Computer animation of the Hyper-X aircraft, the first jet aircraft designed to fly at more than 5 times the speed of sound, (Mach 5), before launch. The 4 meter-long Hyper-X is carried below the wing of a B-52 aircraft on the tip of a Pegasus booster rocket. The rocket carries the Hyper-X to an altitude of about 30,000 meters. The aircraft and rocket then separate, and the unpiloted Hyper-X burns hydrogen fuel to fly at hypersonic speeds of up to Mach 10. The Hyper-X uses oxygen from the atmosphere for combustion, rather than having its own supply like a rocket. This increases its payload and range. Live testing began in 2001; today the project remains in limbo.