The North American X-15 was a hypersonic rocket-powered aircraft that the United States Air Force and NASA used for a series of experimental aircraft. North American was an aeronautical company that build the amazing aircraft, and in the 1960s, the X-15 set speed and altitude records.
The maximum speed of the aircraft was 4,520 mph, with a range of 280 mi and rate of climb of 60,000 ft/min. In the 60s, the X-15 traveled to the edge of outer space, helping NASA and the Air Force collect invaluable data.
During the X-15 program, several pilots tested the aircraft and pushed it to the limits. The last flight took off in 1970. In 2005, all of the pilots that meet the 50 mile altitude were awarded NASA astronaut wings. Only one pilot failed to meet the criteria.
William J. “Pete” Knight pushed the aircraft to the fastest limits, achieving speed of 4,250 mph and 4,519 mph (just one mph short of the maximum speed limit). Joseph A. Walker, on the other hand, took the plane to the highest altitude, reaching 65.8 mi and 67.0 mi.