William J. Knight took the X-15A-2 hypersonic rocket-powered aircraft to 102,100 feet (31,100 meters) over Mud Lake, Nevada when Flight 188 reached a record-setting top speed of 4,520 mph (7,270 km/h), Mach 6.70.

The X-15 number 2 on, flight 74, was damaged during landing on November 9, 1962, and was repaired and updated to become the X-15A-2.

William J. Knight was a test pilot for the United States Air Force and NASA.

The scramjet was found on Edwards Air Force Base's bombing range.

At Edwards Air Force Base two radio relay stations and six emergency landing strips were built on the dry lake beds.

Touchdown was at 14:40:07 local time at Edwards Air Force Base after 342.79 (213 miles) of flight.

North American F-100 Super Sabre, Lockheed F-104 Starfighter and Douglas F5D Skylancer jets were used as chase planes, that tailed the X-15A-2 as long as it could at launch and also as the X-15A-2 landed.

The external tanks were jettisoned 67.4 seconds after launch at a speed of Mach 2.0 and 70,000 feet.

Flight 188 held the crewed winged spaceplane speed record till it was passed by STS-1 of the Space Shuttle Columbia on April 14, 1981.

Knight was awarded the Harmon International Aviation Trophy in 1969 for his record setting flight by President Lyndon Johnson.

[4] X-15A-2 Number 2 aircraft was taken to the National Museum of the United States Air Force in Dayton, Ohio[2] and repainted for permanent display.