However the program was delayed for three years after the first launch failed due to miscalculation of maximum aerodynamic loads during acceleration to scramjet ignition speed.
The X-43A fuselage formed a critical elements of the engine, with the forebody acting as the intake for the airflow and the aft section serving as the nozzle. The Hyper-X program was a joint NASA Dryden/NASA Langley conducted under NASA's Aeronautics and Space Transportation Technology Enterprise. NASA Langley had overall management of the Hyper-X program and led the technology development effort. Dryden's primary responsibility was to fly three unpiloted X-43A research vehicles to help prove both the engine technologies, the hypersonic design tools and the hypersonic test facilities developed at Langley.
The first flight mission profile was for NASA Dryden's NB-52 aircraft to climb to 7600 m and release the modified Pegasus launch vehicle. For each flight the booster accelerated the X-43A research vehicle to the test conditions (Mach 7 or 10) at approximately 30 km altitude, where it separated from the booster and then fly under its own power and preprogrammed control. Flights of the X-43A originated from the Dryden/Edwards Air Force Base area, and the missions occurred within the Western Sea Range off the coast of California.
The B-52 Dryden used to carry the X-43A and launch vehicle to test altitude was the oldest B-52 on flying status. The aircraft, on loan from the U.S. Air Force, had been used on some of the most important projects in aerospace history. It was one of two B-52s used to air launch the three X-15 hypersonic aircraft for research flights. It also was used to drop test the various wingless lifting bodies, which contributed to the development of the Space Shuttle. In addition, the B-52 was part of the original flight tests of the Pegasus booster. .
On Aug. 11, 1998, the first piece of hardware was delivered to NASA - a scramjet engine used for a series of ground tests in NASA Langley's 2.4-m-high Temperature Tunnel. This engine could later be used for flight if necessary.
Orbital Sciences Corp., Dulles, Va., designed and built three Pegasus-derivative launch vehicles for the series of X-43A vehicles, a process supervised by Dryden. A successful critical design review for the launch vehicle was held at Orbital's Chandler, Ariz., facility in December 1997.
NASA selected MicroCraft Inc., Tullahoma, Tenn., in March 1997 to fabricate the unpiloted research aircraft for the flight research missions, two flights at Mach 7 and one at Mach 10 beginning in 2000. Micro-Craft was aided by Boeing, which was responsible for designing the research vehicle, developing flight control laws and providing the thermal protection system; GASL Inc., which built the scramjet engines and their fuel systems and providing instrumentation for the vehicles; and Accurate Automation, Chatanooga, Tenn.
Hyper-X Vehicle Specifications
Hyper-X Launch Vehicle
X-43A Research Vehicle
Gross mass: 1,000 kg (2,200 lb).
Height: 3.66 m (12.00 ft).