NASA 

National Aeronautics and 

Facts

Space Administration 

Dryden Flight Research Center 

P.O. Box 273

Edwards, California 93523 

Voice 661-276-3449 

FAX 661-276-3566 

pao@dfrc.nasa.gov FS-2003-10-036 DFRC 

D-558-1

The D-558-I "Skystreaks" were among the early transonic research airplanes like the X-1, X-4, X-5, and XF92A. Three of the single-seat, straight-wing aircraft flew in a joint program involving the National Advisory 

Committee for Aeronautics (NACA), the Navy-Marine Corps, and the Douglas Aircraft Co. from 1947 to 1953. 

In the process, the Skystreaks set several world speed records. 

The division of responsibility among the partners was that Douglas flew a contractor program on the first 

Skystreak to investigate its performance, handled major maintenance and performed any modifications. The 

NACA's Muroc Flight Test Unit, redesignated the High-Speed Flight Research Station in 1949 and now named 

the NASA Dryden Flight Research Center, purchased fuel and oil from the Army Air Forces (Air Force after 

September 1947), provided and installed instrumentation, performed the flight research on the number two and 

three aircraft, and took care of routine flight maintenance and inspection on them. The Navy paid the expenses 

of Douglas Aircraft, including engine overhaul and replacement, and its pilots did some of the flying. 

The (Roman numeral) I in the aircraft's designation referred to the fact that the Skystreak was the phase-one 

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version of what had originally been conceived as a 

three-phase program, with the phase-two aircraft 

having swept wings. The third phase, which never 

came to fruition, would have involved constructing a 

mock-up of a combat-type aircraft embodying the 

results from the testing of the phase one and two 

aircraft. 

Douglas pilot Eugene F. May flew the number one 

Skystreak for the first time on April 14, 1947, at 

Muroc Army Airfield (later renamed Edwards Air 

Force Base) in Calif. The goals of the program were to 

investigate the operation of a straight-wing configuration in the lower third of the transonic speed range 

(which extended from roughly 0.7 to 1.3 times the 

speed of sound) and to obtain data about flight in that 

speed range that were not available from existing wind 

tunnels. 

The three aircraft, equipped with Allison J-35-A-11 

turbojet engines, gathered a great deal of data on 

handling qualities, tail loads, buffeting, pressure 

distribution, plus static and dynamic longitudinal as 

well as lateral stability and control and the effects of 

vortex generators on undesirable handling characteristics. Together with other transonic research airplanes, 

the D-558-I research results validated the data from 

wind tunnels then being developed by the NACA, 

which required basic data for comparison to ensure 

there were no unforeseen errors in their development. 

Both kinds of data were then available for use by 

designers of new military aircraft, such as those in the 

century series of fighters (F-100, F-102, and so forth.) 

Design 

The need for transonic research airplanes grew out of 

two conditions that existed in the early 1940s. One 

was the absence of accurate wind tunnel data for the 

speed range from roughly Mach 0.8 to 1.2. The other 

was the fact that fighter aircraft like the P-38 "Lightning" were approaching these speeds in dives and 

breaking apart from the effects of compressibility— 

increased density and disturbed airflow as the speed 

approached that of sound, creating shock waves. 

People in the aeronautics community—especially the 

NACA, the Army Air Forces (AAF), and the Navy— 

agreed on the need for a research airplane with enough 

structural strength to withstand compressibility effects 

in the transonic region. The AAF preferred a rocketpowered aircraft and funded the X-1, while the NACA 

and Navy preferred a more conservative design and 

pursued the D-558, with the NACA also supporting 

the X-1 research. 

The Navy contracted with Douglas to design the 

airplane, and in the course of the design process, the 

D-558 came to be divided into two separate phases, 

with phase one being a straight-wing turbojet aircraft 

and phase two consisting of a swept-wing design with 

turbojet and rocket propulsion. The Douglas design 

team, headed by Edward H. Heinemann, used NACA 

information and airfoil shapes. It tested its models in 

NACA and California Institute of Technology wind 

tunnels. And it relied on NACA recommendations, 

such as putting the horizontal stabilizer of the D-558-I 

high on the vertical tail to avoid the wake from the 

wing. As with the X-1, the D-558-1 also featured, at 

NACA suggestion, a horizontal stabilizer that was 

thinner than the wing so as to avoid simultaneous 

shock wave effects for the wing and horizontal tail. 

Also at NACA suggestion and like the X-1, the stabilizer was movable in flight to provide pitch (nose up 

or down) control when shock waves made the elevators ineffective. 

What the Skystreak lacked was an ejection seat. The 

design team had considered one, but given the technology of the day, the team discovered that the force 

necessary to propel the seat and pilot higher than the 

vertical tail exceeded the pilot's physiological limits. 

Hence, Douglas provided instead a jettisonable nose 

capsule from which the pilot could bail out if the 

airplane were high enough. 

When Commander Turner F. Caldwell set the world's 

speed record in the D-558-1 (NACA140), the Navy 

Bureau of Aeronautics stated in a message to the 

NACA, "A great measure of the credit for the success 

of the D-558 airplane speed record flight is due to the 

NACA. The highly important introductory research 

and investigation program leading to recommendations on airplane configuration problems was essential 

in the development of this airplane." 

Instrumentation 

The NACA-Muroc instrumentation section under 

Gerald M. Truszynski installed a 12-channel oscillograph to record the data from strain gauges; a 60-

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capsule manometer to record pressure distribution; 

transmitters for data on control-wheel and pedal 

forces; recorders for the positions of ailerons, elevators, and rudder-controls; an accelerometer; a telemeter and switch to transmit airspeed, altitude, normal 

acceleration, and the positions of ailerons and elevators; an airspeed-altitude recorder; a sideslip-angle 

transmitter; and a camera to record the instrument 

readings on the pilot's control panel. All of this instrumentation—some 634 pounds—was ready on 

Skystreak number two by the late fall of 1947. 

Program History 

The three Skystreaks flew a total of 229 times from 

1947 to 1953, including 101 contract flights in the 

number one aircraft (Bureau No. 37970—NACA 140), 

46 by the Skystreak number two (Bureau Number 

37971—NACA 141), and 82 by the number three 

aircraft (Bureau Number 37972—NACA 142). NACA 

140's flights were all completed as part of the contractor program, although Caldwell flew it on four passes 

on August 20, 1947, averaging 640.663 miles per hour 

over a measured course, setting a new world airspeed 

record. Five days later, however, Marine Major 

Marion Carl surpassed the record, flying NACA 141 

an average 650.796 miles per hour in four passes over 

the course. The NACA never flew the number one 

airplane, using it instead for spares support of the 

number three aircraft. 

NACA 141 made 27 flights by Douglas, Navy and 

Marine pilots before being instrumented for NACA 

flights, all flown by Howard C. Lilly. Although both 

NACA 140 and 141 had been painted scarlet for 

improved visibility, in flying the aircraft both Douglas 

and NACA personnel discovered that the scarlet color 

was difficult to discern against the dark blue desert 

sky. During the winter of 1947-1948, NACA repainted 

NACA 141 with a white color. 

In the spring of 1948, Lilly flew five research flights 

gathering data on directional stability. On April 29, he 

reached a speed of Mach 0.88 at 36,000 feet (roughly 

580 miles per hour). Unfortunately, on his next flight, 

the compressor section of his J-35 engine disintegrated, severing the elevator and rudder cables and 

resulting in his loss of control over the airplane at a 

comparatively low speed and altitude. He died in the 

subsequent crash. 

Following the recommendations of the accident board, 

Douglas technicians added duplicate control cables, 

armor plating around the emergency fuel pump and 

fuel lines, and wire-wound fuel hoses to NACA 142, 

repainting it white in the process. 

In 1949, NACA pilots Robert A. Champine and John 

H. Griffith began flying NACA 142, gathering data

about handling qualities, aileron effectiveness and 

pressure distribution. On November 29, 1950, following the conclusion in June of the extended pressuredistribution studies, NACA pilot A. Scott Crossfield 

began a series of buffeting, tail loads, and longitudinal 

stability investigations that lasted until October 1951. 

NACA pilots Walter P. Jones and Joseph A. Walker 

also participated in this series of flights. 

Crossfield and fellow NACA pilots Stanley P. 

Butchart and John B. McKay flew a series of flights 

gathering data on lateral and dynamic stability from 

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June 1952 through April 1953. This was followed by 

McKay and Crossfield's investigation of the effects of 

tip tanks on the Skystreak's buffet characteristics. 

These concluded with Crossfield's final flight in the 

airplane on June 10, 1953. 

Although it was slower and more conventional than 

the rocket-powered X-1 and D-558-II, the Skystreak 

performed valuable services as a first-generation 

transonic research airplane. Even the loss of NACA 

141 and Howard Lilly served a purpose because it 

resulted in a greater appreciation for the dangers of 

research flying. As a result, the safety modifications to 

the Skystreak were also made to other research airplanes, especially the Northrop X-4 and the Bell X-5. 

Together with the X-1 and the D-558-II, the Skystreak 

was one of the few sources of data on transonic flight 

conditions in the period 1947 to 1950 until the NACA 

developed better wind tunnels. These aircraft then 

contributed data to validate that derived from the 

tunnels by providing a reality check in the form of 

corresponding information from a real flight environment. Embodying the state of the art in aeronautics 

when built, these aircraft also tested whether the 

various components in their design operated together 

when flown. The data that resulted enabled the armed 

services and industry to advance the state of the art in 

the century series of fighters and other aircraft built in 

the 1950s, using data from the research airplanes in 

the areas of controllability, stability, changes in stability and in tailplane orientation. Like the X-1, D-558-I, 

and D-558-II, all the century series fighters employed 

movable hoizontal stabilizers because the research 

airplanes had shown that they provided excellent 

controllability near the speed of sound, whereas the 

elevator was ineffective in providing pitch control in 

that speed range. 

The Aircraft 

The Skystreaks were approximatley 35 feet long, 12 

feet high, and 25 feet across the wing span. They were 

powered by one Allison J-35-A-11 engine (developed 

by General Electric as the TG-180), which was rated 

at 5,000 pounds of static thrust. The airplane carried 

230 gallons of aviation fuel (kerosene). 

NACA 140 is located at the Naval Aviation Museum 

in Pensacola, Fla. NACA 142 is at the Marine Corps 

Air Ground Museum, Quantico, Va. 

For Further Reading 

The best single source on the Skystreak is Richard P. 

Hallion's "Supersonic Flight: Breaking the Sound 

Barrier and Beyond, The Story of the Bell X-1 and 

Douglas D-558" (revised edn.; London and Washington, 1997). One of the Skystreak pilots, A. Scott 

Crossfield, has told about his own flying career in 

"Always Another Dawn: The Story of a Rocket Test 

Pilot" (Cleveland, 1960). 

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