First B-52 captive flight of X-43A/Pegasus stack

This 59 second video shows the first flight of the B-52 with the Hyper-X / X-43A attached. There is no release of the Hyper-X

With a contract awarded to MicroCraft, Inc., Tullahoma, Tennessee, in March of 1997, NASA embarked on a significant new project to demonstrate the use of supersonic combustion ramjet (scramjet) technologies at hypersonic speeds on sub-scale vehicles now known as X-43As. Three of these vehicles are being fabricated at MicroCraft. The Hyper-X Program seeks to demonstrate airframe-integrated, air-breathing engine technologies that promise to increase aircraft speeds and payload capacities for reusable space launchers.

Scramjets employ ramjet engines in which the internal airflow remains supersonic. Ramjets operate by combustion of fuel in a stream of air compressed by the forward speed of the vehicle, unlike a normal jet engine in which compressor blades perform that function. Normal ramjets operate with subsonic internal airflow and combustion; they operate from a speed of about Mach 2 to Mach 5. With supersonic combustion, scramjets can operate at speeds faster than the Mach 6.7 speed achieved by the rocket-powered X-15. Scramjets can potentially carry more payload than rockets because they are air-breathing and do not have to carry their own supply of oxygen.

This joint program among Langley Research Center, Hampton Virginia, Dryden Flight Research Center, Edwards, California, and industry seeks to fulfill a key NASA goal of providing next-generation design tools and experimental aircraft to increase design confidence and cut the design cycle time for aircraft. Langley has been leading the effort to develop the new technology. Dryden has been responsible for the flight research effort as well as managing the fabrication of the X-43A vehicles and expendable booster rockets that will carry them to speeds of Mach 7 (two flights) and Mach 10 (one flight). The program has also assembled an industrial team providing some of the flight components.

These components include the venerable Dryden B-52, which will carry a modified Pegasus¨ (a registered trademark of Orbital Sciences Corporation of Dulles, Virginia) launch vehicle to which the X-43A will be attached. The flights will carry the vehicles over the Sea Test Range off the coast of southern California, where the B-52 will drop the launch vehicle at altitudes ranging between 18,000 and 39,000 feet. The X-43A will be boosted to the respective Mach 7 and Mach 10 speeds, whereupon it will separate from the launch vehicle and demonstrate the scramjet technology.

The objectives of the unpiloted flights include: the first-ever free-flight demonstration of an airframe-integrated scramjet; the verification of wind-tunnel tests, computational predictions, and analyses of the technology; and ultimately, the scaling of the design concepts to future operational air-breathing hypersonic cruise and space-access vehicles. This effort is challenging because of the limitations on testing in ground facilities and the inherent uncertainties associated with computational methods. Full-scale testing requires flight research.

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