X-15

North American X-15

Mission Profile

The North American X-15 was a rocket-powered experimental hypersonic aircraft jointly operated by NASA and the U.S. Air Force, designed to investigate aerodynamics, propulsion, structures, and human factors at speeds exceeding Mach 6 and altitudes above 100 km. Standing 15.5 m long with a 1.2 m wingspan and powered by a single XLR-99 engine generating 254 kN of thrust, it was air-launched from a B-52 carrier aircraft. Completing 199 flights from 1959 to 1968, the X-15 reached a maximum speed of Mach 6.7 and a peak altitude of 107.96 km, with eight flights crossing the Kármán line — earning those pilots U.S. Air Force astronaut wings and making the X-15 the first crewed reusable spacecraft.