The US Air Force X-15 is the worlds fastest aircraft in History. 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 as part of the X-plane series of experimental aircraft.
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The X-15 set speed and altitude records in the 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design. As of September 2015, the X-15 holds the official world record for the highest speed ever reached by a manned, powered aircraft. Its maximum speed was 4,520 miles per hour , or Mach 6.72.
During the X-15 program, 13 flights by eight pilots met the Air Force spaceflight criterion by exceeding the altitude of 50 miles (80 km), thus qualifying the pilots for astronaut status.
The Air Force pilots qualified for astronaut wings immediately, while the civilian pilots were awarded NASA astronaut wings in 2005, 35 years after the last X-15 flight. The sole Navy pilot in the X-15 program never took the aircraft above the requisite 50 mile altitude.
Of the 199 X-15 missions, two flights (by the same pilot) qualified as space flights per the international definition of a spaceflight by exceeding 100 kilometers (62.1 mi) in altitude.