X-51 Waverider

The X-51 Waverider is an unmanned scramjet demonstration aircraft designed to meet the requirements of the US Air Force as part of the WaveRider programme.   The lifting body design provides the vehicle with a substantial amount of lift for flights without being dependent on the wings and the Waverider takes advantage of compression lift produced by the body own shock waves.

The X-51 is principally used to demonstrate the speeds and various aspects of hypersonic flight and is being developed to operate at speeds of more than Mach 7 at an altitude of 50,000ft.
During flight demonstrations, the X-51 is carried by a B-52 to an altitude of about 50,000 feet (9.5 mi) and then released where a solid rocket booster accelerates the X-51 to approximately Mach 4.5 (3,000 mph). The booster is then dropped and the X-51 scramjet accelerates it to a top flight speed near Mach 6 (4,000 mph).

The X-51 program was a cooperative effort by the United States Air Force, DARPA and NASA.