ground-Recorded Sonic 

Boom Signatures of F/A-18 Aircraft in Formation Flight.” In Baize, 1995 

Sonic Boom Workshop 1, 220–243.

Baize, Donald G., Peter G. Coen, Chris S. Domack, James A. Fenbert, Karl 

A. Geiselhart, Marcus O. McElroy, Kathy E. Needleman, and Lori P. 

Ozororski. “A Performance Assessment of Eight Low-Boom High-Speed 

Civil Transport Concepts.” In McCurdy, 1994 Sonic Boom Workshop: 

Configuration Design, Analysis, and Testing, 149–170.

Banke, Jim. “Quieter Flight: A Balancing Act.” Aerospace America, March 

2011, 38–43.

Barger, Raymond L. “Sonic-Boom Wave-Front Shapes and Curvatures 

Associated with Maneuvering Flight.” NASA TP-1611 (December 

1979).

 1. See notes for additional magazine and newspaper articles, news releases, and similar sources.
308

Quieting the Boom

Barger, Raymond L., W.D. Beasley, and J.D. Brooks. “Laboratory 

Investigation of Diffraction and Reflection of Sonic Booms by 

Buildings.” NASA TN D-5830 (June 1970).

Beasly, W.D., J.D. Brooks, and R.L. Barger. “A Laboratory Investigation of 

N-Wave Focusing.” NASA TN D-5306 (July 1969).

Beissner, F.L. “Application of Near-Term Technology to a Mach 2.0 Variable 

Sweep Wing Supersonic Cruise Executive Jet.” NASA CR-172321 

(March 1984).

Beissner, F.L. “Effects of Emerging Technology on a Convertible, Business/

Interceptor, Supersonic Cruise Jet.” NASA CR-178097 (May 1986).

Beissner, F.L., W.A. Lovell, A. Warner Robins, and E.E. Swanson. “Effects 

of Advanced Technology and a Fuel-Efficient Engine on a SupersonicCruise Executive Jet with a Small Cabin.” NASA CR-172190 (August 

1983).

Bishop, Dwight E. “Noise and Sonic Boom Impact Technology: PCBOOM 

Computer Program for Sonic Boom Research Technical Report” 1. 

HSD-TR-88-014 (October 1988).

Bloom, A.J., G. Kost, J. Prouix, and R.L. Sharpe, “Response of Structures 

to Sonic Booms Produced by XB-70, B-58, and F-104 Aircraft...at 

Edwards Air Force Base, Final Report,” NSBEO 2-67 (October 1967).

Bobbitt, Percy J. “Application of Computational Fluid Dynamics and 

Laminar Flow Technology for Improved Performance and Sonic Boom 

Reduction.” In Darden, 1992 Sonic Boom Workshop 2, 137–144.

Bobbitt, Percy J., and Domenic Maglieri. “Dr. Antonio Ferri’s Contribution 

to Supersonic Transport Sonic-Boom Technology.” Journal of Spacecraft 

and Rockets 40, no. 4 (July–August 2003): 459–466.

Boeing Commercial Airplanes. “High-Speed Civil Transport Study; Final 

Report.” NASA CR-4234 (September 1989).

Borsky, Paul M. “Community Reactions to Sonic Booms in the Oklahoma 

City Area” 2, “Data on Community Reactions and Interpretations.” 

USAF Aerospace Medical Research Laboratory (August 1965). http://
309

Selected Bibliography

www.norc.org/NR/rdonlyres/255A2AA2-B953-4305-9AD0-B8ABCC824FA9/0/NORCRpt_101B.pdf.

Brain, Marshall. “How Stereolithography 3-D Layering Works.” Accessed 

July 30, 2011, http://computer.howstuffworks.com/stereolith.htm.

Bruner, H.S. “SSBJ—A Technological Challenge.” ICAO Journal 46, no. 8 

(August 1991): 9–13.

Bui, Trong T. “CFD Analysis of Nozzle Jet Plume Effects on Sonic Boom 

Signature.” AIAA paper no. 2009-1054 (January 2009).

Busemann, Adolf. “Sonic Boom Reduction.” In Seebass, Sonic Boom 

Research: Proceedings of a Conference, 79–82.

Carlson, Harry W. “An Investigation of Some Aspects of the Sonic Boom by 

Means of Wind-Tunnel Measurements of Pressures about Several Bodies 

at a Mach Number of 2.01.” NASA TN D-161 (December 1959).

Carlson, Harry W. “Configuration Effects on Sonic Boom.” In NASA 

Langley, “Proceedings of NASA Conference on SST Feasibility.” 381–

398 (December 1963).

Carlson, Harry W. “Correlation of Sonic-Boom Theory with Wind Tunnel 

and Flight Measurements.” NASA TR-R-213 (December 1964).

Carlson, Harry W. “Experimental and Analytical Research on Sonic Boom 

Generation at NASA.” In Seebass, Sonic Boom Research: Proceedings of a 

Conference, 9–23.

Carlson, Harry W. “Simplified Sonic-Boom Prediction.” NASA TP-1122 

(March 1978).

Carlson, Harry W. “Some Notes on the Status of Sonic Boom Prediction 

and Minimization Research.” In Schwartz, Third Conference on Sonic 

Boom Research, 395–400.

Carlson, Harry W. “The Lower Bound of Attainable Sonic-Boom 

Overpressure and Design Methods of Approaching This Limit.” NASA 

TN D-1494 (October 1962).
310

Quieting the Boom

Carlson, Harry W. “Wind Tunnel Measurements of the Sonic-Boom 

Characteristics of a Supersonic Bomber Model and a Correlation with 

Flight-Test Ground Measurements.” NASA TM X-700 (July 1962).

Casper, J.H., S.E. Cliff, D.A. Durston, M.S. McMullen, J.E. Melton, 

M.A. Park, and S.D. Thomas. “Assessment of Near-Field Sonic Boom 

Simulation Tools.” AIAA paper no. 2008-6592 (August 2008).

Cheung, Samsun, and Thomas A. Edwards. “Supersonic Airplane Design 

Optimization Method for Aerodynamic Performance and Low Sonic 

Boom.” In Darden, 1992 Sonic Boom Workshop 2, 31–44.

Cheung, Samsun. “Supersonic Civil Airplane Study and Design: 

Performance and Sonic Boom.” NASA CR-197745 (January 1995).

Clark, Buhr, and Nexen (company name). “Studies of Sonic Boom 

Damage.” NASA CR-227 (May 1965).

Clark, Evert. “Reduced Sonic Boom Foreseen for New High-Speed Airliner.” 

New York Times, January 14, 1965, 7, 12.

Cleveland, Robin O., David T. Blackstock, and Mark F. Hamilton. “Effect 

of Stratification and Geometrical Spreading on Sonic Boom Rise Time.” 

In McCurdy, 1994 Sonic Boom Workshop: Configuration, Design, Analysis, 

and Testing, 19–38.

Cliatt, Larry J., Trong Bui, and Edward A. Haering. “Overview of the 

LaNCETS Flight Experiment and CFD Analysis.” PowerPoint presentation. Fundamental Aeronautics Annual Meeting, Atlanta, GA, October 

2, 2008.

Cliff, Susan E. “Computational/Experimental Analysis of Three Low Sonic 

Boom Configurations with Design Modifications.” In Darden, 1992 

Sonic Boom Workshop 2, 89–118.

Cliff, Susan E., Timothy J. Baker, and Raymond M. Hicks. “Design 

and Computational/Experimental Analysis of Low Sonic Boom 

Configurations.” In McCurdy, 1994 Sonic Boom Workshop: Configuration 

Design, Analysis, and Testing, 33–57.
311

Selected Bibliography

Coen, Peter G. “Development of a Computer Technique for Prediction 

of Transport Aircraft Flight Profile Sonic Boom Signatures.” NASA 

CR-188117 (March 1991).

Coen, Peter G. “Fixing the Sound Barrier: Three Generations of U.S. 

Research into Sonic Boom Reduction...and What It Means to the 

Future.” PowerPoint presentation. FAA Public Meeting on Advanced 

Technologies and Supersonics, Washington, DC, July 14, 2011.

Coen, Peter G. “Fundamental Aeronautics Program Supersonics Project.” 

PowerPoint presentation. Fundamental Aeronautics Technical 

Conference, Cleveland, OH, March 15–17, 2011.

Coen, Peter G. “Fundamental Aeronautics Program Supersonics Project.” 

PowerPoint presentation. Fundamental Aeronautics Technical 

Conference, Cleveland, OH, March 13–15, 2012.

Coen, Peter G. “Supersonic Vehicles Technology: Sonic Boom Technology 

Development and Demonstration.” PowerPoint presentation. FAA Civil 

Supersonic Aircraft Technical Workshop, Arlington, VA, November 13, 

2003.

Coen, Peter G. “Supersonics Program Overview.” PowerPoint presentation. 

NASA Fundamental Aeronautics Annual Meeting, New Orleans, LA, 

October 30, 2007.

Coen, Peter G. (for Kevin P. Shepherd). “Human Response to Sonic 

Booms.” PowerPoint presentation, FAA Civil Supersonic Aircraft 

Technical Workshop, Arlington, VA, November 13, 2003.

Coen, Peter G., and Roy Martin. “Fixing the Sound Barrier,” PowerPoint 

presentation. Experimental Aircraft Assoc. AirVenture, Oshkosh, WI, 

July 2004.

Coen, Peter G., David H. Graham, Domenic J. Maglieri, and Joseph W. 

Pawlowski. “QSP Shaped Sonic Boom Demo.” PowerPoint presentation. 

43rd AIAA Aerospace Sciences Meeting, Reno, NV, January 10, 2005.

Coen, Peter G., David H. Graham, Domenic J. Maglieri, and Joseph W. 

Pawlowski. “Origins and Overview of the Demonstration Program.” 
312

Quieting the Boom

PowerPoint presentation. 43rd AIAA Aerospace Sciences Meeting, Reno, 

NV, January 10, 2005.

Coen, Peter G., Lou Povinelli, and Kas Civinskas, “Supersonics Program 

Overview.” PowerPoint presentation. NASA Fundamental Aeronautics 

Program Annual Meeting, Atlanta, GA, October 7–9, 2008.

Coen, Peter G., Mary Jo Long-Davis, and Louis Povinelli. “Fundamental 

Aeronautics Program Supersonics Project, Reference Document.” May 

26, 2006. Accessed March 15, 2009, http://www.aeronautics.nasa.gov/fap/

documents/html.

Cole, M.J., and M.B. Freeman. “Analysis of Multiple Scattering of Shock 

Waves by a Turbulent Atmosphere.” In Schwartz, Third Conference on 

Sonic Boom Research, 67–74.

Collogan, David. “Manufacturers, NASA, Working on BizJet Sonic Boom 

Project.” Aviation Week, July 18, 2005. http://www.aviationweek.com/aw/

generic/story_generic.jsp?channel=businessweekly&id=news/SONB07185.

xml&headline=Manufacturers,%20NASA%20Working%20On%20

Bizjet%20Sonic%20Boom%20Project.

Collogan, David. “Two Groups Vie To Develop Supersonic Business Jets,” 

Aviation Week, October 18, 2004. http://www.aviationweek.com/aw/

generic/story_generic.jsp?channel=businessweekly&id=news/SUPER10184.

xml.

Covault, Craig. “NASA Advances Supersonic Technology.” Aviation Week

(January 10, 1977): 16–18.

Cowart, Robbie. “Supersonic Technology Development.” PowerPoint 

presentation. FAA Public Meeting on Advanced Technologies and 

Supersonics, Washington, DC, July 14, 2011.

Creech, Gray. “Getting Loud Now: Enjoy Peace and Quiet Then.” Dryden 

Flight Research Center, May 27, 2011. http://www.nasa.gov/centers/

dryden/Features/scamp.html.

Creech, Gray. “ICAO Team Witnesses Sonic Boom Research Flights.” 

Dryden Flight Research Center, September 29, 2009. http://www.nasa.

gov/centers/dryden/Features/icao_sonic_booms.html.
Selected Bibliography

313

Creech, Gray. “Supersonic Diving: Quieting the Boom.” Dryden Flight 

Research Center, June 18, 2009. http://www.nasa.gov/centers/dryden/

Features/sonicbobs.html.

Croft, John. “Engineering through the Sound Barrier.” Aerospace America

42, no. 9 (September 2004): 24–31. 

Cumming, Stephen B., Michael A. Frederick, and Mark S. Smith. 

“Aerodynamic Effects of a 24-foot Multi-segmented Telescoping Nose 

Boom on an F-15B Airplane.” NASA TM-2008-214634 (April 2008). 

Also published as AIAA paper no. 2007-6638 (August 2007).

Cunningham, Aimee. “Sonic Booms and Human Ears: How Much Can 

the Public Tolerate?” Popular Science, July 30, 2004. www.popsci.com/

military-aviation-space/article/2004-07/sonic-booms-and-human-ears.

Dahlke, Hugo E., G.T. Kantarges, T.E. Siddon, and J.J. Van Houten. “The 

Shock-Expansion Tube and Its Application as a Sonic Boom Simulator.” 

NASA CR-1055 (June 1968).

Darden, Christine M. “Affordable/Acceptable Supersonic Flight: Is It Near?” 

40th Aircraft Symposium, Japan Society for Aeronautical and Space 

Sciences (JSASS), Yokohama (October 2002).

Darden, Christine M. “Charts for Determining Potential Minimum SonicBoom Overpressures for Supersonic Cruise Aircraft.” NASA TP-1820 

(May 1981).

Darden, Christine M. “Minimization of Sonic-Boom Parameters in Real 

and Isothermal Atmospheres.” NASA TN D-7842 (March 1975).

Darden, Christine M. “Progress in Sonic-Boom Understanding: Lessons 

Learned and Next Steps.” In McCurdy, 1994 Sonic Boom Workshop, 

Configuration, Design, and Testing, 269–292.

Darden, Christine M. “Sonic Boom Minimization with Nose-Bluntness 

Relaxation.” NASA TP-1348 (January 1979).

Darden, Christine M. “Sonic Boom Theory—Its Status in Prediction and 

Minimization.” AIAA paper no. 76-1 (January 1976).
314

Quieting the Boom

Darden, Christine M., and Robert J. Mack. “Current Research in SonicBoom Minimization.” In Driver, Proceedings of the SCAR Conference

(1976), pt. 1, 525–541. 

Darden, Christine M., Robert J. Mack, Kathy E. Needleman, Daniel G. 

Baize, Peter G. Coen, Raymond L. Barger, N. Duane Melson, Mary 

S. Adams, Elwood W. Shields, and Marvin E. McGraw. “Design and 

Analysis of Low Boom Concepts at Langley Research Center.” In 

Whitehead, 1991 HSR Workshop, pt. 2, 673–700.

DeMeis, Richard. “Sukhoi and Gulfstream Go Supersonic.” Aerospace 

America 28, no. 4 (April 1990): 40–42.

Dornheim, Michael A. “Will Low Boom Fly? NASA Cutbacks Delay Flight 

Test of Shaped Demonstrator, But Work on It Continues.” Aviation Week

(November 7, 2005): 68–69.

Douglas Aircraft Company. “1989 High-Speed Civil Transport Studies.” 

NASA CR-4375 (May 1991).

Downing, J. Micah. “Lateral Spread of Sonic Boom Measurements from 

U.S. Air Force Boomfile Flight Tests.” In Darden, 1992 Sonic Boom 

Workshop 1, 117–136.

Downing, J. Micah, Noel Zemat, Chris Moss, Daniel Wolski, E. Chung 

Sukhway, Kenneth Plotkin, and Domenic Maglieri. “Measurement of 

Controlled Focused Sonic Booms from Maneuvering Aircraft.” Journal of 

the Acoustical Society of America 104, no. 1 (July 1998): 112–121.

Dumond, J.W.M., E.R. Cohen, W.K.H. Panfsky, and E. Deeds. “A 

Determination of the Wave Forms and Laws of Propagation and 

Dissipation of Ballistic Shock Waves,” Journal of the Acoustical Society of 

America 18, no. 1 (January 1946): 97–118.

Edge, Philip M., and Harvey H. Hubbard. “Review of Sonic Boom 

Simulation Devices and Techniques,” Journal of the Acoustical Society of 

America 51, no. 2, pt. 3 (February 1972): 724–728.

Edge, Philip M., and William H. Mayes. “Description of Langley LowFrequency Noise Facility and Study of Human Response to Noise 

Frequencies Below 50 cps.” NASA TN D-3204 (January 1966).
315

Selected Bibliography

Edwards, Thomas A., Raymond Hicks, Samson Cheung, Susan CliffHovey, Mike Madison, and Joel Mendoza. “Sonic Boom Prediction and 

Minimization Using Computational Fluid Dynamics.” In Whitehead, 

1991 HSR Workshop, pt. 2, 721–738.

FAA, “Civil Aircraft Sonic Boom,” Federal Register 35, no. 4 (April 16, 

1970): 6189–6190.

Ferri, Antonio, and Ahmed Ismail. “Analysis of Configurations.” In 

Schwartz, Second Conference on Sonic Boom Research, 73–88.

Ferri, Antonio, Huai-Chu Wang, and Hans Sorensen. “Experimental 

Verification of Low Sonic Boom Configuration.” NASA CR-2070 (June 

1973).

Ferri, Antonio. “Airplane Configurations for Low Sonic Boom.” In 

Schwartz, Third Conference on Sonic Boom Research, 255–276.

Fields, James M. “Reactions of Residents to Long-Term Sonic Boom Noise 

Environments,” NASA CR-201704 (June 1997).

Fields, James M., Carey Moulton, Robert M. Baumgartner, and Jeff 

Thomas. “Residents’ Reactions to Long-Term Sonic Boom Exposure: 

Preliminary Results.” In McCurdy, 1994 Sonic Boom Workshop: 

Atmospheric Propagation and Acceptability, 209–217.

Findley, Donald S. “Vibration Responses of Test Structure no. 2 during 

the Edwards AFB Phase of the National Sonic Boom Program,” NASA 

TM-X-72704 (June 1975).

Findley, Donald S., Vera Huckel, and Herbert R. Henderson. “Vibration 

Responses of Test Structure no. 1 During the Edwards AFB Phase of the 

National Sonic Boom Program,” NASA TM-X-72706 (June 1975).

Flynn, Edward O. “Lowering the Boom on Supersonic Flight Noise.” 

Aerospace America 40, no. 2 (February 2002): 20–21.

Francombe, R. “LTM—A Flexible Processing Technology for Polymer 

Composite Structures.” Paper presented at NATO Research and 

Technology Organization (RTO) Applied Vehicle Technology (AVT) 

specialists meeting on low-cost composite structures, Loen, Norway, 
316

Quieting the Boom

May 7–11, 2001. Accessed August 28, 2011. ftp.rta.nato.int/public//

PubFullText/RTO/...///MP-069(II)-(SM1)-12.pdf.

Friedman, M.P., E.J. Kane, and A. Sigalla. “Effects of Atmosphere and 

Aircraft Motion on the Location and Intensity of a Sonic Boom.” AIAA 

Journal 1, no. 6 (June 1963): 1327–1335.

Fryer, B.A., “Publications in Acoustics and Noise Control from the NASA 

Langley Research Center During 1940–1976.” NASA TM X-7402 (July 

1977).

Gardner, John H., and Peter H. Rogers. “Thermospheric Propagation of 

Sonic Booms from the Concorde Supersonic Transport.” Naval Research 

Laboratory Memo Report 3904 (February 1979).

George, Albert R. “Lower Bounds for Sonic Booms in the Midfield.” AIAA 

Journal 7, no. 8 (August 1969): 1542–1545. 

George, Albert R. “The Effects of Atmospheric Inhomogeneities on Sonic 

Boom.” In Schwartz, Third Conference on Sonic Boom Research, 33–58.

George, Albert R. “The Possibilities for Reducing Sonic Booms by Lateral 

Redistribution.” In Seebass, Sonic Boom Research: Proceedings of a 

Conference, 83–93.

George, Albert R., and R. Seebass. “Sonic Boom Minimization Including 

Both Front and Rear Shocks.” AIAA Journal 9, no. 10 (October 1971): 

2091–2093.

George, Albert R., and R. Seebass. “Sonic-Boom Minimization,” Journal 

of the Acoustical Society of America 51, no. 2, pt. 3 (February 1972): 

686–694. 

Gill, Peter M. “Nonlinear Acoustic Behavior at a Caustic.” Ph.D. thesis. 

Cornell University, June 1974.

Graham, David H. “Shaped Sonic Boom Demonstrator Program.” 

PowerPoint presentation. FAA Civil Supersonic Aircraft Technical 

Workshop, Arlington, VA, November 13, 2003.
317

Selected Bibliography

Graham, David H., and Roy Martin. “Aerodynamic Design and Validation 

of SSBD Aircraft.” Northrop Grumman Corp. PowerPoint presentation. 

Shaped Sonic Boom Experiment Closeout Workshop, NASA Langley 

Research Center, Hampton, VA, August 17, 2004.

Graham, David H., John A. Dahlin, Juliet A. Page, Kenneth J. Plotkin, 

and Peter G. Coen. “Wind Tunnel Validation of Shaped Sonic Boom 

Demonstration Aircraft Design.” AIAA paper no. 2005-7 (January 

2005).

Graham, David H., John A. Dahlin, Keith B. Meredith, and Jay L. Vadnais, 

“Aerodynamic Design of Shaped Sonic Boom Demonstration Aircraft.” 

AIAA paper no. 2005-8 (January 2005).

Green, Karen S., and Terrill W. Putnam. “Measurements of Sonic Booms 

Generated by an Airplane Flying at Mach 3.5 and 4.8.” NASA TM 

X-3126 (October 1974).

Greene, Randall, and Richard Seebass. “A Corporate Supersonic Transport.” 

In Huebner et al., Transportation Beyond 2000: Technologies Needed for 

Engineering Design, Proceedings of a Workshop Held in Hampton, Virginia, 

September 26–28, 1995. Pt. 1. NASA CP-10184 (February 1996), 

491–508.

Guiraud, J.P. “Focalization in Short Non-Linear Waves,” NASA Technical 

Translation F-12,442 (September 1969).

Haering, Edward A., and James E. Murray. “Shaped Sonic Boom 

Demonstration/Experiment Airborne Data: SSBD Final Review.” 

PowerPoint presentation. Shaped Sonic Boom Experiment Closeout 

Workshop. NASA Langley Research Center, Hampton, VA, August 17, 

2004.

Haering, Edward A., James E. Murray, Dana D. Purifoy, David H. Graham, 

Keith B. Meredith, Christopher E. Ashburn, and Lt. Col. Mark Stucky. 

“Airborne Shaped Sonic Boom Demonstration Pressure Measurements 

with Computational Fluid Dynamics.” AIAA paper no. 2005-9 (January 

2005).

Haering, Edward A., James W. Smolka, James E. Murray, and Kenneth 

J. Plotkin. “Flight Demonstration of Low Overpressure N-Wave 
318

Quieting the Boom

Sonic Booms and Evanescent Waves.” Presented at 17th International 

Symposium on Nonlinear Acoustics. International Sonic Boom Forum, 

State College, PA, July 21–22, 2005.

Haering, Edward A., Jr., and James E. Murray. “Shaped Sonic Boom 

Demonstration/Experiment Airborne Data SSBD Final Review.” 

PowerPoint presentation. NASA Langley Research Center, Hampton, 

VA, August 17, 2004.

Haering, Edward A., L.J. Ehernberger, and Stephen A. Whitmore. 

“Preliminary Airborne Experiments for the SR-71 Sonic Boom 

Propagation Experiment.” In Baize, 1995 Sonic Boom Workshop 1, 

176–198.

Haering, Edward A., Larry J. Cliatt, Thomas J. Bunce, Thomas B. 

Gabrielson, Victor W. Sparrow, and Lance L. Locey. “Initial Results from 

the Variable Intensity Sonic Boom Propagation Database.” AIAA paper 

no. 2008-3034 (May 2008).

Haering, Edward A., Stephen A. Whitmore, and L.J. Ehernberger. 

“Measurement of the Basic SR-71 Airplane Near-Field Signature.” In 

McCurdy, 1994 Sonic Boom Workshop: Configuration, Design, Analysis, 

and Testing, 171–197.

Hagerman, Eric. “All Sonic, No Boom.” Popular Science, March 2007. http://

www.popsci.com/military-aviation-space/article/2007-03/all-sonic-no-boom.

Haglund, George T. “HSCT Designs for Reduced Sonic Boom.” AIAA 

paper no. 91-3103 (September 1991).

Haglund, George T., and Edward J. Kane. “Flight Test Measurements and 

Analysis of Sonic Boom Phenomena Near the Shock Wave Extremity.” 

NASA CR-2167 (February 1973).

Haglund, George T., and Steven S. Ogg. “Two HSCT Mach 1.7 Low Sonic 

Boom Designs.” In Darden, 1992 Sonic Boom Workshop 2, 65–88.

Hailey, Albion B. “AF Expert Dodges Efforts To Detail ‘Sonic Boom’ Loss.” 

Washington Post, August 25, 1960, A15.
319

Selected Bibliography

Hallion, Richard P. “Richard Whitcomb’s Triple Play.” Air Force Magazine

93, no. 2 (February, 2010): 68–72.

Hartwich, Peter M., Billy A. Burroughs, James S. Herzberg, and Curtiss 

D. Wiler. “Design Development Strategies and Technology Integration 

for Supersonic Aircraft of Low Perceived Sonic Boom.” AIAA paper no. 

2003-0556 (January 2003).

Hayes, Wallace, and Rudolph C. Haefeli. “The ARAP Sonic Boom 

Computer Program.” In Schwartz, Second Conference on Sonic Boom 

Research, 151–158.

Hayes, Wallace, Rudolph C. Haefeli, and H.E. Kulsrud. “Sonic Boom 

Propagation in a Stratified Atmosphere with Computer Program.” NASA 

CR-1299 (April 1969).

Hayes, Wallace. “Brief Review of the Basic Theory,” Journal of the Acoustical 

Society of America 39, no. 5, pt. 2 (November 1966): 3–6.

Henne, Preston A. “Case for a Small Supersonic Civil Aircraft.” Journal of 

Aircraft 42, no. 3 (May–June 2005): 765–774.

Heppenheimer, T.A. “The Boom Stops Here.” Air & Space Magazine, 

October–November 2005. http://www.airspacemag.com/flight-today/boom.

html.

Herbert, Adam J. “Long-Range Strike in a Hurry.” Air Force Magazine 87, 

no. 11 (November 2004): 27–31.

Hicks, Raymond M., and Joel P. Mendoza. “Prediction of Sonic Boom 

Characteristics from Experimental Near Field Results.” NASA TM-X1477 (November 1967).

Higgins, Thomas H. “Sonic Boom Research and Design Considerations in 

the Development of a Commercial Supersonic Transport.” Journal of the 

Acoustical Society of America 39, no. 5, pt. 2 (November 1966): 526–531.

Hilton, David A., D.J. Maglieri, and N.J. McLeod. “Summary of Variations 

of Sonic Boom Signatures Resulting from Atmospheric Effects.” NASA 

TM-X-59633 (February 1967).
320

Quieting the Boom

Hilton, David A., D.J. Maglieri, and R. Steiner. “Sonic-Boom Exposures 

During FAA Community Response Studies over a 6-Month Period in the 

Oklahoma City Area.” NASA-TN-D-2539 (December 1964).

Hilton, David A., Harvey. H. Hubbard, Vera Huckel, and Domenic J. 

Maglieri. “Ground Measurements of Sonic-Boom Pressures for the 

Altitude Range of 10,000 to 75,000 Feet.” NASA TR R-198 (July 1964).

Hilton, David A., Vera Huckel, and Domenic J. Maglieri. “Sonic Boom 

Measurements During Bomber Training Operations in the Chicago 

Area.” NASA TN D-3655 (October 1966).

Hoffman, Sherwood. “Bibliography of Supersonic Cruise Aircraft Research 

(SCAR)” [1972-77]. NASA RP-1003 (November 1977).

Hoffman, Sherwood. “Bibliography of Supersonic Cruise Research (SCR) 

Program from 1977 to Mid-1980.” NASA RP-1063 (December 1980).

Holloway, P.F., G.A. Wilhold, J.H. Jones, F. Garcia, and R.M. Hicks. 

“Shuttle Sonic Boom—Technology and Predictions.” AIAA paper no. 

73-1039 (October 1973).

Howe, Donald C., Frank Simmons, and Donald Freund. “Development of 

the Gulfstream Quiet Spike for Sonic Boom Minimization.” AIAA paper 

no. 2008-124 (January 2008).

Hubbard, Harvey H., and Domenic J. Maglieri. “Factors Affecting 

Community Acceptance of the Sonic Boom.” In NASA Langley, 

“Proceedings of NASA Conference on SST Feasibility.” December 1963, 

399–412.

Hubbard, Harvey H., and Domenic J. Maglieri. “Sonic Boom Signature 

Data from Cruciform Microphone Array Experiments During the 

1966–67 EAFB National Sonic Boom Evaluation Program.” NASA TN 

D-6823 (May 1972).

Hubbard, Harvey H., Domenic J. Maglieri, and David G. Stephens. “Sonic 

Boom Research—Selected Bibliography with Annotation.” NASA TM 

87685 (September 1986).
321

Selected Bibliography

Huber, Mark. “Mach 1 for Millionaires.” Air & Space Magazine, March–

April 2006. http://www.airspacemag.com/flight-today/millionaire.html.

Jones, L.B. “Lower Bounds for Sonic Bang in the Far Field.” Aeronautical 

Quarterly 18, pt. 1 (February 1967): 1–21.

Jones, L.B. “Lower Bounds for Sonic Bangs.” Journal of the Royal 

Aeronautical Society 65, no. 606 (June 1961): 433–436.

Jones, L.B. “Lower Bounds for the Pressure Jump of the Bow Shock of a 

Supersonic Transport.” Aeronautical Quarterly 21 (February 1970): 1–17.

Jones, Stacy V. “Sonic Boom Researchers Use Simulator,” New York Times, 

May 10, 1969, 37, 41.

Jordan, Gareth H. “Flight Measurements of Sonic Booms and Effects of 

Shock Waves on Aircraft.” Society of Experimental Test Pilots Quarterly 

Review 5, no. 1 (1961): 117–131.

Kamran Fouladi. “CFD Predictions of Sonic-Boom Characteristics for 

Unmodified and Modified SR-71 Configurations.” In McCurdy, 1994 

Sonic Boom Workshop: Configuration, Design, Analysis, and Testing, 

219–235.

Kane, Edward J. “A Study to Determine the Feasibility of a Low Sonic 

Boom Supersonic Transport.” AIAA paper no. 73-1035 (October 1973).

Kane, Edward J. “Some Effects of the Atmosphere on Sonic Boom.” In 

Seebass, Sonic Boom Research: Proceedings of a Conference, 49–64

Keefe, Fred, and Grover Amen. “Boom.” The New Yorker, May 16, 1962, 

33–34.

Kerr, Richard. “East Coast Mystery Booms: Mystery Gone but Booms 

Linger On.” Science 203, no. 4337 (January 19, 1979): 256.

Kinney, Jeremy. “NASA and the Evolution of the Wind Tunnel.” In Hallion, 

NASA’s Contributions to Aeronautics 2, 310–365.

Klinger, R.T. “YF-12A Flight Test Sonic Boom Measurements.” Lockheed 

Advanced Development Projects Report SP-815 (June 1965).
322

Quieting the Boom

Klos, Jacob, and R.D. Bruel. “Vibro-Acoustical Response of Buildings Due 

to Sonic Boom Exposure: June 2006 Field Test.” NASA TM 2007-

214900 (September 2007).

Klos, Jacob. “Vibro-Acoustic Response of Buildings Due to Sonic Boom 

Exposure: July 2007 Field Test.” NASA TM-2008-215349 (September 

2008).

Komadina, Steve. “Quiet Supersonic Platform (QSP).” PowerPoint presentation. FAA Civil Supersonic Aircraft Technical Workshop, Arlington, VA, 

November 13, 2003.

Kroo, Ilan, and Alex VanDerVelden. “The Sonic Boom of an Oblique Flying 

Wing.” AIAA paper no. 90-4002 (October 1990).

Kroo, Ilan. “Sonic Boom of the Oblique Flying Wing.” Journal of Aircraft

31, no. 1 (January–February 1994): 19–25.

Lee, Christopher A. “Design and Testing of Low Sonic Boom 

Configurations and an Oblique All-Wing Supersonic Transport.” NASA 

CR-197744 (February 1995).

Lee, Robert E., and J. Micah Downing. “Boom Event Analyzer Recorder: 

the USAF Unmanned Sonic Boom Monitor.” AIAA paper no. 93-4431 

(October 1993).

Levine, Jay. “Lowering the Boom.” X-Press, July 29, 2005. http://www.nasa.

gov/centers/dryden/news/X-Press/stories/2005/072905.

Lina, Lindsay J., and Domenic J. Maglieri. “Ground Measurements of 

Airplane Shock-Wave Noise at Mach Numbers to 2.0 and at Altitudes to 

60,000 Feet.” NASA TN-D-235 (March 1960).

Lipkens, Bart, and David T. Blackstock. “Model Experiments to Study 

the Effects of Turbulence on Risetime and Waveform of N Waves.” In 

Darden, 1992 Sonic Boom Workshop 1, 97–108.

Lomax, Harvard. “Preliminary Investigation of Flow Field Analysis 

on Digital Computers with Graphic Display.” In Schwartz, Second 

Conference on Sonic Boom Research, 67–72.
323

Selected Bibliography

Lundberg, B.K.O. “Aviation Safety and the SST.” Astronautics and 

Aeronautics 3, no. 1 (January 1966): 25–30.

Lung, J.L., B. Tiegerman, N.J. Yu, and A.R. Seebass. “Advances in Sonic 

Boom Theory.” In Aerodynamic Analyses Requiring Advanced Computers, 

pt. 2, 1033–1047.

Lux, David, L.J. Ehernberger, Timothy R. Moes, and Edward A. Haering. 

“Low-Boom SR-71 Modified Signature Demonstration Program.” In 

McCurdy, 1994 Sonic Boom Workshop: Configuration, Design, Analysis and 

Testing, 237–248.

MacDonald, G.J., S.M. Flatte, R.L. Garwin, and F.W. Perkins. “Jason 1978 

Sonic Boom Report.” SRI International, Arlington, VA. JSR-78-09 

(November 1978).

Mack, Robert J. “A Whitham-Theory Sonic-Boom Analysis of the TU-144 

Aircraft at Mach Number of 2.2.” In McCurdy, 1995 Sonic Boom 

Workshop 2, 1–16. 

Mack, Robert J. “Wind-Tunnel Overpressure Signatures from a Low-Boom 

HSCT Concept with Aft-Mounted Engines.” In McCurdy, 1994 Sonic 

Boom Workshop: Configuration Design, Analysis, and Testing, 59–70.

Mack, Robert J., and Christine M. Darden. “Limitations on WindTunnel Pressure Signature Extrapolation.” In Darden, 1992 Sonic Boom 

Workshop, 2, 201–220.

Mack, Robert J., and Christine M. Darden. “Some Effects of Applying 

Sonic Boom Minimization to Supersonic Cruise Aircraft Design.” AIAA 

paper no. 79-0652 (March 1979).

Mack, Robert J., and Christine M. Darden. “Wind-Tunnel Investigation of 

the Validity of a Sonic-Boom-Minimization Concept.” NASA TP-1421 

(October 1979).

Mack, Robert J., and Kathy E. Needleman. “A Methodology for Designing 

Aircraft to Low Sonic Boom Constraints.” NASA TM-4246 (February 

1996).
324

Quieting the Boom

Maglieri, Domenic J. “A Brief Review of the National Aero-Space Plane 

Sonic Booms Final Report.” USAF Aeronautical Systems Center. TR-94-

9344 (December 1992).

Maglieri, Domenic J. “Compilation and Review of Supersonic Business 

Jet Studies from 1963 through 1995,” NASA CR-2011-217144 (May 

2011).

Maglieri, Domenic J. “Sonic Boom Research: Some Effects of Airplane 

Operations and the Atmosphere on Sonic Boom Signatures.” NASA 

SP-147 (1967).

Maglieri, Domenic J., and Donald L. Lansing. “Sonic Booms from Aircraft 

in Maneuvers.” NASA TN D-2370 (July 1964).

Maglieri, Domenic J., and Garland J. Morris. “Measurement of Response 

of Two Light Airplanes to Sonic Booms.” NASA TN D-1941 (August 

1963).

Maglieri, Domenic J., and Harry W. Carlson. “The Shock-Wave Noise 

Problem of Supersonic Aircraft in Steady Flight.” NASA Memo 3-4-59L 

(April 1959).

Maglieri, Domenic J., and Harvey H. Hubbard. “Ground Measurements of 

the Shock-Wave Noise from Supersonic Bomber Airplanes in the Altitude 

Range from 30,000 to 50,000 Feet.” NASA TN-D-880 (July 1961).

Maglieri, Domenic J., and Percy J. Bobbitt. “History of Sonic Boom 

Technology Including Minimization.” Hampton, VA: Eagle Aeronautics, 

November 2001.

Maglieri, Domenic J., and V.S. Richie. “In-Flight Shock-Wave 

Measurements Above and Below a Bomber Airplane at Mach Numbers 

from 1.42 to 1.69.” NASA TN-D-1968 (October 1963).

Maglieri, Domenic J., David A. Hilton, Vera Huckel, Herbert R. 

Henderson, and Norman J. McLeod. “Measurements of Sonic Boom 

Signatures from Flights at Cutoff Mach Number.” In Schwartz, Third 

Conference on Sonic Boom Research, 243–254.
325

Selected Bibliography

Maglieri, Domenic J., Harvey H. Hubbard, and Donald L. Lansing, 

“Ground Measurements of the Shock-Wave Noise from Airplanes in 

Level Flight at Mach Numbers to 1.4 and Altitudes to 45,000 Feet.” 

NASA TN D-48 (September 1959).

Maglieri, Domenic J., J.O. Powers, and J.M. Sands. “Survey of United 

States Sonic Boom Overflight Experimentation.” NASA TM-X-66339 

(May 1969).

Maglieri, Domenic J., Percy J. Bobbitt, Steven J. Massey, Kenneth J. 

Plotkin, Osama A. Kandil, and Xudong Zheng. “Focused and SteadyState Characteristics of Shaped Sonic Boom Signatures: Prediction and 

Analysis.” NASA CR-2011-217156 (June 2011).

Maglieri, Domenic J., Vera Huckel, and H.R. Henderson. “Sonic Boom 

Measurements for SR-71 Aircraft Operating at Mach Numbers to 3.0 

and Altitudes to 24834 Meters.” NASA TN D-6823 (September 1972).

Maglieri, Domenic J., Vera Huckel, and Tony L. Parrott. “Ground 

Measurements of Shock-Wave Pressure for Fighter Airplanes Flying at 

Very Low Altitudes.” NASA TN D-3443 (July 1966).

Maglieri, Domenic J., Victor E. Sothcott, and Thomas N. Keefer. “A 

Summary of XB-70 Sonic Boom Signature Data, Final Report.” NASA 

CR 189630 (April 1992).

Maglieri, Domenic J., Victor E. Sothcott, and Thomas N. Keefer. 

“Feasibility Study on Conducting Overflight Measurements of Shaped 

Sonic Boom Signatures Using the Firebee BQM-34E RPV.” NASA 

CR-189715 (February 1993).

Maglieri, Domenic J., Victor E. Sothcott, Thomas N. Deffer, and Percy J. 

Bobbitt. “Overview of a Feasibility Study on Conducting Overflight 

Measurements of Shaped Sonic Boom Signatures Using RPV’s.” In 

Whitehead, 1991 HSR Workshop, pt. 2, 787–807.

Maglieri, Domenic J., Victor E. Sothcroft, and John Hicks. “Influence of 

Vehicle Configurations and Flight Profile on X-30 Sonic Booms.” AIAA 

paper no. 90-5224 (October 1990).
326

Quieting the Boom

Malkin, Myron S., ed. “Environmental Impact Statement: Space Shuttle 

Program (Final),” Headquarters NASA (April 1978).

Marconi, Frank, Larry Yeager, and H. Harris Hamilton. “Computation of 

High-Speed Inviscid Flows About Real Configurations.” In Aerodynamic 

Analyses Requiring Advanced Computers, pt. 2, 1411–1453.

Marconi, Frank, Manuel Salas, and Larry Yeager. “Development of 

Computer Code for Calculating the Steady Super/Hypersonic Inviscid 

Flow Around Real Configurations.” NASA CR-2675 (April 1976).

Mascitti, Vincent R. “A Preliminary Study of the Performance and 

Characteristics of a Supersonic Executive Aircraft.” NASA TM-74055 

(September 1977).

Maurice, Lourdes. “Civil Supersonic Aircraft Advanced Noise Research.” 

PowerPoint presentation. FAA Public Meeting on Advanced Technologies 

and Supersonics, Washington, DC, July 14, 2011.

McAnich, Gerry L. “Atmospheric Effects on Sonic Boom—A Program 

Review.” In Darden, 1991 HSR Workshop, pt. 1, 1201–1207.

McCurdy, David A. and Sherilyn A. Brown. “Subjective Response to 

Simulated Sonic Boom in Homes.” In Blaize, 1995 Sonic Boom Workshop

1, 278–297.

McCurdy, David A., Sherilyn A. Brown, and R. David Hilliard. “An 

In-Home Study of Subjective Response to Simulated Sonic Booms.” 

In McCurdy, 1994 Sonic Boom Workshop: Atmospheric Propagation and 

Acceptability, 193–207.

McLean, F. Edward, and Barrett L. Shrout. “A Wind Tunnel Study of SonicBoom Characteristics for Basic and Modified Models of a Supersonic 

Transport Configuration.” NASA TM X-1236 (May 1966).

McLean, F. Edward, and Barrett L. Shrout. “Design Methods for 

Minimization of Sonic Boom Pressure-Field Disturbances.” Journal of the 

Acoustical Society of America 39, no. 5, pt. 2 (November 1966): 519–525. 
327

Selected Bibliography

McLean, F. Edward, Raymond L. Barger, and Robert J. Mack. “Application 

of Sonic-Boom Minimization Concepts in Supersonic Transport Design.” 

NASA TN-D-7218 (June 1973).

McLean, F. Edward, Robert J. Mack, and Odell A. Morris. “Sonic Boom 

Pressure-Field Estimation Techniques,” Journal of the Acoustical Society of 

America 39, no. 5, pt. 2 (November 1966): 510–518.

McLean, F. Edward. “SCAR Program Overview,” In Proceedings of the SCAR 

Held at Langley Research Center, Hampton, Virginia, November 9–12, 

1976, pt. 1, 1–4.

McLean, F. Edward. “Some Nonasymptotic Effects of the Sonic Boom of 

Large Airplanes.” NASA TN D-2877 (June 1965).

Meredith, Keith. “SSBE—Flight Test to CFD Comparison.” PowerPoint 

presentation. Langley Research Center, Hampton, VA, August 17, 2004.

Meredith, Keith., John A. Dahlin, David H. Graham, Michael B. 

Malone, Edward A. Haering, Juliet A. Page, and Kenneth J. Plotkin. 

“Computational Fluid Dynamics Comparison and Flight Test 

Measurement of F-5E Off-Body Pressures.” AIAA paper no. 2005-6 

(January 2005). 

Miller, David S., and Harry W. Carlson. “A Study of the Application of Heat 

or Force Fields to the Sonic-Boom-Minimization Problem.” NASA TN 

D-5582 (December 1969).

Miller, Denise M., and Victor W. Sparrow. “Assessing Sonic Boom 

Responses to Changes in Listening Environment, Signature Type, and 

Testing Methodology.” Journal of the Acoustical Society of America 127, 

issue 3 (2010): 1898.

Miranda, L.R., R.D. Elliott, and W.M. Baker. “A Generalized Vortex 

Lattice Method for Subsonic and Supersonic Flow Applications.” NASA 

CR-2895 (December 1977).

Moes, Timothy R. “Objectives and Flight Results of the Lift and Nozzle 

Change Effects on Tail Shock (LaNCETS) Project.” PowerPoint presentation. International Test & Evaluation Association, Antelope Valley 

Chapter, February 24, 2009.
328

Quieting the Boom

Mola, Roger A. “This Is Only a Test.” Air & Space Magazine, March–April 

2006. http://www.airspacemag.com/history-of-flight/this-is-only-a-test.html.

Morgan, Daniel, and Carl E. Behrens. “National Aeronautics and Space 

Administration: Overview, FY2009 Budget, and Issues for Congress.” 

Congressional Research Service, February 26, 2008.

Morgenstern, John M. “Low Sonic Boom Design and Performance of a 

Mach 2.4/1.8 Overland High-Speed Civil Transport.” In Darden, 1992 

Sonic Boom Workshop 2, 55–63.

Morgenstern, John M., Alan Arslan, Victor Lyman, and Joseph Vadyak. “F-5 

Shaped Sonic Boom Persistence of Boom Shaping Reduction Through 

the Atmosphere.” AIAA paper no. 2005-12 (January 2005).

Morgenstern, John M., David D. Bruns, and Peter P. Camacho. “SR-71A 

Reduced Sonic Boom Modification Design.” In McCurdy, 1994 Sonic 

Boom Workshop: Configuration, Design, Analysis, and Testing, 199–217.

Morgenstern, John M., Nicole Norstrud, Marc Stelnack, and Craig 

Skoch. “Final Report for the Advanced Concept Studies for Supersonic 

Commercial Transports Entering Service in the 2030 to 2035 Period, 

N+3 Supersonic Program.” NASA CR-2010-216796 (October 2010).

Morring, Frank. “Rudderless: NASA Aeronautics Chief Hopes New 

Administrator Will Push for Clear Policy To Guide Facility Closings.” 

Aviation Week, March 7, 2005, 28–30.

Morris, Jefferson. “Quiet, Please: With More Emphasis on Partnering, 

NASA Continues Pursuit of Quieter Aircraft.” Aviation Week, June 25, 

2007, 57–58.

NASA, Langley Research Center. “Proceedings of NASA Conference on 

Supersonic-Transport Feasibility Studies and Supporting Research, 

September 17–19, 1963.” NASA TM X-905 (December 1963).

Nixon, Charles W., and Harvey H. Hubbard. “Results of the USAF-NASAFAA Flight Program To Study Community Response to Sonic Booms in 

the Greater St. Louis Area.” NASA-TN-D-2705 (May 1965).
329

Selected Bibliography

Nixon, Charles W., H.K. Hille, H.C. Somner, and E. Guild. “Sonic Booms 

Resulting from Extremely Low Altitude Supersonic Flight: Measurements 

and Observations on Houses, Livestock, and People.” AMRL TR-68-52 

(October 1968).

Norris, Guy, and Graham Warwick. “Sound Barrier,” Aviation Week, June 

4/11, 2012, 50–53.

Norris, Stephen R., Edward A. Haering, and James E. Murray. “GroundBased Sensors for the SR-71 Sonic Boom Propagation Experiment.”

1995 Sonic Boom Workshop 1, 199–218.

Northrop Grumman Corporation. “Shaped Sonic Boom Demo Flight Test 

Program.” PowerPoint presentation. NASA Langley Research Center, 

Hampton, VA, August 17, 2004.

Page, Juliet A., and K.J. Plotkin. “An Efficient Method for Incorporating 

Computational Fluid Dynamics into Sonic Boom Theory.” AIAA paper 

no. 91-3275 (September 1991).

Pawlowski, Joseph W., David H. Graham, Charles H. Boccadoro, Peter G. 

Coen, and Domenic J. Maglieri. “Origins and Overview of the Shaped 

Sonic Boom Demonstration Program.” AIAA paper no. 2005-5 (January 

2005).

Phillips, Edward H. “Shock Wave: Flying Faster than Sound Is the Holy 

Grail of Business Aviation.” Aviation Week, October 8, 2007, 50–51.

Pierce, Allan D., and Victor W. Sparrow. “Relaxation and Turbulence Effects 

on Sonic Boom Signatures.” In Whitehead, First Annual HSR Workshop, 

pt. 1, 1211–1234.

Plattner, C.M. “XB-70A Flight Research: Phase 2 To Emphasize Operational 

Data.” Aviation Week, June 13, 1966, 60–62.

Plotkin, Kenneth J. “Perturbations Behind Thickened Shock Waves.” In 

Schwartz, Third Conference on Sonic Boom Research, 59–66.

Plotkin, Kenneth J. “State of the Art of Sonic Boom Modeling.” Journal 

of the Acoustical Society of America 111, no. 1, pt. 3 (January 2002): 

530–536.
330

Quieting the Boom

Plotkin, Kenneth J. “The Effect of Turbulence and Molecular Relaxation 

on Sonic Boom Signatures.” In Whitehead, 1991 HSR Workshop, pt. 1, 

1241–1261.

Plotkin, Kenneth J. “Theoretical Basis for Finite Difference Extrapolation of 

Sonic Boom Signatures.” In Baize, 1995 Sonic Boom Workshop 1, 54–67.

Plotkin, Kenneth J., and Domenic J. Maglieri. “Sonic Boom Research: 

History and Future.” AIAA paper no. 2003-3575 (June 2003).

Plotkin, Kenneth J., and Fabio Grandi. “Computer Models for Sonic Boom 

Analysis: PCBoom4, CABoom, BooMap, CORBoom.” Wyle Report 

WR-02-11 (June 2002).

Plotkin, Kenneth J., and J.M. Cantril. “Prediction of Sonic Boom at a 

Focus.” AIAA paper no. 76–72 (January 1976).

Plotkin, Kenneth J., and Roy Martin. “NASA Shaped Sonic Boom 

Experiment: Pushover Focus Maneuver, Final Data Review.” PowerPoint 

presentation. NASA Langley Research Center, Hampton, VA, August 17, 

2004.

Plotkin, Kenneth J., C.L. Moulton, V.R. Desai, and M.J. Lucas. “Sonic 

Boom Environment Under a Supersonic Military Operating Area.” 

Journal of Aircraft 29, no. 6 (November–December 1992): 1069–1072.

Plotkin, Kenneth J., Domenic J. Maglieri, and Brenda M. Sullivan. 

“Measured Effects of Turbulence on the Loudness and Waveforms of 

Conventional and Shaped Minimized Sonic Booms.” AIAA paper no. 

2005-2949 (May 2005).

Plotkin, Kenneth J., Edward A. Haering, James E. Murray, Domenic J. 

Maglieri, Joseph Salamone, Brenda M. Sullivan, and David Schein. 

“Ground Data Collection of Shaped Sonic Boom Experiment Aircraft 

Pressure Signatures.” AIAA paper no. 2005-10 (January 2005).

Plotkin, Kenneth J., Jason R. Matisheck, and Richard R. Tracy. “Sonic 

Boom Cutoff Across the United States.” AIAA paper no. 2008-3033 

(May 2008).
331

Selected Bibliography

Plotkin, Kenneth J., Juliet Page, and Michah Downing. “USAF SingleEvent Sonic Boom Prediction Model: PCBoom3.” In McCurdy, 1994 

Sonic Boom Workshop: Atmospheric Propagation and Acceptability Studies, 

171–184.

Plotkin, Kenneth J., Juliet Page, David H. Graham, Joseph W. Pawlowski, 

David B. Schein, Peter G. Coen, David A. McGurdy, Edward A. 

Haering, James E. Murray, L.J. Ehernberger, Domenic J. Maglieri, Percy 

J. Bobbitt, Anthony Pilon, and Joe Salamone. “Ground Measurements of 

a Shaped Sonic Boom.” AIAA paper no. 2004-2923 (May 2004).

Plotkin, Kenneth J., Roy Martin, Domenic J. Maglieri, Edward A. Haering, 

and James E. Murray. “Pushover Focus Booms from the Shaped Sonic 

Boom Demonstrator.” AIAA paper no. 2005-11 (January 2005).

Poling, Hugh W. “Sonic Boom Propagation Codes Validated by Flight Test.” 

NASA CR-201634 (October 1996). 

Porter, Lisa J. “NASA’s Aeronautics Program.” PowerPoint presentation. 

Fundamental Aeronautics Annual Meeting, New Orleans, October 30, 

2007. http://www.aeronautics.nasa.gov/fap/PowerPoints/ARMD&FA_Intro.pdf.

Raspet, Richard, Henry Bass, Lixin Yao, and Wenliang Wu. “Steady State 

Risetimes of Shock Waves in the Atmosphere.” In Darden, 1992 Sonic 

Boom Workshop 1, 109–116.

Roberds, Richard M. “Sonic Boom and the Supersonic Transport.” Air 

University Review 22, no. 7 (July–August 1971): 25–33.

Runyan, Larry J., and Edward J. Kane. “Sonic Boom Literature Survey2, 

Capsule Summaries.” Boeing Commercial Airplane Company for the 

FAA. DTIC AD-771274 (September 1973).

Sands, Johnny M. “Sonic Boom Research (1958–1968).” FAA DTIC AD 

684806 (November 1968).

Schultz, James. “HSR Leaves Legacy of Spinoffs.” Aerospace America 37, no. 

9 (September 1999): 28–32.

Schwartz, Ira R. “Sonic Boom Simulation Facilities,” In AGARD, Aircraft 

Engine Noise and Sonic Boom, paper 29.
332

Quieting the Boom

Seebass, A. Richard, and A.R. George. “Sonic Boom Minimization Through 

Aircraft Design and Operation.” AIAA paper no. 73-241 (January 1973).

Seebass, A. Richard, and A.R. George. “Design and Operation of Aircraft 

To Minimize their Sonic Boom.” Journal of Aircraft 11, no. 9 (September 

1974): 509–517.

Seebass, A. Richard, and Brian Argrow. “Sonic Boom Minimization 

Revisited.” AIAA paper no. 98-2956 (November 1998).

Seebass, A. Richard. “Comments on Sonic Boom Research.” In Schwartz,

Third Conference on Sonic Boom Research, 411.

Seebass, A. Richard. “History and Economics of, and Prospects for, 

Commercial Supersonic Transport.” Paper 1 in NATO Research and 

Technology Organization, Fluid Dynamics Research on Supersonic Aircraft. 

Proceedings of a course held in Rhode Saint-Genèse, Belgium, May 

25–29, 1998. RTO-EN-4 (November 1998).

Seebass, A. Richard. “Nonlinear Acoustic Behavior at a Caustic.” In 

Schwartz, Third Conference on Sonic Boom Research, 87–122.

Seebass, A. Richard. “Sonic Boom Minimization.” Paper 6 in NATO 

Research and Technology Organization, Fluid Dynamics Research on 

Supersonic Aircraft. Proceedings of a course held in Rhode Saint-Genèse, 

Belgium, May 25–29, 1998. RTO-EN-4 (November 1998).

Shapely, Deborah. “East Coast Mystery Booms: A Scientific Suspense Tale.” 

Science 199, no. 4336 (March 31, 1978): 1416–1417.

Shepherd, Kevin P. “Overview of NASA Human Response to Sonic Boom 

Program.” In Whitehead, 1991 HSR Workshop, pt. 3, 1287–1291.

Shepherd, Kevin P., Brenda M. Sullivan, Jack E. Leatherwood, and David 

A. McCurdy. “Sonic Boom Acceptability Studies.” In Whitehead, 1991 

HSR Workshop, pt. 3, 1295–1311.

Shin, Jaiwon. “ARMD Overview.” PowerPoint presentation, NASA 

Aeronautics Fundamental Aeronautics Program Technical Conference, 

Cleveland, OH, March 13, 2012.
333

Selected Bibliography

Siclari, M.J. “Ground Extrapolation of Three-Dimensional Near-Field CFD 

Predictions for Several HSCT Configurations,” In Darden, 1992 Sonic 

Boom Workshop 2, 175–200.

Siclari, M.J. “Sonic Boom Predictions Using a Modified Euler Code.” 1991 

HSR Workshop, pt. 2, 760–784.

Siclari, M.J. “The Analysis and Design of Sonic Boom Configurations 

Using CFD and Numerical Optimization Techniques.” In McCurdy, 

1994 Sonic Boom Workshop: Configuration Design, Analysis, and Testing, 

107–128.

Smith, Harriet J. “Experimental and Calculated Flow Fields Produced by 

Airplanes Flying at Supersonic Speeds.” NASA TN-D-621 (November 1960).

Smolka, James W., Leslie Molzahn, and Robbie Cowart. “Flight Testing of 

the Gulfstream Quiet Spike on a NASA F-15B.” PowerPoint presentation. December 11, 2008.

Smolka, James W., Robert A. Cowart, and nine others. “Flight Testing of 

the Gulfstream Quiet Spike on a NASA F-15B.” Paper presented to the 

Society of Experimental Test Pilots, Anaheim, CA, September 27, 2007.

Spearman, M. Leroy. “The Evolution of the High-Speed Civil Transport.” 

NASA TM-109089 (February 1994).

Spivey, Natalie D., Claudia Y. Herrera, Roger Turax, Chan-gi Pak, and 

Donald Freund. “Quiet Spike Build-up Ground Vibration Testing 

Approach.” NASA TN 2007-214625 (November 2007).

Stanford Research Institute. “Sonic Boom Experiments at Edwards Air Force 

Base; Interim Report.” National Sonic Boom Evaluation Office. DTIC 

AD 0655310 (July 1967).

Stuart, William G. “Northrop F-5 Case Study in Aircraft Design.” AIAA 

(September 1978).

Sturgielski, R.T., L.E. Fugelso, L.B. Holmes, and W.J. Byrne. “The 

Development of a Sonic Boom Simulator with Detonable Gases.” NASA 

CR-1844 (November 1971).
334

Quieting the Boom

Sullivan, Brenda M. “Design of an Indoor Sonic Boom Simulator at 

NASA Langley Research Center.” Paper presented at Noise-Con 2008, 

Baltimore, MD, July 12–14, 2008.

Sullivan, Brenda M. “Metrics for Human Response to Sonic Booms.” 

PowerPoint presentation. FAA Civil Supersonic Aircraft Technical 

Workshop, Arlington, VA, November 13, 2003.

Sullivan, Brenda M. “Research at NASA on Human Response to Sonic 

Booms.” Paper presented at 5th International Conference on Flow 

Dynamics, Sendai, Japan, November 17–20, 2008.

Sullivan, Brenda M. “Research on Subjective Response to Simulated 

Sonic Booms at NASA Langley Research Center.” Paper presented at 

International Sonic Boom Forum, State College, PA, July 21–22, 2005.

Sullivan, Brenda M. “Sonic Boom Modeling Technical Challenges.” CASI 

document no. 200700363733 (October 2007).

Sullivan, Brenda M. Jacob Klos, Ralph D. Buehrle, David A. McCurdy, and 

Edward A. Haering. “Human Response to Low-Intensity Sonic Booms 

Heard Indoors and Outdoors.” NASA TM-2010-216685 (April 2010).

Sweetman, Bill. “Back to the Bomber.” Jane’s International Defence Review

37, no. 6 (June 2004): 54–59.

Sweetman, Bill. “Whooshhh!” Popular Science. Posted on July 30, 

2004, accessed on November 13, 2011. http//www.popsci.com/

military-aviation-space/article/2004-07/whooshhh.

Taylor, Albion D. “The TRAPS Sonic Boom Program.” NOAA Technical 

Memorandum ERL ARL-87 (July 1980).

Taylor, J.P., and E.G.R, “A Brief Legal History of the Sonic Boom in 

America.” In Aircraft Engine Noise and Sonic Boom. Conference paper no. 

42. NATO Advisory Group for Aerospace Research and Development, 

Neuilly sur Seine, France (1969).

Thomas, Charles L. “Extrapolation of Sonic Boom Pressure Signatures by 

the Waveform Parameter Method.” NASA TN D-6823 (June 1972).
335

Selected Bibliography

Tirpak, John. “The Bomber Roadmap.” Air Force Magazine 82, no. 6 (June 

1999): 30–36.

Tomboulian, Roger. “Research and Development of a Sonic Boom 

Simulation Device.” NASA CR-1378 (July 1969).

TRACOR, Inc. “Public Reactions to Sonic Booms.” NASA CR-1665 

(September 1970).

Tracy, Richard. “Aerion Supersonic Business Jet.” PowerPoint presentation. 

FAA Public Meeting on Advanced Technologies and Supersonics, 

Washington, DC, July 14, 2011.

Tu, Eugene, Samson Cheung, and Thomas Edwards. “Sonic Boom 

Prediction Exercise: Experimental Comparisons.” In McCurdy, 1994 

Sonic Boom Workshop: Configuration Design, Analysis, and Testing, 13–32.

Unger, George. “HSR Community Noise Reduction Technology Status 

Report.” In Whitehead, 1991 HSR Workshop, pt. 1, 259–283.

Wall, Robert. “New Technologies in Quest of Quiet Flight.” Aviation Week, 

January 8, 2001, 61–62. 

Wallace, Lane E. “The Whitcomb Area Rule: NACA Aerodynamics Research 

and Innovation.” Chapter 5 in Pamela E. Mack, ed. From Engineering 

Science to Big Science. NASA SP-4219 (1998). http://history.nasa.gov/

SP-4219.htm.

Warwick, Graham, William Garvey, Joseph C. Anselmo, and Robert Wall. 

“Open Season: As if the Economy Were Not Enough, Business Aviation 

Becomes a Scapegoat for Executive Excess.” Aviation Week, March 2, 

2009, 20–22.

Warwick, Graham. “Cut to the Bone.” Aviation Week, February 27, 2012, 33.

Warwick, Graham. “DARPA Kills Oblique Flying Wing.” Aviation 

Week, October 1, 2008. http://www.aviationweek.com/aw/generic/story.

jsp?id=news/OBLI10018c.xml.

Warwick, Graham. “Fight for Flight.” Aviation Week, April 23/30, 2012, 

52–54.
336

Quieting the Boom

Warwick, Graham. “Forward Pitch.” Aviation Week, October 20, 2008, 

22–23.

Warwick, Graham. “Quiet Progress: Aircraft Designers Believe They Can 

Take the Loud Boom out of Supersonic Travel.” Flight International, 

October 20, 2004, 32–33.

Warwick, Graham. “Sonic Dreams.” Flight International, May 6, 2003, 34–37.

Warwick, Graham. “Sonic Overture: European Researchers Test the Waters 

on International Supersonic Collaboration.” Aviation Week, July 13, 

2009, 53–54.

Wedge, Robert H. and 20 co-authors. “N Plus 3 Advanced Concept

Studies for Supersonic Commercial Transport Aircraft Entering Service

in the 2030–2035 Period.” NASA CR-2011-217084 (April 2011).

Welge, Harry R., and 13 coauthors. “N+2 Supersonic Concept

Development and System Integration.” NASA CR-2010-216842

(August 2010).

Weinstein, Leonard M. “An Electronic Schlieren Camera for Aircraft Shock 

Wave Visualization.” In Baize, 1995 Sonic Boom Workshop 1, 244–258.

Weinstein, Leonard M. “An Optical Technique for Examining Aircraft 

Shock Wave Structures in Flight.” In McCurdy, 1994 Sonic Boom 

Workshop, Atmospheric Propagation and Acceptability, 1–18.

Wenk, Edward. “SST—Implications of a Political Decision.” Astronautics 

and Aeronautics 9, no. 10 (October 1971): 40–49.

Whitham, G.B. “On the Propagation of Weak Shock Waves.” Journal of 

Fluid Dynamics 1, no. 3 (September 1956): 290–318. http://journals.

cambridge.org/action/displayJournal?jid=JFM.

Whitham, G.B. “The Flow Pattern of a Supersonic Projectile.” 

Communications on Pure and Applied Mathematics 5, no. 3 (1952). http://

www3.interscience.wiley.com/journal/113395160/issue.
337

Selected Bibliography

Wiley, John. “The Super-Slow Emergence of Supersonic, Sixty Years after 

Glamorous Glennis Made History.” Business & Commercial Aviation 101, 

no. 3 (September 2007): 48–50.

Willshire, William L., and David Chestnut, eds. “Joint Acoustic Propagation 

Experiment (JAPE-91) Workshop.” NASA CR 3231 (1993).

Willshire, William L., and David W. DeVilbiss. “Preliminary Results from 

the White Sands Missile Range Sonic Boom Propagation Experiment.” 

In Darden, 1992 Sonic Boom Workshop 1, 137–144.

Wilson, J.B. “Quiet Spike: Softening the Sonic Boom.” Aerospace America

45, no. 10 (October 2007): 38–42.

Wlezien, Richard, and Lisa Veitch. “Quiet Supersonic Platform Program.” 

AIAA paper no. 2002-0143 (January 2002).

Yao, Lixin, Henry E. Bass, Richard Raspert, and Walter E. McBride. 

“Statistical and Numerical Study of the Relation Between Weather and 

Sonic Boom.” In Whitehead, 1991 HSR Workshop, pt. 3, 1263–1284.

Web Sites

Aerion Corporation. Accessed October 12, 2011. http://aerioncorp.com/.

Aerographer/Meteorology. Table 1-6, U.S. Standard Atmosphere Heights 

and Temperatures. Accessed August 27, 2011. http://www.tpub.com/content/aerographer/14269/css/14269_75.htm.

Airpower: Missiles and Rockets in Warfare. Accessed January 15, 2009. 

http://www.centennialofflight.gov/essay/Air_Power/Missiles /AP29.htm.

BBC. In Depth Farewell to Concorde. Last updated August 15, 2007. 

Accessed September 21, 2011. http://news.bbc.co.uk/1/hi/in_depth/

uk/2003/concorde_retirement/.

Call for Information on Supersonic Aircraft Noise. Federal Register, May 23, 

20003. http://www.federalregister.gov/articles/2003/05/1308/.
338

Quieting the Boom

Department of Defense Appropriations Act 2001, Public Law 106-259, 114 

Stat. 656 (August 9, 2001). Accessed November 13, 2011. http://www.

gpo.gov/fdsys/pkg/PLAW-106publ259/pdf.

Department of Defense Fiscal Year (FY) 2004/FY 2005 Biennial Budget 

Estimates: Research, Development, Test and Evaluation Defense-Wide 

1. Defense Advanced Research Projects Agency (February 2003). 

Accessed June 29, 2011. http://www.darpa.mil/WorkArea/DownloadAsset.

aspx?id=1635.

Department of Defense Fiscal Year 2005 Biennial Budget Estimates: 

Research, Development, Test and Evaluation Defense-Wide 1. Defense 

Advanced Research Projects Agency (February 2004). Accessed June 29, 

2011. http://www.darpa.mil/WorkArea/DownloadAsset.aspx?id=1634.

Department of Defense FY 2001 Budget Estimates: Research, Development, 

Test and Evaluation Defense-Wide 1. Defense Advanced Research 

Projects Agency (February 2000). Accessed June 29, 2011. http://www.

darpa.mil/WorkArea/DownloadAsset.aspx?id=1638.

Department of Defense FY 2002 Amended Budget Submission: Research, 

Development, Test and Evaluation Defense-Wide 1. Defense Advanced 

Projects Agency (June 2001). Accessed June 29, 2011. http://www.darpa.

mil/WorkArea/DownloadAsset.aspx?id=1637.

Department of Defense FY 2003 Budget Submission: Research, 

Development, Test and Evaluation Defense-Wide 1, Defense Advanced 

Projects Agency (February 2002). Accessed June 29, 2011. http:// 

comptroller.defense.gov/defbudget/fy2003/budget_justification/pdfs/03_

RDT_and_E/darpa_vol1.pdf.

FAA Historical Chronology, 1926–1996. Accessed February 1, 2009. http://

www.faa.gov/about/media/b-chron.pdf.

FAA. Supersonic Aircraft Noise. Accessed October 25, 2011. http://www.faa.

gov/about/office_org/headquarters_offices/apl/noise_emissions/supersonic_aircraft_noise/. Contains links to related documents, including “Public 

Meetings on Advanced Technologies and Supersonics,” held in 2009, 

2010, and 2011.
339

Selected Bibliography

Gulfstream Aerospace Corp. “The History of Gulfstream, 1958–2008.” 

Accessed November 13, 2011. http://www.gulfstream.com/history/.

Jones, Robert T. “Adolf Busemann, 1901–1986.” Memorial Tributes 3. 

National Academy of Engineering (1989), 62–67. Accessed July 3, 2011. 

http://www.nap.edu/openbook.php?record_id=1384.

Krause, Fred. “Naval Air Station Fallon Adversaries, Part One: VFC-13 

Saints.” Accessed July 21, 2011. http://modelingmadness.com/scotts/features/

krausevfc13g.htm.

Marine Fighter Training Squadron 401. Accessed July 21, 2011. http://www.

yuma.usmc.mil/tenantcommands/vmft401.html.

NASA Aeronautics Research Mission Directorate. 2011 Fundamental 

Aeronautics Technical Conference Recap. Accessed October 2, 2011. 

http://www.aeronautics.nasa.gov/fap/meeting_recap_2011.html. Contains 

links to 2011 presentations as well as to 2007, 2008, and 2009 conference recaps and related presentations.

NASA Aeronautics Research Mission Directorate. Fundamental Aeronautics 

Program Documents Library. Last updated July 25, 2011. Accessed 

October 30, 2011. http://www.aeronautics.nasa.gov/fap/documents.html.

NASA. Budget Request Summaries. FYs 2004–2009. Accessed September 

25, 2011. http://www.nasa.gov/news/budget/index.html.

Naval Air Station Fallon. Accessed July 21, 2011. http://www.cnic.navy.mil/

Fallon/About/index.htm.

Northrop F-5. Wikipedia. Accessed July 18, 2011. http://en.wikipedia.org/

wiki/Northrop_F-5.

Northrop Grumman Corp. “F-5 Tiger.” Accessed July 18, 2011. http://www.

as.northropgrumman.com/products/f5tiger/index.html.

Pojman, Paul. “Ernst Mach.” The Stanford Encyclopedia of Philosophy

(Summer 2011 Edition), edited by Edward N. Zalta. Accessed November 

5, 2011. http://plato.stanford.edu/archives/sum2011/entries/ernst-mach/.
340

Quieting the Boom

Quiet Supersonic Platform (QSP) Systems Studies and Technology 

Integration. Commerce Business Daily, SOL RA 00-48. Posted on 

CBDNet, August 16, 2000. Accessed August 18, 2011. http://www. 

fedmine.us/freedownload/CBD/CBD-2000/CBD-2000-18au00.html.

Sonic Boom. USAF Fact Sheet. October 2005. http://www.af.mil/factsheets/

fsID=184.

Supersonic Business Jet. “Quiet Supersonic Transport (QSST).” Accessed 

October 10, 2011. http://www.supersonic-business-jet.com/prototypes/quiet_

supersonic_transport.php.

Time&Date.com. “Sunrise and Sunset/Moonrise and Moonset in Los Angeles.” 

August 2003. Accessed August 30, 2011. http://www.timeanddate.com/

worldclock/astronomy.html?n=137&month=8&year=2003.

University of Colorado. Biography of A. Richard Seebass. Accessed April 27, 

2011. http://www.colorado.edu/aerospace/ARichardSeebass.html.

Valiant Air Command Warbird Museum. Accessed October 29, 2011. http://

www.vacwarbirds.org/.

Weather Warehouse. “Jacksonville Cecil Field Airport, 7/24/03.” 

Accessed August 11, 2011. https://weather-warehouse.com/WxHubP/

WxSPM531874661_174.28.158.213/1_Jacksonville.

Windows to the Universe. “Layers of the Earth’s Atmosphere.” Accessed June 

15, 2011. http://www.windows2universe.org/earth/Atmosphere/layers.html.

Wlezien, Richard. Biography. Accessed April 30, 2011. http://www.

richwelzein.com/Personal/Wlezien.html.

XB-70. NASA Dryden Fact Sheet. Accessed March 10, 2009. http://www.

nasa.gov/centers/dryden/new/FactSheets/FS-084-DFRC_prt.htm.
341

Acronyms List

ACTIVE Advanced Control for Integrated Vehicles Experiment 

AEDC Arnold Engineering Development Center 

AFFTC Air Force Flight Test Center 

AFRL Air Force Research Laboratory 

AGARD Advisory Group for Aerospace Research and 

Development 

AIAA American Institute of Aeronautics and Astronautics

AMRL Aerospace Medical Research Laboratory 

AOA angle of attack 

ARAP Aeronautical Research Associates of Princeton 

ARC3D Ames Research Center 3-Dimensional (CFD code) 

ARMD Aeronautics Research Mission Directorate 

ASA Acoustical Society of America 

AST Advanced Supersonic Technology 

AVTIP Air Vehicles Technology Integration Program 

B&K Brül and Kjaer 

BAC British Aircraft Corporation 

BADS Boom Amplitude and Direction Sensor 

BASS Boom Amplitude and Shape Sensor 

BBC British Broadcasting Corporation

BEAR Boom Event Analyzer Recorder 

BLM Bureau of Land Management 

BREN Bare Reactor Experiment Nevada 

BUNO Bureau Number

CAD computer-aided design 

CASA Construcciones Aeronauticas Sociedad Anonima 

CASI Center for AeroSpace Information 

CDR critical design review 

CFD computational fluid dynamics 

CFR Code of Federal Regulations 

CP Conference Publication 

CR Contractor Report 

CRADA Cooperative Research and Development Agreement 

DACT Dissimilar Air Combat Tactics 

DAQ data acquisition 
342

Quieting the Boom

DARPA Defense Advanced Research Projects Agency

DAT digital audio tape 

dB decibel

DFRC Dryden Flight Research Center

DGPS Differential Global Positioning System 

DOD U.S. Department of Defense 

DOT U.S. Department of Transportation 

DTIC Defense Technical Information Center 

EAA Experimental Aircraft Association 

ECS environmental control system 

EIS environmental impact statement 

F Fahrenheit

FAA Federal Aviation Agency, later Administration 

FAR Federal Aviation Regulation 

FCC Federal Communications Commission

FCF functional check flight 

FORTRAN Formula Translation

FRC Flight Research Center

FRR flight readiness review

FY fiscal year 

GASL General Applied Sciences Laboratories

GCNSfv Generalized Compressible Navier-Stokes Finite Volume 

(CFD code)

GPO Government Printing Office 

GPS Global Positioning System 

HISAC French acronym for High-Speed Aircraft Industrial 

Project 

HLFC hybrid laminar flow control 

HPCCP High Performance Computing and Communications 

Program 

HSCT High-Speed Civil Transport 

HSFRS High-Speed Flight Research Station 

HSR High-Speed Research

HUD heads-up display 

Hz hertz

IBM formerly International Business Machines 

ICAO International Civil Aviation Organization

IDR interim design review 

IFCS Intelligent Flight Control Systems 

IFF identification friend or foe 

IHONORS In-Home Noise Generation/Response System 
343

Acronyms List

IPT integrated product team 

IRIG Inter-Range Instrumentation Group 

IRIS Information Retrieval and Indexing System

ISSM Inlet Spillage Shock Measurement 

JAPE Joint Acoustic Propagation Experiment 

JASA Journal of the Acoustical Society of America 

JAXA Japan Aerospace Exploration Agency 

km kilometers

kph kilometers per hour

L/D lift-to-drag ratio 

LaNCETS Lift and Nozzle Change Effects on Tail Shocks LBEV 

low-boom experimental vehicle 

lb/ft2 pounds per square foot

LEX leading edge extension 

MCAS Marine Corps Air Station 

MIL-STD Military Standard 

MIM3D-SB Multigrid Implicit Marching in Three Dimensions for 

Sonic Booms

MIT Massachusetts Institute of Technology

MLT modified linear theory 

NACA National Advisory Committee for Aeronautics 

NAS Naval Air Station 

NASP National Aerospace Plane 

NAVAIR Naval Air Systems Command 

NAWS Naval Air Weapons Station

NBAA National Business Aviation Association 

NGC Northrop Grumman Corporation 

NGSA Northrop Grumman [facility], St. Augustine 

NOAA National Oceanic and Atmospheric Administration 

NORAD North American Air Defense Command 

NRA NASA Research Announcement 

NRL Naval Research Laboratory 

NSBEO National Sonic Boom Evaluation Office 

NSBIT Noise and Sonic Boom Impact Technology 

NTRS NASA Technical Reports Server 

NYU New York University 

OAST Office of Aeronautics and Space Technology 

OEM original equipment manufacturer 

OML outer mold line 

OST Office of Science and Technology 

PAC Presidential Advisory Committee 
344

Quieting the Boom

PARTNER Partnership for Air Transportation Noise and Emissions 

Reduction 

PDR preliminary design review 

PDT Pacific daylight time 

PE program element 

PLdB perceived-level decibel 

PNdB perceived noise decibel 

psf pounds per square foot 

QSP Quiet Supersonic Platform 

QSST Quiet Small Supersonic Transport 

R&D Research and Development 

RAF Royal Air Force 

RFI Request for Information 

RFP Request for Proposal

ROA Research Opportunities in Aviation 

RP Reference Publication 

RPV remotely piloted vehicle 

RQDS Research Quick Data System 

SABER Small Airborne Boom Event Recorder 

SAC Strategic Air Command 

SAI Supersonic Aerospace International 

SASS Supersonic Acoustics Signature Simulator 

SBDWG Sonic Boom Demonstration Working Group 

SCAMP Superboom Caustic Analysis and Measurement Program 

SCAR Supersonic Cruise Aircraft Research 

SCAT Supersonic Commercial Air Transport

SCIA Supersonic Cruise Industry Alliance 

SCR Supersonic Cruise Research 

SETP Society of Experimental Test Pilots 

SonicBOBS Sonic Booms on Big Structures 

SonicBREWS Sonic Boom Resistant Earthquake Warning System 

SP Special Publication 

SPF/DB superplastic forming and diffusion bonding 

SRI Stanford Research Institute 

SSBD Shaped Sonic Boom Demonstrator/Demonstration 

SSBDWG Shaped Sonic Boom Demonstration Working Group 

SSBE Shaped Sonic Boom Experiment 

SSBJ supersonic business jet 

SST Supersonic Transport (program)

STOL short takeoff and landing 

STS Space Transportation System (Shuttle) 
345

Acronyms List

TACTS Tactical Air Combat Training System 

TEAC formerly Tokyo Electro Acoustic Company

TEAM Three-dimensional Euler/Navier-Stokes Aerodynamic 

Method 

TM Technical Memorandum 

TM-X formerly classified Technical Memorandum 

TN Technical Note 

TP Technical Paper 

TPS Test Pilot School 

TR Technical Report 

TRAPS Tracing Rays and Aging Pressure Signatures 

TYCOM Type Command (U.S. Navy) 

UHF ultrahigh frequency

UK United Kingdom

UPS3D Universal Parabolized Simplified Navier-Stokes Code

USAF United States Air Force 

VCE variable cycle engine 

VFC Composite Fighter Squadron 

VIBES Variable Intensity Boom Effect on Structures 

WSPR Waveforms and Sonic Booms Perception and Response
346

About the Author

Lawrence R. Benson attended the University of Maryland at College Park, 

where he received a master’s degree in 1967 specializing in military and diplomatic history. After serving in the U.S. Army with a tour in Vietnam, Mr. 

Benson became a civilian employee of the Air Force in 1971. During the 

next 30 years, he worked in a variety of administrative positions and as a 

historian at 10 locations in the United States, Turkey, and Germany. He has 

researched and written numerous official histories, monographs, articles, book 

reviews, and studies on a range of topics related to military operations, international relations, and aerospace technology. After retiring in 2000 as chief 

of the Air Force Historian’s Pentagon Office, he coauthored Reflections of a 

Technocrat: Managing Defense, Air, and Space Programs during the Cold War with 

former Secretary of the Air Force John. L. McLucas. Most recently, Benson 

wrote “Softening the Sonic Boom: 50 Years of NASA Research” in NASA’s 

Contributions to Aeronautics, a case study that laid the foundation for writing 

this book. He and his wife, Carolyn, live in Albuquerque, NM.
347

Index

Numbers in bold indicate pages with photos or figures

A

A-4 rockets, 27n5

A-4 Skyhawk, 153, 154

A-12/YF-12 aircraft, 43

academic community

funding for research, 73

HISAC participation, 248

information sharing and research 

partnerships, 39, 43, 50

Partnership for Air Transportation Noise and 

Emissions Reduction (PARTNER) Center of 

Excellence, 248, 251

QSP sonic boom minimization research, 134

SCR/SCAR/AST program role, 68

sonic boom acceptability, responsibility for, 

125

sonic boom conference participation, 91

SSBJ studies and proposals, 124

Ackeret, Tracy, 292

Acoustical Society of America (ASA), 39, 45–46, 

118–19n83, 270

acoustical wave front, 77, 77

acoustic rays, 54, 55, 56, 64n68, 71, 231, 231

acronyms list, 341–45

AD-1 program, 85n48

Adamson, Eric, 293

Advanced Control for Integrated Vehicles 

Experiment (ACTIVE) project, 262

Advanced Subsonic Transport, 109

Advanced Supersonic Platform Industry Day, 

130, 132, 144n65

Advanced Supersonic Technology (AST) program, 

67. See also Supersonic Cruise Research 

(SCR)/Supersonic Cruise Aircraft Research 

(SCAR)/Advanced Supersonic Technology (AST) 

program

Advisory Group for Aerospace Research & 

Development (AGARD, NATO), 49–50

Aerion Corporation

laminar flow technology development and 

testing, 283n94

sonic boom conference participation, 270

SSBJ studies and proposals, 249, 259, 268, 

270

aerodynamics

aerodynamic minimization calculations, 

computer program for, 74

boundary conditions, 73

equivalent bodies of revolution, 41

fluid dynamics, relationship to, 40

high-speed frictionless flow computations, 

74, 79

low-boom, high-drag paradox, 75, 75, 91

numerical calculations correlation with flight 

test data, 48–49

sonic booms and, 11–12

SST research and development, 11–12, 

42–50

wind tunnel research on shock waves, 12

Aerodyne, 133

Aeronautical Research Associates of Princeton 

(ARAP), 48

Aeronautical Research Associates of Princeton 

(ARAP) Program, 48–49, 71, 72, 78–79, 89

Aeronautical Research Institute of Sweden, 47, 

71
348

Quieting the Boom

Aeronautical Research Laboratory, 4

Aeronautical Systems Corporation, 138–39

Aeronautics Research Mission Directorate 

(ARMD), 256, 257–58

Aerospace Defense Command, 78

Aerospace Industries Association, 214

Airbus, 248

aircraft and jet aircraft

advances in design of, 9, 271–72

afterburners and fuel consumption, 8

business (corporate) jets, 128, 259–60, 267, 

282n89

Century series fighters and interceptors, 4, 

5, 6–8

CFD analysis and low-boom aircraft 

configurations, 49

design for sonic boom minimization, x–xi, 

6, 9–12, 42–50, 53, 53, 56–58, 69–73, 

72, 75–76, 78–80, 79, 80, 270–71, 271, 

285n112

distances flown by early supersonic aircraft, 

8

global recession effects on manufacturing 

of, 259–60

naming of, 29n19

noise and sonic boom rules and regulations, 

49–50, 53, 68–69, 72–73, 77, 78, 82n7, 

122, 214–15, 248, 249–50, 259

transonic and supersonic aircraft 

development, 2, 3–9, 5, 7

weight of aircraft and sonic booms, 15, 123, 

139

See also civilian aircraft; military aircraft; 

supersonic business jets (SSBJs); 

Supersonic Transport (SST)

aircraft industry

design of commercial aircraft, 39

global recession effects on, 259–60, 271

HSR communication problems and 

competition issues, 107

information sharing and research 

partnerships, 39, 43, 50

noise and sonic boom rules and regulations 

and viability of SSBJs, 214–15, 259

Request for Proposals for SST, 44

SCR/SCAR/AST program role, 68

sonic boom acceptability, responsibility for, 

125

sonic boom conference participation, 91

sonic boom research, 72–73

SSBJ studies and proposals, 124–28

air defense aircraft and exercises, 7–9

Air Force, U.S. (USAF)

advanced fighter trainer aircraft, ix

Aeronautical Research Laboratory, 4

Aerospace Medical Division, Biomedical 

Laboratory, 14–15

bomber roadmap and technology 

development, 128–29, 139

Community and Structural Response 

Program (Bongo), 17, 18

DACT and aggressor squadrons, 153–54

information sharing and research 

partnerships, 39

International Fighter Aircraft competition, 

152–53

long-range-strike platform study and 

proposals, 139

museum, 21

National Sonic Boom Evaluation Office 

(NSBEO), 22

Noise and Sonic Boom Impact Technology 

(NSBIT) program, 89

Oklahoma City Public Reaction Study (Bongo 

II), 18

QSP capacity, range, and specifications, 131

sonic boom research, 13–19

Tactical Air Command, 153

Test Pilot School, 217, 219, 221, 264

transonic and supersonic aircraft 

development, 3–9, 12
349

Index

transonic and supersonic flight development, 

2, 4, 5

White Sands Missile Range tests, 18–19

X-54A concept, 259

Air Force Academy, 52

Air Force Flight Test Center (AFFTC)

atmospheric effects, measurement of, 

15–16

Blackbird sonic boom research, 21

Century series aircraft testing, 4

Little Boom project, 15

SonicBOBS project, 265

sonic boom research, 25

XB-70 Valkyrie sonic boom research, 20–21, 

34–35nn65–66

Air Force Flight Test Museum, 265

Air Force Plant 42, Palmdale, 15, 204–5, 204

Air Force Propulsion Laboratory, 133

Air Force Research Laboratory (AFRL), 139, 157, 

216

Air France Concorde flights, 84n34

AIRPLANE code, 98, 99, 114n32

air traffic control system, 268

Air Vehicles Technology Integration Program 

(AVTIP), 216

Aldrich, Gary, 221, 224–25, 228, 290

Alford, William, 10, 31n36

Allan, Jack, 199n70

altitude

atmospheric changes and, 69–70

sonic boom production and, 4, 15–16, 108

aluminum construction materials, 43, 138

American Institute of Aeronautics and 

Astronautics (AIAA)

conferences and meetings, 79, 86n55, 137, 

145–46n91, 229, 242n100

honors and tributes for SSBD participants, 

235

information sharing and research 

partnerships, 39

American Recovery and Reinvestment Act, 260, 

268

Ames Research Center

ARC3D code, 162–63, 195n17

CFD and oblique-wing aircraft research, 100

CFD and sonic boom minimization research, 

95–100

CFD research, 49

HSR communication problems and 

competition issues, 107

NFBoom program, 173

Numerical Aerodynamic Simulation Facility, 

95

simulation improvement through CFD, 

257–58

sonic boom research, 12, 55, 71

supersonic flight research, 12

supersonic transport research and 

development, 9–10

Supersonic Wind Tunnel, 139

Unitary Plan Wind Tunnel, 95, 96

wind tunnel research on sonic booms, 95, 96

Anderson, Robert, 92

angle of attack (AOA), 40

animals

chicken eggs sonic boom study, 19

shock wave effects on, 12, 76, 77, 107

sonic boom effects on, 12, 14, 24, 76, 77, 

89

Apollo program, 25, 36n82, 51, 76

Applewhite, Keith, 180, 200n85, 236n2, 236n4, 

290, 291

ARAP (Aeronautical Research Associates of 

Princeton) Program, 48–49, 71, 72, 78–79, 

89

ARC3D (Ames Research Center 3-Dimensional) 

code, 162–63, 195n17

area rule, 6, 41, 46

Arizona State University, 134, 137, 138

Army, U.S., White Sands Missile Range tests, 

18–19
350

Quieting the Boom

Arnold Engineering Development Center (AEDC), 

182–83

Arslan, Alan, 293

artillery shells and firearms, 1, 3

Ashburn, Chris, 292, 293

Ashtech and Ashtech Z-12 GPS receiver, 159–

60, 189, 193, 199n74, 207, 210, 223, 252

Atlanta, public opinion surveys in, 24–25

atmosphere and atmospheric conditions

altitude and changes in, 69–70

digital images of shock waves, 117n63

freezing signature through effects in 

atmosphere, 49

isothermal atmosphere, 69–70, 74–76

measurement of atmospheric effects, 15–16

schlieren imaging system photos of shock 

waves in, 104, 105

shock wave characteristics and, 64n68

sonic boom behavior and variations in, 

15–16, 56, 108

sonic boom research, overpressure 

measurements, and, 18, 23–24, 24

speed of sound, shock waves, and 

atmospheric conditions, 1–2, 27n2

turbulence and sonic booms, 18, 18, 22, 26, 

49, 54, 56, 103–5, 104, 108, 108, 217, 

225, 229–31, 230, 232

visibility of shock waves and, 161–62

wind, N-wave signatures, and strenth of 

sonic booms, 19, 19, 56

Atomic Energy Commission, Jackass Flats BREN 

Tower research, 25–26, 25, 26, 49, 54

avalanche studies, 19

Aviation Week and Space Technology, 235, 250, 

256, 260

B

B-1B Lancers, 129

B-2 Spirit bomber, 129, 132, 205

B-52/B-52H Stratofortress bomber, 16, 129

B-58 Hustler bomber

characteristics and capabilities, 7, 8

in-flight shock wave measurement, 16, 16

National Sonic Boom Evaluation Program, 

22–24

N-wave signature, 23–24, 24

public opinions and complaints about sonic 

booms from, 8, 17, 18, 19, 19

refueling of, 8, 31n32

sonic boom carpets, 8, 21, 31n32

sonic boom research, 13, 15, 17, 20, 

34–35nn65–66

White Sands Missile Range tests, 19

wind tunnel research, 41

B-70 bomber, 10. See also XB-70 Valkyrie

BADS (Boom Amplitude and Direction Sensor) 

system, 209, 210, 212, 219, 227, 252

Baize, Donald, 100–101, 101

Baldini, Larry, 291

ballistic cracks and waves, 1, 3

Barents, Brian, 249

Bare Reactor Experiment Nevada (BREN) Tower 

sonic boom research, 25–26, 25, 26, 54

Barger, Raymond, 71–72, 77, 77, 94

Barnes, Diane, 291

BASS (Boom Amplitude and Shape Sensor), 219, 

227, 252

Bass, Henry, 104, 116n61

Bass, Robert M., 249

Batteas, Frank, 226

Battelle Memorial Institute, Center for HighSpeed Commercial Flight, 90

Baxter, Tom, 292, 293

BEARs (Boom Event Analyzer Recorders), 89, 

104, 106

Beck, Mike, 208

Beech C-45 aircraft, 17

Beechcraft aircraft, 133, 144n69

Bell XS-1/X-1 aircraft, xii, 2, 3, 27–28nn6–8, 

28n10, 209, 256, 266

Bender, Anne, 292

Berger, David, 209, 292
351

Index

Biegner, Rich, 287

Big Boom, Project, 15

Biomedical Laboratory (USAF Aerospace Medical 

Division), 14–15

Birmingham, 227, 296

Blackstock, David, 104, 116n61

Blanik sailplane. See L-23 Blanik sailplane

Bobbitt, Percy “Bud”

CFD applications, 97

QSP program sonic boom strategy, 130

SSBD design, 172, 175

SSBD Working Group member, 155, 288

SSBE Working Group member, 289

Boccadoro, Charles W.

accident and injury of, 188

CRADA for F-5E SSBD, 185

DARPA industry day participation, 132

education and career of, 132

honors and tributes for SSBD research, 235

Martin and role in QSP program, 156

QSP design concept, 136–37

QSP program, team-oriented approach to, 

133

QSP program participation, 132

sonic boom demonstrator selection, 149–50, 

156

SSBD flight postponement consideration, 

206

SSBD flight tests, 207

SSBD flight to Palmdale, 191

SSBD Management Team member, 157, 

215, 287

SSBD modifications oversight role, 188

SSBD proposal, 149

SSBD success, presentation about, 214

SSBE Program Management Team member, 

288

strike aircraft concept, 132

bodies of revolution, 3, 41

Boeing 2707-200 SST, 48

Boeing 2707-300 SST, 48, 53, 53, 55, 124

Boeing Company

aircraft design and sonic boom minimization, 

268–69

Air Force Plant 42 facility, 205

computer programs and data analysis for 

boom minimization, 44–45

F-16XL low-boom modifications, 260–61, 

260

FAA workshop presentation, 239n54

financial problems of, 53

HSCT development costs, 109

HSCT program, 90, 91, 106, 125

HSCT sonic boom minimization research, 

107

information sharing and research 

partnerships, 50

long-range-strike platform proposals, 139

low-boom transport concepts, 72

McDonnell Douglas, absorption of, 106, 132

N+2 quiet supersonic airplane concept, 257, 

258, 268–69, 269

N+3 quiet supersonic airplane concept, 258, 

269, 269

QSP design concept, 134–35, 138, 146n96, 

269

QSP program and advances in research and 

skills, 139

QSP program participation, 130

SCAMP project, 267

SCAR demonstrator, 80

sonic boom conference participation, 270

SSBD design and CFD analysis, 174

SSBD flight and T-38 chase plane, ix–x, x, 

190–91

SSBD ground sensors and data-collection 

equipment, 209–10

SSBE ground sensors and data-collection 

equipment, 219

SSBE participation, 216

SSBJ studies and proposals, 124, 126, 248, 

268
352

Quieting the Boom

SST contract award, 46

SST designs, 48, 53, 53

SST proposal, 44

Boeing Phantom Works

QSP proposal and contract, 132

Sonic Boom Mitigation Project, 250–51, 260

Bomben, Craig, 226

Bongo operation (Community and Structural 

Response Program, St. Louis), 17, 18

Bongo II operation (Oklahoma City Public 

Reaction Study), 18

Booker, Carl, 291

Boom Amplitude and Direction Sensor (BADS) 

system, 209, 210, 212, 219, 227, 252

Boom Amplitude and Shape Sensor (BASS), 219, 

227, 252

BOOMAP2 program, 89

Boom Event Analyzer Recorders (BEARs), 89, 

104, 106

Boomfile database, 89, 103, 111n2

Boron, California, 21

BQM-34E Firebee II remotely piloted vehicles, 

101, 102, 107, 115n50, 130, 150, 155

BREN (Bare Reactor Experiment Nevada) Tower 

sonic boom research, 25–26, 25, 26, 54

Briggs, Steven R., 184–85

British Aerospace, 121

British Overseas Airways Corporation Concorde 

flight, 84n34

Britt, Terry, 290

Brownlow, Dale, 186, 190, 290

Bruner, Sam, 288, 289

Bryan, Mike, viii, ix–x, 190–91, 203–5, 289

buildings. See structures (buildings)

Burleson, Carl, 248

Burne, Merv, 291

Busemann, Adolf, 6, 47, 61n37

Bush administration and George W. Bush, 250, 

257

business (corporate) jets, 128, 259–60, 267, 

282n89. See also supersonic business jets 

(SSBJs)

C

C-45 aircraft, 17

C-47 transport, 13–14

C-131B aircraft, 22

Campos, Norma, 292

Canada, 152

canards, 10, 11, 72, 249, 262, 269

Carlson, Harry W.

aircraft design and sonic boom minimization, 

55, 71–72, 78, 79

B-58 wind tunnel research, 41

flight plan phases and severity of sonic 

booms, 41

flight tests, importance of, 26

SCAT-15F concept, 45, 45

sonic boom characteristics prediction 

method, 76, 89

sonic boom conference participation, 45, 46, 

47, 48

sonic boom research, 12

SST design and wind tunnel research, 

41–42

SST feasibility studies review, 43

wind tunnel data correlation with flight test 

data, 41–42, 47, 47

wind tunnel research, 40–42, 59n4

caustics, 26, 26, 49, 54, 55, 77, 231, 231, 

266–67, 282n87

Cecil Commerce Center/Cecil Field, ix, 184, 

203–4, 294

Center for AeroSpace Information (CASI), 30n23, 

85

Center for High-Speed Commercial Flight, 

Battelle Memorial Institute, 90

Central Washington University, 267

Century series fighters and interceptors, 4, 5, 

6–8
353

Index

Cessna, 248, 250–51, 267

Cessna 150 aircraft, 22

Chance Vought F8U-3 aircraft, 13, 14

Chapman, Dean R., 73

Chapman, Rob, 144n65

Cheung, Samson, 95–96, 98

Chicago

B-58 bomber sonic boom tests, 19, 19

public opinion surveys in, 24–25

China Lake Naval Air Weapons Station (NAWS)

Air Test and Evaluation Squadron 31 (VX-31), 

227

atmospheric and weather conditions data 

from, 228

flight to St. Augustine from, 296

surveys of public opinion about sonic booms, 

107

test pilot from, 205, 221, 289

civilian aircraft

design of commercial aircraft, 39

Hustler performance and feasibility of 

supersonic transport, 8–9

hypersonic flight for, 90

QSP program applications, 131, 137–38, 

139

supersonic aircraft development, 9, 39, 271

supersonic aircraft development, support 

for, 90

See also supersonic business jets (SSBJs)

Cliatt, Larry, 267

Cliff, Susan, 98

Clinton administration and William J. Clinton, 

109

Coen, Peter G.

CRADA for F-5E SSBD, 185

HSCT low-boom configurations, assessment 

of, 100–101, 101

HSCT sonic boom minimization research, 94

ISSM flights, 162

public opinions about sonic booms, 271

QSP program sonic boom strategy, 130

quiet sonic boom signature, conditions for, 

268

SonicBOBS project, 265–66

Sonic Boom Mitigation Project, 250

sonic boom simulation research, 215

SSBD design success, 214

SSBD program role, 157, 287, 292

SSBD success and flattened signature 

shape, 212

SSBE program role, 216–17, 228, 288, 293

Supersonics Project, 256

Cold War and aircraft development and 

deployment, 4, 151–52, 154

Cole, W.J., 54, 184

Collard, Mark, 291

Colorado Rockies sonic boom research, 19

Colt aircraft, 17

Columbia University, 47, 54

Community and Structural Response Program, 

St. Louis (Bongo operation), 17, 18

computational fluid dynamics (CFD)

acoustic vibrations, development of model 

of, 257

advances in, 98, 99, 100, 269, 284n103

aircraft design applications, 49

Ames research on, 49

benefits and importance of, 73–74, 93–94, 

106–7

codes for, 96–98, 99, 100, 100, 114n32, 

162–63, 195n17

computer graphics and flow-field analysis, 

49, 54

design process for sonic boom minimization, 

100, 100

development of, 73–74

F-5E shock waves, CFD-generated image of, 

171, 172

flight test data correlation with CFD 

calculations, 101–3, 102, 103, 115–

16n53, 162–63, 163, 233–34, 233
354

Quieting the Boom

HSCT design and sonic boom minimization 

research, 95–101, 97, 98, 101

ISSM flight data analysis, 159, 162–63, 

162, 163

limitations of, 99, 109

N+2 quiet supersonic airplane design and, 

269, 284n103

oblique-wing aircraft research, 100

power of computers to run, 97

Quiet Spike retractable nose-boom concept, 

252–53, 255, 255

research on, 49, 73, 257–58

sonic boom minimization research and, 

93–94, 95–101

sonic boom propagation, development of 

model, 257

sonic boom signature through turbulence 

and, 229–30, 230

sonic boom simulation research, 257–58

SSBD design, 171–75, 195n22

wind tunnel data correlation with CFD codes, 

96, 97–98, 175–80, 177, 182–83

computers and computer programs

aerodynamic minimization calculations, 

computer program for, 74

ARAP Program, 48–49, 71, 72, 78–79, 89

computer graphics and flow-field analysis, 

49, 54

high-speed frictionless flow computations, 

74, 79

programs and data analysis for boom 

prediction and minimization, 28n8, 44–45, 

46, 47, 48–49, 56, 71, 72, 76, 89–90, 

102, 115–16n53, 172, 173

SEEB program, 172, 173

shock wave research and analysis, 54

super computers and parallel processors, 

development of, 49, 97

TRAPS program, 89, 102

waveform parameter program, 71, 76, 

89–90, 96, 98, 102

Concorde airliner

aircraft engine noise and sonic boom 

challenges, 50, 78

British-French agreement for development 

of, 43–44, 122

economic success and viability of, 122, 247

engines, 125

environmental impact issues, 107

flight routes, 75, 84n34

HSCT compared to, 90–91

information sharing and research 

partnerships, 39, 50

materials for and construction of, 43, 138

operating costs of, 75, 80

opposition to flights of, 78

overflight regions, limitations on, 75, 77, 247

passenger loads to support, 122

retirement of, 247, 269

secondary booms, 78

sonic boom measurement study, 77

technical success of, 122

conferences and symposia, 43–44, 45–50, 

52–53, 91, 92–93, 106, 118–19n83, 229, 

242nn99–100, 270–71

Congress, U.S.

complaints to about sonic booms, 7

NASA budget and funding, 274n14

SCR/SCAR/AST program funding, 69

SST program funding, 55, 57, 67

supersonic flight research, funding for, 67

Construcciones Aeronauticas Sociedad Anonima 

(CASA), 124, 141n22

Convair B-58 Hustler. See B-58 Hustler bomber

Cooperative Research and Development 

Agreement (CRADA), 184–86, 216

Coordinating Committee on Sonic Boom Studies, 

22

Corda, Steven, 288

Cornell University, 46, 47, 53, 70, 74, 77, 

85n47, 140n1, 212
355

Index

corporate (business) jets, 128, 259–60, 267, 

282n89. See also supersonic business jets 

(SSBJs)

Corskery, John, 290

Council of of European Aerospace Societies/

Confederation of European Aerospace 

Societies, 229, 242n99

Cowart, Robert A. “Robbie,” 253, 255–56

Croxton, Malcolm, 199n70

Cruickshank, Dennis, 291

Crusader fighter, 13

Cudnik, Jason, 262, 263

Cutler, Tim, 291

D

DACT (Dissimilar Air Combat Tactics), 153–54

Dahlin, John A., 162–63

Dallas, public opinion surveys in, 24–25

Darden, Christine M.

aircraft design and sonic boom minimization, 

75–76, 78–80, 79, 80

CFD and HSCT sonic boom minimization, 96

education and background of, 75, 84n33

HSCT sonic boom minimization research, 94

low-boom, high-drag paradox, 75, 75

minimization theory, revision of, 74–76, 

78–80

SCAR conference presentation, 75

sonic boom conference participation, 91, 

106

sonic boom estimation charts, 81

sonic boom minimization computer program 

(SEEB), 172, 173

SSBD ground sensor positioning, 209

wind tunnel research, limitations of, 97

Dassault Aviation

HISAC participation, 248, 268

SSBJ study and proposal, 127–28

Dassault Aviation Falcon, 128

Dassault Aviation Mirage III, 165n17

data collection and analysis

Boomfile database, 89, 103, 111n2

Chicago B-58 bomber tests, 19, 19

Community and Structural Response 

Program, St. Louis (Bongo operation), 17, 

18

computer programs and data analysis for 

boom minimization, 28n8, 44–45, 46, 

47, 48–49, 56, 71, 72, 76, 89–90, 102, 

115–16n53, 172, 173

in-flight shock wave measurement, 16

flight test data correlation with CFD 

calculations, 101–3, 102, 103, 115–

16n53, 162–63, 163

flight test data correlation with numerical 

calculations, 48–49

flight test data correlation with wind tunnel 

data, 41–42, 44–45, 47

ISSM data-collection equipment, 157–58, 

159–60, 161

National Sonic Boom Evaluation Program, 

22–24, 217

Oklahoma City Public Reaction Study (Bongo 

II), 18

precision in collection, 233

SR-71 shock wave measurement flights, 

108, 108

SSBD data-collection instruments, 189–90, 

189, 193, 206–7, 220–21

SSBD data sharing requirement, 157

SSBD flight test plan development, 191–92

SSBD ground sensors and data-collection 

equipment, 206, 207–10, 210, 212, 213, 

237n26

SSBD team, x, 292–93

SSBE data analysis and significance of 

findings, 229–35, 230, 231, 232, 233, 

234

SSBE data collection equipment, 

arrangements, and capabilities, 217, 

218–21, 218, 219, 220, 223–24, 225, 

225, 227–29, 230
356

Quieting the Boom

SSBE team, 227, 228, 293

White Sands Missile Range tests, 18–19

wind tunnel data correlation with CFD codes, 

96, 97–98, 175–80, 177, 182–83

XB-70 data and records, restoration and 

digitization of, 103

XB-70 Valkyrie sonic boom research, 21

Defense, U.S. Department of (DOD)

East Coast mystery boom research, 78

JASON scientific advisory group, 78

public response to sonic booms, awareness 

of, 44

SST research and development, 10

supersonic bomber development, 128–29

X-30 NASP program, 90–91

Defense Advanced Research Projects Agency 

(DARPA)

Advanced Supersonic Platform Industry Day, 

130, 132, 144n65

data sharing requirement, 157

hypersonic flight technology development, 

90

mission of, 128

QSP program development, 129–30

SSBD program role, ix, x

SSBD success, publicity and news release 

about, 213–14

Supersonic Aircraft Noise Mitigation 

program, 129

Switchblade oblique-wing study, 139, 259

Tactical Technology Office, 130, 131

See also Quiet Supersonic Platform (QSP) 

program

Denver, public opinion surveys in, 24–25

Desert Storm, 154

Dick, Dwight “Tricky”

expertise of, 213

F-5E return to Fallon, 213, 224

SSBD chase plane pilot, 207, 211–13, 289

SSBE chase plane pilot, 221, 222–24, 289

Difenderfer, Jim, 291

Directed Technologies, 133

Discovery, 265

Dissimilar Air Combat Tactics (DACT), 153–54

Douglas A-4 Skyhawk, 153, 154

Douglas Aircraft Company, 90, 91, 92, 125

Downen, Cathy, 288, 289

drag

CFD and measurement of effects of, 99

computer programs and data analysis for 

boom minimization, 46

nose design and, 79

QSP lift-to-drag ratio, 131, 136

sonic booms and, 139

wind tunnel research, 40

Driver, Cornelius “Neil,” 10, 66, 68

Dryden Flight Research Center (DFRC)/Flight 

Research Center (FRC)/High-Speed Flight 

Research Station (HSFRS)

AD-1 program, 85n48

Blackbird sonic boom research, 21

F/A-18 near-field shock wave experiments, 

103, 155

fighter aircraft and repeatable reduced sonic 

booms, 140n12

in-flight shock wave measurement probes, 

266

flight test support personnel, 291–92

ISSM flights, 160–62

laminar flow research, 133–34

LaNCETS project, 261–63, 261, 262, 263, 

280n66, 280n70

Low Boom/No Boom maneuver, 246, 251–

52, 263–65, 265

naming of, 12

Quiet Spike retractable nose-boom concept, 

253–56, 254, 276n29

renaming of, 77

SCAMP project, 266–67, 282n87

SCR/SCAR/AST program flights, 77

SonicBOBS project, 265–66

sonic boom database, 265
357

Index

sonic boom research, 15, 25, 77, 85n48

SonicBREWS project, 266

SR-71 low-boom modification and flight 

tests, 88, 102–3, 103

SR-71 shock wave measurement flights, 

107–8, 108

SSBD flight test and data collection role, 211

SSBD flight test plan development, 191

SSBD ground sensors and data-collection 

equipment, 207–10, 210, 220–21

SSBE flight-readiness reviews and flight 

clearance, 218

SSBE ground sensors and data-collection 

equipment, 219–21, 227

SSBE participation, 216

structures, research on sonic boom effects 

on, 263–66, 264

supersonic aircraft research and 

development, 2–4, 12

WSPR project, 267

X-15 sonic boom research, 16, 33n53

XB-70 Valkyrie sonic boom research, 20–21, 

34–35nn65–66

Dulles International Airport, 78

Durston, Donald A., 173

Dyer, Joseph, 185, 198n61

E

EADS (European Aeronautic Defence and Space 

Company), 141n22, 248

Eagle Aeronautics/Eagle Engineering

F-5 nose modifications, 171

Firebee sonic boom research, 101, 155

in-flight shock wave measurement probes, 

266

Maglieri role at, 97, 124

QSP program sonic boom strategy, 130

QSP subcontractor relationship with NGC, 

132, 133, 150

SCAMP project, 267

sonic boom expertise at, 133

sonic boom minimization and demonstrator 

selection, 149–50

SSBD design, 175

SSBE ground sensors and data-collection 

equipment, 219

SSBE participation, 216

XB-70 records, restoration of, 103

East Coast mystery booms, 78

Edwards, Glen, 3

Edwards, Thomas, 95–96, 98

Edwards Air Force Base

atmospheric and weather conditions data 

from, 228

Boomfile database, 89, 111n2

Century series fighters and interceptors, 4, 

5, 6–8

environmental concerns at SSBD test area, 

208–9, 211

naming of, 3

shock wave research, 16

sonic boom flight tests, 4, 13–16, 17, 19

Space Shuttle sonic boom effects over, 

76–77

SSBD flight chronology, 294–96

SSBD ground sensors and data-collection 

equipment, 206, 207–10, 210, 212, 213, 

237n26

SSBD test area, xi, 207–10, 208, 211

SSBE test area, 217, 221–22

structures, research on sonic boom effects 

on, 264, 264

supersonic flight testing at, 3

surveys of public opinion about sonic booms, 

107

XB-70 Valkyrie sonic boom research, 21

See also Dryden Flight Research Center 

(DFRC)/Flight Research Center (FRC)/HighSpeed Flight Research Station (HSFRS)

Eggers, Alfred, 10

Eglin Air Force Base, 6

Ehernberger, L.J. “Jack,” 102, 292
358

Quieting the Boom

Eisenhower administration and Dwight D. 

Eisenhower, 10

engine inlet shock waves

CFD and prediction of, 106–7, 150

F-5E inlet location and, 155

inlet-canopy formation flight test, 103

inlets located under airframe and, 150

measurement of, 157–58

prevention of, 99–100

SSBD modifications and, 234–35, 234

top-mounted inlets and, 133, 136–37, 137, 

138

engine nacelles

CFD and analysis of effects of, 98, 98

QSP design concept, 137

wind tunnel research, 94–95, 99–100

engines

F-5E engines, 153

QSP contract awards, 138

QSP program development, 133, 135, 135, 

136–37, 137

sound suppression and weight of, 122

turbofan engines, 126, 133

turbojet development, 151

variable cycle engine (VCE) program, 68, 122

English Electric Aviation, 43

Entry, Landing, and Descent (ELD) vehicle, 

285n115

environmental impact issues

Concorde airliner, 107

High-Speed Civil Transport (HSCT), 91–92, 

107

noise and sonic boom rules and regulations, 

49, 53, 68–69, 72–73, 77, 78, 82n7, 122, 

214–15, 248, 249–50, 259

Space Shuttle/Space Transportation System 

(STS), 76–77, 85n43

SSBD test area concerns, 208–9, 211

SST design, 39

environmental impact of aircraft designs, 39

Environmental Protection Agency/Environmental 

Science Services Administration, 25

Epke, Greg, 293

equivalent bodies of revolution, 41

Euler, Leonhard, 73, 74

Euler code, 96, 98, 114n32, 172

Euler/Navier-Stokes code, 98, 114n32

Europe

economic and fiscal problems in, 259–60

High-Speed Aircraft Industrial Project 

(HISAC), 247–48, 267–68

European Aeronautic Defence and Space 

Company (EADS), 141n22, 248

Ewers, Richard “Dick,” 213, 221, 289

Experimental Aircraft Association, 242n99

F

F-4/F-4C/F-4H Phantom II

Air Force use of, 152, 153

Boomfile database information, 111n2

DACT training, 154

maintenance of, 152

sonic boom complaints, 17

strength of sonic booms produced, 15

F-5-21 aircraft, 152

F-5 aircraft

building of, 124

Cold War and development of, 151–52

DACT and aggressor squadrons, 153–54

design and development of, 151–54

production of, 152, 153

tail surfaces, 196n28, 198n53

Vietnam War and development and 

deployment of, 152–54

F-5A/B Freedom Fighter, 152, 153

F-5E Inlet Spillage Shock Measurements (ISSM)

atmospheric conditions and visibility of shock 

waves, 161–62

CFD and analysis of data, 159, 162–63, 

162, 163
359

Index

data-collection equipment, 157–58, 

159–60, 161

flight tests and data collection, 159–62, 

161, 175

probe aircraft, 158, 159, 160–61, 161

purpose of tests, 158, 159

success of tests, 163

test pilots, 160–61, 289

F-5E Tiger II fighters

capabilities, range, and specifications, ix, 

150–51, 151, 153, 154–55

contract for, 152

DACT and aggressor squadrons, 153–54

development of, 152–53

engines, 153

fire control systems and radar, 153

maintenance of, 154

Marine Corps use of, 154

naming of, 153

Navy aircraft, 148, 154, 156, 161, 178, 

211–12, 212

operating costs of, 155

shock waves, CFD-generated image of, 171, 

172

sonic boom demonstrator selection, 150–51, 

151, 154–55, 156, 158

SSBD data-collection flight chase plane, 

202, 207, 211–13, 212, 294–95

SSBD preliminary flight tests, 158

SSBE data-collection flight chase plane, 218, 

221, 222–24, 295

test pilot, 289

F-5F Tiger II trainer, 150, 151, 152–53, 155, 

172, 174, 179, 183

F-5 Shaped Sonic Boom Demonstrator (SSBD)

audible difference in sonic booms, 212, 214

availability of aircraft to modify for, 155, 157, 

183–86

contributions to technology and research, 

234–35

CRADA for loan of, 184–86, 216

Critical Design Review, 178, 180

data-collection flights, 202, 205–6

design of and nose modifications, ix–xi, x, 

150–51, 151, 155, 171–75, 173, 174, 

178–79, 179, 183, 195n22, 234–35, 

234, 286

engine tuneup for maximum thrust, 206, 207

envelope-expansion flights, 190, 191, 193, 

203–4, 205–6

exterior paint and pinstripes, x, xi, 190, 212

flight and data-collection instruments, 189–

90, 189, 193, 206–7, 220–21

flight from St. Augustine to Palmdale, viii, 

ix–xi, x, 190–91, 203–5, 294

flight-readiness reviews and flight clearance, 

192–93

flight test area, xi, 207–10, 208, 211

flight test numbering, 204

flight test plan and number of flights, 

191–92, 212

flight tests, 206–7, 211–13, 212, 238n32, 

294–96

flight tests, length of, 204

flight tests and weather, 205, 206, 207, 226

flight to St. Augustine, 221, 227, 296

functional check flights, 186, 203–4, 205–6, 

294

ground checkouts, 193

ground sensors and data-collection 

equipment, 206, 207–10, 210, 212, 213, 

237n26

Interim Design Review, 161–62, 175

Mach number parameters and air 

temperature, 186, 205, 206, 207, 213

museum home for, 235, 272

nose glove and fairings, fabrication and 

installation of, 180–82, 181, 186–91, 

187, 188, 190

nose glove and fairings, materials for, 180, 

181, 186–87, 188
360

Quieting the Boom

nose landing gear door component, 190–91, 

190, 193

Pelican nickname, 192, 203

photos of, viii, x

postponement of flights, recommendation 

for, 206

Preliminary Design Review, 178, 185

redesignation of F-5E, 190

restoration to original condition and return of 

after demonstration, 185, 186, 216, 218

selection of, 150–51, 151, 154–55, 156

shock wave generation by, 286

specifications and modifications, 158, 

297–99, 298, 299

stability and control after modifications to, 

181, 183, 192, 203

success of, publicity and news release about, 

213–14

success of tests, 212, 212, 213–14, 216, 

234–35, 234, 247, 272

test pilots, viii, 192, 205, 289

wind tunnel testing, 170, 175–80, 176, 177, 

182–83, 183

See also Shaped Sonic Boom Experiment 

(SSBE)

F8U-3 aircraft, 13, 14

F-14 aircraft, 111n2

F-15 aircraft

Boomfile database information, 111n2

DACT training, 154

ISSM probe aircraft, 158

JAPE flight tests, 104

F-15B aircraft

experiments with and modifications to, 262

in-flight shock wave measurement probes, 

266

flight test support personnel, 291–92

ISSM probe aircraft, 159, 160–61, 161, 

206–7

laminar flow technology development and 

testing, 283n94

LaNCETS project, 261–63, 261, 262, 263, 

280n66, 280n70

landing gear problem, 222

near-field shock wave research, 232–33, 

233

Quiet Spike retractable nose-boom concept, 

253–56, 253, 254, 255, 276n29

SSBD data-collection flight chase planes, 

202, 206–7, 210, 213, 220–21, 294–95

SSBE data-collection equipment, 220–21, 

220

SSBE data-collection flight chase plane, 220, 

221, 222, 225–26, 226, 232–33, 233, 

295–96

test pilot, 221, 289

F-15E Strike Eagle, 102

F-16 aircraft, 102, 111n2, 154

F-16A aircraft, 154

F-16N aircraft, 154

F-16XL aircraft

design and capabilities of, 102, 121

low-boom modifications to, 260–61, 260

shock wave measurement flights, 88, 102, 

107–8, 108, 159, 217

F-20 Tigershark, 156

F-21 (Kfir C.1) fighters, 154, 165n17

F-86 Sabre, 5–6

F-100 Super Sabre, 4, 5, 13, 16, 152

F-101 Voodoo

air defense exercises, 8

design of, 5

flight testing, 4

sonic boom research, 13, 18

F-102/YF-102 Delta Dagger, 4, 5, 6, 8

F-104/XF-104 Starfighter

air defense exercises, 8

BREN Tower sonic boom research, 26, 26

design of, 5, 6, 133

in-flight shock wave measurement, 16

flight testing, 4
361

Index

National Sonic Boom Evaluation Program, 

22–24

N-wave signature, 23–24, 24

Oklahoma City Public Reaction Study (Bongo 

II), 18

sonic boom research, 13, 15, 17

turbulence and sonic boom carpets, 18, 18

White Sands Missile Range tests, 19

F-105/YF-105 Thunderchief

design of, 5, 6

flight testing, 4

sonic boom damage from, 52

sonic boom research, 13

F-106 Delta Dart

air defense exercises, 8

Community and Structural Response 

Program (Bongo), 17, 18

design of, 4, 6

National Sonic Boom Evaluation Program, 

22–24

Oklahoma City Public Reaction Study (Bongo 

II), 18

Safe Slide project, 19

sonic booms from, 78

F-111 aircraft, 104, 111n2, 154

F/A-18 Hornets

Boomfile database information, 111n2

ISSM probe aircraft, 158, 159, 161

Low Boom/No Boom maneuver, 246, 251–

52, 263–65, 265

Navy aircraft, 154

near-field shock wave experiments, 103, 

155

SCAMP project, 267

shaped sonic boom demonstration with, 155

SSBD flights chase plane, 205, 206, 213, 

294–95

SSBD flight to St. Augustine, 227, 296

SSBE flights chase plane, 221, 222, 295, 

296

structures, research on sonic boom effects 

on, 264–65, 265

test pilots, 289

WSPR project, 267

F/A-18E/F Super Hornet, 139

Fairchild Swearingen SSBJ, 121, 124–25

Fallica, Jim, 290

Fallon Naval Air Station

adversary training at, 154

Composite Fighter Squadron Thirteen (VFC13), 154, 158, 160–62, 184, 207, 213, 

217–18, 221

Dick and F-5E return to, 213, 224

ISSM flight support from, 158, 160–62

Naval Strike and Air Warfare Center, 154

SSBD support from, 184

far-field shock waves, 40–41, 44, 71, 108, 234

Federal Aviation Administration/Federal Aviation 

Agency (FAA)

air defense exercises, 8

BREN Tower research, 25–26, 25, 26

Colorado Rockies sonic boom research, 19

Community and Structural Response 

Program (Bongo), 17, 18

East Coast mystery boom research, 78

information sharing and research 

partnerships, 39

meetings and workshops, 214–15, 217, 

247, 248, 270–71, 284n108

NextGen air traffic control system, 268

noise and sonic boom rules and regulations, 

49, 53, 68–69, 72–73, 77, 78, 82n7, 122, 

214–15, 248, 249–50, 259

Office of Environment and Energy, 248

Oklahoma City Public Reaction Study (Bongo 

II), 18

Partnership for Air Transportation Noise and 

Emissions Reduction (PARTNER) Center of 

Excellence, 248, 251, 270

public response to sonic booms, awareness 

of, 44
362

Quieting the Boom

sonic boom acceptability, responsibility for, 

125

sonic boom research, 17, 24–26

SSBE ground sensors and data-collection 

equipment, 219, 227

SST research and development, 10–11

supersonic flight research, funding for, 67

supersonic transport development, support 

for, 9–10

Supersonic Transport Development Office, 18

White Sands Missile Range tests, 18–19

workshop on jet noise and sonic booms, 

214–15, 239n54, 247

Federation of American Scientists, 78

Ferri, Antonio

background of, 48

death of, 71

GASL role, 51

near-field shock wave research, 71

sonic boom conference participation, 48

SST design and sonic boom minimization, 

48, 53–54

supersonic overflight regions, limitations on, 

54–55

F-function theory and results, 4, 16, 46, 48, 56, 

71

Fidell Associates, 267

field tests, scope of research with, 12

firearms and artillery shells, 1, 3

Firebee II BQM-34E remotely piloted vehicles, 

101, 102, 107, 115n50, 130, 150, 155

Flight Research Center (FRC). See Dryden Flight 

Research Center (DFRC)/Flight Research 

Center (FRC)/High-Speed Flight Research 

Station (HSFRS)

flight tests

Big Boom project, 15

CFD calculations correlation with flight test 

data, 101–3, 102, 103, 115–16n53, 

162–63, 163, 233–34, 233

contributions from and importance of, 26

F/A-18 near-field shock wave experiments, 

103, 155

in-flight shock wave measurement, 4, 16, 

16, 22, 266

HSCT sonic boom minimization research, 

101–5, 102, 103, 104

isolated areas for, 16–17

JAPE flight tests, 103–4

Little Boom project, 13–14

Littleman project, 17

numerical calculations correlation with flight 

test data, 48–49

scope of research with, 12, 13–21, 24–26, 

34–35nn65–66

shock wave measurement flights, 4, 16, 16, 

22, 88, 102, 107–8, 108, 159

SR-71 low-boom modification and flight 

tests, 88, 102–3, 103

SR-71 shock wave measurement flights, 

107–8, 108, 159

strength of sonic booms produced, 15

wind tunnel data correlation with flight test 

data, 41–42, 44–45, 47

See also F-5 Shaped Sonic Boom 

Demonstrator (SSBD); Shaped Sonic Boom 

Experiment (SSBE)

Florida, Space Shuttle sonic boom effects over, 

76–77

fluid dynamics, aerodynamics relationship to, 40

focused boom research, 77, 89–90, 217, 222, 

223, 224, 231–32, 231, 266–67, 282n87

Forest Service, U.S., 19

Foster, Pat, 290, 291

Foxgrover, Mike, 291

France

aircraft engine noise and sonic boom 

challenges, 50

Concorde development agreement with 

Great Britain, 43–44, 122

information sharing and research 

partnerships, 39, 50
363

Index

supersonic airliner development, 9

Freund, Donald D., 253

Friedman, M.B., 54

Fundamental Aeronautics Program, 256–61, 

268, 283n95, 285n115

fuselages

design of for supersonic flight, 6

SCAT configurations, 10, 11

G

Ganguin, Robert, 293

Garry, John, 291

GCNSfv (Generalized Compressible NavierStokes Finite Volume) CFD program, 162–63, 

174, 179, 195n17, 234

Geiger Field, 19

General American Research Division sonic boom 

research, 50

General Applied Sciences Laboratories (GASL) 

sonic boom simulation, 51–52

General Aviation Manufactures Association, 214

General Dynamics, 128

General Dynamics F-16 aircraft, 102, 111n2, 

154

General Dynamics F-16XL aircraft. See F-16XL 

aircraft

General Electric

F-5 aircraft engines, 153

FAA workshop presentation, 239n54

jet engine publicity flight, 21

QSP contract award, 133, 138

QSP subcontractor relationship with NGC, 

133

SSBD engine maintenance for maximum 

thrust, 206

SSBJ studies and proposals, 248

turbojet development, 151

Generalized Compressible Navier-Stokes Finite 

Volume (GCNSfv) CFD program, 162–63, 174, 

179, 195n17, 234

General Motors Allison Transmission, 133

George, Albert R.

bow and tail wave lowering and sonic boom 

reduction, 54, 63–64n65

contributions of, 70–71

minimization research, 46, 53

minimization theory, confirmation of, 212

minimization theory and aircraft design, 

57–58, 69–71, 78–80, 134

photo of, 70

sonic boom conference participation, 46, 

47, 91

SSBD success and flattened signature 

shape, 212

turbulence and sonic boom research, 54

Georgia Tech, 269

Germany, 2, 27n5

Glacier National Park Safe Slide project, 19

Glennan, T. Keith, 11

Glenn Research Center/Lewis Research Center

Fundamental Aeronautics meeting, 268, 

283n95

naming of, 10

SSBD wind tunnel testing, 170, 175–80, 

176, 177

supersonic transport research and 

development, 9–10

Goldin, Daniel S. “Dan,” 109, 131

Goodlin, Chalmers “Slick,” 28n10

Goodyear blimp (Mayflower), 15, 22, 217

Graham, David H. “Dave”

data collection equipment, 157–58

experience and expertise of, 155

FAA workshop presentation, 215

honors and tributes for SSBD research, 235

ISSM flight data analysis, 162–63

ISSM flights, 159

sonic boom demonstrator selection, 149–50, 

156

SSBD data collection role, 211, 215, 292

SSBD design, 172

SSBD design success, interviews about, 214
364

Quieting the Boom

SSBD stability and control concerns, 181

SSBD success and flattened signature 

shape, 212

SSBD wind tunnel testing, 175

SSBD Working Group member, 155, 287

SSBE program role, 228, 288, 293

Great Britain (United Kingdom)

aircraft engine noise and sonic boom 

challenges, 50

Concorde development agreement with 

France, 43–44, 122

F-5E aggressor squadrons, 154

information sharing and research 

partnerships, 39, 50

supersonic airliner development, 9

Greene, Randall, 121–22

Grindle, Thomas, 253

Grumman Aerospace Corporation

Gulfstream Aerospace and, 125

high-speed frictionless flow computations, 

74, 79

HSCT sonic boom minimization research, 

107

Northrop Corporation, merger with, 107

See also Northrop Grumman Corporation 

(NGC)

Grumman Corporate Research Center, 96

Guiraud, John Pierre, 77

Gulfstream Aerospace Corporation

FAA workshop presentation, 215, 239n54

founder of, 249

General Dynamics acquisition of, 128

mobile sonic boom simulator research, 248, 

270

noise mitigation program, lobbying for, 129

QSP sonic boom minimization research, 133, 

136–37

Quiet Spike retractable nose-boom concept, 

251, 252–56, 253, 254, 255, 276n29

SCAMP project, 267

SonicBOBS project, 265

sonic boom conference participation, 270

Sonic Boom Mitigation Project, 250–51

SSBD data-collection flight chase planes,

210, 212

SSBD ground sensors and data-collection 

equipment, 209–10

SSBE ground sensors and data-collection 

equipment, 219, 227

SSBE participation, 216

SSBJ studies and proposals, 125, 128, 215, 

248, 259, 268, 270

Sukhoi Design Bureau relationship with, 125

Supersonics Project, 268

The Whisper SSBJ, 259

WSPR project, 267

X-54A concept, 259

Gulfstream G-V aircraft, 210, 212

Gustafson, Mark, 157, 287

H

Haering, Edward A. “Ed”

BADS system design, 209

CFD calculations correlation with flight test 

data, 233–34, 233

data collection equipment, 157–58

environmental concerns at SSBD test area, 

208–9

experience and expertise of, 157–58

ISSM flight data analysis, 162–63

ISSM flights, 159–62

LaNCETS project, 280n66

Low Boom/No Boom maneuver, 252

SR-71 low-boom modification and flight 

tests, 102

SR-71 shock wave measurement flights, 

108, 159

SSBD flight instrumentation, 189

SSBD flight tests, 158

SSBD ground sensors and data-collection 

equipment, 208, 209

SSBD program role, 157, 287, 292
365

Index

SSBE data collection and analysis role, 228, 

230, 293

SSBE Program Management Team member, 

288

SSBE Working Group member, 288

Haglund, George, 99, 107

Halaby, Najeeb E., 11

Hamilton, H. Harris, 74

Harder, Adam, 288, 289

Harper Dry Lake, 208, 211, 217, 237n22, 

237n26

Hartwich, Peter, 288

Hasseem, Habeeb, 290

Hawaii, Space Shuttle sonic boom effects over, 

85n43

Hawker aircraft, 133, 144n69

Hawker Beechcraft Corporation, 144n69

Hayes, Wallace D.

aerodynamics research and expertise of, 46

ARAP program, 48–49, 71

bow and tail wave lowering and sonic boom 

reduction, 63–64n65

inescapability of sonic booms, 46

minimization research, 46, 53

shock wave theory and sonic boom 

mitigation, 49

sonic boom conference participation, 46, 

48, 91

Heely, Timothy, 185

Henderson, Herbert R., 25, 36n82, 53

Henne, Preston “Pres,” 250, 255

HFL03 Euler time-relaxation code, 99

Higgins, Edgar “Sting,” 160–61, 289

High Performance Computing and 

Communications Program (HPCCP), 96

High-Speed Aircraft Industrial Project (HISAC), 

247–48, 267–68

High-Speed Civil Transport (HSCT)

capacity, range, and specifications, 90–91, 

92, 107, 108

CFD and sonic boom minimization research, 

95–101, 97, 98, 101

CFD design process, 100, 100

cost for development of, 109

design and development of, 90–95, 98–99, 

100–101, 101, 121

environmental impact issues, 91–92, 107

flight tests, 101–5, 102, 103, 104

sonic boom minimization research, 91–95, 

93, 94, 106–7, 128

sonic booms and overflight restrictions, 91, 

92, 106, 107

speed and fuel characteristics, 90

surveys of public opinion about sonic booms 

and, 105–6, 107

technology development to support, 90

weight and size of, 107

wind tunnel research, 94–95, 94, 96

See also High-Speed Research (HSR) 

program

High-Speed Flight Research Station (HSFRS), 

2–3. See also Dryden Flight Research Center 

(DFRC)/Flight Research Center (FRC)/HighSpeed Flight Research Station (HSFRS)

High-Speed Research (HSR) program

aircraft engine noise and sonic boom 

challenges, 122–23

approval for, 91

CFD and sonic boom minimization research, 

93–94, 95–101, 97, 98, 101

challenges and problems associated with, 

107, 109, 121

contributions to supersonic flight research, 

108–10, 118n78, 118–19n83

flight tests, 101–5, 102, 103, 104

focus of research, 91, 92, 93, 106–10

funding for, 91, 106

meetings and workshops, 92–93, 95–100, 

106, 108–9, 112n15, 118n78

Phase I, 91–95

Phase II, 92, 106–10
366

Quieting the Boom

sonic boom minimization research, 92–94, 

93, 106–7

surveys of public opinion about sonic booms 

and, 105–6, 107

termination of program, 109

XB-70 boom signature database use, 

34–35n66

See also High-Speed Civil Transport (HSCT)

High-Stability Engine Control project, 262

Hill, Thomas, 253, 255

Hilliard, David, 287, 289

Hilton, David A., 25, 36n82

HLFC (hybrid laminar flow control), 97

Holloman Air Force Base, 19

Honeywell, 133

Hong, Dick, 290

House Variable Intensity Boom Effect on 

Structures (House VIBES), 264, 265

Howe, Donald, 256

Howell, Kathleen, 292

Hubbard, Harvey H.

F-106 sonic boom study, 78

flight plan phases and severity of sonic 

booms, 43

NSBIT program role, 89

photo of, 12

sonic boom conference participation, 45

sonic boom research, 12

SST feasibility studies review, 43

humans. See people/humans

Hunton, Lynn, 55

Huntsville, ix, 294

hybrid laminar flow control (HLFC), 97

hypersonic flight

for civilian aircraft, 90

interest in and support for, 90, 111n9

shock wave reduction, 70

sonic boom carpets, 55

Hypersonics Project, 285n115

I

IBM (International Business Machines), 44

Ikawa, Hideo, 151, 172

impulses, 53, 57, 57, 65n77, 69–70, 141n17, 

229–30

Indian Springs, Nevada, 13–14

indoor vibrations, annoyance about, 57, 58, 

123–24, 141n17

Ingalls, Mike, 156, 184–85, 291

In-Home Noise Generation/Response System 

(IHONORS), 105, 105

Institute for Aerospace Studies, University of 

Toronto, 76

Intelligent Flight Control Systems (IFCS), 262

International Business Machines (IBM), 44

International Civil Aviation Organization (ICAO) 

Committee for Aviation Environmental 

Protection, 248, 249, 259, 260, 265, 270

International Fighter Aircraft competition, 

152–53

J

Jackass Flats BREN Tower research, 25–26, 25, 

26, 49, 54

Jacksonville, Cecil Commerce Center/Cecil Field, 

ix, 184, 203–4, 294

James, Russell, 292

Japan Aerospace Exploration Agency (JAXA), 

258, 268

jet aircraft. See aircraft and jet aircraft

Johnson, Lyndon, 49

John Volpe Center, U.S. Department of 

Transportation, 227

Joint Acoustic Propagation Experiment (JAPE, 

NATO), 103–4

Joint Chiefs of Staff, 14

Joint Task Force II, 14

Jones, J. Lloyd, 73

Jones, L.B., 43, 54

Jones, Thomas, 151, 267

Jordan, Gareth, 15
367

Index

K

Kane, Edward J., 47, 72, 78

KC-135 Stratotanker, 22, 253

Kelly, Robert, 80

Kennedy administration and John F. Kennedy, 

10, 12

Kennedy International Airport, 78

Kentron International SSBJ studies and 

proposals, 126–27, 127

Kfir C.1 (F-21) fighters, 154, 165n17

King, Jonathan, 292

Kinn, Patricia, 292

Klingbeil, Ellen, 292

Komadina, Steve

DARPA industry day participation, 132

FAA workshop presentation, 215

QSP design concept, 137

QSP program participation, 132

sonic boom demonstrator selection, 149–50

SSBD data collection team member, 215, 

292

Korea, 153

Krake, Keith, 291

Kuntz, Herb, 293

L

L-23 Blanik sailplane

SSBE data-collection equipment, 219–20, 

220

SSBE data-collection flights, 217, 221, 222, 

223, 224–25, 230, 230, 295–96

structures, research on sonic boom effects 

on, 264–65

test pilots, 290

laboratory devices. See simulators and 

laboratory devices

laminar flow

active laminar flow, 133

funding for research, 138

hybrid laminar flow control (HLFC), 97

natural laminar flow, 129, 133–34, 137

QSP program goals, 136

QSP program timeline and activities, 135

technology development and testing, 268, 

283n94

LaNCETS (Lift and Nozzle Change Effects on 

Tail Shocks) project, 261–63, 261, 262, 263, 

280n66, 280n70

Landis, Tony, 292

Langley Research Center

Acoustics Division, 15, 93, 103–5, 209–10

Aeronautical Systems Division, 68

CFD and sonic boom minimization research, 

96–101

CFD research, 73

Chicago B-58 bomber sonic boom tests, 

19, 19

Community and Structural Response 

Program (Bongo), 17, 18

field test research on sonic booms, 12

in-flight flow-field measurement probe, 22

flight test research on sonic booms, 12

House VIBES, 265

HSCT low-boom configurations, assessment 

of, 100–101, 101

HSCT sonic boom minimization research, 91, 

93–101, 107

HSR communication problems and 

competition issues, 107

Low-Frequency Noise Facility, 51, 51

Oklahoma City Public Reaction Study (Bongo 

II), 18

reports and technical publications on SST 

program, 55–56, 56

SCAMP project, 267

SCAT-15F concept, 45, 45

SCR/SCAR/AST conference, 75, 80

SCR/SCAR/AST program role, 68

shock wave research, 16

simulation improvement through CFD, 

257–58
368

Quieting the Boom

simulators and laboratory devices, 50–52, 

51, 105, 105, 215, 258

SonicBOBS project, 265

sonic boom conference participation, 45–46, 

91, 93

sonic boom flight tests, 15

sonic boom research, 6, 12, 13, 53, 71–72

SSBD ground sensors and data-collection 

equipment, 207–10

SSBE closeout workshop, 229

SSBE ground sensors and data-collection 

equipment, 219, 227

SSBE participation, 216

SSBJ studies and proposals, 125–26

SST feasibility studies review, 43–44

SST sonic boom level goal, 39

structures, research on sonic boom effects 

on, 264

supersonic flight research, 12, 13

Supersonic Pressure Tunnel (4-by-4-foot) 

testing, 17, 40–41, 59n4

supersonic transport research and 

development, 9–10

Supersonic Vehicles Technology program, 

215

turbulence and sonic boom research, 103–5, 

104

Unitary Plan Wind Tunnel, 38, 78–80, 95, 

99–100

VORLAX methodology, 173

wind tunnel research on sonic booms, 12, 

38, 47, 47, 78–80, 94–95, 96

WSPR project, 267

Larson, Nils, 262, 263, 267

Lavoie, Joseph, 290

Learjet, 249

Leatherwood, Jack, 105

Lewis Research Center. See Glenn Research 

Center/Lewis Research Center

lift

CFD and prediction of effects of, 99

compression lift and B-70 design, 10

computer programs and data analysis for 

boom minimization, 46

QSP lift-to-drag ratio, 131, 136

sonic booms and, 6, 15, 16, 123, 139, 252

SST design and sonic boom minimization, 48

SST design and wind tunnel research, 

41–42

wind tunnel research, 40

Lift and Nozzle Change Effects on Tail Shocks 

(LaNCETS) project, 261–63, 261, 262, 263, 

280n66, 280n70

Limon, Andy, 290

Ling-Temco-Vought, 50, 152

Little Boom, Project, 13–14

Littleman, Project, 17

Lockheed Engineering & Sciences Company, 

100–101, 101, 103–4

Lockheed Martin/Lockheed

aircraft design and sonic boom minimization, 

268–69

Air Force Plant 42 facility, 205

AST program and model, 66, 82n6

FAA workshop presentation, 239n54

International Fighter Aircraft competition, 

152

long-range-strike platform proposals, 139

N+2 quiet supersonic airplane concept, 257, 

258, 268–69, 269

N+3 quiet supersonic airplane concept, 258, 

269, 269

noise mitigation program, lobbying for, 129

QSP design concept, 134–35, 269

QSP program participation, 130

sonic boom conference participation, 270

Sonic Boom Mitigation Project, 250–51

SSBD design and CFD analysis, 174–75, 

195n22

SSBD ground sensors and data-collection 

equipment, 209–10
369

Index

SSBE flight-readiness reviews and flight 

clearance, 218

SSBE participation, 216

SSBJ development, interest in, 121

SSBJ studies and proposals, 128, 248

SST contract award, 46

SST proposal, 44, 48

Lockheed Martin/Lockheed Skunk Works 

(Lockheed Advanced Development Company)

Air Force Plant 42 facility, 205

low-boom aircraft designs, 128, 249

QSP concept funding, 138

QSP design concept, 138, 139

QSP proposal and contract, 132, 138

SSBJ studies and proposals, 249

stealth technology development, 128

Lockheed YF-12 Blackbird. See YF-12 Blackbird

Lomax, Harvard, 49

Lombardo, Joe, 268

London, bombing of and sonic bangs, 2

Long, Darryl “Spike”

SSBD flight chronology, 294–95

SSBD test flights, 205, 206–7, 212–13, 289

SSBE test pilot, 221

Los Angeles, public opinion surveys in, 24–25

Low Boom/No Boom maneuver, 246, 251–52, 

263–65, 265

Low-Frequency Noise Facility (Langley Research 

Center), 51, 51

Lundberg, B.K.O., 63n54

Lung, Joseph Liu, 74

Lux, David, 102

Lyman, Victor, 289

Lynn, Roger, 291

M

Mach, Ernst, 1

Mach number

Mach cutoff signature, 26, 26, 54, 56, 

64n75

naming of, 1

speed of sound, shock waves, and sonic 

booms, 1–2, 4–5, 27–28nn5–8, 28n10

SSBD Mach number parameters and air 

temperature, 186, 205, 206, 207, 213

transonic flight, 2, 28n10

Mack, Robert

aircraft design and sonic boom minimization, 

71–72, 75–76, 78–80, 79, 80

HSCT sonic boom minimization research, 94, 

99–100, 107

low-boom, high-drag paradox, 75, 75

SCAR conference presentation, 75

wind tunnel research, limitations of, 97

Madison, Steve, 191, 287, 288, 290, 291

Magee, Todd, 174, 288, 289, 292

Magellan Navigation/Magellan Corporation, 

199n74

Maglieri, Domenic J.

AST/SCAR program role, 68

BREN Tower sonic boom research, 25

Eagle Engineering role, 97, 124

F-106 sonic boom study, 78

flight plan phases and severity of sonic 

booms, 43, 46

focused boom research, 231–32

NSBIT program role, 89

photo of, 12

QSP program sonic boom strategy, 130

reports and technical publications by, 64n73

RPV flight tests, 101, 102, 115n50, 150

sonic boom conference participation, 45, 46

sonic boom demonstrator selection, 149–50

sonic boom research, 12

SSBD Working Group member, 155, 288

SSBE data collection and analysis role, 228, 

230, 293

SSBE Working Group member, 289

SSBJ proposals, summary of, 124, 141n21

SST feasibility studies review, 43

XB-70 records, restoration of, 103

Malacrida, Robert “Critter,” 221, 290
370

Quieting the Boom

Malone, Michael, 162–63

Mangus, John, 292

Marconi, Frank, 74

Marine Corps, U.S.

aggressor squadron at Yuma (Marine Fighter 

Training Squadron 40), 154, 185

F-5E aircraft, 154, 185–86

Mars, mission to, 250

Marshall Space Flight Center, ix, 77

Martin, M.L. “Roy”

airport runway length for landing F-5E, 184

experience and expertise of, 155–56

ISSM flights, 159–60

QSP program participation, 156

sonic boom demonstrator selection, 156, 

158

SSBD design, 174

SSBD design success, interviews about, 214

SSBD F-5 functional check flights, 186

SSBD flight chronology, 294–96

SSBD flight test plan development, 192

SSBD flight to Palmdale, ix–x, 190–91, 

203–5

SSBD flight to St. Augustine, 221, 227, 296

SSBD ground checkouts, 193

SSBD Mach number parameters and air 

temperature, 186, 205, 206

SSBD preliminary flight tests, 158

SSBD test flights, viii, 192, 205, 211–12, 

213, 215, 289

SSBD Working Group member, 155, 287

SSBE test flights, 221–26, 241nn81–82, 

289

SSBE Working Group member, 288

storms near home of, 205

VFC-13 support for SSBD, 184

Martin Marietta Corporation, 128. See also

Lockheed Martin/Lockheed

Mascitti, Vincent R., 66, 68, 125–26

Maskiell, Andrew, 292

Massachusetts Institute of Technology (MIT) Gas 

Turbine Laboratory, 133

Maurice, Lourdes, 270

Mayflower (Goodyear blimp), 15, 22, 217

McCleskey, Steve, 290

McCurdy, David “Dave,” 105, 287, 289, 292

McDonnell Douglas

Boeing absorption of, 106, 132

HSCT sonic boom minimization research, 

107

International Fighter Aircraft competition, 

152

low-boom aircraft configurations, 99

SSBJ development, interest in, 121

McDonnell Douglas Aerospace West, 103

McDonnell Douglas F-15E aircraft. See F-15E 

Strike Eagle

McKee, William F. “Bozo,” 11

McKendrick, Nate, 291

McLean, F. Edward

AST/SCAR program role, 66, 68

minimization research, 53

Request for Proposals for SST, 44

SCAT-15F concept, 45, 45

shock wave theory and sonic boom 

mitigation, 44, 49

sonic boom conference participation, 45–46, 

48

McLucas, John L., 85n50

McNamara, Robert, 11, 44

McPhillips, Darren, 290

MDBOOM program, 102, 115–16n53

Memphis, 227, 296

Meredith, Keith B.

CFD calculations correlation with flight test 

data, 233–34, 233

ISSM flight data analysis, 162–63

SSBD design, 172, 174

SSBD wind tunnel testing, 175

SSBD Working Group member, 287

SSBE Working Group member, 288
Index

371

meteors, 1

MetroLaser, Inc., 267

Meyer, Paul, 215

Meyer, Robert E., 250, 251

MiG-17 aircraft, 153

MiG-21 aircraft, 152, 153, 154

military aircraft

bomber roadmap and technology 

development, 128–29, 139

executive order for sonic boom reduction, 

257

fighter aircraft and repeatable reduced sonic 

booms, 140n12

International Fighter Aircraft competition, 

152–53

long-range-strike platform study and 

proposals, 139

NSBIT program, 89

quiet supersonic aircraft and QSP program 

applications, 128–30, 131, 137–39

sonic boom prediction computer programs, 

89–90

supersonic aircraft development, 3–9, 5, 7, 

128–29

MIM3D-SB (Multigrid Implicit Marching in Three 

Dimensions for Sonic Booms) code, 96, 98, 

99, 100, 100

Minneapolis, public opinion surveys in, 24–25

Miramar Naval Air Station, 153, 154

modified linear theory (MLT), 95, 99, 106–7

Moes, Timothy R. “Tim,” 102, 160, 262, 291

Mojave Airport, 184, 207, 211, 222

Mojave Desert, 2, 4, 107, 208

Molzahn, Leslie, 253, 256

momentum equation, 73, 74

Morgenstern, John

CFD and sonic boom signature through 

turbulence, 229–30, 230

HSCT sonic boom minimization research, 

107, 128

low-boom aircraft configurations, 98–99

SR-71 low-boom modification and flight 

tests, 103

SSBD design, 174–75

SSBD program role, 157, 288, 293

SSBE Working Group member, 289

SSBJ studies and proposals, 128

Morris, Sue, 287

Multigrid Implicit Marching in Three Dimensions 

for Sonic Booms (MIM3D-SB) code, 96, 98, 

99, 100, 100

Muroc Army Airfield, 2, 28n7. See also Dryden 

Flight Research Center (DFRC)/Flight Research 

Center (FRC)/High-Speed Flight Research 

Station (HSFRS)

Murray, James “Jim,” 209, 228, 292, 293

N

N+1 quiet supersonic business jet, 257, 269

N+2 quiet supersonic airplane concept, 257, 

258, 268–69, 269

N+3 quiet supersonic airplane concept, 258, 

269, 269

N-102 aircraft, 151

N-156 aircraft, 151, 152

nacelles. See engine nacelles

NASA Technical Report Server (NTRS), 30n23

National Academy of Sciences, 44, 50

National Aeronautics and Space Administration 

(NASA)/National Advisory Committee on 

Aeronautics (NACA)

Aeronautics Research Mission Directorate 

(ARMD), 256, 257–58

budget and funding for, 67, 250, 258, 260, 

268, 271, 274n14, 284n107, 285n115

Center for AeroSpace Information (CASI), 

30n23

honors and tributes for SSBD participants, 

235

information sharing and research 

partnerships, 39, 43, 50

low-boom aircraft design development, 250
372

Quieting the Boom

Office of Advanced Research and Technology, 

47, 49

Office of Aeronautics and Space Technology 

(OAST), 68

Partnership for Air Transportation Noise and 

Emissions Reduction (PARTNER) Center of 

Excellence, 248, 251

public response to sonic booms, awareness 

of, 44

purpose and mission of, 9

QSP capacity, range, and specifications, 131

Research Announcements (NRAs), 258

Research Opportunities in Aviation (ROA) 

program, 258

Russian partnership with, 108

SSBD success, publicity and news release 

about, 213–14

SSBJ studies and proposals, 125–27, 127, 

249–50

SST research and development, 10–12

transonic and supersonic flight development, 

2

Turning Goals into Reality Partnership Award, 

235

National Aero-Space Plane (NASP)

funding for, 106

interest in and support for, 90–91

Orient Express moniker, 90

technology development to support, 90, 91

X-30 NASP program, 90–91

National Business Aviation Association (NBAA), 

249

national defense aircraft and sonic booms, 7–9

National Oceanic and Atmospheric 

Administration (NOAA), BREN Tower research, 

25–26, 25, 26

National Opinion Research Center, University of 

Chicago, 18

National Park Service Safe Slide project, 19

National Research Council, 109, 128, 136, 

145n82, 270

National Sonic Boom Evaluation Office (NSBEO), 

22

National Sonic Boom Evaluation Program, 

22–24, 217

NATO. See North Atlantic Treaty Organization 

(NATO)

Naval Air Systems Command (NAVAIR) NAS 

Patuxent River, 160, 184–86, 191, 192–93, 

216

Naval Research Laboratory (NRL), 78

Naval Strike and Air Warfare Center, 154

Navier, Claude-Louis, 73–74

Navier-Stokes code, 98, 114n32

Navier-Stokes equations, 73–74

Navy, U.S.

CRADA for F-5E SSBD, 184–86, 216

F-5E aircraft, 148, 154, 156, 161, 178, 

211–12, 212

F-5E aircraft, museum home for, 235, 272

F-5 use by, ix

Fighter Weapons School, 153

sonic boom research, 25, 36n82

Top Gun training, 153, 154

NCG. See Northrop Grumman Corporation (NGC)

near-field shock waves, 40–41, 44, 45–46, 49, 

71, 103, 106–7, 155, 234–35, 234

Needleman, Kathy, 94, 100–101, 101

Nehring, Dan, 290

Nellis Air Force Base, 13, 105–6, 154

NetJets, 121, 215, 248

Nevada

F-5E aggressor squadrons, 154

surveys of public opinion about sonic booms, 

107

XB-70 Valkyrie sonic boom research, 21

Nevadomsky, John, 184, 203, 290

New York, Kennedy International Airport, 78

New York University (NYU), 47, 53, 71

NextGen air traffic control system, 268

NF-156F aircraft, 152

NFBoom program, 173
373

Index

Nixon, Richard M., 53, 67

Noffz, Gregory, 293

Noise and Sonic Boom Impact Technology 

(NSBIT) program, 89

North American Air Defense Command (NORAD), 

7–9

North American Aviation SST proposal, 44

North American B-70 bomber, 10. See also

XB-70 Valkyrie

North American F-86 Sabre, 5–6

North American Rockwell SSBJ concept, 80, 80, 

125–26

North American XB-70 Valkyrie. See XB-70 

Valkyrie

North Atlantic Treaty Organization (NATO)

Advisory Group for Aerospace Research & 

Development (AGARD), 49–50

Joint Acoustic Propagation Experiment 

(JAPE), 103–4

North Carolina, 78

Northrop, Jack, 151

Northrop Corporation, Grumman merger with, 

107

Northrop F-5A/B Freedom Fighter, 152, 153

Northrop F-5 aircraft. See F-5 entries

Northrop F-20 Tigershark, 156

Northrop Grumman B-2 Spirit bomber, 129, 132, 

205

Northrop Grumman Corporation (NGC)

Advanced Composites Manufacturing Center, 

181, 181

Advanced Systems Development Center, 158

aircraft design competence, ix

DARPA industry day participation, 132, 

144n65

HSCT sonic boom minimization research, 

107

Integrated Systems Sector (ISS), ix, 132, 

138, 144n66, 155, 156, 172, 188, 259

long-range-strike platform proposals, 139

low-speed wind tunnel, 182–83, 183

merger to form, 107

QSP concept capacity, range, and 

specifications, 138

QSP concept funding, 138

QSP concept model and wind tunnel testing, 

139

QSP design concept, 120, 134–35, 136–39, 

137

QSP partnership relationship, 132

QSP program and advances in research and 

skills, 139

QSP program participation, 130, 132

QSP proposal and contract, 132–33, 136, 

138, 144n68

QSP subcontractor relationships, 132–33, 

150

Quiet Spike retractable nose-boom concept, 

251

SCAMP project, 267

shaped sonic boom workshop, 157–58

sonic boom demonstrator selection, 149–51, 

151

Sonic Boom Mitigation Project, 250–51

SSBD contract award, 138, 156, 172

SSBD funding, 138, 156, 172, 216

SSBD program role, ix–x, x

SSBD proposal, 149–51, 151, 156

SSBD success, publicity and news release 

about, 213–14

SSBD team members, 215

SSBE flight-readiness reviews and flight 

clearance, 218

SSBE ground sensors and data-collection 

equipment, 219, 227

SSBE participation, 216–17

SSBJ studies and proposals, 248

stealth technology development, 132, 205

Switchblade oblique-wing study, 259

Teledyne Ryan purchase, 150

vehicle design team, 290

Northrop Grumman Corporation (NGC) Palmdale
374

Quieting the Boom

facilities at, 204–5, 204

flight test support personnel, 291

SSBD flight to Palmdale, viii, ix–xi, x, 190–

91, 203–5, 294

SSBD ground sensors and data-collection 

equipment, 209–10

Northrop Grumman Corporation (NGC) Saint 

Augustine (NGSA)

experience and expertise of technicians at, 

184

F-5E maintenance at, 154

flight testing and telemetry instrumentation 

at, 190

flight test support personnel, 290–91

Ingalls role at, 156

nose glove and fairings, fabrication and 

installation of, 186–91, 187, 188, 190

selection of for SSBD modifications, 183–84

SSBD engine maintenance for maximum 

thrust, 206

SSBD flight to, 221, 227, 296

SSBD flight to Palmdale from, viii, ix–xi, x, 

190–91, 203–5, 294

SSBD maintenance at, 186

Northrop N-102 aircraft, 151

Northrop N-156 aircraft, 151, 152

Northrop NF-156F aircraft, 152

Northrop RF-5A Freedom Fighter, 152

Northrop RF-5E Tigereye, 150, 151, 153, 155

Northrop T-38 Talon. See T-38 Talon

Northrop TZ-156 aircraft, 151, 152

Northrop YB-49 flying wing, 3

Northrop YF-5A aircraft, 152

Northrop YF-23 fighter, 132, 139, 155

Northrop YT-38 aircraft, 151

Norwood, Darrell, 199n70

nose design

aerodynamics research and, 75

blunt-nosed aircraft, 71, 75, 75, 79

bow waves and, 75, 75

drag and, 79

extension to slow bow shock wave, 69

F-5E configuration, ix, x, x, 150–51, 151, 

155, 171–75, 173, 174

Firebee II BQM-34E RVPs, 101, 102

loft, 171

low-boom, high-drag paradox, 75, 75, 91

sharp-nosed aircraft, 75, 75, 79

NPSOL code, 100, 100

NSBIT (Noise and Sonic Boom Impact 

Technology) program, 89

Numbers, Keith, 288, 289

Numerical Aerodynamic Simulation Facility, 95

numerical calculations correlation with flight test 

data, 48–49

O

Obama administration and Barack Obama, 260

oblique-wing aircraft, 100, 123, 139, 259

Okada, Dustin, 292

Oklahoma City Public Reaction Study (Bongo 

II), 18

Old Dominion University, 175

Olsen, Barbara, 185

Orbital Sciences Corporation, 199n74

organizations, professional and research, 39, 68

Overholt, Matthew, 94

ozone layer, 39

P

Pa-25 aircraft, 221, 224–25, 290

Page, Juliet

ISSM flight data analysis, 162–63

MDBOOM program development, 102

SSBD design, 175

SSBD Working Group member, 155, 288

SSBE Working Group member, 289

Palmdale and Air Force Plant 42, 15, 204–5, 

204. See also Northrop Grumman Corporation 

(NGC) Palmdale

Parie, James, 292

Parker, Bob, 290
375

Index

Partnership for Air Transportation Noise and 

Emissions Reduction (PARTNER) Center of 

Excellence, 248, 251, 270

Patuxent River Naval Air Station, 160, 184–86

Paulson, Allen E., 249

Paulson, J. Michael, 249

Pawlowski, Joseph W.

CRADA for F-5E SSBD, 184–85

F-5E and RF-5E development role, 153

honors and tributes for SSBD research, 235

ISSM flights, 160, 162

QSP and DARPA solicitations, coordination of 

responses to, 132

sonic boom demonstrator selection, 149–50

SSBD design success, interviews about, 214

SSBD modifications oversight role, 188

SSBD problems, delays, and miracles, 227

SSBD program role, 155, 157, 215, 287

SSBD proposal management, 149, 164n1

SSBD wind tunnel testing, 178

SSBD Working Group rules, 158

SSBE program role, 217, 288, 293

Pawnee Pa-25 aircraft, 221, 224–25, 290

PBOOM program, 172, 173

PCBoom program, 89, 102, 173

PCBoom3 program, 89–90, 102

PCBoom4 program, 28n8, 231, 252

Pedroza, Eddy, 290

Pendleton, Oregon, 25

Pennsylvania State University, 251, 265, 267, 

270

people/humans

acoustic vibration effects on, 257

attitudes and opinions about sonic booms, 

12, 15, 17, 18, 24–25, 26, 70, 105–6, 

107, 138, 215, 231, 248, 267, 271

indoor vibrations, annoyance about, 57, 58, 

123–24, 141n17

National Sonic Boom Evaluation Program, 

23–24

perceived noise decibel (PNdB), 23–24

response to sonic booms, awareness of, 44

shock wave effects on, 12, 14, 76, 77

simulators for research on sonic boom 

effects on, 50, 105, 105, 215, 248, 258

sonic boom effects on, 13, 14–15, 53–54, 

76, 77

startle response, 25, 103

White Sands Missile Range tests, 19

perceived noise decibel (PNdB), 23–24

Philippines, 154

Pierce, Allan D., 91, 104

Pilon, Tony, 174, 288, 289, 293

Piper Colt aircraft, 17

Plotkin, Kenneth J. “Ken”

bow and tail wave lowering and sonic boom 

reduction, 63–64n65

education of, 77

focused boom research, 77, 231–32

ISSM flight data analysis, 162–63

MDBOOM program development, 102

PCBoom3 program, 89–90

sonic boom minimization and demonstrator 

selection, 149–50

SSBD data collection role, 211, 292

SSBD design, 174

SSBD success and flattened signature 

shape, 212

SSBD Working Group member, 155, 288

SSBE data collection and analysis role, 228, 

230, 293

SSBE Working Group member, 289

turbulence and sonic boom research, 54

Wyle Laboratories employment of, 77

Poncer, James, 288

Porter, Lisa, 251, 256

Porter, Tom, 288, 289

Powell, Clemans A., 91

Pratt & Whitney

FAA workshop presentation, 239n54

N+2 quiet supersonic airplane concept, 

268–69, 269
376

Quieting the Boom

QSP contract award, 133

QSP subcontractor relationship with NGC, 

133

SSBJ studies and proposals, 248

PRC Kentron, 126. See also Kentron International 

SSBJ studies and proposals

Princeton University, 47, 53, 71, 100, 134

Purifoy, Dana

F-16XL shock wave measurement flights, 

102, 159

ISSM flights, 159, 160–61

landing gear problem, 222

SSBD chase plane pilot, 206–7, 213, 289

SSBE chase plane pilot, 221, 222, 225–26, 

289

Q

QuakeGuard, 266

Quesada, Elword R. “Pete,” 11

Quiet Small Supersonic Transport (QSST), 249

Quiet Spike retractable nose-boom concept, 

251, 252–56, 253, 254, 255, 276n29

Quiet Supersonic Platform (QSP) program

birth of, 129–31

budget and funding for, 129, 138, 139

capacity, range, and specifications, 129, 131

civilian aviation applications, 131, 137–38, 

139

collaborative focus of, 134

construction materials, 138

contract and funding amounts, 138

contract awards, 132–36, 144n68, 156, 

171

contributions to technology and research, 

139, 149

design and development of concepts, 120, 

134–39, 135, 137, 146n96, 269

engine technology solicitations and 

contracts, 133, 135, 135, 136–37, 137

FAA workshop presentation, 215, 239n54

flight chronology, 294–96

goal of, 129, 131, 136, 139

industry participants, 130, 132–36

management of, 130, 134, 139

military applications, 128–30, 131, 137–39

overflight regions and unrestricted 

operations, 131, 215

overpressure reduction requirements, 131

Phase I, 130, 132–36, 135, 137, 171

Phase II, 130, 135, 136–39, 137

Phase III, 136

phasing out of, 139

progress on concepts and technology 

development, 136, 247

proposals and contract awards, 132–36, 

144n68, 156

sonic boom minimization and noise reduction 

solicitations and contracts, 130–31, 133–

34, 135–36, 135, 137, 137, 139

sonic boom minimization success, 139

timeline and program activities, 135–36, 

135

See also Shaped Sonic Boom Demonstration 

(SSBD) program

R

Raytheon Corporation

FAA workshop presentation, 239n54

QSP concept funding, 138

QSP design concept, 137, 139

QSP partnership relationship with NGC, 132

QSP subcontractor relationship with NGC, 

133

Raytheon Aircraft Company, 133, 144n69

Sonic Boom Mitigation Project, 250–51

SSBD data-collection flight chase planes, 

210, 212

SSBE participation, 216

SSBJ studies and proposals, 248

Raytheon Premier I aircraft, 210, 212

Read, David, 228
377

Index

Reagan administration and Ronald Reagan, 81, 

111n9, 126

remotely piloted vehicles (RPVs), 101, 102, 107, 

115n50, 130, 150, 155

Reno Aeronautics Corporation, 133–34, 249

Research Opportunities in Aviation (ROA) 

program, 258

Reynolds, Osborne, 59n3

Reynolds number, 40, 59n3

RF-5A Freedom Fighter, 152

RF-5E Tigereye, 150, 151, 153, 155

Rhoades, Carrie, 262

Richwine, David “Dave,” 157, 160, 287

Rider, Chuck, 291

rise time, 56–57, 57, 69–70, 72, 104, 231, 252

Robins, A. Warner

SCAT-15F concept, 45, 45

SSBJ study and proposal, 126

supersonic transport research and 

development, 10

Rochat, Judy, 228

Rogers Dry Lake, 2, 217, 222

Rolls-Royce

N+2 quiet supersonic airplane concept, 269, 

269

Rolls-Royce–Snecma Olympus 493 engine, 

125

SSBJ studies and proposals, 248

Rood, Rich, 292

Ross, Jim, 292

Roswell, x, 294

Roussel, Larry, 290

Royal Air Force, 4–5, 8

Rung, Corry, 291

Runyan, H.L., 53

Russia

aircraft industry and Cold War, 125

fighter aircraft from, 154

NASA partnership with, 108

Ryan BQM-34E Firebee II remotely piloted 

vehicles, 101, 102, 107, 115n50, 130, 150, 

155

S

SABER (Small Airborne Boom Event Recorder) 

device, 210, 219–20, 225, 227, 230

Safe Slide, Project, 19

St. Augustine and St. Johns County Airport, 

184, 203, 227. See also Northrop Grumman 

Corporation (NGC) Saint Augustine (NGSA)

Salamone, Joe

SSBD program role, 288, 292

SSBE program role, 228, 230, 289, 293

Sandberg, Jim, 185

Scaled Composites, 183, 186

Schein, David “Dave,” 228, 288, 292, 293

Schkolnik, Gerard, 256, 289

schlieren imaging system photos of shock 

waves, 104, 105

Scholz, Al, 290, 291

Schueler, Kurt, 288

Schwartz, Ira R., 49, 52, 53

Scott Air Force Base, 17

Seebass, A. Richard

aerodynamic minimization calculations, 

computer program for, 74

caustics and focused boom research, 77

computer program named after, 172

contributions of, 70–71

death of, 134

education and career of, 140n1, 142n38

minimization research, 46, 53

minimization theory, confirmation of, 212

minimization theory and aircraft design, 

57–58, 69–71, 78–80, 122, 123–24, 

134, 141n17

photo of, 70

shock wave characteristics research, 54, 55

sonic boom conference participation, 46, 48

SSBJ development, support for, 121, 122
378

Quieting the Boom

SSBJ studies and proposals, 128

supersonic overflight regions, limitations on, 

54–55

von Kármán Institute presentation, 121, 122

SEEB program, 172, 173

Sei, Vince “Opus,” 221, 290

Seismic Warning Systems, Inc, 266, 267

Seymour, Scott, 188

shadow zones, 49

Shaped Sonic Boom Demonstration (SSBD) 

program

aircraft design based on, 271

budget and funding for, 138, 156, 172, 216

configurations and options for demonstration, 

155

contributions to technology and research, 

234–35

data collection team, x, 292–93

data sharing requirement, 157, 174–75

environmental concerns at test area, 208–9, 

211

flight and data-collection instruments, 

157–58, 159–60, 161, 189–90, 189, 

193, 206–7, 220–21

goal of, x–xi

ground sensors and data-collection 

equipment, 206, 207–10, 210, 212, 213, 

237n26

honors and tributes given to participants, 

235

ISSM flights, 158, 159–63

lessons learned, 216, 267

management team, 155, 157, 287

NGC contract award, 138, 156, 172

NGC proposal, 149–51, 151, 156

probe aircraft, 158

problems, delays, and miracles, 188, 190–

91, 226–27

proposals and contract awards, 156

publicity and news release about, 213–14

QSP program and, x, 135, 136, 149

reports and technical publications, 229, 

300–301

selection of demonstrator aircraft, 149–51, 

151

success of, 212, 212, 213–14, 216, 234–

35, 234, 247, 250, 272

test pilots, 289

timeline and program activities, 135, 136

Working Group formation and membership, 

155–58, 172, 174–75, 287–88

workshop on, 157–58

See also F-5 Shaped Sonic Boom 

Demonstrator (SSBD)

Shaped Sonic Boom Experiment (SSBE)

audible difference in loudness of sonic 

booms, 230–31

CFD calculations correlation with flight test 

data, 233–34

closeout workshop, 229

conference and report presentations, 229, 

242nn99–100

contributions to technology and research, 

234–35

data analysis and significance of findings, 

229–35, 230, 231, 232, 233, 234

data collection equipment, arrangements, 

and capabilities, 217, 218–21, 218, 219, 

220, 223–24, 225, 225, 227–29, 230

data collection team, 227, 228, 293

flight-readiness reviews and flight clearance, 

218

flight test area, 217, 221–22

flight test plan and number of flights, 216, 

217–18

flight tests, 221–27, 226, 230, 241nn81–

82, 295–96

flight tests, length of, 222

flight tests and weather, 226, 229–30

functional check flights, 222

funding for, 216

goal of, 216
379

Index

highest airspeed flight test, 224, 241n81

honors and tributes given to participants, 

235

lessons learned, 267

near-field shock wave research, 232–33, 

232, 233

preparations for, 216–21

program management team, 216–17, 288

pushover maneuver and focused booms, 

217, 222, 223, 224, 231–32, 231

QSP program and, 136

reports and technical publications, 300–301

success of, 272

test pilots, 289–90

timeline and program activities, 135, 136

turbulence and sonic boom research, 217, 

225, 229–31, 230, 232

Working Group formation and membership, 

216–17, 229, 288–89

Shepherd, Kevin, 105, 248, 287, 289

Sherman, Mark, 290

Shin, Jaiwon, 258

SHOCKN code, 108

shock waves

acoustic rays, 54, 55, 56, 64n68, 71, 231, 

231

aircraft design to reduce, x–xi, 6, 9–12, 

42–50, 69–72, 72

air pressure and pressure changes, 3, 3, 

16, 16

animals, effects on, 12, 76, 77, 107

atmospheric conditions and visibility of, 

161–62

bow waves, 3–4, 3, 16, 16, 41, 45, 54, 72, 

75, 75, 79, 234–35

CFD and shock wave calculations, 96–98, 

97

characteristics of, 54, 64n68

compression lift and B-70 design, 10

diffraction of into shadow zones, 49

digital images of, 117n63

expansion of and energy dissemination, 54, 

55, 64n68

F-5 shock waves, 286

far field, 40–41, 44, 71, 108, 234

flattop signature, 47, 47, 79

in-flight measurement of, 4, 16, 16, 22, 266

freezing signature through effects in 

atmosphere, 49

lowering bow and tail waves and sonic boom 

reduction, 54, 63–64n65

multiple waves, 16, 40

near field, 40–41, 44, 45–46, 49, 71, 103, 

106–7, 155, 234–35, 234

near-field shock wave experiments, 103, 

155, 232–33, 232, 233

nonlinear shock wave behavior, 49

N-wave signature, 16, 16, 23–24, 24

N-wave signature and acceptable noise level, 

53–54

N-wave signature and shock cone, 3–4, 3, 

6, 64n68

overpressure measurements, 13–19, 21

overpressure prediction, 57

overpressure reduction solutions, 42, 45–47, 

48, 56–58, 57, 70, 79, 79

people, effects on, 12, 14, 76, 77

phantom body to eliminate, 57, 69, 76

photos of, 1

prediction of evolution of, 56

quiet sonic boom signature, conditions for, 

268

research on, 12

schlieren imaging system photos of, 104, 

105

speed of sound, sonic booms, and, 1–2, 

3–5, 27–28nn5–8, 28n10

structures, effects on, 12, 76, 77

successful flattened signature shape, 212, 

212, 213–14, 216, 234–35, 234

tail waves, 3–4, 3, 6, 16, 16, 54, 79

temperature and, 1–2, 18, 27n2, 78
380

Quieting the Boom

wind, N-wave signatures, and strenth of 

sonic booms, 19, 19, 56

wind tunnel research, 12, 17, 40–42, 42, 

59n4

Short Takeoff and Landing (STOL) Maneuvering 

Technology Demonstration, 262

Shrout, Barrett L., 45–46

Siclari, Michael, 96, 98, 100, 107

Silva, Perry, 291

Simmons, Frank, III, 253, 256

simulators and laboratory devices

improvement of through CFD, 257–58

Langley experiments and research, 50–52, 

51, 248

mobile sonic boom simulator, 248, 270

Numerical Aerodynamic Simulation Facility, 

95

scope of research with, 12

sonic boom effects, research on, 76, 105, 

105, 215, 248, 257–58

Skoshi Tiger (Little Tiger) evaluation, 152, 153

Skyshield I air exercise, 7

Skyshield II air exercise, 7–8

Skyshield III air exercise, 8

Small Airborne Boom Event Recorder (SABER) 

device, 210, 219–20, 225, 227, 230

Smith, Leslie, 293

Smith, Mark

nose glove and fairings, fabrication of, 181

SSBD modifications role, 186, 187, 190, 

215, 290

Smith, Richard G., III, 215

Smolka, Jim

ISSM preliminary flight, 159

LaNCETS project, 262–63, 263

Low Boom/No Boom maneuver, 252

Quiet Spike retractable nose-boom concept, 

253, 255

Quiet Supersonic Platform (QSP) program, 

256

SSBD chase plane pilot, 205, 206, 289

SSBE chase plane pilot, 221, 289

Society of Automotive Engineers, 242n99

Society of Experimental Test Pilots, 242n99, 

255–56

Soltani, Aziz, 290

sonic bangs, 60n12

Sonic Boom Mitigation Project, 250–51, 260, 

275n22

sonic boom research

advances and progress in, 106–7, 271–72

Air Force role in, 13–19

animals, effects on, 12, 14, 24, 76, 77, 89

atmospheric effects, measurement of, 

15–16, 18, 18, 23–24, 24

atmospheric effects, understanding of, 56

bow and tail wave lowering and sonic boom 

reduction, 54, 63–64n65

BREN Tower research, 25–26, 25, 26, 54

caustics, 26, 26, 49, 54, 55, 77, 266–67, 

282n87

CFD and sonic boom minimization research, 

93–94, 95–101

charts for estimating sonic booms, 81

Colorado Rockies sonic boom research, 19

Community and Structural Response 

Program (Bongo), 17, 18

computer programs and data analysis 

for boom minimization, 44–45, 46, 47, 

48–49, 56, 71, 72, 76, 89–90, 102, 

115–16n53, 172, 173

conferences and symposia, 43–44, 45–50, 

52–53, 91, 92–93, 106, 118–19n83, 

229, 242nn99–100, 270–71

focused boom research, 77, 89–90, 266–

67, 282n87

focused boom research and pushover 

maneuver, 217, 222, 223, 224, 231–32, 

231

funding for, 72–73, 79

future research area recommendations, 

109–10
381

Index

heroic era of, 25

HSR program contributions to, 108–10, 

118n78, 118–19n83

information sharing and research 

partnerships, 39, 43, 50

isolated areas for, 16–17

light aircraft, effects on, 17

low-boom, high-drag paradox, 75, 75, 91

low-boom designs, practical applications for, 

92–93

low-boom transport feasibility study, 72

low-boom X-plane, 136, 249–50, 251, 270, 

271

minimization, first experimental attempt at, 

41

minimization and aircraft design, x–xi, 6, 

9–12, 42–50, 53, 53, 56–58, 69–73, 

72, 75–76, 78–80, 79, 80, 270–71, 271, 

285n112

minimization and flight profiles, 56–57, 

64n75

minimization and HSCT program, 91–95, 93, 

94, 106–7, 128

minimization of sonic booms, brainpower and 

research for, 42–50

minimization theory, confirmation of, 212

minimization theory, revision of, 74–76

minimization theory and aircraft design, 

57–58, 69–71, 78–80, 122, 123–24, 

134, 141n17

NASA role in, 9, 12

NASA specialized research programs, 47

Oklahoma City Public Reaction Study (Bongo 

II), 18

people, effects on, 13, 14–15, 53–54, 76, 

77

perceived noise decibel (PNdB), 23–24

prediction and minimization techniques, 

advances in, 74–81, 85n43

QSP program, 130–31, 133–34, 135–36, 

135, 137, 137, 139

reliability of outcomes of, 55

reports and technical publications on, 

55–56, 56, 64n73, 73, 229, 300–301

SCR/SCAR/AST program, 68–69

SST research and, 10–12, 13, 17, 19, 26, 

55–58, 56, 64n73

strength of sonic booms produced, 15

structures, effects on, 12, 13, 14, 17, 18, 

19, 24, 76, 77, 89, 263–66, 264

surveys of public opinion, 12, 15, 17, 18, 

24–25, 26, 105–6, 107, 138, 215, 267

White Sands Missile Range tests, 18–19

See also flight tests; simulators and 

laboratory devices; wind tunnels

Sonic Boom Resistant Earthquake Warning 

System (SonicBREWS), 266

sonic booms

acceptability of, responsibility for, 125

aerodynamics and, 11–12

altitude and production of, 4, 15–16, 108

atmospheric conditions and production of, 

15–16, 56, 108

audible differences in loudness, 212, 214, 

230–31

carpets, 2, 8, 18, 18, 21, 31n32, 52, 55

causes of, 1, 3–5

concept and definition of, 60n12

control and abatement rules and regulations, 

49–50, 53, 68–69, 72–73, 77, 78, 82n7, 

122, 214–15, 248, 249–50

damage claim amounts, 17, 18, 19

damage from and complaints about, 4–9, 8, 

17, 24, 25, 31n32, 52

double-boom sounds, 3–4

drag and, 139

fighter aircraft and repeatable reduced sonic 

booms, 140n12

flight plan phases and severity of, 4–5, 8, 

15–16, 21, 31n32, 39, 41, 43, 46, 122, 

126, 231, 266–67

human-produced, 1, 2, 27n5
382

Quieting the Boom

inescapability of, 46, 47

lift and, 6, 15, 16, 123, 139, 252

natural, 1

N-wave signature, 16, 16, 23–24, 24

N-wave signature and acceptable noise level, 

53–54

N-wave signature and shock cone, 3–4, 3, 6

prediction of evolution of, 56

pressure spikes and noise from, 4

quiet sonic boom signature, conditions for, 

268

secondary booms, 78

speed of sound, shock waves, and, 1–2, 

3–5, 27–28nn5–8, 28n10

SST sonic boom level goal, 39

super booms, 6, 77

supersonic flight and, 2, 3–4

theoretical ways of minimization, 46

turbulence and, 18, 18, 22, 26, 49, 54, 56, 

103–5, 104, 108, 217, 225, 229–31, 

230, 232

weight of aircraft and, 15, 123, 139

wind, N-wave signatures, and strenth of 

sonic booms, 19, 19, 56

Sonic Booms on Big Structures (SonicBOBS), 

265–66

Sonic Boom Symposium (ASA), 45–46

SONIC program, 48

Sorensen, Hans, 71

sound, speed of

rate of, 1–2, 27n2

shock waves, sonic booms, and, 1–2, 3–5, 

27–28nn5–8, 28n10

temperature and, 1–2, 27n2, 86n52

sound barrier, breaking of, 2, 28n7

South Carolina, 78

Soviet Union, 9

Space Defense Initiative, 111n9

Space Shuttle/Space Transportation System 

(STS)

budget and funding for, 250

ceramic tile use on, 61n37

environmental impact statement, 76–77

environmental impact statement and sonic 

booms, 85n43

high-speed frictionless flow computations 

and aerodynamics of, 74

sonic boom predictions, 76–77

X-15 sonic boom research, 33n53

Space Technology Program, 285n115

Spain

Construcciones Aeronauticas Sociedad 

Anonima (CASA), 124, 141n22

F-5 aircraft production, 152

spark-discharge system, 50

SPLTFLOW-3D code, 195n22

Spooner, John, 291

Springs, Tony, 144n65

SR-71 Blackbird

Boomfile database information, 111n2

JAPE flight tests, 104

low-boom modification and flight tests, 88, 

102–3, 103

National Sonic Boom Evaluation Program, 

22–24

shock wave measurement flights, 107–8, 

108, 159, 217

sonic boom research, 21, 24–25, 70

training program, 24

Srenco, Ron, 290

stability, 40

Stack, John P., 12

stainless steel construction materials, 43

Stanford University, 133, 134

Stencel, Larry, 291

Stevens, Ted, 129

Stokes, George Gabriel, 73–74

Strategic Air Command (SAC)

air defense aircraft and exercises, 7–9

Community and Structural Response 

Program (Bongo), 17, 18

SR-71 Blackbird training program, 24
383

Index

structures (buildings)

acoustic vibration effects on, 257

indoor vibrations, annoyance about, 57, 58, 

123–24, 141n17

shock wave effects on, 12, 76, 77

simulators for research on sonic boom 

effects on, 50

sonic boom effects on, 12, 13, 14, 17, 18, 

19, 24, 76, 77, 89, 263–66, 264

Stuart, Jerry, 290

Stucky, Mark “Forger,” 221, 228, 290

Su-51 supersonic business jet, 125

Sukhoi Design Bureau

Gulfstream Aerospace relationship with, 125

HISAC participation, 248, 268

SSBJ studies and proposals, 125

Sullivan, Brenda

audible difference in loudness of sonic 

booms, 230–31

sonic boom simulation research, 105, 215, 248

SSBE data collection and analysis role, 228, 

230, 293

SSBE Working Group member, 289

Superboom Caustic Analysis and Measurement 

Program (SCAMP), 266–67, 282n87

super booms, 6, 77

Supersonic Acoustics Signature Simulator II 

(SASSII), 270

Supersonic Aerospace International (SAI), 249, 

259, 274n9

Supersonic Aircraft Noise Mitigation program, 129

supersonic business jets (SSBJs)

capacity, range, and specifications, 121–24

concepts, studies, and proposals for, 80, 

80, 124–28, 141n21, 215, 247–51, 257, 

268, 270

funding for development of, 127

indoor vibrations and design of, 123–24, 

141n17

N+1 quiet supersonic business jet, 257, 269

noise and sonic boom rules and regulations 

and viability of, 214–15, 248, 259

QSP design concept, 139

QSP program applications, 131

routing of, 124

SCAMP project, 266–67, 282n87

sonic boom minimization designs, 121–24, 

128, 249–51

support for and interest in development of, 

121–24, 127, 128, 247–51

US and NASA role in development of, 122, 

249–50

The Whisper SSBJ, 259

Supersonic Commercial Air Transport (SCAT)

design and development of, 9–12, 11

flight plan phases and severity of sonic 

booms, 41

SCAT-4, 10, 11

SCAT-15, 10, 11, 69

SCAT-15F, 45, 45

SCAT-16, 10, 11, 44

SCAT-17, 10, 11, 44

sonic boom research and, 26

wing configurations, 10, 11, 45, 45

Supersonic Cruise Industry Alliance (SCIA), 248

Supersonic Cruise Research (SCR)/Supersonic 

Cruise Aircraft Research (SCAR)/Advanced 

Supersonic Technology (AST) program

aircraft design criteria, 69

AST model, 66, 82n6

ATF-100, 69

cancellation of, 67, 80–81

conference at Langley, 75, 80

establishment of, 67

focus of, 67–68, 73

funding for, 69, 80–81

naming of, 67

organization of, 68

reports and technical publications, 73

sonic boom research, 68–73

SSBJ study and proposal, 125–26
384

Quieting the Boom

supersonic flight

advances and progress in research, 108–10, 

271–72

conferences and symposia, 43–44, 45–50, 

52–53, 91, 106, 118–19n83, 270–71

design and development of aircraft for, 2, 

3–9, 5, 7, 75, 109–10

distances flown by early supersonic aircraft, 8

executive order for R&D plan, 257

flight plan phases and severity of sonic 

booms, 4–5, 8, 15–16, 21, 31n32, 39, 41, 

43, 46, 122, 126, 231, 266–67

funding for research, 67

future research area recommendations, 

109–10

low-boom aircraft configurations, 99

low-boom transport feasibility study, 72

NASA research on, 12

noise and sonic boom control and abatement 

rules and regulations and prohibition of, 

49–50, 53, 68–69, 72–73, 77, 78, 82n7, 

122, 214–15, 248, 249–50, 259

operating costs of aircraft, 75

overflight regions, limitations on, 54–55, 

68–69, 72–73, 75, 77, 82n7, 91, 92, 106, 

107, 214–15, 271

renewed interest in and support for, 90

sonic booms and, 2, 3–4

viability of large aircraft for, 122

See also High-Speed Civil Transport (HSCT); 

High-Speed Research (HSR) program; 

supersonic business jets (SSBJs); 

Supersonic Commercial Air Transport (SCAT)

Supersonics Project, 256–61, 265, 266–67, 

268–69, 285n115

Supersonic Transport (SST)

aircraft engine noise and sonic boom 

challenges, 50, 78, 122–23

approval for development of, 12

cancellation of, 55, 57, 67

computer programs and data analysis for 

design of, 44–45, 46, 47, 48–49

criticism of and opposition to, 52–55, 63n54

data and scientific knowledge from program, 

26

design and development of, 10–12, 39

design of for sonic boom minimization, 

42–50, 53–55, 53

environmental impact of, 39

feasibility studies review, 43–44

funding for, 10–11, 53, 55, 122

materials for and construction of, 43

passenger loads to support, 122

Presidential Advisory Committee (PAC) for, 

11

Request for Proposals to aircraft industry, 44

sonic boom carpets, 52

sonic boom level goal, 39

sonic boom research and, 10–12, 13, 17, 

19, 26, 55–58, 56, 64n73

support for development of, 10–11

test beds, 10, 20

wind tunnel research and design of, 41–42

See also Concorde airliner; Tu-144 aircraft

Supersonic Vehicles Technology program, 215

Swain, John, 228, 292, 293

swept wing aircraft, 6, 72

Switchblade oblique-wing study, 139, 259

Switzerland

F-5 aircraft production, 153

F-5E buy back from, 156, 185, 186, 203

T

T-38 Talon

Boomfile database information, 111n2

capabilities, range, and specifications, ix, 

151, 154

DACT and aggressor squadrons, 154

design and development of, 151

JAPE flight tests, 104

production of, 151, 152
385

Index

shock wave photos with schlieren imaging 

system, 104, 105

SSBD flight chronology, 294

SSBD flight to Palmdale, ix–x, 190–91, 

203–5, 294

test pilot, 289

Taiwan

F-5 aircraft production, 153

F-5E buy back from, 203

Taylor, Albion D., 89

TEAM (Three-dimensional Euler/Navier-Stokes 

Aerodynamic Method) code, 98, 114n32

Techsburg, 133

Teets, Ed, 292

Teledyne Ryan, 150

temperature

altitude, atmospheric changes, and, 69–70

N-wave shape and overpressure and, 15

shock waves and, 1–2, 18, 27n2, 78

simulators and laboratory devices for 

research on, 50

sonic boom behavior and variations in, 56, 

78, 86n52

sonic boom research, overpressure 

measurements, and, 18

speed of sound and, 1–2, 27n2, 86n52

SSBD Mach number parameters and air 

temperature, 186, 205, 206, 207, 213

Tetra Tech, 267

TF-15A trainer, 262

The Right Stuff (Wolfe), 2

thermodynamics, advances in, 74

The Whisper SSBJ, 259

Thomas, Carla, 213, 292

Thomas, Charles, 71, 76, 89–90, 96, 98, 102

Thomson, Michael “Mike,” 206, 213, 226, 262, 

263, 291

Thorne, William “W.D.,” 206, 291

Three-dimensional Euler/Navier-Stokes 

Aerodynamic Method (TEAM) code, 98, 

114n32

thunder, 1

Tinker Air Force Base

Oklahoma City Public Reaction Study (Bongo 

II), 18

SSBD flights, ix–x, 294, 296

titanium construction materials, 43

Toberman, Michael, 253

Tonopah, Nevada, 14

Top Gun training, 153, 154

Tracing Rays and Aging Pressure Signatures 

(TRAPS) program, 89, 102

TRACOR, Inc., 24

Tracy, Richard, 249

TRANAIR code, 114n32

transonic flight

design of aircraft for, 6

development of aircraft for, 2

Mach number, 2, 28n10

Transportation, U.S. Department of (DOT), 11, 

67, 227

Transport Canada, 251

TRAPS (Tracing Rays and Aging Pressure 

Signatures) program, 89, 102

Triumph Aerospace Systems, 266

troposphere, 27n2

Trott, Jay, 144n65

Trout, Martin, 291

Tschida, Thomas, 292

Tu-20 Bear bombers, 78

Tu-144 aircraft, 75, 108

turbulence and sonic booms, 18, 18, 22, 26, 

49, 54, 56, 103–5, 104, 108, 108, 217, 225, 

229–31, 230, 232

Turning Goals into Reality Partnership Award 

(NASA), 235

TZ-156 aircraft, 151, 152

U

Ueda, Jim, 290

Unitary Plan Wind Tunnel (Ames), 95, 96
386

Quieting the Boom

Unitary Plan Wind Tunnel (Langley), 38, 78–80, 

95, 99–100

United Kingdom. See Great Britain (United 

Kingdom)

United States (US)

aerospace and technological developments, 

9

aircraft engine noise and sonic boom 

challenges, 50

economic and fiscal problems in, 259–60, 

271

United States Air Force Museum, 21

University of Arizona, 140n1

University of California, 270

University of Chicago, National Opinion Research 

Center, 18

University of Colorado, 47, 134, 140n1, 142n38

University of Southern California, 242n99

University of Toronto, 76, 105

UPS and UPS3D parabolized Navier-Stokes 

codes, 98, 99, 114n32

V

V-2 ballistic missile, 2

Vadnais, Jay, 172

Vadyak, Joe, 288, 289

Valiant Air Command Museum, 235, 272

Vandenberg Air Force Base, 228

variable cycle engine (VCE) program, 68, 122

Vartio, Eric, 290, 291

Veitch, Lisa, 185, 287

Vietnam War and aircraft development and 

deployment, 152–54

Visco, Christine, 291

von Kármán, Theodore, 51

von Kármán Institute for Fluid Dynamics, 121, 

132

VORLAX methodology, 173

Vulcan bombers, 8

W

Walkden, Frank, 6, 16, 30n25, 41, 43, 252

Walker, Steven H. “Steve”

honors and tributes for SSBD research, 235

QSP program management, 139

SSBD flight tests, 207

SSBD program role, 157, 287

Walker Air Force Base, x

Wallops Island Station

schlieren imaging system photos of shock 

waves at, 104, 105

sonic boom research, 13, 14

sonic boom research on structures, 17

tower for sonic boom research, 26

Washington, DC, Dulles International Airport, 78

Wasson, Rich, 293

waveform parameter program, 71, 76, 89–90, 

96, 98, 102

Waveforms and Sonic Boom Perception and 

Response (WSPR), 267

WC-135B aircraft, 22

Webb, James, 11

Weidlinger Associates, 133

weight of aircraft and sonic booms, 15, 123, 

139

Weinstein, Leonard, 104, 105, 117n63

Weir, Tom, 207

Western USA Sonic Boom Survey, 105–6, 107

Westra, Bryan, 293

Whelan, David, 131

Whitcomb, Richard, 6, 10, 46

White House

executive order for aeronautics R&D plan, 257

Office of Science and Technology (OST), 22, 

90

White Sands Missile Range tests, 18–19, 103–4

Whitham, Gerald B., 3–4, 6, 16, 29n17, 30n25, 

40, 41, 43, 56

Wilcox, Nancy, 292

Williams Air Force Base, x
387

Index

wind, N-wave signatures, and strenth of sonic 

booms, 19, 19, 56

wind tunnel models

mounting of, 41, 176, 176, 178

precision of, 41

Reynolds number and scaling of, 40

size and characteristics of, 40–41, 180

SSBD model, 170, 175–76, 176, 178, 

182–83, 183, 198n53

XB-70 model, 42

wind tunnel research

accuracy and reliability of, 41–42

benefits and importance of, 40

CFD calculations correlation with wind tunnel 

data, 96, 97–98, 175–80, 177, 182–83

far fields, 40–41

flight test data correlation with wind tunnel 

data, 41–42, 44–45, 47

HSCT sonic boom minimization research, 

94–95, 94, 96

Langley sonic boom research, 12, 38, 47, 47

limitations of, 97–98

low-boom models and boom minimization 

research, 78–80, 79, 99–100

near fields, 40–41, 45–46

near-field shock wave research, 71

QSP concept model and wind tunnel testing, 

139

SCAT-15F concept, 45

shock waves, 12, 17, 40–42, 42, 59n4

sonic booms, 4, 12, 40–42, 42, 59n4

SSBD program, 170, 175–80, 176, 177, 

182–83, 183

wind tunnels

Ames Supersonic Wind Tunnel, 139

Ames Unitary Plan Wind Tunnel, 95, 96

Langley 4-by-4-foot Supersonic Pressure 

Tunnel, 17, 40–41, 59n4

Langley Unitary Plan Wind Tunnel, 38, 

78–80, 95, 99–100

NGC low-speed tunnel, 182–83, 183

wings

arrow-wing configurations, 42, 45, 45, 72, 

72, 79, 80, 80, 126

boom minimization designs, 72, 72, 78–80, 

79, 80

cranked-arrow-wing configuration, 102, 121, 

125, 138–39

delta-wing configurations, 44, 48, 53, 72, 79

design of for supersonic flight, 6

laminar flow technology development and 

testing, 283n94

NGC concept design, 138–39

oblique-wing aircraft research, 100, 123, 

139, 259

SCAT configurations, 10, 11, 45, 45

swept wing aircraft, 6, 72

Switchblade oblique-wing study, 139, 259

variable sweep wings, 126–27, 127

Wlezien, Richard

Fundamental Aeronautics Program, 256

honors and tributes for SSBD research, 235

low-boom aircraft design development, 250

NASA Headquarters role, 139

QSP concept designs, 135

QSP contract award criteria, 134

QSP program management, 130

QSP program progress, 136

SSBD design review, 185

SSBD design success, 214

SSBD program role, 157, 287

Wolfe, Tom, 291

Wolz, Rob, 288, 289

World War II, 2, 27n5

Wright-Patterson Air Force Base, 4, 89

WSPR (Waveforms and Sonic Boom Perception 

and Response), 267

Wyle Laboratories

In-Home Noise Generation/Response System 

(IHONORS), 105, 105

ISSM flight data analysis, 162–63

MDBOOM program, 102, 115–16n53
388

Quieting the Boom

PCBoom program, 173

Plotkin employment at, 77

QSP subcontractor relationship with NGC, 

132, 133, 150

SCAMP project, 267

sonic boom expertise at, 133

sonic boom minimization and demonstrator 

selection, 149–50

SSBD design, 175

SSBD ground sensors and data-collection 

equipment, 208, 209

SSBE ground sensors and data-collection 

equipment, 219, 227

SSBE participation, 216

surveys of public opinion about sonic booms, 

107

WSPR project, 267

X

X-15 aircraft

shock wave research in supersonic pressure 

tunnel, 17

sonic boom research, 16, 33n53

Space Shuttle and sonic boom research, 76

termination of program, 21

X-30 NASP program, 90–91

X-54A concept, 259, 270

XB-70 Valkyrie

characteristics and capabilities, 20

data and records, restoration and digitization 

of, 103

design and development of, 10

National Sonic Boom Evaluation Program, 

22–24

N-wave signature, 23–24, 24

sonic boom carpets, 21

sonic boom research, 20–21, 34–35nn65–

66, 57

SST design proposal, basis for, 44

SST test beds, 10, 20

stainless steel skin, 43

termination of program, 21

wind tunnel model, 42

XB-70-1 test bed, 20, 21, 22

XB-70-2 test bed, 20, 21, 22

XF-104 Starfighter, 4

X-plane, low-boom, 136, 249–50, 251, 270, 271

XS-1/X-1 aircraft, xii, 2, 3, 27–28nn6–8, 

28n10, 209, 256, 266

Y

Yasaki, Chris, 290

Yazejian, Joan, 190, 293

YB-49 flying wing, 3

Yeager, Chuck, 2, 27–28nn6–8, 209, 258

Yeager, Larry, 74

YF-5A aircraft, 152

YF-12 Blackbird

National Sonic Boom Evaluation Program, 

22–24

SCR/SCAR/AST program flights, 77

sonic boom research, 21, 23

YF-23 fighter, 132, 139, 155

YF-100 Super Sabre, 4

YF-102 Delta Dagger, 4

YF-105 Thunderchief, 4

YO-3A aircraft, 108, 108, 217

York, Tom, 290

YT-38 aircraft, 151

Yuma Marine Corps Air Station, 154, 185

Z

ZEPHYRUS code, 108