English: The X-15 flight crew, left to right:

Air Force Captain — Joseph "Joe" Henry Engle,
Air Force Major — Robert Aitken "Bob" Rushworth,
NASA pilot — John Barron "Jack" McKay,
Air Force Major — William John "Pete" Knight,
NASA pilot — Milton "Milt" Orville Thompson,
NASA pilot — William Harvey "Bill" Dana.

First flown in 1959 from the NASA High Speed Flight Station (later renamed the Dryden Flight Research Center), the rocket-powered X-15 was developed to provide data on aerodynamics, structures, flight controls and the physiological aspects of high speed, high altitude flight. Three were built by North American Aviation for NASA and the U.S. Air Force.

They made a total of 199 flights during a highly successful research program lasting almost ten years. The X-15's main rocket engine provided thrust for the first 80 to 120 seconds of a 10 to 11 minute flight; the aircraft then glided to a 200 mph landing. The X-15 reached altitudes of 354,200 feet (67.08 miles) and a speed of 4,520 mph (Mach 6.7).