Douglas D-558-2 Skyrocket
     On November 20, 1953, the Douglas D-558-2 Skyrocket became the first aircraft to fly faster than Mach 2, twice the speed of sound. Piloted by A. Scott Crossfield, it was air-launched from a U.S. Navy Boeing P2B-1S (B-29) the swept-wing, rocket-powered D-558-2 reached Mach 2.005 in a shallow dive at 18,898 meters (62,000 feet).   This swept wing research plane attained Mach 2.005 (1,291 mph) while in a shallow dive at an altitude of 62,000 feet. Seconds afterward, the plane’s XLR-8 rocket engine exhausted its fuel supply and shut down. Crossfield glided earthward to a smooth dead-stick landing on Muroc Dry Lake, at Edwards Air Force Base, California.
      D-558-2 #2 was just one of six different D558 research airplanes ordered by the U.S. Navy from the Douglas Aircraft Company for obtaining aerodynamic information at transonic and supersonic speeds. The Navy issued a letter of intent to Douglas on June 22, 1945, for construction of six Model D-558 aircraft, having straight, thin wing and tail surfaces, and turbojet propulsion.
      The D-558-1 and D-558-2 greatly differed from one another in detail design and there was little commonality between them. Both took off from the ground. Because of its engine type and airframe design, the D-558-1 was limited to approximately Mach 1, the speed of sound. The more powerful D558-2, using its 6,000-pound-thrust rocket engine fueled with liquid oxygen and diluted ethyl alcohol, could easily exceed Mach 1. The safety hazards of operating a heavily loaded rocket-propelled airplane from the ground later caused Douglas to modify the D-558-2 #2 and #3 for air launching from the bomb bay of a converted Boeing P2B-1S (Navy B-29) Superfortress. At the same time, Douglas modified the D-558-2 #2 to all-rocket propulsion, utilizing the space formerly taken up by its turbojet engine for additional rocket fuel. Thus modified, the D-558-2 #2 was capable of reaching Mach 2, which it did while being flown in a special high-speed flight research program by the National Advisory Committee for Aeronautics (NACA).
     The D-558-1 and D-558-2 were of mixed aluminum and magnesium construction. Both types featured jettisonable nose sections to serve as emergency escape capsules. and both were designed to carry heavy instrumentation payloads for flight research purposes. The first two D-558-1 Skystreaks were bright glossy red overall, but the D-558-1 #3 and later D-558-2 Skyrockets were glossy white, which proved more desirable for optical tracking purposes. The historic Douglas D558-2 #2, NACA 144, the first Mach 2 airplane, is in the collection of the National Air and Space Museum.
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