EDWARDS AIR FORCE BASE, Calif -- The first captive-carry flight NASA’s X-43A hypersonic research vehicle took place aboard a B-52 over the Pacific Test Range. The vehicle was mated to a Pegasus booster rocket and carried on the B-52’s wing pylon. The X‑43A was powered by a scramjet, a supersonic combustion ramjet integrated with its lower fuselage and designed for speeds up to Mach 10. This was the first hypersonic (Mach 5+) research program since the X-15.
The NASA X-43 was an experimental unmanned hypersonic aircraft with multiple planned scale variations meant to test various aspects of hypersonic flight. It was part of the X-plane series and specifically of NASA's Hyper-X program. It set several airspeed records for jet aircraft. The X-43 is the fastest aircraft on record at approximately Mach 9.6. A winged booster rocket with the X-43 placed on top, called a "stack", was drop launched from a Boeing B-52 Stratofortress. After the booster rocket (a modified first stage of the Pegasus rocket) brought the stack to the target speed and altitude, it was discarded, and the X-43 flew free using its own engine, a scramjet. The first plane in the series, the X-43A, was a single-use vehicle, of which three were built. The first X-43A was destroyed after malfunctioning in flight in 2001. Each of the other two flew successfully in 2004, setting speed records, with the scramjets operating for approximately 10 seconds followed by 10-minute glides and intentional crashes into the ocean. Plans for more planes in the X-43 series have been suspended or cancelled, (and replaced by the USAF managed X-51 program).
The X-43 was a part of NASA's Hyper-X program, involving the American space agency and contractors such as Boeing, Micro Craft Inc, Orbital Sciences Corporation and General Applied Science Laboratory (GASL). Micro Craft Inc. built the X-43A and GASL built its engine. One of the primary goals of NASA's Aeronautics Enterprise was the development and demonstration of technologies for air-breathing hypersonic flight. Following the cancellation of the National Aerospace Plane (NASP) program in November 1994, the United States lacked a cohesive hypersonic technology development program. As one of the "better, faster, cheaper" programs developed by NASA in the late 1990s, Hyper-X used National Aerospace Plane technology, which moved it quickly toward the demonstration of hypersonic air breathing propulsion. The Hyper-X Phase I was a NASA Aeronautics and Space Technology Enterprise program conducted jointly by the Langley Research Center, Hampton, Virginia, and the Dryden Flight Research Center, Edwards, California. Langley was the lead center and responsible for hypersonic technology development. Dryden was responsible for flight research. Phase I was a seven-year, approximately $230 million, program to flight-validate scramjet propulsion, hypersonic aerodynamics and design methods. Subsequent phases were not continued, as the X-43 series of aircraft was replaced in 2006 by the X-51.