The North American X-15 was a hypersonic rocket-powered aircraft operated by the United States Air Force and the National Aeronautics and Space Administration (N.A.S.A.) as part of the X-plane series of experimental aircraft.
The X-15 set speed and altitude records in the 1960s, reaching the edge of outer space and returning with valuable data used later in aircraft and spacecraft design.
The X-15's official world record for the highest speed ever recorded by a manned, powered aircraft, set in October 1967 when William J. "Pete" Knight flew Mach 6.72 at 102,100 feet (31,120 m), a speed of 4,520 miles per hour (7,274 km/h), has remained unchallenged as of May 2017.
