02/28/2008. Remarks by Jack McKillop: "This is second of three X-15-NAs, a rocket-powered research aircraft that were built for air-launched hypersonic research. The first aircraft made its first captive flight on March 10, 1959 beneath the wing of a Boeing NB-52B Stratofortress.
The first powered flight was made by this aircraft on September 17, 1959. During this flight, the pilot, Scott Crossfield, reached 1,564 mph (2,518 kmh) or Mach 2.11 and 52,341 ft (15,953 m). By June 1961, these aircraft had reached 4,093 mph (6,587 kmh) and climbed as high as 217,000 ft (66,142 m). The third aircraft built eventually reached an altitude of 314,750 ft (95,936 m).
This aircraft suffered extensive structural damage when it made an emergency landing in Nevada on September 9, 1962 and it was sent back to North American for repairs and modifications including lengthening the fuselage, reshaping the windshield, etc. When returned to service, it reached a speed of 4,520 mph (7,274 kmh) or Mach 6.7. This is the fastest a winged, piloted aircraft has ever flown.
Read also the History Brief .