X-43B aircraft. Computer artwork of NASA's X-43B or Hypersonic Experimental Vehicle (Hyper-X) in flight. The Hyper-X programme was started in 1996 to test the scramjet-powered jet engine and to design a plane that could be used at hypersonic speeds. The scramjet engines, unlike rockets that must carry both oxygen and fuel, use oxygen from the air scooped up as the aircraft flies at over 5 times the speed of sound (Mach 5). The X-43A craft broke up on its test flight in 2001, which has now been attributed to modelling inaccuracies during the design stage. The X-43B is a much larger plane than the X-43A and if constructed is to be used as a reusable launch vehicle for spacecraft.