Fastest rocket plane

What to remember

Mach 6.7: that was the pace reached by William “Pete” Knight on 3 October 1967, on X-15 Flight 188, the fastest of the program. The rocket plane reached 7,274 km/h, or 4,519 mph.

The North American X-15 was an experimental spaceplane jointly operated by the U.S. Air Force and NASA. Knight was one of twelve pilots who flew it, and he had also been selected for the X-20 Dyna-Soar program. The record flight was made in the X-15A-2, the second of three planes in the fleet, and set the speed record for flight in a winged, powered aircraft.

Two weeks later, on October 17, Knight flew X-15 Flight 190 and climbed above 50 miles. That flight qualified him as an astronaut under the US definition.