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-1994-11-035 DFRC 

D-558-II 

D-558-II Skyrocket being launched from a P2B. 

The Douglas D-558-II "Skyrockets" were among the early transonic research airplanes like the X-1, X-4, X-5, 

and X-92A. Three of the single-seat, swept-wing aircraft flew from 1948 to 1956 in a joint program involving 

the National Advisory Committee for Aeronautics (NACA), with its flight research done at the NACA's Muroc 

Flight Test Unit in Calif., redesignated in 1949 the High-Speed Flight Research Station (HSFRS); the NavyMarine Corps; and the Douglas Aircraft Co. The HSFRS is now known as the NASA Dryden Flight Research 

Center. The Skyrocket made aviation history when it became the first airplane to fly twice the speed of sound. 

The II in the aircraft's designation referred to the fact that the Skyrocket was the phase-two version of what had 

originally been conceived as a three-phase program, with the phase-one aircraft having straight wings. The third 

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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 John F. Martin made the first flight at 

Muroc Army Airfield (later renamed Edwards Air 

Force Base) in Calif. on February 4, 1948. The goals 

of the program were to investigate the characteristics 

of swept-wing aircraft at transonic and supersonic 

speeds with particular attention to pitch-up 

(uncommanded rotation of the nose of the airplane 

upwards)--a problem prevalent in high-speed service 

aircraft of that era, particularly at low speeds during 

take-off and landing and in tight turns. 

The three aircraft gathered a great deal of data about 

pitch-up and the coupling of lateral (yaw) and longitudinal (pitch) motions; wing and tail loads, lift, drag, 

and buffeting characteristics of swept-wing aircraft at 

transonic and supersonic speeds; and the effects of the 

rocket exhaust plume on lateral dynamic stability 

throughout the speed range. (Plume effects were a 

new experience for aircraft.) The number three aircraft also gathered information about the effects of 

external stores (bomb shapes, drop tanks) upon the 

aircraft's behavior in the transonic region (roughly 0.7 

to 1.3 times the speed of sound). 

In correlation with data from other early transonic 

research aircraft such as the XF-92A, this information 

contributed to solutions to the pitch-up problem in 

swept-wing aircraft. 

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. At the NACA's suggestion, based on the research of Robert Jones at 

Langley and captured German documents, Douglas 

and the Navy had agreed to the swept-wing design, 

and to provide sufficient power to propel the sweptwing airplane past Mach 1, they also agreed to add 

rocket propulsion. 

Then, to fit both a turbojet and rocket engine in the 

phase two aircraft required a new fuselage. Like the 

D-558-I, the Skyrocket featured a horizontal stabilizer 

high on the vertical tail to avoid the wake from the 

wing. As with the X-1 and the D-558-1, the Skyrocket 

also featured, at NACA suggestion, a horizontal 

stabilizer that was thinner than the wing and movable 

in flight so as to avoid simultaneous shock wave 

effects for the wing and horizontal tail and to provide 

pitch (nose up or down) control when shock waves 

made the elevators ineffective. While Douglas was 

constructing the D-558-IIs, the NACA continued to 

furnish the contractor data it needed on aircraft performance based on tests in Langley wind tunnels and 

with rocket-propelled models from the Wallops Island 

Pilotless Aircraft Research Station. 

Program History 

The three airplanes flew a total of 313 times--123 by 

the number one aircraft (Bureau No. 37973--NACA 

D-558-II Skyrocket on the Lakebed at Edwards AFB. 

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143), 103 by the second Skyrocket (Bureau No. 

37974--NACA 144), and 87 by airplane number three 

(Bureau No. 37975--NACA 145). Skyrocket 143 flew 

all but one of its missions as part of the Douglas 

contractor program to test the airplane's performance. 

NACA aircraft 143 was initially powered by a 

Westinghouse J-34-40 turbojet engine configured only 

for ground take-offs, but in 1954-55 the contractor 

modified it to an all-rocket air-launch capability 

featuring an LR8-RM-6, 4-chamber Reaction Motors 

engine rated at 6,000 pounds of thrust at sea level (the 

Navy designation for the Air Force's LR-11 used in 

the X-1). In this configuration, NACA research pilot 

John McKay flew the airplane only once for familiarization on September 17, 1956. The 123 flights of 

NACA 143 served to validate wind-tunnel predictions 

of the airplane's performance, except for the fact that 

the airplane experienced less drag above Mach 0.85 

than the wind tunnels had indicated. 

NACA 144 also began its flight program with a 

turbojet powerplant. NACA pilots Robert A. 

Champine and John H. Griffith flew 21 times in this 

configuration to test airspeed calibrations and to 

research longitudinal and lateral stability and control. 

In the process, during August of 1949 they encountered pitch-up problems, which NACA engineers 

recognized as serious because they could produce a 

limiting and dangerous restriction on flight performance. Hence, they determined to make a complete 

investigation of the problem. 

In 1950, Douglas replaced the turbojet with an LR-8 

rocket engine, and its pilot, William B. Bridgeman, 

flew the aircraft seven times up to a speed of Mach 

1.88 (1.88 times the speed of sound) and an altitude of

79,494 feet (the latter an unofficial world's altitude 

record at the time, achieved on August 15, 1951). In 

the rocket configuration, a Navy P2B (Navy version of 

the B-29) launched the airplane at approximately 

30,000 feet after taking off from the ground with the 

Skyrocket attached beneath its bomb bay. During 

Bridgeman's supersonic flights, he encountered a 

violent rolling motion known as lateral instability that 

was less pronounced on the Mach 1.88 flight on 

August 7, 1951, than on a Mach 1.85 flight in June 

when he pushed over to a low angle of attack (angle of 

the fuselage or wing to the prevailing wind direction). 

The NACA engineers studied the behavior of the 

aircraft before beginning their own flight research in 

the airplane in September 1951. Over the next couple 

of years, NACA pilot A. Scott Crossfield flew the 

airplane 20 times to gather data on longitudinal and 

lateral stability and control, wing and tail loads, and 

lift, drag, and buffeting characteristics at speeds up to 

Mach 1.878. 

At that point, Marine Lt. Col. Marion Carl flew the 

airplane to a new (unofficial) altitude record of 83,235 

feet on August 21, 1953, and to a maximum speed of 

Mach 1.728. 

Following Carl's completion of these flights for the 

Navy, NACA technicians at the High-Speed Flight 

Research Station (HSFRS) near Mojave, Calif., outfitted the LR-8 engine's cylinders with nozzle extensions 

to prevent the exhaust gas from affecting the rudders 

at supersonic speeds. This addition also increased the 

engine's thrust by 6.5 percent at Mach 1.7 and 70,000 

feet. 

Even before Marion Carl had flown the Skyrocket, 

HSFRS Chief Walter C. Williams had petitioned 

Graphic showing the D-558-II Wing Configurations. 

NACA headquarters unsuccessfully to fly the aircraft 

to Mach 2 to garner the research data at that speed. 

Finally, after Crossfield had secured the agreement of 

the Navy's Bureau of Aeronautics, NACA director 

Hugh L. Dryden relaxed the organization's usual 

practice of leaving record setting to others and consented to attempting a flight to Mach 2. 

In addition to adding the nozzle extensions, the NACA 

flight team at the HSFRS chilled the fuel (alcohol) so 

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more could be poured into the tank and waxed the 

fuselage to reduce drag. With these preparations and 

employing a flight plan devised by project engineer 

Herman O. Ankenbruck to fly to approximately 

72,000 feet and push over into a slight dive, Crossfield 

made aviation history on November 20, 1953, when he 

flew to Mach 2.005 (1,291 miles per hour). He became the first pilot to reach Mach 2 in this, the only 

flight in which the Skyrocket flew that fast. 

Following this flight, Crossfield and NACA pilots 

Joseph A. Walker and John B. McKay flew the airplane for such purposes as to gather data on pressure 

distribution, structural loads, and structural heating, 

with the last flight in the program occurring on December 20, 1956, when McKay obtained dynamic 

stability data and sound-pressure levels at transonic 

speeds and above. 

Meanwhile, NACA 145 had completed 21 contractor 

flights by Douglas pilots Eugene F. May and Bill 

Bridgeman in November 1950. In this jet-and-rocketpropelled craft, Scott Crossfield and Walter Jones 

began the NACA's investigation of pitch-up lasting 

from September 1951 well into the summer of 1953. 

They flew the Skyrocket with a variety of wing-fence, 

wing-slat, and leading-edge chord extension configurations, performing various maneuvers as well as 

straight-and-level flying at transonic speeds. While 

fences significantly aided recovery from pitch-up 

conditions, leading edge chord extensions did not, 

disproving wind-tunnel tests to the contrary. Slats 

(long, narrow auxiliary airfoils) in the fully open 

position eliminated pitch-up except in the speed range 

around Mach 0.8 to 0.85. 

In June 1954, Crossfield began an investigation of the 

effects of external stores (bomb shapes and fuel tanks) 

upon the aircraft's transonic behavior. McKay and 

Stanley Butchart completed the NACA's investigation 

of this issue, with McKay flying the final mission on 

August 28, 1956. 

Besides setting several records, the Skyrocket pilots 

had gathered important data and understanding about 

what would and would not work to provide stable, 

controlled flight of a swept-wing aircraft in the transonic and supersonic flight regimes. The data they 

gathered also helped to enable a better correlation of 

wind-tunnel test results with actual flight values, 

enhancing the abilities of designers to produce more 

capable aircraft for the armed services, especially 

those with swept wings. Moreover, data on such 

matters as stability and control from this and other 

early research airplanes aided in the design of the 

century series of fighter airplanes, all of which featured the movable horizontal stabilizers first employed 

on the X-1 and D-558 series. 

The Aircraft 

All three of the Skyrockets had a height of 12 feet 8 

inches, a length of 42 feet, and 35-degree swept wings 

D-558-II 3-Dimentional Drawing 

with a span of 25 feet. 

Until configured for air launch, NACA 143 featured a 

Westinghouse J-34-40 turbojet engine rated at 3,000 

pounds of static thrust. It carried 260 gallons of 

aviation gasoline and weighed 10,572 pounds at takeoff. 

NACA 144 (and NACA 143 after modification in 

1955) was powered by an LR-8-RM-6 rocket engine 

rated at 6,000 pounds of static thrust. Its propellants 

were 345 gallons of liquid oxygen and 378 gallons of 

diluted ethyl alcohol. In its launch configuration, it 

weighed 15,787 pounds. 

NACA 145 had both an LR-8-RM-5 rocket engine 

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rated at 6,000 pounds of static thrust and featured a 

Westinghouse J-34-40 turbojet engine rated at 3,000 

pounds of static thrust. It carried 170 gallons of liquid 

oxygen, 192 gallons of diluted ethyl alcohol, and 260 

gallons of aviation gasoline for a launch weight of 

15,266 pounds. 

NACA 143 is currently in storage at the Planes of 

Fame Museum, Ontario, California. The second 

Skyrocket, NACA 144, is in the Smithsonian 

Institution's National Air and Space Museum in 

Washington, D.C. NACA 145 is on display in front of 

the Antelope Valley College in Lancaster, California. 

For Further Reading 

The best single source on the Skyrocket 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 Skyrocket pilots, A. Scott 

Crossfield (with Clay Blair, Jr.), has told about his 

own flying career in Always Another Dawn: The Story 

of a Rocket Test Pilot (Cleveland, 1960). Another 

Skyrocket pilot, William Bridgeman, has related his 

experiences in a book written with Jacqueline Hazard, 

The Lonely Sky (New York, 1955). 

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