Volume 40, Number 2 Summer 2023

NASA HISTORY

NEWS&NOTES

VIEW FROM ABOVE 

NASA’S AERONAUTICS RESEARCH 

CONTINUES TO GENERATE LIFT

 The Lockheed F-104 Starfighter in flight in 1977. The NASA 

Starfighters flew for 38 years, providing valuable flight research 

data and flying safety chase missions. (Photo credit: NASA)

2 From the Chief Historian

4 Flight Craft: When Spaceflight 

Is Really Aeronautics

9 Flight with Light: Beam-Powered 

Propulsion Experiments at NASA

12 The Chase Air Force: In Pursuit of 

the Space Shuttle Columbia

16 Subsonic Fixed Wing to Sustainable 

Flight National Partnership

21 Reassessing the 50-Year 

Supersonic Speed Limit

23 Traffic Management in the Air and in Orbit

27 The NACA Spurs U.S. Jet 

Propulsion Success

30 Ingenuity and Coaxial Rotor Systems

33 The NASA Aeronautics Book Series

35 Upcoming Meetings

NASA HISTORY OFFICE

OFFICE OF COMMUNICATIONS

National Aeronautics and 

Space Administration
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

ON 3 MARCH 1915, in a largely 

unnoticed rider attached to the 

Naval Appropriations Bill, a 

novel organization was created. The 

stated purpose of this body would be 

to “supervise and direct the scientific 

study of the problems of flight, with a 

view to their practical solution, and to 

determine the problems which should 

be experimentally attacked, and to discuss their solution and their application 

to practical questions.”1

Over the next 43 years of its existence, 

the National Advisory Committee 

for Aeronautics (NACA) dedicated 

its efforts to doing just that—using a 

ranging, experimental infrastructure 

to solve challenging problems and offer 

practical solutions. 

The incorporation of the NACA into 

NASA on 1 October 1958 was, on the 

surface at least, the passing of an era. 

Space, not aeronautics, now appeared 

to be the primary font of national 

technological pride. The all-absorbing 

program to reach the Moon by the end 

of the decade, combined with the arms 

race, gave rocketry pride of place. 

But the basic research thread has 

remained strong at NASA. Historian 

Robert Ferguson attributes this survival to the pace of technological 

change. For Ferguson, a century plus 

of flight research has yet to resolve 

fundamental challenges. Engineers 

“pushed aircraft performance to faster 

speeds and higher altitudes, and, when 

they reached practical and economic 

barriers to going 

faster and higher, 

they turned their 

attention to efficiency, safety, and 

maneuverability.”2

Today, NASA Aeronautics continues 

this tradition of basic 

research with a focus 

on ultra-efficient 

airliners, high-speed 

commercial flight, 

future airspace and 

safety, and advanced 

air mobility.

I recently spoke with 

Bob Pearce, Associate Administrator 

of NASA’s Aeronautics Research 

Mission Directorate (ARMD), about 

the NACA heritage and the importance of history to his directorate’s 

work.3 Pearce has years of experience 

working on strategy, analysis, and 

planning with both industry and government—experience that includes 

work on the F-14 Tomcat, the Defense 

Advanced Research Projects Agency’s 

(DARPA’s) X-29 Forward Swept 

Wing Demonstrator, and the Federal 

Aviation Administration’s (FA A’s) 

Next Generation Air Transportation 

System (NextGen). 

During our conversation, Pearce 

stressed the importance of the NACA 

heritage, not only to aeronautics, but 

to the Agency. One of the key thrusts 

has been a government commitment 

to the research and technology transfer 

process. Pearce points out that “in the 

early days of aviation, the government 

oversaw much of the research and technology that ensured future vehicles 

and future operations would be more 

efficient, more effective—higher, faster, 

further. All of those fundamentals continue to push industry to the leading 

edge while we support them in the 

early days of the market.”4

The value of this history to ARMD is 

not lost on Pearce, who sees a clear connection between past lessons learned 

and current projects:

From the 

Chief Historian

 In this 1955 photo, Brent Creer consults with NACA pilot 

George Cooper in the North American F86-A #135 aircraft on 

the ramp in front of hangar 211 at Ames Research Center. 

(Photo credit: NACA) 

2
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

History informs the future. If 

we don’t know the history, we 

are doomed to repeat it. But I 

think the better we understand 

that history the more we can 

facilitate better planning for 

the future, we can set better 

strategy. Another thing is, and 

I think this is especially true in 

advanced concepts and technology, oftentimes, what we are 

looking at today is not the first 

time we’ve looked at it. Advanced 

air mobility—this idea of an air 

taxi—has been around since 

the beginning of aviation and 

there have been times in our 

past where there’s been serious 

study...and it just wasn’t quite 

ready; the technologies just 

weren’t quite there. Nevertheless, 

understanding what happened 

during those periods, what the 

barriers were they couldn’t overcome, what the issues were, are 

really useful to know.... They 

didn’t make it in the past but we 

can understand why and we can 

overcome those challenges. If 

we really believe that, then let’s 

take the next swing at it. We 

are doing that with supersonics.... [Similarly for] Advanced 

air mobility, we know what the 

issues were in the past and we 

believe we have solutions to 

those as well.5

In response to how it feels to occupy a 

position once held by Neil Armstrong 

at ARMD, Pearce noted,

It is an honor, a privilege, and 

it is the best job I can imagine. 

I look at it as I don’t have to be 

the smartest person in the room, 

I just need to enable all of the 

brilliant folks across NASA to 

come together and work for the 

common set of goals. That’s 

my challenge because smart 

people are independent thinkers and they want to take their 

own paths and that’s why we 

hire them. But we also need to 

inspire them to work together to 

make big things happen—to do 

the hard things that need to be 

accomplished. No one person 

can do that. We have to do it 

together.... The special thing 

that we’re able to do at NASA 

is to motivate people with [its] 

awesome mission. My job is to 

do just that.6

The essays in this issue of News & 

Notes canvas important chapters in the 

history of aeronautics at NASA. The 

articles are wide-ranging, including 

examinations of the fundamental overlap between spaceflight and aeronautics, 

the historical quest to harness microwave energy for powered flight, T-38s, 

coaxial rotor systems for Ingenuity, 

air traffic control, jet propulsion, and 

sustainable and supersonic flight. Tony 

Springer spotlights the significant 

contribution to capturing this history 

made with the Aeronautics Book Series 

developed by NASA ARMD. 

Ultimately, we hope this issue inspires 

others to consider researching and 

learning about this important history. 

As the NASA Aeronautics leadership, 

workforce, and partners consider 

“Aviation Beyond 2040,” it is critical 

that we not lose the lessons of the past 

and continue holding to the basic 

research thread at the heart of the 

NACA’s and NASA’s Aeronautics mission since 1915. 

Brian C. Odom

Chief Historian

Endnotes

1 Alex Roland, Model Research: The 

National Advisory Committee for 

Aeronautics, 1915 –1958, vol.  2 

(Washington, DC: NASA SP-4103, 

1985), p. 394, https://history.nasa.

gov/SP-4103vol2.pdf.

2 Robert G. Ferguson, NASA’s First 

A: Aeronautics from 1958 to 2008. 

(Washington, DC: NASA SP-4412, 

2011), p. 7, https://history.nasa.gov/

SP-4412.pdf.

3 Robert A. Pearce biography, https://

www.nasa.gov/aeroresearch/

robert-pearce-bio.

4 Robert A. Pearce, interview by Brian 

Odom, 2 May 2023. I hope to have a 

full transcript of this interview posted 

to the NASA History website soon.

5 Ibid.

6 Ibid.

 Bob Pearce, Associate Administrator for 

NASA’s Aeronautics Research Mission 

Directorate. (Photo credit: NASA/Bill 

Ingalls) 

From the Chief Historian (continued)

3
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

» By James Anderson, Historian, Ames Research Center

E

VERY ROCKET that leaves Earth 

must ascend through our atmosphere. Every spacecraft that 

returns to Earth must survive a fiery 

reentry. Every mission that lands 

on another world with an atmosphere cannot achieve that feat with 

rocket science alone. Some of the 

most consequential advancements in 

the history of spaceflight have been, 

fundamentally, practical solutions to 

aeronautical problems.

Many of those problems emerged 

during and shortly after World War II. 

In a section of his recent book published 

by the NASA History Division, NACA 

to NASA to Now, former NASA Chief 

Historian Roger Launius summarized 

ten influential research and development efforts that the NACA undertook 

during the war. Work conducted across 

the three NACA research laboratories 

led to flight becoming more efficient, 

more easily controlled, and less likely 

to result in fatal crashes.1 Efficiency 

gains were most closely associated with 

the development of low-drag airfoils, 

which increased the amount of laminar 

(i.e., smooth, not turbulent) flow over 

an aircraft’s wing. Here, the specific 

shape of an airfoil was the primary concern, not the material it was made of or 

even its weight, although those factors 

were important, too. Shape—a property fundamental to how we describe 

Flight Craft: 

When Spaceflight 

Is Really Aeronautics

Some of the most consequential advancements in 

the history of spaceflight 

have been, fundamentally, 

practical solutions to aeronautical problems.

 H. Julian “Harvey” Allen explaining the blunt-body concept at a chalkboard in 1957, the 

same year that his landmark report written with Alfred Eggers was declassified. (Photo 

credit: NACA)

 A test model of the M-2 lifting body 

undergoing a heat transfer distribution 

test in the 1-foot hypervelocity wind tunnel at Ames in 1962. (Photo credit: NASA)

4
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

the world around us—may seem irrelevant in the environment of outer space 

where air resistance does not apply, but 

the importance of shape is profound for 

moving through an atmosphere.

In the 1930s, it was already common 

among aerodynamicists to calculate 

the pressure distribution across an 

airfoil of a given shape. The development of laminar-flow airfoils, on 

the other hand, required performing 

“the more difficult inverse calculation 

of [determining] the shape to give a 

desired pressure distribution,” which 

became even more pressing during the 

war as planes began approaching the 

speed of sound.2 A laborious method 

for solving this calculation existed, but 

it was simplified greatly by H. Julian 

“Harvey” Allen, based upon work he 

had started in 1936 while working 

in Eastman Jacobs’s Variable Density 

Tunnel Section at Langley Aeronautical 

Laboratory. The work culminated in 

the 1945 report, “General Theory of 

Airfoil Sections Having Arbitrary 

Shape or Pressure Distribution.”3 By 

that time, Allen was the head of the 

Theoretical Aerodynamics Section at 

the recently opened Ames Aeronautical 

Laboratory. As World War II ended, 

the combination of rocket technology 

and the advent of nuclear weapons led 

to the development of intercontinental 

ballistic missiles, which reached speeds 

and altitudes high enough that their 

trajectories coming back down to Earth 

subjected the missiles to heat sufficient 

to destroy their cargo.

The heating problem, as it was known, 

required aerodynamicists to confront 

problems related not just to aerodynamics, but aerothermodynamics. Sleek 

and slender shapes had reduced drag 

and improved aerodynamic efficiency 

in both subsonic and even early supersonic flight, but reentry speeds easily 

surpass five times the speed of sound, 

or Mach 5, which is the common 

marker for differentiating supersonic 

flight from the realm of hypersonics. 

Here again, shape proved to be crucial. 

Instead of reducing drag, the problem 

became what to do with the excess heat. 

Allen realized that if the air itself in 

the flow around the reentering craft 

absorbed more of the heat, then less of 

that heat energy would go into raising 

the temperature of the craft’s surface. A 

strong shock wave in front of the craft 

could accomplish this. The idea likely 

occurred to Allen in 1951. Over the 

course of 1952, Allen worked with his 

colleague, Alfred J. Eggers, to draft a 

paper that would be published in April 

1953.4 Much like Allen’s approach to 

low drag, his and Eggers’s intention was 

“to simplify and generalize” the heating 

Flight Craft: When Spaceflight Is Really Aeronautics (continued)

 The strong bow shock wave is visible 

here as the dark curved line extending 

from the top to the bottom of the image, 

just to the left of this finned hemispherical model, illustrating the blunt-body 

concept. (Photo credit: NACA)

 Alfred Eggers (second from the right) sits at a table with the three other principal contributors to the lifting-body concept, seen here in February 1963, a year before their patent 

for the “Flight Craft” was officially filed. George Kenyon (left) carried out the testing of the 

spacecraft at subsonic speeds to develop its landing capability. Seated between Kenyon 

and Eggers is George Edwards, who supervised the low-speed testing. Clarence 

Syvertson (right), a future Ames Center Director, coordinated the hypersonic testing. The 

scale model of the lifting body sits atop a model of a generic upper-stage booster. (Photo 

credit: NASA)

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NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

problem, which they did, while also 

demonstrating the superiority of “the 

blunt shape.”5 This landmark paper—

and its implications for the literal shaping of reentering craft at hypersonic 

speeds that eventually emerged, as 

adoption was not immediate—led one 

author to remark that, “Quite probably, 

it is the single most important paper 

ever written in the field of hypersonics.”6

 When combined with an ablative 

heatshield, the amount of heat reaching 

the craft is reduced even further. The 

impact on the approach to spacecraft 

design eventually became significant, 

but the insights were not limited to just 

capsule-like designs.

Capsules are restricted in their aerodynamic capabilities, while many other 

shapes can incorporate the blunt body 

concept.7 Recognizing the limitations 

of a capsule for flight—especially given 

the very questionable aerodynamic stability of blunt body designs, in spite 

of how effective at solving the heating 

problem they were—Allen and Eggers 

led a number of subsequent NACA 

studies that investigated these questions of stability.8

 Flight testing of the 

X-1 and the X-2 had already given indications of instability issues that would 

accompany hypersonic flight—another 

major challenge in addition to the 

heating problem.9 As Allen and Eggers 

conducted their stability studies, the 

NACA and the Air Force were shaping what would become arguably the 

most significant testing program in the 

history of hypersonics: the X-15. The 

X-15 program was fully contracted 

with North American in 1956. As that 

program progressed and hypersonic 

research developed across the NACA, 

Eggers had turned his attention to the 

development of a wind tunnel that 

would allow a freely launched model 

to experience the variation in atmospheric density that accompanies reentry from the thinner outer layers down 

to the ground. The Atmosphere-Entry 

Simulator, as it was known, was prototyped in 1956, and construction of 

the full-size version began in 1957.10

With Sputnik and the absorption of the 

NACA into the newly created NASA, 

the more explicit focus on spaceflight 

and crewed spaceflight gave Eggers a 

new context in which to apply these 

theoretical and experimental insights 

to aeronautical problems.

The embodiment of these years of 

research came together in a patent 

that Eggers and three of his colleagues 

eventually filed in 1964 with the 

Flight Craft: When Spaceflight Is Really Aeronautics (continued)

 The figures on this page of the Eggers et al. patent for the “Flight Craft” (i.e., lifting body) 

depict the entire voyage, beginning with launch to separation, carrying out the mission in 

space, and finally reentering and landing. (Source: United States Patent and Trademark 

Office, http://www.uspto.gov)

“Quite probably, it is the 

single most important 

paper ever written in the 

field of hypersonics.”

6
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

very generic-sounding title: Flight 

Craft. The craft would be “suitable 

for space flight, entry from space 

into an atmosphere, and atmospheric 

flight”—achieving an entire mission 

to orbit or even deep space without 

being restricted to parachutes limiting 

their mobility upon landing.11 The 

nose would be “blunted” to address 

the heating problem—naturally—

and what further distinguished the 

flight craft from winged aircraft and 

X vehicles, like the X-15 and the X-20 

Dyna-Soar, was the additional space 

inside the craft that the shape afforded, 

which was not available to any supersleek designs. The high volumeto-surface ratio was envisioned as 

allowing crew, equipment, and its own 

propulsion system. But even without 

its own propulsion system, it was still 

flight-worthy in the manner of a glider. 

Easily sitting atop a rocket, the flight 

craft was envisioned as operating across 

a huge range of velocities, regardless 

of whether it left Earth’s atmosphere 

or not.

The Flight Craft is what became known 

as a lifting body. Research into lifting 

bodies continued and was not limited 

to Eggers and his group, but it was the 

Eggers concept that inspired R. Dale 

Reed at NASA’s Flight Research Center 

at Edwards Air Force Base (presentday NASA Armstrong) to build his 

own scale model as a proof-of-concept. 

Reed enlisted the help of some NASA 

colleagues and persuaded their center’s 

leadership to support what became 

a 12-year research program in which 

eight different lifting body designs 

were f lown, beginning with the 

unpowered, plywood-framed “M2-F1 

to the rocket-powered, extra-sleek, allmetal supersonic X-24B.”12 The return 

to sleek and away from the “bulbous” 

shape of the M2-F1 is another story, 

but the blunt-body concept remains, 

and lifting-body research informed 

the development of the (winged) 

Space Shuttle. Numerous challenges 

still exist in the realm of hypersonic 

flight, especially the development 

of an air-breathing engine that can 

accommodate the transition from suband supersonic to hypersonic flight 

itself. And despite recent attention to—

and claims about—hypersonics on the 

world stage, the world has yet to see a 

truly hypersonic plane that can surpass 

what the X-15 program achieved with 

Mach 6.7.

Flight Craft: When Spaceflight Is Really 

Aeronautics (continued)

 The M2-F1 Lifting Body is seen here under tow, high above Rogers Dry Lake near 

NASA’s Flight Research Center, Edwards, California. R. Dale Reed effectively 

advocated the project with the support of NASA research pilot Milt Thompson. 

Together, they gained the support of Flight Research Center Director Paul Bikle. 

After a six-month feasibility study, Bikle gave approval in the fall of 1962 for the 

M2-F1 to be built. (Photo credit: NASA) R. Dale Reed with his model of the M2-F1 

in front of the actual lifting body. Reed 

used the model to show the potential of 

the lifting bodies to colleagues at the 

Flight Research Center (present-day 

NASA Armstrong Flight Research 

Center). Dale’s wife, Donna, filmed those 

early tests with their 8-mm home camera. 

(Photo credit: NASA) 

7
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

For spaceflight, applications of the 

blunt-body concept are still visible today, 

from the shape of the Orion spacecraft 

to the heatshields of uncrewed spacecraft entering the atmospheres of other 

worlds, such as probes sent to the gas 

giants and the aeroshells encapsulating 

the rovers as they land on Mars.13

These present-day examples illustrate 

both the extent to which aeronautics 

research remains intimately tied to 

spaceflight and how practical solutions 

can emerge from investigating fundamental aeronautical problems. 

Endnotes

1 Roger D. Launius, NACA to NASA to 

Now: The Frontiers of Air and Space in 

the American Century (Washington, 

DC: NASA SP-2022-4419, 2022); see 

chapter 3 and, in particular, figure 

3-5.

2 Walter G. Vincenti, John W. Boyd, 

and Glenn E. Bugos, “H. Julian Allen: 

An Appreciation,” Annual Review of 

Fluid Mechanics 39 (2007): 3.

3 Ibid. For the report, see NACA 

TR-833.

4 Vincenti, Boyd, and Bugos. “H. Julian 

Allen: An Appreciation,” 5.

5 H. Julian Allen and Alfred Eggers, 

Jr., “A Study of the Motion and 

Aerodynamic Heating of Ballistic 

Missiles Entering the Earth ’s 

Atmosphere at High Supersonic 

Speeds,” NACA RM-A53D28, 1953. 

The paper was declassified in 1957 

and appeared subsequently as NACA 

TN-4047 and also as NACA Report 

1381.

6 T. A. Heppenheimer, Facing the 

Heat Barrier: A History of Hypersonics

(Washington, DC: NASA SP-4232, 

2007), p. 29.

7 A fascinating comparison is found in 

the development of Soviet spacecraft 

designs. The Soviet approach relied 

upon simplicity, too, as Sergei Korolev 

preferred the sphere for its inherent 

stability and its simplicity in the 

design of Vostok, compared to the 

truncated cone of Mercury. While 

both shapes are blunt, the Soviets 

surrounded the spherical Vostok with 

heatshield material. That added significant weight, but it was less of a concern given the lifting capability that 

the Soviets possessed with their rockets. For more comparisons between 

the American and Soviet approaches 

in this era, see Ezell, Edward Clinton, 

and Linda Neuman Ezell, The 

Partnership: A History of the ApolloSoyuz Test Project (Washington, DC: 

NASA SP-4209, 1978), pp. 66–73. 

And for more in-depth coverage of 

the Soviet program itself, see Asif A. 

Siddiqi, Challenge to Apollo: The Soviet 

Union and the Space Race, 1945–1974

(Washington, DC: NASA SP 2000-

4408, 2000).

8 Edwin P. Hartman, Adventures in 

Research: A History of Ames Research 

Center 1940–1965 (Washington, DC: 

NASA SP-4302), 1970, pp. 266–270. 

More generally, hypersonic research 

began to expand to all of the NACA 

laboratories in 1954. Langley had 

opened an 11-inch hypersonic wind 

tunnel in 1947 (the same year, incidentally, that humans first f lew 

faster than the speed of sound), but 

it was not until 1954 that hypersonic 

research began to expand beyond 

Langley within the NACA.

9 Dennis R. Jenkins, Hypersonics Before 

the Shuttle: A Concise History of the 

X-15 Research Airplane, Monographs 

in Aerospace Histor y, No. 18 

(Washington, DC: NASA SP-2000-

4518), p. 10.

10 Edwin P. Hartman, Adventures in 

Research: A History of Ames Research 

Center 1940–1965 (Washington, DC: 

NASA SP-4302, 1970), p. 238.

11 Alfred J. Eggers, Jr., Clarence A. 

Syvertson, George G. Edwards, and 

George C. Kenyon, 1966, Flight 

Craft, U.S. Patent 3,276,722, filed 

4 February 1964 and issued 4 October 

1966.

12 R. Dale Reed, Wingless Flight: The 

Lifting Body Story. (Washington, DC: 

NASA SP-4220) 1998, p. ix.

13 Beyond capsules and lifting bodies, 

aeronautics is now perhaps most visible in space exploration in the success 

of the Mars Helicopter, Ingenuity, and 

its more than 50 successful flights on 

Mars since achieving the first-ever test 

of powered flight on another planet. 

For more on this topic, see “Ingenuity 

and Coaxial Rotor Systems” later in 

this issue.

Flight Craft: When Spaceflight Is Really Aeronautics (continued)

For spaceflight, applications of the blunt-body 

concept are still visible 

today, from the shape 

of the Orion spacecraft 

to the heatshields of 

uncrewed spacecraft 

entering the atmospheres 

of other worlds....

8
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Watch William Brown’s helicopter 

flight and JPL/Goldstone tests.

Flight with Light: 

Beam-Powered Propulsion 

Experiments at NASA

» By Christian Gelzer, Historian, Armstrong Flight Research Center

I

N OCTOBER 1964 the Raytheon 

Company held a news conference 

during which employee William 

Brown demonstrated a scaled helicopter in flight. What made this special 

was that the helicopter flew not with 

on-board batteries or a gas engine but 

with power beamed to it as microwave energy. So long as the helicopter received the beam, it flew. Walter 

Cronkite was there and had a segment 

about the flight during his nightly news 

program. For Brown more than anyone, this was validation of a concept 

he’d first argued for in 1961. He kept 

at it, and between 1969 and 1975, he 

(Raytheon) led a joint NASA and U.S. 

Air Force project, culminating in 1975 

in a demonstration at the Goldstone 

Complex in California that successfully 

transmitted a 30-kilowatt beam over 

1 mile with 84 percent efficiency.

Generally speaking, “power beaming 

is the efficient point-to-point transfer 

of electrical energy across free space 

by a directive electromagnetic beam.”1

Nikola Tesla was the first to suggest that “electromagnetic radiation 

through tuned circuitry” was possible, 

and he spent many years and a great 

deal of money trying to demonstrate 

it, with little success. Other attempts 

also fell short, principally because the 

wavelengths at which they transmitted 

the energy had little range: the beam 

dissipated logarithmically over distance. Efficiency of the transmission 

and reception were the pivotal issues 

with power beaming. But Tesla was a 

believer and told Popular Science that 

someday airplanes would be “powered 

by wireless.”2

In the years following Brown’s successes, others explored power beaming, including the experimental 

Canadian Stationary High Altitude 

Relay Platform (SHARP). An airplane 

with a large receiver disk as part of the 

fuselage, in the 1980s SHARP demonstrated that a ground-based power 

source could follow an aircraft in flight, 

and the aircraft could receive and process this beam (DC to AC) in flight 

wirelessly. NASA continued its investment in this concept by supporting 

internal research and funding studies 

with universities and industry.3

 An airplane is powered using 

visible light during an initial 

test at NASA’s AFRC. The PV 

cell is 30 inches long. (Photo 

credit: NASA)

9
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Flight with Light: Beam-Powered Propulsion 

Experiments at NASA (continued)

Earth’s atmosphere distorts waves passing through it, which reduces both the 

range and the focus of beamed energy. 

Visible light has the least range and 

power transmission. Microwave energy 

is less affected by such conditions, 

explaining its appeal. In a seemingly 

retrograde move, in 2002 NASA’s 

Armstrong Flight Research Center 

(AFRC) began a series of tests using an 

11-oz mylar, balsa wood, and carbon 

fiber airplane with a 6-watt electric 

motor turning a propeller and a large 

sheet of photovoltaic cells attached 

vertically to its ventral area. While an 

engineer directed a searchlight at the 

photovoltaic (PV) panel, a pilot flew 

the airplane. Not surprisingly, the airplane’s engine received only 3 watts of 

power at a range of 18 meters—a 4 percent transmission efficiency—but that 

was not the point: it was the first time 

that optical energy had been beamed to 

an aircraft to power it for stable, continuous flight. (Brown’s helicopter was 

tethered and used microwaves.) Tim 

Blackwell notes, “The demonstration 

had two purposes...address the engineering issues...and increase public 

awareness [and] the engineers planted 

the seed for a practical demonstration 

of wireless power transmission.”4 This 

investigation was not retrograde at 

all but, rather, one step back for two 

steps forward. The second phase was 

a collaboration with researchers at 

NASA’s Marshall Space Flight Center 

(MSFC) and the University of Alabama 

Huntsville. Lasers might seem a logical step, but until recently they could 

not meet the power beaming system’s 

needs. That changed when, in 2003, 

Watch NASA AFRC’s power 

beaming flight that used 

visible light.

The second iteration of the original aircraft carried a PV capable of receiving power from clustered, tunable lasers. (Photo credit: NASA)

Watch a video of the 

laser-powered flight.

10
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

the team flew much the same airplane 

at MSFC using a set of clustered, tunable lasers at the source, and similarly 

configured PV cells at the receiver. 

Two months after this demonstration, 

the team flew a scaled helicopter using 

the same system. This was the first successful transmission of power via laser 

to a moving machine.

Wireless energy transmission is broadly 

appealing. Beaming energy to satellites in geosynchronous orbit (which 

consume electricity at a rate greater 

than can be replenished through 

solar arrays) or sending energy to 

Earth from a space-based solar farm 

are just a few of the potential applications. Researchers are eyeing power 

beaming to power lunar exploration, 

military defense, recharging stations, 

or in-flight power for autonomous 

aircraft, and to transmit energy via 

point-to-point wireless transmission 

on Earth when standard transmission 

methods are too expensive. In 2009 

NASA sponsored a laser-powered space 

elevator competition. And of course, 

putting a cluster of satellites in orbit 

around another planet, each capable 

of transmitting energy via microwave 

or laser, could indefinitely power an 

airplane or a ground-based vehicle on 

that planet. The European Aeronautic 

Defence and Space Company (EADS) 

has operated a scaled automobile with 

a laser. The power beaming research 

paths are diverse as optimum methods 

for various circumstances are not yet 

completely defined, but NASA’s 2003 

explorations of laser-beamed propulsion with a small electric airplane 

showed a new path in delivering power 

in flight was possible. 

Additional Sources

Carlos Algora, Ivan Garcia, Marina 

Delgado, Rafael Pena, Carmen 

Vazquez, Manuel Hinojosa, and 

Ignacio Rey-Stolle, “Beaming power: 

Photovoltaic laser power converters 

for power-by-light,” Joule 6, no. 2 (16 

February 2022): 340–368.

H. E. Bennett, John D. G. Rather, and 

E. E. Montgomery IV, “Free-electron 

laser power beaming to satellites at 

China Lake, California,” Nuclear 

Instruments and Methods in Physics 

Research Section A: Accelerators, 

Spectrometers, Detectors and Associated 

Equipment 341, Nos. 1–3 (1 March 

1994): 124–131.

W. C. Brown, “The History of Power 

Transmission by Radio Waves,” in 

IEEE Transactions on Microwave 

Theory and Techniques 32, no. 9 

(September 1984): 1230–1242. 

W. C. Brown, “Experimental Airborne 

Microwave Supported Platform,” Technical Report No. RADC-TR-65-188 

Raytheon Co., Burlington, MA 

(December 1965).

Mark H. Machina, Peter Koert, and James 

T. Cha, “Power-Beaming—Energy 

Transmission at 35 GHz and Higher 

Frequencies,” AIA A 1992–2027. 

14th International Communication 

Satellite Systems Conference and 

Exhibit (March 1992).

NASA Office of the Chief Technologist, 

“Power Beaming Challenge,” https://

www.nasa.gov/offices/oct/

early_stage_innovation/centennial_

challenges/beaming_tether/

(accessed 5 May 2023).

John D. G. Rather, “Power beaming 

research at NASA,” SPIE Proceedings 

1628 (1 May 1992).

Endnotes

1 Christopher T. Rodenbeck, Paul I. Jaffe, 

Bernd H. Strasser, Paul E. Hausgen, 

James O. McSpadden, Hooman 

Kazemi, Naoki Shinohara, Brian B. 

Tierny, Christopher B. DePuma, and 

Amanda P. Self. “Microwave and 

Millimeter Wave Power Beaming,” 

IEEE Journal of Microwaves 1, no. 1 

(January 2021): 229–259, https://

ieeexplore.ieee.org/stamp/stamp.

jsp?tp=&arnumber=9318744

accessed 28 April 2023); Daniel 

Edward Raible, “High Intensity 

Laser Power Beaming for Wireless 

Power Transmission” (master’s thesis, Cleveland State University, OH, 

2008).

2 Arthur Fisher, “Secret of Perpetual 

Flight? Beam-Power Plane,” Popular 

Science 232, no. 1 (January 1988): 

62–65.

3 T. Cummings, J. Janssen, J. Karnesky, 

D. Laks, M. Santillo, B. Strause, 

L. N. Myrabo, A. Alden, P. Bouliane, 

and M. Zhang, “6 GHz microwave 

power-bea ming demonstration 

with 6-kV rectenna and ion-breeze 

thruster,” AIP Conference Proceedings 

Second International Symposium on 

Beamed Energy Propulsion 702 (2004): 

430–442.

4 Tim Blackwell, “Recent demonstrations of Laser power beaming at 

DFRC and MSFC,” AIP Conference 

Proceedings 766, no. 1 (27 April 2005): 

73–85.

Flight with Light: Beam-Powered Propulsion Experiments at NASA (continued)

Researchers are eyeing 

power beaming to power 

lunar exploration, military 

defense, recharging 

stations, or in-flight power 

for autonomous aircraft....

11
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

» By Jennifer Ross-Nazzal, Historian, Johnson Space Center

I

N 1980, as NASA prepared for the 

launch of its first reusable spacecraft, 

the Space Shuttle Columbia, astronauts from the 1978 class of astronauts 

received their technical assignments. 

One of those assignments was chase 

crew for the orbital test flights of the 

Shuttle. “Everybody wanted to do that,” 

Richard O. Covey recalled. “That was a 

premier assignment,” especially for the 

historic STS-1 flight.1 Pilots would fly 

the T-38 trainer aircraft, which sat two 

people, the pilot and a backseater, who 

was a mission specialist. 

Given the newness of the spacecraft, 

NASA named chase plane crews to the 

first four Shuttle test flights, tasked 

to rendezvous with Columbia as the 

orbiter reentered Earth’s atmosphere 

and landed. During these final minutes, at about 30,000 feet, the chase 

crews called out the altitude and air 

speed from their T-38s, to see if they 

matched the orbiter’s. The Space 

Shuttle commander, then approaching 

the dry lakebed and preparing to land, 

used that information to check against 

the orbiter’s readings. If the vehicle’s 

systems were not accurate, he could 

rely on the chase crew’s measurements. 

Chase crews also documented any 

structural issues or visible tile damage 

by photographing the Shuttle from different angles as it landed. 

For pilots, there was no better place to 

be than flying in the T-38, and Jon A. 

McBride, a naval aviator selected as an 

The Chase Air Force: 

In Pursuit of the Space Shuttle Columbia

 Portrait of the STS-2 Chase 

Team including (left to right) 

F. Richard “Dick” Covey, 

Kathryn D. Sullivan, Ken Baker, 

Loren J. Shriver, Jeffrey A. 

Hoffman, and Robert L. “Hoot” 

Gibson. (Photo credit: NASA)

12
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

astronaut in 1978, headed the STS-1 

team. The preparation for the first 

flight of the Shuttle was so consuming that his classmate Sally K. Ride 

later joked that “everybody was part 

of the chase crew on STS-1!” NASA 

intended to land the vehicle at Edwards 

Air Force Base, but the team had to 

be prepared for other contingency 

landing spots, including White Sands 

Northrup Strip in New Mexico and 

Kennedy Space Center. So they trained. 

Maybe a bit too much. McBride and 

his team “practiced a thousand times, 

three hundred times [in] each place,” 

and he “knew the topography of those 

three sites just like [his] backyard.”2

Because this was the “world’s most complicated rendezvous and fly,” and chase 

crews only had a 5-second window 

to catch the Shuttle, McBride’s effort 

quickly grew to the size of an “empire” 

with his team dubbed the “Chase Air 

Force.” Thinking back to those years, 

Kathryn D. Sullivan said, “It just 

seemed like every time you turned 

around there were eighteen airplanes 

flying off in a giant gaggle somewhere 

to go practice.” George D. “Pinky” 

Nelson, who flew with McBride on 

STS-1, remembered, “There were just 

a ton of us, and every once in a while...

there’d be eleven T-38s lined up on the 

ramp” at NASA’s Aircraft Operations 

in El Paso, Texas, near White Sands.3

The crews trained using an SR-71 or 

a T-38 as the “spacecraft” at all three 

locations: Edwards, Kennedy, and 

White Sands. During runs, two T-38s 

approached the “Shuttle” working 

with ground controllers at nearby Air 

Force bases in California, New Mexico, 

and Florida, as well as Kennedy Space 

Center. Simulations required the assistance of ground control to rendezvous 

with the “Shuttle” because the T-38 did 

not have an on-board radar system.4

By April 1981, the crews were ready. 

On the day of the STS-1 launch, 

Nelson was flying in the back seat of a 

T-38 at Cape Canaveral, where he witnessed the liftoff of the Space Shuttle 

Columbia. As he saw the vehicle climb, 

he thought of all the problems the program had tackled before this day and 

said, “I’ll be damned! It worked.”5

Two days later, in California, just after 

the chase crew took off to rendezvous 

with Columbia, the radar team in Los 

Angeles lost power. Fortunately, ground 

control at Edwards was able to take 

over, allowing McBride to line up with 

the Shuttle’s wing, so Nelson could 

photograph the incoming spacecraft.6

Everyone was jubilant at the success 

of the mission, especially the astronaut 

corps. At the STS-1 post-landing party, 

the Astronaut Office “royally roasted” 

the chase team for being overprepared. 

Memories of the flight were featured in 

a slide show and included the development of the orbiter, the crew training, 

and then—just for fun—someone 

mentioned the chase team’s preparation and included a photograph of 15 

bombers. They roasted someone else, 

I’ll be damned! It worked.

—George D. “Pinky” Nelson

 The STS-1 Chase Team, joined by Sally K. Ride, poses in front of a 

T-38. The Shuttle Chase Team patch is shown on the left. (Photo 

credit: NASA/Robert L. “Hoot” Gibson)

The Chase Air Force: In Pursuit of the Space Shuttle Columbia (continued)

13
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

The Chase Air Force: In Pursuit of the Space Shuttle Columbia (continued)

then returned to the chase team at the 

Cape, “and there’d be this field full 

of airplanes, 1,000 airplanes in this 

picture.” The corps “hammered” the 

team because they blew their budget 

and flew way too often. The astronauts, 

Sullivan explained, “quickly turned 

this into large amounts of teasing at 

Jon that he had just ramped this all up 

into the world’s biggest boondoggle.” 

All teasing aside, George W. S. Abbey, 

then head of Flight Crew Operations, 

was not pleased with just how much 

NASA’s “Air Force” had spent and told 

the four pilots that they could not fly 

for the next six months.7

When STS-2 came around, Robert 

L. “Hoot” Gibson used a different 

approach. He came up with a reasonable plan for training the chase crew. 

He determined how much training 

time the chase crew needed to be prepared and how many trips they should 

make to each possible landing site. “We 

actually did it without exceeding our 

flight time, so I got big points with 

George for pulling that off,” he said.8

As STS-2 Commander Joe Engle lined 

Columbia up for reentry, Gibson successfully rendezvoused with the spacecraft and recalled Kathryn Sullivan 

taking “one of the most gorgeous photos to come out of the chase program, 

and it was the underside of Columbia 

with the blue sky and some wispy 

clouds above it.”9

Covey led the team for STS-3, the only 

mission to land at White Sands. The 

intercept was made even more challenging because Mission Control had the 

STS-3 team fly a “straight-in approach” 

instead of the usual approach of “coming over the field and making a big 

turn.” On the day of landing the area 

experienced high winds, which also 

made it difficult to rendezvous with the 

vehicle. Covey had to fly with the landing gear down so that he and Ronald 

E. McNair, in the back seat, could stay 

with Commander Jack R. Lousma as 

he flew Columbia on the final approach. 

Otherwise, their T-38 would quickly 

pass the orbiter and negate their purpose. He ended up exceeding the 

landing gear limits for when it was 

down, and when he returned to El Paso, 

Aircraft Operations grounded his plane. 

Luckily, he had a spare to fly home in!10

Covey had to fly with the 

landing gear down so that 

he and Ronald E. McNair, 

in the back seat, could stay 

with Commander Jack R. 

Lousma as he flew Columbia on the final approach.

 This view of the Space Shuttle Columbia (STS-2) was made with a hand-held 70-mm 

camera in the rear station of the T-38 chase plane. Mission specialist/astronaut Kathryn 

D. Sullivan exposed the frame as astronauts Joe Engle and Richard H. Truly aboard 

Columbia guided the vehicle to an unpowered but smooth landing on the desert area of 

Edwards Air Force Base in California. The view provides a good study of the 

high-temperature protection material on the underside of the spacecraft that is exposed 

to the friction on the atmospheric entry on the return to Earth. Also note trails from the 

wing tips. (Photo credit: NASA)

14
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

For STS-4, the final flight of the test 

program, Jerry L. Ross and Guy S. 

Gardner flew Chase 1. On a very memorable Fourth of July, they met up with

Columbia, and Ross snapped a picture 

as the wheels touched down and threw 

“smoke up on the runway.”11

Today, there are no plans to use the 

T-38s to call out the altitude and 

speed of the Orion Multi-Purpose 

Crew Vehicle. Raymond Heineman 

of Johnson Space Center’s Aircraft 

Operations explains, “It’s a different 

type of landing. With the Shuttle, it 

was just a big glider. So it made more 

sense [to use a chase crew], but with 

a capsule coming out on a parachute, 

it’s just not something we can do with 

a [T]-38.”12

Even though NASA will not use the 

jet for Artemis, the T-38 demonstrated 

its value to the Space Shuttle Program 

and the astronaut corps. The T-38 is 

an essential trainer designed to help 

astronauts work as a crew to make 

time-critical decisions. Astronauts 

from the 1978 and 1980 classes who 

flew chase missions played an integral 

role in the orbital test flights and those, 

along with their other assignments, 

helped them feel “like we had become 

a real part, like a real astronaut by then, 

a part of the program, ready to go out 

and fly.” And as an added bonus, the 

chase crews took some amazing photos 

of the spacecraft during landing, some 

of which are shown here.13 

The Chase Air Force: In Pursuit of the Space Shuttle Columbia (continued)

 Top: The STS-3 Chase Team poses for a photo at Dryden Flight Research Center. (Photo 

credit: NASA) Bottom: Photo taken by the Shuttle Chase Team on 4 July 1984 as STS-4 

touches down on the runway at Edwards Air Force Base. Another T-38 chase plane is 

visible in the background. (Photo credit: NASA)

Endnotes

1 Richard O. Covey, interview by 

Jennifer Ross-Nazzal, 1 November 

2006, transcript, Johnson Space 

Center (JSC) Oral History Project. 

2 Sally K. Ride, interview by Rebecca 

Wright, 22 October 2002, transcript, 

JSC Oral History Project; Jon A. 

McBride, interview by Ross-Nazzal, 

17 April 2002, transcript, JSC Oral 

History Project. 

3 McBride interview; George D. “Pinky” 

Nelson, interview by Ross-Nazzal, 

6  May 2004, transcript, JSC Oral 

History Project; Kathryn D. Sullivan, 

interview by Ross-Nazzal, 10 May 

2007, transcript, JSC Oral History 

Project. 

4 McBride interview; Covey interview. 

5 Nelson interview. 

6 Ibid. 

7 Sullivan interview; Robert L. “Hoot” 

Gibson, interview by Ross-Nazzal, 

1  November 2013, transcript, JSC 

Oral History Project. 

8 Gibson interview. 

9 Ibid. 

10 Covey interview. 

11 Jerry L. Ross, interview by RossNazzal, 26 January 2004, transcript, 

JSC Oral History Project. 

12 Raymond G. Heineman in discussion 

with the author, 14 April 2023.

13 Nelson interview. 

15
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

The Evolution of NASA’s Sustainable Flight Portfolio

» By John A. Gould, Writer for NASA Aeronautics Research Mission Directorate

NASA’S CONTRIBUTIONS to 

aeronautics are numerous, 

wide-ranging, and fundamental. 

Over the decades, many technologies 

now commonplace in aviation—turbofan jet engines, glass cockpits, runway 

grooves, even the airfoil itself—trace 

their origins to NASA and its predecessor organization, the National 

Advisory Committee for Aeronautics 

(NACA). Several of these contributions 

led to more environmentally friendly 

practices such as reducing fuel burn; 

winglets, for instance, have saved billions of gallons of jet fuel since NASA 

developed them and aircraft manufacturers began introducing them.1

 The 

latest iteration of NASA’s far-reaching 

strategic goals for aviation, the 

Sustainable Flight National Partnership 

(SFNP), is a collaboration between 

NASA’s Aeronautics Research Mission 

Directorate (ARMD) and partners in 

industry, government, and academia to 

accomplish the aviation community’s 

goal of net-zero carbon emissions by 

2050.2 The partnership includes a suite 

of projects across ARMD’s portfolio; 

for example, SFNP’s centerpiece is the 

recently announced Sustainable Flight 

Demonstrator. Under a Funded Space 

Act Agreement, NASA and Boeing 

are developing a large-scale flight 

demonstrator to prove an ultra-efficient 

aerodynamic configuration called a 

Transonic Truss-Braced Wing (TTBW), 

as well as other new technologies.3 The 

Sustainable Flight Demonstrator and 

other projects in the Sustainable Flight 

National Partnership are working on 

a timeline to have their technologies 

ready for potential adoption into airliners during the 2030s. The partnership’s 

origins were initially organized in, and 

can still largely be characterized by, 

four major research areas: the TTBW, 

small-core gas turbines, high-rate composite manufacturing, and electrified 

aircraft propulsion—all intended for 

the single-aisle aircraft market, which 

is anticipated to face great demand for 

new aircraft beginning in the 2030s.4

Combined, these green technologies 

represent a significant advancement 

toward the goal of net-zero carbon 

emissions in aviation by 2050.

Subsonic Fixed Wing to 

Sustainable Flight 

National Partnership

 The illustration above shows three sustainable subsonic fixed wing design concepts 

chosen for possible development: the 

“double bubble,” blended wing body, and 

the truss-braced wing. (Image credit: NASA)

16
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

These four areas of research go back 

further than the Sustainable Flight 

National Partnership’s announcement 

in June 2021, however. ARMD initiated the strategy for flight research 

goals that would lead to the partnership’s current portfolio as far back as 

2007. Following an executive order 

and policy plan established by the 

Bush administration in 2006 and 2007 

asserting a need for the United States to 

maintain leadership in aeronautics and 

looking forward with NASA’s goals for 

aviation in mind, ARMD set the stage 

with a framework of three time periods during which research technology 

could feasibly transition to the aviation 

industry. Near-term N+1 technologies 

could enter service in the 2010s; midterm N+2 in the 2020s; and far-term 

N+3 in the 2030s. Two projects within 

NASA’s Fundamental Aeronautics 

Program—Subsonic Fixed Wing and 

Environmentally Responsible Aviation 

(ERA)—would carry out the research 

and development necessary to successfully identify and select the technologies that could both transition to 

industry in the prescribed timeframe 

and achieve the greatest impact on 

advancing aeronautical capabilities.5

Subsonic Fixed Wing’s N+3 activities 

aiming at the 2030s, in particular, is 

where the Sustainable Flight National 

Partnership can trace its heritage. These 

projects had a critical role in narrowing 

down the green technologies NASA is 

now pursuing with more rigor. This 

down-selection process saw numerous 

concepts studied and tested, including 

several different aircraft configurations such as TTBW designs—close 

variants of the design selected for the 

Sustainable Flight Demonstrator.

The story of this research began in 2008 

when NASA awarded research contracts 

for airframe configurations as part of 

N+3’s Phase 1 activities. Key drivers 

in identifying the type of research to 

pursue were reducing energy costs, 

environmental damage, and airport 

noise. Six teams were selected, with 

two working on supersonic commercial flight research and four working on 

NASA’s energy and environment goals 

under Subsonic Fixed Wing—each 

to carry out research through 2010.6

The four teams included Boeing, with 

an electrified truss-braced wing configuration in several design variants 

named “Subsonic Ultra Green Aircraft 

Research,” also known as SUGAR; the 

Massachusetts Institute of Technology 

(MIT) and Aurora, with a boundary 

layer ingestion design concept known 

as the “double bubble” for its unique 

twin-tubed shape; General Electric, 

which made a case that the 2030s may 

need short-range, point-to-point vehicles seating no more than 20 passengers; and Northrop Grumman, which 

examined a more conventional shortrange tube-and-wing airframe with 

advanced technology.7

Each of these teams’ ideas were studied and evaluated during Phase 1 and 

promising work continued into N+3’s 

Phase 2—where their design concepts 

evolved, as well as the key, tall-pole 

technologies involved in bringing them 

to fruition.8 For example, General 

Electric’s partner Cessna examined composite skins, and Northrop Grumman 

examined active flow control. MIT 

and Aurora’s double bubble configuration was, at the time, unique in the 

field. N+3 gave industry the chance to 

examine future ideas that were riskier 

for them to invest in independently.9

In parallel with N+3 Phase 2 and the 

beginning of the Obama administration, 

N+2 ground and flight research was 

occurring under the ER A project. 

Formulated in 2009, ERA signified a 

new approach for NASA in its aeronautics portfolio. NASA was able to 

advocate for a down-selecting process, 

purposing ERA to narrow down which 

technologies held the most promise for 

development, as opposed to the more 

common approach of specific research 

goals to achieve on a certain timeframe. 

At the time, other ARMD projects did 

not have this down-selection structure, 

and many later projects would be formulated with this approach. ERA’s 

formulation is also of note for being the 

first project in some time to bring a new 

increase to NASA’s aeronautics budget, 

which had significantly decreased since 

the 1990s.10

Though ERA’s mid-term N+2 research 

does not largely feed into what would 

become Sustainable Flight National 

Partnership research projects, a handful 

of key contributions are distinguishable. For example, ERA successfully 

built a large-scale multi-bay from 

stitched-resin-infused composites that 

gave validity to advanced composites for 

non-circular shapes on board aircraft.11

ERA’s formulation is also 

of note for being the first 

project in some time to 

bring a new increase 

to NASA’s aeronautics 

budget, which had 

significantly decreased 

since the 1990s.

Subsonic Fixed Wing to Sustainable Flight National Partnership (continued)

17
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

This work related to the blended wing 

body concept proposed by Boeing. In 

addition, ERA researched for potential acceleration to the N+2 timeframe 

certain N+3 concepts such as boundary 

layer ingestion for the double bubble.

Ultimately, much of the double bubble work would remain with Subsonic 

Fixed Wing and N+3. Notably, the configuration necessitated the small-core 

gas turbines—because the proximity 

of the twin engines at the aircraft’s rear 

prevented a higher bypass ratio from 

being achieved by increasing the size 

of the fan, the jet engine core had to 

be made smaller. Thus, small-core gas 

turbines saw their entry in support of 

this research.12

Meanwhile, Subsonic Fixed Wing continued with N+3 Phase 2, which concluded in 2014. Each of the four teams 

conducted a sort of capstone test of 

their key technologies. The first wind 

tunnel test involving Boeing’s TTBW 

design occurred in 2013 at NASA’s 

Langley Research Center in Virginia 

using a 13-foot (4-meter)-long structurally scaled model.13 The purpose was 

to determine the validity of Boeing’s 

TTBW concept—most pertinently, 

whether the fuel-savings estimates 

were indeed accurate and feasible. The 

test confirmed both variables were as 

predicted and provided confidence in 

the benefits of the design configuration. 

Amongst the four designs, the TTBW 

began to endure as a subject for further 

study, though the blended wing body 

and double bubble were still close contenders at the time.14

Subsonic Fixed Wing to Sustainable Flight National Partnership (continued)

 This chart, included in a presentation given in May 2010 by Rich Wahls, Ruben Del Rosario, and Greg Follen, shows metrics for the N+1, 

N+2, and N+3 studies. Note how N+3’s studies focus on research that could reach a Technology Readiness Level of 4–6 in 2025—similar 

to SFNP’s timeline. (Image Credit: NASA)

18
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Subsonic Fixed Wing to Sustainable Flight National Partnership (continued)

In 2014, NASA began the five-yearlong Advanced Composites project. 

The project sought to improve methods and tools to reduce the development and certification timeline for 

composite structures, functioning 

alongside composite materials research 

occurring in the ERA and Subsonic 

Fixed Wing projects.15 Notably, the 

Advanced Composites project saw the 

creation of the Advanced Composites 

Consortium—a public-private partnership consisting of government, 

industry, and academic organizations 

collaborating on composites research 

and development.16 This consortium 

continues to play a key role in NASA’s 

current composites research and manufacturing activities.

In 2015, ERA concluded, but a new 

development arose that would inform 

the choices managers made on the 

future of ARMD’s portfolio. As part of 

a new initiative for 21st-century transportation, the White House included 

in the President’s Budget Request for 

Fiscal Year 2016 a substantial increase 

in funding for NASA’s aeronautics 

research. NASA, in turn, conceived 

“New Aviation Horizons”—a 10-year 

initiative to build several new X-plane 

aircraft to perform major technology 

demonstrations alongside industry and 

government partners.17

Though the proposed budget increase 

did not ultimately occur, the discussion 

surrounding its possibility would lead 

to significant advances in NASA’s strategy for flight research. NASA put out a 

request for proposals, conducted studies 

on various flight demonstrator configurations alongside industry, and established dialogue with industry leaders 

that proved useful to both parties.18 After 

a several-month process, five industry 

teams informed NASA about the types 

of airplanes and objectives best suited 

for their long-term needs. Combined 

with the N+3 down-selections, these 

interactions further refined areas of 

research to pursue for the 2030s timeframe. The TTBW configuration, for 

example, became a clear contender 

for further study. Manufacturing 

composites at a high rate emerged as 

a challenge that, if solved, could lead 

to wide-reaching changes in aircraft 

design efficiency, including use in a 

more fuel-efficient single-aisle aircraft 

that would require much higher production rates to meet demand relative 

to other aircraft classes.19

Additionally, with the kickoff of the 

X-57 Maxwell aircraft in 2016, an 

expanded emphasis was placed on electrification by ARMD leadership. What 

was previously a multi-faceted strategy 

became focused on future electrified 

powertrain demonstrations at full 

demonstrator aircraft scale. Soon thereafter, the Electrified Powertrain Flight 

Demonstration (EPFD) project began. 

Subsonic Fixed Wing had envisioned 

a demonstrator aircraft since formulation because any move from a conventional airliner configuration would 

require full-scale integrated demonstration. EPFD is effectively a spinoff 

of Subsonic Fixed Wing focusing on 

electrified aircraft propulsion via a fullsized turboprop-based flight demonstrator aircraft. Subsonic Fixed Wing 

was transformed into today’s Advanced 

Air Transport Technology project, 

and subject matter experts from the 

project worked to advance more technology and reduce risk for EPFD. In 

2018, five areas of research were on the 

table: ultra-efficient airframes (TTBW 

and blended wing body), small-core 

gas turbines, electrification, advanced 

airframe structures (composites), and 

boundary layer ingestion. Ultimately, 

managers decided four research areas 

 Boeing’s 13-foot semi-span Subsonic Ultra Green Aircraft Research (SUGAR) model 

underwent testing at Langley Research Center’s Transonic Dynamics Tunnel in December 

2013. (Photo credit: NASA/Langley Research Center/Sandie Gibbs)

19
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Subsonic Fixed Wing to Sustainable Flight National Partnership (continued)

were a more effective distribution of 

resources, and boundary layer ingestion 

was not included moving forward.20

Three years later, in 2021, NASA 

announced the Sustainable Flight 

National Partnership working in these 

four major research areas.21 Two new 

projects emerged simultaneously: 

Hybrid Thermally Efficient Core, 

working on a hybridized small-core 

gas turbine, and Hi-Rate Composite 

Aircraft Manufacturing, working to 

accelerate the speed of composites manufacturing. With these projects formed 

alongside the already established 

EPFD and the just recently announced 

Sustainable Flight Demonstrator project utilizing a TTBW configuration, 

NASA’s Sustainable Flight National 

Partnership is airborne and actively 

working on a more sustainable future for 

aviation. Summed up by Dr. Richard 

Wahls, Subsonic Fixed Wing’s project 

scientist and now mission integration 

manager of the Sustainable Flight 

National Partnership:

It’s amazing we’ve been evolving this since 2008 and that it’s 

still happening. We’re a little 

more than halfway now to what 

we envisioned all those years 

ago. These projects we call the 

Sustainable Flight National 

Pa rtnership a re not just 

unfunded lines on a paper—

they have backing, support, and 

lots of cost sharing partners. It’s 

not a dream anymore.22 

Endnotes

1 National Aeronautics and Space 

Administration, “NASA Contributions: Winglets,” NASA.gov, 5 January 2015, https://www.nasa.gov/aero/

nasa-contribution-winglets.html.

2 National Aeronautics and Space 

Administration, “Sustainable Flight 

National Partnership,” NASA.gov, 

7 February 2022, https://www.nasa.

gov/sfnp/.

3 Robert Margetta, “NASA Issues 

Award for Greener, More FuelEfficient Airliner of Future,” NASA.

gov, 18 January 2023, https://

www.nasa.gov/press-release/nasaissues-award-for-greener-more-fuelefficient-airliner-of-future.

4 Jim Banke, “NextGen Aircraft Design 

Is Key to Aviation Sustainability,” 

NASA.gov, 16 April 2020, https://

www.nasa.gov/aero/nextgenaircraft-design-is-key-to-aviationsustainability.

5 Peter W. Merlin, Green Light for 

Green Flight: NASA’s Contributions to 

Environmentally Responsible Aviation,

(Washington, DC: NASA SP-2020-

646, 2020), https://www.nasa.gov/

sites/default/files/atoms/files/greenlight-for-green-flight-tagged.pdf, pp. 

3–4.

6 Beth Dickey, “NASA Awards Future 

Vehicle Aircraft Research Contracts,” 

NASA.gov, 6 October 2008, https://

www.nasa.gov/home/hqnews/2008/

oct/HQ_C08-060_ARMD_

contracts.html#.ZF3XAnbMJPZ.

7 Jim Banke, “Beauty of Future 

Airplanes Is More than Skin Deep,” 

NASA.gov, 17 May 2010, https://

www.nasa.gov/topics/aeronautics/

features/future_airplanes.html.

8 Rich Wahls, Ruben Del Rosario, and 

Greg Follen, “Overview of the NASA 

N+3 Advanced Transport Aircraft 

Concept Studies” (presentation, 2nd 

UTI AS-MITACS International 

Workshop on Aviation and Climate 

Change, Toronto, Canada, 27–28 

May 2010), http://goldfinger.utias.

utoronto.ca/IWACC2/IWACC2/

Program_files/Wahls.pdf.

9 Rich Wahls, interview by the author, 

27 April 2023.

10 Wahls interview, 2023.

11 Jim Banke, “PRSEUS Composite 

Survives Torturous Testing,” NASA.

gov, 6 August 2015, https://www.

nasa.gov/aero/prseus-compositesurvives-torturous-testing.

12 Ibid.

13 National Aeronautics and Space 

Administration, “In Future Aircraft 

Designs We ‘Truss,’” NASA.gov, 

24 January 2014, https://www.nasa.

gov/aero/boeing_sugar_wind_

tunnel.html.

14 Wahls interview, 27 April 2023.

15 David Meade, “Five Year Study of 

Advanced Composites Enters Final 

Review,” NASA.gov, 9 October 

2019, https://www.nasa.gov/feature/

langley/five-year-study-of-advancedcomposites-enters-final-review.

16 J. D. Harrington et al., “NASA 

Creates Partnership to Advance 

Composite Materials for Aircraft of 

the Future,” NASA.gov, 2 April 2015, 

https://www.nasa.gov/press/2015/

april/nasa-creates-partnership-toadvance-composite-materials-foraircraft-of-the-future.

17 Jay Levine, “X-planes Could Lead to 

Substantial Aviation Improvements 

and Big Economic Benefits,” NASA.

gov, 18 March 2016, https://www.nasa.

gov/feature/x-planes-could-lead-tosubstantial-aviation-improvementsand-big-economic-benefits.

18 National Aeronautics and Space 

Administration, “NASA Seeks 

Proposa ls to Support X-Plane 

Development,” NASA.gov, 22 July 

2016, https://www.nasa.gov/aero/

proposals-ultra-efficient-x-planes.

19 Wahls interview, 2023.

20 Ibid.

21 National Aeronautics and Space 

Administration, “NASA Aims for 

Climate-Friendly Aviation,” NASA.

gov, 2 June 2021, https://www.nasa.

gov/aeroresearch/nasa-aims-forclimate-friendly-aviation

22 Wahls interview, 2023.

20
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Reassessing the 

50-Year Supersonic 

Speed Limit

» By Jim Banke, Senior Writer, 

NASA’s Aeronautics Research Mission Directorate

J

UST OVER 50 YEARS AGO, the 

federal government banned all 

civilian supersonic flights over 

land. The rule prohibits non-military 

aircraft from flying faster than sound 

so their resulting sonic booms will 

not startle the public below or concern them about potential property 

damage. Officially put into effect on 

27 April 1973, the ban’s introduction 

was strongly influenced by public opinion surveys in cities where supersonic 

military jets were flown overhead, and 

many said they didn’t like what they 

heard or the way their windows rattled 

because of the sonic booms.

Boom Boom

The origins of supersonic flight go back 

to 14 October 1947, the first time the 

rocket-powered XS-1 airplane broke 

the sound barrier and initiated the 

heroic era of faster-than-sound research. 

Despite early interest in what was then 

a mysterious phenomenon created 

as airplanes fly faster than the speed 

of sound and generate atmospheric 

shock waves we hear as sonic booms, 

there were few tools and only limited 

data available to help us understand 

what was happening. No one gave the 

sonic booms a second thought, mostly 

because few people lived where the 

research was taking place. But as the 

Air Force and Navy began to deploy 

large numbers of 

supersonic jets at 

bases around the 

nation, interest 

in sonic booms 

quickly grew as 

more of the public became exposed to 

the often-alarming noise.

Beginning in 1956 and continuing 

well into the 1960s, the Air Force, the 

Navy, NASA, and the Federal Aviation 

Administration (FA A) employed 

resources to study how sonic booms 

formed under various conditions, what 

their effects might be on buildings, and 

how the public would react in different 

locations. Through those years, through 

the use of many types of supersonic jets, 

residents of Atlanta, Chicago, Dallas, 

Denver, Los Angeles, and Minneapolis, 

among others, were exposed to sonic 

booms from military fighter jets and 

bombers flying overhead at high altitude. Two concentrated studies—one 

over St. Louis in 1961 and the other 

over Oklahoma City in 1964 (dubbed 

Bongo and Bongo II, respectively)—

left no doubt the public was not fully 

supportive of routine sonic booms 

coming down from above. The tests 

generated national news and fueled 

strongly negative sentiment about 

supersonic flight.

The Supersonic Transport

As the work to better understand and 

predict sonic boom formation continued, it gave rise to the first notions 

of how to minimize a sonic boom by 

changing an airplane’s shape. The 

U.S. government began to work with 

industry to develop the Supersonic 

Transport, or SST.

In June 1963, President John F. 

Kennedy announced the plan for a 

U.S. SST project aimed to produce 

the prototype for a new commercial 

supersonic airliner, capable of carrying 

as many as 300 passengers anywhere 

in the world at speeds as great as three 

times the speed of sound. (Note that 

the speed of sound varies depending on 

things like temperature and altitude. 

At sea level and 68 degrees Fahrenheit, 

it is 768 mph.)

The aviation community was racing 

to develop its understanding of supersonic shock waves to reduce the SST’s 

potential sonic boom noise levels. But 

those researchers couldn’t outpace the 

speed at which environmental concerns 

 The U.S. Air Force B-58 Hustler supersonic bomber was one of 

many military jets used during the 1960s to generate sonic booms 

over U.S. cities to see how the public would react to the sound. The 

research helped lead to a ban on civilian faster-than-sound flight 

over land beginning in 1973. (Photo credit: U.S. Air Force)

21
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

and policy discussions were cropping 

up, threatening to ground the aircraft 

before it was even built.

Three events during the summer of 1968 

demonstrate the rising negative sentiment toward sonic booms. Firstly, on 

31 May, during a ceremony at the Air 

Force Academy in Colorado, an F-105 

Thunderchief fighter jet broke the sound 

barrier flying 50 feet over the school 

grounds. The sonic boom blew out 200 

windows on the side of the iconic Air 

Force Chapel and injured a dozen people. A week later, on 8 June, the New 

York Times published an editorial using 

the incident in Colorado to underscore 

the danger sonic booms presented to the 

nation’s peace and well-being, claiming 

many are “scared to death of it.” This 

was followed on 21 July with Congress 

directing the FAA to develop standards 

for the “Control and Abatement of 

Aircraft Noise and Sonic Boom.”

Within a couple of years, the FAA 

formally proposed a rule that would 

restrict operation of civil aircraft at 

speeds greater than Mach 1. Then in 

May of 1971, Congress canceled the 

SST program, and the rule banning 

civil supersonic flights over land went 

into effect two years later.

During this same time, Great Britain 

and France were developing and 

test-flying the Concorde, which went 

on to provide commercial supersonic 

air travel between 1976 and 2003. 

There were many reasons for its demise, 

including a deadly crash in 2000, but 

economic and environmental issues top 

the list. Restrictions against flying faster 

than sound over land due to the bans in 

the United States and elsewhere greatly 

limited its revenue-generating options.

Speed vs. Sound

Moving ahead, to lift the ban and 

enable a viable market for supersonic 

air travel over land, the idea has been 

proposed to base new rules on a different standard than before. The speed 

limit created in 1973 didn’t consider 

the possibility that an airplane could 

fly at supersonic speeds but not create 

sonic booms that would affect people 

below. It was a fair assessment at the 

time because the technology required 

to make that happen didn’t yet exist.

“It’s a rule that many people today 

aren’t aware of, yet it’s at the heart of 

what our Quesst mission with its quiet 

supersonic X-59 airplane is all about,” 

said Peter Coen, NASA’s Quesst mission integration manager. “So, instead 

of a rule based solely on speed, we are 

proposing the rule be based on sound. 

If the sound of a supersonic flight isn’t 

loud enough to bother anyone below, 

there’s no reason why the airplane can’t 

be flying supersonic.”

NASA’s X-59 is designed to fly faster 

than sound, but with drastically 

reduced noise—people below would 

hear sonic “thumps” rather than 

booms, if they hear anything at all. To 

test the public’s perception of this noise, 

part of the Quesst plan includes flying 

the X-59 over several communities and 

surveying how people react.

NASA will deliver the results to U.S. 

and international regulators, who will 

consider new rules that would lift the 

ban that has been in place for so long. 

The goal is for a regulatory shift that 

focuses on the sound an aircraft creates 

instead of a speed limit.

“We’re definitely ready to write a new 

chapter in the history of supersonic 

flight, making air travel over land 

twice as fast, but in a way that is safe, 

sustainable, and so much quieter than 

before,” Coen said. 

A version of this article was published 

on www.nasa.gov on 27 April 2023 

and is informed by the work of Lawrence 

Benson, author of Quieting the Boom: 

The Shaped Sonic Boom Demonstrator 

and the Quest for Quiet Supersonic 

Flight.

Reassessing the 50-Year Supersonic Speed 

Limit (continued)

 NASA’s X-59, seen in this illustration, is designed to fly faster than sound but 

generate quieter sonic “thumps” rather than booms. To test the public’s perception 

of this noise, part of the Quesst plan includes flying the X-59 over several communities to survey how people react. (Image credit: Lockheed Martin)

22
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

AS THE COMPLEX space operating environment becomes more crowded with more operating 

satellites and debris, the subjects of 

Space Situational Awareness (SSA) 

and Space Traffic Management (STM) 

deserve more concerted attention. 

While we have had more than 60 years 

of satellites in the large expanse of nearEarth space with only a handful of collisions, this likely will change as space 

becomes more congested. One model 

that analysts frequently invoke for STM 

is air traffic management (ATM), in 

part because of its much longer history. 

To appreciate some of the similarities 

and differences, this article takes a brief 

look at some specific aspects of ATM’s 

development and assesses a few of the 

similarities and differences with STM.

Virtually since its beginning, air traffic 

control has had to address the issue of 

nations lofting planes whose locations 

and routes they did not want to disclose, usually for military reasons. The 

landmark 1944 “Chicago Convention” 

for international aviation law, which 

created the International Civil Aviation 

Organization (ICAO), specifically 

excluded “state aircraft” (i.e., military 

airplanes; no such distinction exists 

for space objects).2 The solution was 

the adoption of the “due regard” convention that permits nations not to 

disclose the whereabouts of military 

planes provided they didn’t endanger 

other aircraft. This “due regard” consideration also “placed the full burden 

for the avoidance of collision on the 

state aircraft in exchange for the ability 

of those aircraft to operate outside the 

common rules, including the ability to 

be undetectable by other operators and 

service providers.”3 A parallel argument 

for STM could certainly be made, but 

unlike the atmosphere over a nation’s 

landmass, orbital space is decidedly 

not sovereign.

Modern air traffic control traces its 

origins back to a 1956 fatal mid-air 

collision between two planes operating 

over the Grand Canyon. The resulting 

 As the number of objects orbiting Earth continues to multiply, the need for a coordinated scheme for Space Traffic Management becomes critical. The debris field shown 

in this artist’s impression is based on actual data, but the debris objects are shown at 

an exaggerated size to make them visible at the scale shown. (Photo credit: ESA)

Traffic 

Management 

in the Air and 

in Orbit

» By Stephen Garber, Historian, 

NASA Headquarters11

23
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

1958 Federal Aviation Act transformed 

the existing Civil Aeronautics 

Authority into the Federal Aviation 

Administration (FAA). This legislation 

created an independent, unified agency 

to promote and develop air safety for 

both civilian and military aircraft.4 No 

such national or international body 

exists to comprehensively regulate and 

manage space traffic among active satellites, defunct satellites, cislunar and 

planetary spacecraft, and debris.

Approximately 45,000 airplanes operate in U.S. skies every day, and during 

busy periods, about 5,000 planes are in 

the air simultaneously.5 Once a commercial flight takes off, the pilot activates a transponder, which broadcasts 

a signal indicating the plane’s “flight 

number, altitude, speed, and destination.”6

 U.S. airspace is divided into 

21 zones and subdivided into sectors. 

Within each zone are Terminal Radar 

Approach Control (TRACON) airspaces that handle flights into and out 

of numerous airports. A useful analogy 

to planes being “passed off” to different flight controllers is a “zone” defense 

utilized by a football or basketball 

team.7 If an appropriate international 

regulatory body for space existed, this 

approach potentially could be adopted 

for STM.

On 1 January 2020, the FAA required 

that aircraft operating in most controlled U.S. airspace be equipped with 

Automatic Dependent SurveillanceBroadcast (ADS-B) Out technology. 

ADS-B works by periodically, automatically, and actively broadcasting 

an airplane’s position information to 

ground-based air traffic controllers, 

satellites overhead, and other aircraft. More than just a very useful 

tool for controllers, it also provides 

aircraft-to-aircraft communications in 

time-critical situations. ADS-B In is 

an optional tool for pilots to increase 

their situational awareness by obtaining information about nearby aircraft 

that also have this equipment aboard. 

ADS-B is a key technology in the FAA’s 

Next Generation Air Transportation 

System (NextGen), which shifts more 

of air traffic control from groundbased radars to satellites.8

 In addition 

to being useful for air traffic control, 

ADS-B technology can be invaluable 

for search and rescue operations and 

is analogous to the Personal Locator 

Beacons (PLBs) that many backwoods 

hikers use.9 Some researchers have 

looked at analogous technologies that 

could be attached to spacecraft to communicate their locations to analysts on 

Earth; while this would certainly be 

helpful for global STM, there is little 

incentive for satellite operators to fully 

develop and deploy such technology 

at present. 

Pilots of small planes (“general aviation”) often operate under visual flight 

rules (VFR) (“see and avoid”) and are 

encouraged, but not required, to file 

flight plans with the FAA. Spacecraft 

owner-operators are encouraged, but 

not required, to note planned orbital 

maneuvers through the www.spacetrack.org site. Larger commercial 

flights are equipped to fly in more 

inclement weather and thus operate 

under instrument flight rules (IFR) 

and are separated by the FAA’s formal 

air traffic control system. Use of this 

system has significantly increased in 

the last 50 years. Since the construction of new airports and runways hasn’t 

kept pace with the number of flights, 

Traffic Management in the Air and in Orbit (continued)

A visualization of air traffic over the United States at a specific moment in time.

If an appropriate 

international regulatory 

body for space existed, 

this approach potentially 

could be adopted for STM.

24
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

the FAA and NASA have utilized new 

technologies such as GPS to automate 

the system with limited infrastructure.10 Additionally, the very rapid 

increase in drones (remotely piloted 

vehicles or unmanned aerial vehicles) 

over the last 10–20 years for military, 

hobby, remote sensing, and various 

other purposes has greatly complicated 

how airspace is used and regulated, but 

this is a subject for a separate discussion. Again, low-Earth orbit is becoming more crowded with the advent of 

commercial communication satellites, 

which may be analogous to drones filling the skies, but spacecraft are mostly 

robotic and moving much too fast for 

VFR to be practical anyway.

There are a few other differences 

between ATM and STM to keep in 

mind. In terms of licensure and registration, the FAA mandates certain 

physical fitness and medical requirements for aircraft pilots, and there are 

some national regulations for spacecraft 

such as safety regulations for launch 

and radio frequency usage. In terms of 

the right of way for aircraft, a prioritization exists for least maneuverable 

over most maneuverable (e.g., balloons 

over gliders over powered aircraft), 

but the vast majority of space objects 

(i.e., debris and small CubeSats) are 

not maneuverable at all. In terms of 

airborne hazards, typically this is not 

an issue, but the removal of orbital 

debris hazards is figuratively uncharted 

territory (pardon the pun) both technologically and diplomatically. Nationstates can and do establish restricted 

areas for aircraft “no-fly” zones (e.g., 

over military bases or nuclear power 

plants), but again, because space is 

not sovereign, restricted zones cannot 

legally be established in space. Another 

factor to consider is that the vast 

majority of spacecraft are robotic and 

thus largely automated, but autopilot 

or the equivalent of aircraft collision 

avoidance systems really does not exist 

for spacecraft yet. Perhaps last but not 

least, air traffic controllers deliberately 

separate slower from faster aircraft to 

prevent collisions, but this isn’t relevant 

for Earth-orbiting satellites.11

In previous years, some people have 

argued for a centralized, international 

body to handle STM, akin to the 

ICAO, which sets international standards for ATM that individual nations’ 

governments implement; however, 

changes in the commercial space sector 

and other factors no longer make this 

approach realistic.12 As a former air 

traffic controller who now studies space 

situational awareness noted, safety on 

the high seas (a domain, like space, 

that no nation-state owns) relies on “sea 

faring nations of the world to enforce 

the agreed upon standards.” She also 

contends that while space technology is 

more similar to that of aviation, “international maritime agreements may 

provide the more instructive model” 

for STM.13

An important consideration for ATM 

and STM is whether a “top-down” or 

“bottom-up” system is more feasible 

for each of these domains. A top-down 

system entails a centralized body 

with enforcement authority, while a 

bottom-up system relies on decisions 

made by lower-level participants. For 

piloted aircraft, there is a civil national 

air traffic control system run by the 

FAA and an international one run 

by the ICAO that works reasonably 

well with centralized oversight and 

decentralized execution. The Pilot 

in Command rule still applies—the 

individual pilot has ultimate responsibility for the actions of their aircraft.14

This rule also applies to satellites. 

The Satellite Data Association is representative of a bottom-up approach: 

commercial satellite owner-operators 

needed a collision avoidance service, so 

they banded together and created one 

in the absence of a regulatory regime 

(it includes government agencies 

as members).15

Overall, more voluntary coordination 

is needed, both for ATM (especially 

given the proliferation of drones) and 

for STM, but many questions remain. 

Just as pilots file flight plans about their 

intended paths, a spacecraft’s insertion 

and intended orbit is outlined during 

the licensing process, but there is no 

comprehensive mechanism for communicating future orbital maneuvers 

to all relevant space operators. Just as 

driver’s education in the classroom 

and behind the wheel is incentivized 

through decreased insurance premiums, might educational incentives for 

safe and responsible space operators be 

a good idea? If so, how do we oversee 

and hold accountable the users and 

nations within the global commons of 

space? Perhaps a voluntary code of conduct or set of best practices for space 

owners/operators would be useful, but 

would this suffice? 

An important consideration for ATM and STM 

is whether a “top-down” 

or “bottom-up” system is 

more feasible....

Traffic Management in the Air and in Orbit (continued)

25
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Carefully looking at precedents of 

how traffic has been managed in other 

domains should provide policy-makers 

and other space stakeholders with 

insights on the best mixes of regulatory 

rules and norms-based cooperation, 

carrots and sticks, in the increasingly 

complex STM environment. ATM is 

but one realm that may provide some 

instructive lessons, but the air and 

space domains are sufficiently different 

so as to warrant caution in making facile analogies. 

Endnotes

1 This article is adapted from Stephen 

Garber and Marissa Herron, “How 

Has Traffic Been Managed in the 

Sky, on Waterways, and on the Road? 

Comparisons for Space Situational 

Awareness,” 15 June 2020, parts 1 and 

2, at https://www.thespacereview.

com/article/3961/1 and https://www.

thespacereview.com/article/3964/1.

2 Convention on International Civil 

Aviation, Chicago, 7 December 1944, 

https://www.icao.int/publications/

Documents/7300_orig.pdf, p. 3. This 

Chicago convention was convened 

during World War II in significant 

measure to coordinate between the 

United Kingdom and the United 

States, as well as with Canada, 

New Zealand, and Australia. See 

Proceedings of the International Civil 

Aviation Conference, Chicago, Illinois, 

November 1–December 7, 1944, volume 1 (Government Printing Office, 

1948), p. 1.

3 Ruth Stilwell testimony, House Subcommittee on Space and Aeronautics, 

11 February 2020, available from 

https://democrats-science.house.

gov/imo/media/doc/Stilwell%20

Testimony.pdf, p. 13.

4 “A Brief History of the FAA,” https://

www.faa.gov/about/history/brief_

history/ (accessed 22 October 2019); 

John Gelder, “The Federal Aviation 

Act of 1958,” Michigan Law Review 

57, no. 8 (June 1959), passim.

5 “Air Traffic by the Numbers,” 10 

April 2023, https://www.faa.gov/

air_traffic/by_the_numbers/.

6 Craig Freudenrich, “How Air Traffic 

Control Works,” HowStuff Works, 

20 May 2021, https://science.

howstuffworks.com/transport/

flight/modern/air-traffic-control.

htm. An airliner’s transponder 

periodically communicates with 

satellites that can help determine its 

location.

7 Ibid.

8 “Automatic Dependent SurveillanceBroadcast (ADS-B),” 17 January 

12023, https://www.faa.gov/

air_traffic/technology/adsb; “What 

You Need to Know About ADSB,” https://www.aopa.org/go-fly/

aircraft-and-ownership/ads-b. In 

contrast to ADS-B being active, radar 

identifies a plane’s position passively, 

by reflecting a signal sent from the 

ground.

9 See, for example, Mike Collins, 

“ADS-B Joins Search-and-Rescue 

Resources: May Have Helped 

Fi nd Pi lot W ho Ditc hed i n 

Bahamas,” https://www.aopa.org/

news-and-media/all-news/2020/

april/22/ads-b-joins-search-andrescue-resources.

10 Freudenrich, “How Air Traffic 

Control Works.”

11 For a more detailed comparison 

of such factors of travel in the air, 

space, and other domains, please see 

the chart accompanying the Garber 

and Herron article at https://www.

thespacereview.com/archive/3964.

pdf.

12 Daniel Oltrogge testimony, House 

Subc om m it tee on Spac e a nd 

Aeronautics, 11 February 2020, 

https://democrats-science.house.

gov/imo/media/doc/Oltrogge%20

Testimony.pdf, which cites Lt. Col. 

M. C. Smitham, USAF, “The Need

for a Global Space-Traffic-Control

Service: An Opportunity for US

Leadership,” Maxwell Paper No.

57, http://www.au.af.mil/au/awc/

awcgate/maxwell/mp57.pdf.

13 Stilwell testimony, pp. 1 and 4.

14 For a cogent, accessible discussion on 

this point, see Barry Schiff, chapter 

16, “The Responsibilities of the Pilotin-Command” in The Proficient Pilot, 

volume 1, Aircraft Owners and Pilots 

Association, 1980). Schiff begins 

this chapter by noting that FA A 

regulations simply, but importantly, 

dictate that “The pilot in command 

of an aircraft is directly responsible 

for, and is the final authority as to the 

operation of[,] that aircraft” (p. 123). 

Two pages later, he observes that “risk 

management is a critical element of 

flight, tempered by a continual series 

of judgments.”

15 See https://www.space-data.org/sda/

participants/.

Traffic Management in the Air and in Orbit (continued)

Visit NASA’s Orbital Debris 

Program Office website for 

more information about space 

traffic coordination and debris 

remediation. 

26
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

I

N SUMMER 1943, military leaders 

brought a small group of leaders 

from the NACA’s new Aircraft 

Engine Research Laboratory (AERL), 

which is today Glenn Research Center, 

for a secret briefing at General Electric’s 

West Lynn facility, where they were 

shown a new type of aircraft engine, the 

turbojet, and informed of recent developments surrounding it. Counterparts 

in both Britain and Germany had not 

only developed their own jet engines 

but had successfully integrated them 

into aircraft. The United States was racing to catch up by trying to replicate the 

British design. Historians consider the 

failure of the NACA, the nation’s premier aeronautical organization, to foresee the potential of the jet engine to be 

the organization’s greatest failure. Over 

the next 15 years, however, the NACA 

gained expertise in jet propulsion and 

played a vital role in the nation’s subsequent leadership in the field.

Although the NACA maintained 

a Power Plant Committee, and its 

Langley Aeronautical Laboratory 

included a Power Plants Division, it was 

primarily an aerodynamics-based organization. In 1923, a Langley researcher 

concluded that jet engines would be 

too inefficient and impractical for use 

in aircraft. That position held for the 

next 16 years as Frank Whittle and 

Hans von Ohain independently developed jet engines in Europe. In 1939, 

a pair of Langley engineers revisited 

the concept and constructed a test to 

study a ducted fan variation. Although 

they demonstrated the engine could 

produce efficient combustion, the 

device failed during a demonstration 

for NACA officials in 1942 and was 

given up. 

Meanwhile the NACA was expanding and, at the urging of Executive 

Committee member Charles Lindbergh, 

approved construction of a new laboratory dedicated to piston engines. 

Ground was broken in Cleveland for 

the laboratory in January 1941. Shortly 

thereafter, General Henry H. Arnold, 

Chief of the Army Air Corps, learned 

of the German progress on jet propulsion and witnessed first-hand the 

first jet-powered flight in England. In 

response to Arnold’s alarm, the NACA 

established a Special Committee on Jet 

Propulsion that contracted with U.S. 

manufacturers to investigate different 

design options. 

Bell Aircraft built the XP-59A to flighttest General Electric’s (GE) first jet 

engine based on the Whittle model, the 

I-A. The initial flights in October 1942 

were unsatisfactory, and subsequent 

flights in July 1943 with improved I-16 

engines were not much better. It was 

in July 1943 that the AERL team was 

briefed on the activities. 

The NACA Spurs 

U.S. Jet 

Propulsion 

Success

» By Robert Arrighi, Historian,

 NASA Glenn Research Center

 Secret testing of the Bell YP-59A with its I-16 engines in the 

Altitude Wind Tunnel in early 1944. Bell’s chief test pilot, 

Robert Stanley, who was the first American to fly a jet 

aircraft, brought the YP-59A to Cleveland for the tests. 

(Photo credit: NACA)

27
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

The contingent returned to Cleveland 

and immediately began constructing 

a nondescript two-cell facility specifically designed to test the GE engines. 

Researchers began using the facility 

just months later to test the I-A and 

I-16 in ambient conditions. By the end 

of the year, the new Altitude Wind 

Tunnel (AWT) was completed. It was 

the nation’s only tunnel that could 

operate full-scale engines in simulated 

flight conditions. In February 1944, 

a Bell YP-59A with its I-16 engines 

was installed in the AWT. NACA 

researchers were able to improve the 

I-16’s performance by 25 percent 

but could not overcome the engine’s 

inherent shortcomings.

The laboratory’s primary mission during 

the war was improving the existing 

piston engines that powered contemporary military aircraft. Nonetheless, 

there was a ramp-up of turbojet studies during the final two years of the 

conflict. Like the piston engine tests, 

these initial jet investigations were 

geared toward modifications that could 

quickly improve performance, not fundamental for long-term development. 

In January 1944, a YP-80A Shooting 

Star powered by new GE I-40 engines 

was studied in the AWT. The YP-80A 

was the first U.S.-designed jet aircraft 

and the nation’s first to exceed 5,000 

miles per hour.

Meanwhile, engineers at Westinghouse 

and GE’s Schenectady plant were developing new jet engine designs based 

on the axial-flow compressor. Unlike 

West Lynn’s centrifugal designs, which 

relied on a single large rotor to drive 

the airflow, axial-flow engines employ 

a series of linear fan stages to systematically compress the airflow. Power 

can be increased without expanding 

the engine diameter by adding addition 

stages. The AWT tested several variations of Westinghouse’s J30 and GE’s 

J35 engines during 1944. 

Although the Shooting Star and the 

J30-powered FG-Corsair flew briefly 

in the war, the early jet engines made 

little impact. It was the Allied bombers, 

driven by massive piston engines, that 

turned the tide of the war. The piston 

engines were reliable workhorses, but 

by this time their power had plateaued 

at around 3,550 horsepower. The addition of more cylinders and superchargers added weight and complexity, and 

the propeller tip speeds had reached 

their limits. Jet engines, particularly 

axial-flow engines, were the propulsion 

systems of the future. 

Just weeks after the war ended in the 

fall of 1945, the AERL underwent a 

swift, dramatic reorganization to concentrate nearly all of its resources on 

jet propulsion. The goal was not only 

to catch up with the Europeans but to 

leapfrog them. The new focus required 

training for the staff, infrastructure 

modifications, and the construction of 

new facilities designed for jet engines and 

high-speed testing. New divisions were 

created to study compressor and turbine 

design, thrust augmentation, high-temperature materials, and high-altitude 

combustion. Testing was performed on 

components and full-scale engines in a 

variety of environments. 

One of the first things engineers 

noticed is that altitude had more of 

an effect on jet engines than piston 

engines. The AWT was upgraded, 

and several new altitude test chambers were built. Over the next decade, 

nearly every U.S. model of jet engine 

underwent testing in simulated flight 

conditions at the laboratory, including 

the Westinghouse J34 and GE J47, the 

nation’s first commercially successful 

 A GE I-40 jet engine is being prepared for testing in the AERL’s Engine Propeller Research 

Building in 1946. The facility, which was designed to test large piston engines, was 

quickly modified after the war for turbojets. (Photo credit: NACA)

The NACA Spurs U.S. Jet Propulsion Success (continued)

28
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

jet engines. Engine flameouts and 

issues such as compressor windmilling 

were dramatically reduced. Subsequent 

tests included the Pratt & Whitney J57, 

the Rolls-Royce Nene, and GE J79.

Another issue was the need for short 

bursts of power, particularly for takeoffs. Early jet engine nozzles were typically designed to operate at maximum 

speed, so their efficiency decreased 

at slower speeds. NACA researchers 

conducted extensive tests on water 

and alcohol injection, the variable-area 

nozzle, and the afterburner. The first 

operational afterburner was tested on a 

ramjet engine in the AWT in 1945. 

Perhaps the laboratory’s greatest contribution was in the field of turbomachinery. The compressor and turbine 

are the heart of the axial-flow engine. 

NACA engineers worked obsessively 

on the geometry of the compressor stator blades that pushed the air through 

the engine. Turbines, however, posed 

the greatest hurdle in engine design. 

A turbine must withstand the continual stream of hot exhaust gases that 

flow through it and maintain rotation 

of the drive shaft that spins the compressor. NACA researchers conducted 

extensive studies on the intricate 

turbine blade designs, complex cooling systems, and the development of 

high-temperature alloys. 

By the late 1940s, axial-flow compressors had proven themselves in subsonic and supersonic applications, but 

there remained concern regarding the 

performance in the transonic realm. 

NACA researchers in Cleveland developed new stator blade designs and flow 

processes that increased the air pressure at each compressor stage—which 

allowed fewer stages. These designs 

were quickly adapted by manufacturers 

to produce lighter engines. The group 

went on to demonstrate that the limitations of the compressor thought to exist 

at transonic speeds were not valid. In 

1955, the group published a secret compressor design guide that was referred 

to as the “Compressor Bible.”1

The steady improvement of the axial-flow turbojet engine remains one 

of the NACA’s most underappreciated 

accomplishments. The intensive effort 

paid off, with engine thrust increasing from 1,600 pounds to over 10,000 

pounds in just a few years. The advances 

in propulsion were augmented with airframe improvements, the introduction 

of swept wings, and other technologies 

advanced by the NACA. 

Although the military benefitted 

from the introduction of jet-propelled 

fighters and bombers in the 1940s and 

1950s, the jet engine’s larger legacy may 

be the transformation of the airline 

industry. Although the Europeans were 

first to operate jet-powered airliners in 

the mid-1950s, it was the introduction 

of Boeing’s 707 and Douglas’s DC-8 

(both powered by Pratt & Whitney 

J57 engines) in the late 1950s that set 

the new standard. The increase of airline seat capacity in the 1960s, which 

made air travel affordable for ordinary 

citizens, would not have been possible 

without the jet engine.

The new rapid growth of jet airliners in 

the 1960s, however, led to a number of 

other issues requiring attention, including fuel efficiency, emissions reduction, 

and noise abatement. NASA research 

in these areas, which continues today, 

has led to dramatic improvements. 

Endnote

1 “Aerodynamic Design of Axial-flow 

Compressors, Volume 1,” NACA 

Research Memorandum RM E56BO3 

(Cleveland, OH, 1 August 1956).

 The compressor for a Westinghouse 24C 

(J34) engine was damaged during an altitude chamber test in 1947. The two altitude chambers were added to the Engine 

Research Building after the war to alleviate the backlog of turbojet tests scheduled for the AWT. (Photo credit: NACA)

 A Pratt & Whitney J57 engine mounted in 

the AWT in early 1957. The J57, the first 

U.S. jet engine to exceed 10,000 pounds 

of thrust, was used in a host of military 

aircraft including the B-52 Stratofortress, 

F-100 Super Sabre, and U-2 spy plane. 

(Photo credit: NACA)

The NACA Spurs U.S. Jet Propulsion Success (continued)

29
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Ingenuity and Coaxial 

Rotor Systems

» By Joshua Schmidt, Presidential Management Fellow 

detailed at NASA Headquarters

Rotors Out of This World

C

OMPLETING ITS FIRST FLIGHT

on 19 April 2021, NASA’s 

Ingenuity Mars Helicopter 

proved that flight on another planet 

is possible and has paved the way for 

future aircraft in the skies above Mars. 

Originally meant as a technology 

demonstrator with no more than five 

planned flights, Ingenuity has now 

completed more than 50 flights for a 

total of over 90 minutes of flight time 

covering a distance of just over 7 miles. 

Of course, flying in the thin Martian 

atmosphere, with a density of less than 

1 percent of Earth’s, presents its own 

unique challenges for generating the lift 

required to get off the ground, and the 

craft’s coaxial rotors have proven to be 

up to the task.1

Coaxial rotor systems have two rotors 

stacked one atop another with enough 

separation to ensure the blades do not 

collide. Most importantly, the rotors 

turn in opposite directions to provide 

the control needed to maintain a helicopter’s stability in flight. Without the 

anti-torque generated by the contrarotating blades, the aircraft would spin 

out of control. Coaxial rotor systems 

have the advantages of a smaller footprint and more efficient power use over 

other helicopter rotor systems but are 

in most cases more complex. 

Building Ingenuity was not the first 

time NASA and its partners have had 

the opportunity to work with such 

rotor systems. Research into coaxial 

rotors began with NASA’s predecessor 

organization, the National Advisory 

Committee for Aeronautics (NACA), 

not long after the very first flights 

of coaxial helicopters in the country 

nearly 80 years ago.

A Different Kind of System

In 1944, Stanley Hiller, a 19-year-old 

university student, made the first ever 

successful flight of a coaxial helicopter 

in the United States as he piloted his 

XH-44 aircraft into a hover and subsequently performed a small flight in 

the University of California’s Memorial 

Stadium in Berkeley.2 The XH-44 was 

quickly superseded by his next coaxial 

helicopter, the X-2-235. Though neither ever went into full production, the 

Navy’s Bureau of Aeronautics (BoA) 

did procure an unfinished X-2-235 for 

testing under a previous agreement 

with the NACA. 

In May 1945, Captain Robert Hatcher, 

BoA, sent a letter to the NACA specifically requesting integration of its newly 

acquired Hiller coaxial rotor into the 

existing research effort. By this point, 

NACA researchers had studied rotor 

systems on both the Sikorsky R-4 and 

the Piasecki PV-2 helicopters. However, 

both these aircraft utilized a single 

main rotor with a tail rotor to account 

for anti-torque requirements. Hiller’s 

rotorcraft would be the first opportunity for the NACA to test a coaxial 

rotor system. 

In accordance with previous agreements with the BoA, George Lewis, 

the NACA’s Director for Aeronautical 

Research, forwarded along the request 

 Nearly two years after its first flight on Mars, the Ingenuity Mars Helicopter completed its 

50th on 13 April 2023, a few days before this color-enhanced photo of the rotorcraft was 

taken by the Perseverance rover. (Photo credit: NASA/JPL-Caltech/ASU/MSSS)

30
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

to study the Hiller coaxial rotor to the 

Langley wind tunnel research team 

under Research Authorization (RA) 

No. 1354 (Investigation of Torque 

and Thrust Characteristics of Co-Axial 

Helicopter Rotor). The Hiller rotor 

arrived in Langley’s Full-Scale Tunnel 

(FST) for testing in July 1945.3

A First and Only Test

Up until that point, Stanley Hiller had 

been unable to satisfactorily fly his 

XH-44 safely above 35 miles per hour 

(mph), just barely faster than the minimum test speed for the Langley FST.4

To alleviate this problem, Hiller modified his XH-44 design to include a semirigid blade mounting and increased 

the spacing between the rotors. Henry 

J. E. Reid, Engineer-in-Charge of the 

NACA Langley Memorial Laboratory, 

recommended that the X-2-235 rotor 

system supplied for testing be modified 

in line with this new configuration. It 

was decided that the first tests would 

proceed with the rotor in its current 

configuration, with any further modification dependent upon results from 

initial testing.5

Unsurprisingly, those first tests of 

Hiller’s rotor in the Langley full-scale 

tunnel in the summer of 1946 ran into 

severe challenges. Langley researchers 

reported they successfully obtained 

data on Hiller’s rotor in the static 

position for both single and coaxial 

configurations. However, due to excessive vibrations introduced by the rotor 

system into the wind tunnel supports 

and balance system, researchers were 

unable to gather forward flight data in 

the coaxial configuration. 

The issues in testing Hiller’s rigid coaxial rotor, along with subsequent delays 

in Hiller providing specifications for 

his improved system, prompted a suggestion from Henry Reid to seek out 

other options so as to not “overlook a 

rotor system that might be useful.”6

New Opportunities 

A few days before Christmas 1946, 

representatives of Bendix Helicopters 

arrived in Langley to present a film 

showing the capabilities of its coaxial 

helicopter equipped with a 25-foot 

rotor, like the XH-44 and the X-2-235, 

as well as photographs of the company’s larger model with a 48-foot rotor 

diameter. Impressed with the demonstration, F. J. Bailey, an aeronautical 

engineer at Langley drafted a memo 

putting forth the idea of testing the 

Bendix helicopter: 

It is important that the NACA 

test a co-axial rotor as soon as 

a reasonable design becomes 

available. The Bendix may have 

such a design. The Hiller model 

that we now have is not. I think 

we should take steps to examine 

the Bendix machine at the earliest opportunity with the idea 

that it might provide a suitable 

rotor model for co-axial work 

on the test tower.7

With a possible alternative for testing, 

Reid requested that the NACA gather 

additional data on the Bendix coaxial 

rotor hub, and by the end of the summer of 1948, it had procured the coaxial 

rotor of the Bendix Model K. Though 

this system shared the 25-foot diameter 

of the Hiller rotor, the Bendix model 

had already flown successfully up to 

speeds of 90 mph, well above the speeds 

required in the full-scale tunnel.8

Getting Down to Business 

Using the new Bendix rotor system, 

testing of the coaxial rotor system in the 

full-scale tunnel proceeded throughout 

the early 1950s under RA No. 1354 and 

a new RA, 1498 (Investigation of Effects 

of Rotor Arrangement on Aerodynamic 

 Stanley Hiller’s XH-44 coaxial helicopter was donated to the Smithsonian’s National Air 

and Space Museum in 1953 and is on display at its Steven F. Udvar-Hazy Center in 

Virginia. (Photo credit: Smithsonian National Air and Space Museum)

Ingenuity and Coaxial Rotor Systems (continued)

31
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Characteristics of Helicopters). Robert 

Harrington, summarizing the findings, 

provided an important understanding of the hovering performance of a 

coaxial rotor in NACA Technical Note 

2318.9 He further compared his data 

with information gathered from single 

rotor tests to compare the accuracy of 

power calculations between the different systems. 

Richard Dingeldein later expanded 

upon the research in both static thrust 

and forward flight as a part of the test 

regimes he investigated. His results 

once again confirmed the similarities 

in power calculations between coaxial and single rotor systems in a static 

thrust condition. He also observed that 

in level flight, more power is required 

for a coaxial system than a single 

rotor configuration.10

While disadvantageous when compared with single rotor helicopters in 

that specific flight regime, Dingeldein 

noted that coaxial configurations 

have certain advantages that may offset the higher power required in that 

flight regime. 

The Ingenuity design team selected 

a coaxial rotor to utilize such advantages—specifically, the ability of coaxial rotor systems to be more physically 

compact, an important factor for a 

helicopter that needed to fit on the 

Perseverance rover as part of the Mars 

2020 payload. Additionally, these systems are more efficient in generating 

lift, which is critically important in the 

very thin Martian atmosphere. Clearly 

the team of engineers who designed 

Ingenuity built upon this foundation 

of knowledge pioneered decades ago 

by the NACA, and their design choices 

led them to create an aircraft that has 

exceeded performance expectations. 

Endnotes

1 “Mars Helicopter,” NASA, https://

mars.nasa.gov/technology/

helicopter/#Helicopter-Highlights

(accessed 10 May 2023).

2 Stanley Hiller hadn’t ever f lown 

a helicopter before work with the 

XH-44 and had to teach himself while 

building the aircraft. Additionally, his 

original team did not employ an aeronautical engineer through production 

of either the XH-44 or the X-2-235. 

See Jay P. Spenser, Whirlybirds: A 

History of the U.S. Helicopter Pioneers.

Seattle: University of Washington 

Press, 1998.)

3 Herber t Wi l son, “Bu re au of 

Aeronautics Project TED No. NACA 

239—Helicopter rotors—Hiller 

Rotor,” memo for Chief of Research, 

18 July 1946, “Investigation of 

Torque and Thrust Characteristics 

of Co-Axial Helicopter Rotor,” Box 

543, NASA Historical Reference 

Collection, NASA History Division, 

NASA Headquarters, Washington, 

DC (hereafter HRC).

4 Henr y Reid to NAC A, “TED 

No. 239—Helicopter Rotors—

Hiller Rotor,” 29 October 1945, 

“Investigation of Torque and Thrust 

Characteristics of Co-Axial Helicopter 

Rotor,” Box 543, HRC.

5 John Crowley to Langley, “TED 

No. 239—Helicopter Rotors—

Hiller Rotor,” 30 November 1945, 

“Investigation of Torque and Thrust 

Characteristics of Co-Axial Helicopter 

Rotor,” Box 543, HRC.

6 Henry Reid to NACA, “Request for 

information on coaxial rotor built by 

Bendix Helicopters, Inc.,” 7 September 

1947, “Investigation of Torque and 

Thrust Characteristics of Co-Axial 

Helicopter Rotor,” Box 543, NASA 

Historical Reference Collection, 

NASA History Division, NASA 

Headquarters, Washington, DC.

7 F. J. Bailey, “Visit of Messrs. J. A. 

Johnson and J. B. Vernon of Bendix 

Helicopter Company to Langley on 

December 19 and 20, 1946,” memo 

for Chief of Research, 24 December 

1946, “Investigation of Torque and 

Thrust Characteristics of Co-Axial 

Helicopter Rotor,” Box 543, NASA 

Historical Reference Collection, 

NASA History Division, NASA 

Headquarters, Washington, DC.

8 Russel Robinson to BoA, “Procurement of co-axial helicopter rotor,” 15 

December 1947, “Investigation of 

Torque and Thrust Characteristics of 

Co-Axial Helicopter Rotor,” Box 543, 

NASA Historical Reference Collection, NASA History Division, NASA 

Headquarters, Washington, DC.

9 Robert D. Harrington, “Full-ScaleTunnel Investigation of the Static 

Thrust Performance of a Coaxial 

Helicopter Rotor,” NACA TN 2318, 

1951.

10 Richard C. Dingeldein, “WindTunnel Studies of the Performance of 

Multirotor Configurations,” NACA 

TN 3236, 1954.

 A 25-foot-diameter coaxial rotor system 

is prepared for testing at Langley’s fullscale tunnel in 1949. (Photo credit: NACA)

Ingenuity and Coaxial Rotor Systems (continued)

32
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

The NASA Aeronautics 

Book Series

» By Tony Springer, Integration and Management Office Director, 

NASA Aeronautics Research Mission Directorate

T

HE NASA HISTORY SERIES, published by the Agency’s History 

Office, is not NASA’s only series 

of books tackling the history of the 

Agency. The Aeronautics Book Series, 

published by the Aeronautics Research 

Mission Directorate (ARMD), was conceived as a response to the Centennial 

of Flight anniversary on 17 December 

2003. This major anniversary spurred 

a renewed emphasis on informing 

our future workforce of the lessons 

learned from past and current projects 

that would be applicable to aeronautics research projects today and in the 

future. Various aeronautics topics were 

chosen to directly benefit the Agency’s 

workforce, as well as to be useful for 

college students, historians, the technically literate public, and personnel from 

other executive branch organizations. 

The goal for each book was to provide 

an overview of an activity from both 

technical and managerial perspectives. 

Each volume includes references as 

further resources for readers. ARMD 

published 16 volumes in the core 

series with an additional half dozen 

other volumes.

A Few Highlighted Volumes

Apollo of Aeronautics: 

NASA’s Aircraft Energy 

Eff iciency Program, 

1973–1987 by Mark D. 

Bowles was the first volume of the series. NASA’s 

Aircraft Energy Efficiency Program is 

not well known, but a few of the technologies that came out of it, such as 

winglets, have become widely adopted. 

NASA’s renewed focus on the environment was one stimulus for this book. 

Renowned aerospace historian Richard 

Hallion edited most of the volumes in 

the series, helping to shape the content. 

Successive volumes in the series also 

have a more consistent look and feel. 

These later volumes covered topics of 

direct use to current and future projects or subjects whose histories were 

not easily found elsewhere. 

Beyond Tube and Wing: 

The X-48 Blended 

Wing-Body and NASA’s 

Quest to Reshape Future 

Transport Aircraft 

Bruce I. Larrimer

Elegance in Flight: 

A Comprehensive 

History of the F-16XL 

Experimental Prototype 

and Its Role in NASA 

Flight Research 

Albert C. Piccirillo

Flying Beyond the Stall: 

The X-31 and the Advent 

of Supermaneuverability 

Douglas A. Joyce

Green Light for 

Green Flight: NASA’s 

Contributions to 

Environmentally 

Responsible Aviation

Peter W. Merlin

A New Twist in Flight 

Research: The F-18 

Active Aeroelastic 

Wing Project 

Peter W. Merlin

The Power for Flight: 

NASA’s Contributions 

to Aircraft Propulsion

Jeremy R. Kinney

Probing the Sky: 

Selected NACA Research 

Airplanes and Their 

Contributions to Flight 

Curtis Peebles 

Promise Denied: NASA’s 

X-34 and the Quest 

for Cheap, Reusable 

Access to Space 

Bruce I. Larrimer

Quieting the Boom: The 

Shaped Sonic Boom 

Demonstrator and 

the Quest for Quiet 

Supersonic Flight

Lawrence R. Benson

Sweeping Forward: 

Developing and Flight 

Testing the Grumman 

X-29A Forward Swept 

Wing Research Aircraft 

Frederick A. Johnsen

33
NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

Thinking Obliquely: 

Robert T. Jones, the 

Oblique Wing, NASA’s 

AD-1 Demonstrator, 

and Its Legacy 

Bruce I. Larrimer

Unlimited Horizons: 

Design and Development 

of the U-2 

Peter W. Merlin

The series also includes two volumes 

on mishaps: Breaking the Mishap 

Chain: Human Factors 

Lessons Learned from 

Aerospace Accidents 

a n d I n c i d e n t s i n 

Research, Flight Test, 

and Development

by Peter W. Merlin, 

Gregg A. Bendrick, and Dwight A. 

Holland; and the other on autonomous 

systems, Crash Course: 

Lessons Learned from 

Accidents Involving 

Remotely Piloted and 

Autonomous Aircraft

by Peter W. Merlin. 

It’s hard to remember a time before 

electronic publications, but during the 

2010s, e-books were just starting to 

become routinely available. To reach 

a larger audience, ARMD offered 

both print and e-book versions of its 

new publications. 

Outside the NASA Aeronautics Book 

Series, other key volumes sponsored and 

published by ARMD included two volumes on NASA’s contributions to aeronautics and another on high-altitude 

pressure suits. ARMD routinely got 

inquiries from both inside and outside 

the mission directorate about aeronautics technologies, but up to that point, 

there was no single source on the key 

aeronautics advancements developed 

by NASA and its predecessor organization, the NACA. ARMD decided 

to develop such a synopsis, suitable 

for a wide audience, that 

covered many of these 

main areas of aeronautics research undertaken 

by the Agency: NASA’s 

C o n t r i b u t i o n s t o 

Aeronautics, edited by 

Richard P. Hallion. This 

two-volume set brings 

together the expertise of 

multiple authors.

Additionally, several volumes had been 

written on spacesuits, but information 

on aviation pressure suits was lacking. 

D r e s s i n g f o r 

A l t i t u d e : U. S . 

Aviation Pressure 

Suits—Wiley Post 

to Space Shuttle by 

Dennis R. Jenkins was developed as a 

starting point for understanding the history of high-altitude pressure suits used 

for aircraft and the transition into space. 

Utilizing a coffee table format served to 

highlight both the stunning visuals and 

the technical content on the subject. 

Since its inception, the Aeronautics 

Book Series and related ARMD publications have captured a range of aeronautics activities that would have otherwise 

gone undocumented for a broad readership. The Aeronautics Book Series, 

while a great achievement, is currently 

in a holding pattern while new options 

for conveying important information 

about the Agency’s proud aeronautics 

heritage are being explored. 

Details on the volumes of the 

Aeronautics Book Series, 

along with electronic versions, are 

available for free download on 

NASA’s website.

The NASA Aeronautics Book Series (continued)

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NASA HISTORY NEWS&NOTES Volume 40, Number 2 • Summer 2023

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 A Fixed Wing Supersonic Transport in Ames 

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