Flight Test Records: The Douglas D-558-I Skystreak

A Douglas D-558-I Skystreak pictured in flight in the early 1950s. Although less well known than the Bell XS-1, the D-558-I could fill research roles that complemented those of the more glamorous rocket-propelled vessel. . The D-558-I was relatively slow, with a single flight exceeding the speed of sound. However, the jet Skystreak could fly for extended periods of time at transonic speeds, increasing the amount of data that a single flight could provide. In contrast, the rocket-powered XS-1 could only provide transonic data for brief periods of time on each flight. NASA photo

Designed in 1945, the Douglas D-558-I Skystreak was a revolutionary transonic research aircraft designed for the US Navy Bureau of Aeronautics in conjunction with the National Advisory Committee for Aeronautics (NACA). The Skystreak, unlike most American high-speed aerial search vehicles of the day, lifted off the ground on its own. Each had conventional straight wings and tails, with power coming from an Allison J35-A-11 turbojet producing around 5,000 pounds of thrust. Only three of the six planned Skystreaks have been completed. The guy first flew in a dramatic scarlet livery, earning him the nickname “Crimson Test Tube”.

Major Marion Carl (left) and US Navy Commander Turner F. Caldwell stand next to a Douglas D-558-I Skystreak at Muroc Army Airfield (later Edwards Air Force Base) in California, U.S. United). Carl and Caldwell both set world speed records in D-558-I type planes in 1947. (US Navy photo via Wikipedia)

NACA then had its copies repainted white to improve optical tracking and photography. The Skystreaks could carry 634 pounds of instrumentation and were ideal first-generation transonic research aircraft – with complexity only where needed.

The first Skystreak made its maiden flight on April 14, 1947 at Muroc Dry Lake (now known as Edwards Air Force Base). On August 20, the aircraft set a new world speed record of 640.74 mph, with Commander Turner Caldwell (USN) in command. While NACA took delivery of this Skystreak in April 1949, it never actually flew the plane.

The NACA took delivery of the second Skystreak in November 1947. They performed 19 flights in their service until a tragedy struck on May 3, 1948. The engine compressor disintegrated on takeoff and the accident that resulted in follow-up claimed the life of NACA pilot Howard C. Lilly.

In this 1949 photograph of the NACA Muroc flight test unit, the Douglas D-558-I is seen seated on the ramp at South Base, Edwards AFB. Three members of the ground crew are seen posed against the leading edge of the left wing of the aircraft. The D-558-I was designed to be just large enough to accommodate the J35 turbojet, pilot, and instrumentation. The fuselage cross section had to be kept to a minimum, which meant the D-558-I pilots found the cockpit almost too narrow to turn their heads! NASA photo

Douglas delivered the third Skystreak (BuNo.37872) to NACA in 1949 after three test pilots from Douglas and Howard Lilly had already flown it. Aircraft number three resumed the planned flight program from D-558-I # 2. From the first flight in 1949 to 1953, the third Skystreak participated in an intensive flight research program. Seven different NACA test pilots participated in this undertaking which collected important data on the handling of high subsonic aircraft. In total, D-558-I # 3 performed 78 search flights with the NACA before removing the aircraft on June 10, 1953.

In this photo, the Douglas D-558-I # 2 Skystreak is shown with Test Pilot Eugene May (Douglas Aircraft Company) to the left and NACA Search Pilot Howard Lilly to the right. Tragically, this plane crashed on May 3, 1948. Lilly had just taken off and retracted the landing gear when the engine compressor broke. The fragments severed the aircraft’s control lines. Lilly had no chance to escape until the D-558-I reached the lake bed and shattered, costing her her life. One of the roads leading to what is now the Armstrong Flight Research Center (formerly Dryden) is named after Lilly; he was the first NACA search pilot killed in the line of duty. NASA photo

Despite its invaluable service, much of the Skystreak’s research, at least in the public mind, is overshadowed by the Bell XS-1 in which legendary fighter ace and test pilot Chuck Yeager broke the sound barrier. for the first time on October 14, 1947. – although news of this feat did not make the headlines for several months due to the secrecy surrounding it. It should be remembered, however, that the Skystreak played an important role in aeronautical research by being able to fly for long periods at transonic speeds; this freed up the X-1 to aim for fame and finally break the sound barrier, albeit in brief sprints.

Of the three D-558-I built, two are still in a state of conservation, they are Skystreak # 1 (BuNo.37970) at the National Naval Aviation Museum in Pensacola, Florida and Skystreak # 3 (BuNo.37972 ) at the Carolinas Aviation Museum in Charlotte, North Carolina.

Skystreak # 1 in its somewhat unorthodox display frame, mounted on a wall within the National Naval Aviation Museum in Pensacola, Florida. (image by Rob Bixby via Wikipedia)
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