The X-15 rocket research airplane was built by the Los Angeles (Calif.) Division of North American Aviation for the U.S. Air Force, the U.S. Navy, and the National Aeronautics and Space Administration. The airplane was designed to conduct research experiments during actual flight conditions beyond the Earth's atmosphere and to obtain knowledge of aerodynamic heating, re-entry conditions, acceleration and deceleration forces, and reactions of man to weightlessness.
It exceeded its design specifications of 4,000 miles per hour and altitudes up to 50 miles.
On Aug. 22, 1963, NASA pilot Joseph Walker piloted the craft to a record altitude of 354,200 feet, slightly over 67 miles.
On June 27, 1962, Walker attained a record speed of 4,104 miles per hour with a Mach number of 6.00, at 123,700 feet. On Dec. 5, 1963, Maj. Robert A. Rushworth attained a higher Mach number -- 6.06 -- but at the slower speed of 4,018 mph and an altitude of 101,800 feet.
A new version, known as the X-15A-2, designed for flight at eight times faster than sound, at an altitude of 100,000 feet and creating potential temperatures of over 2400 degrees Fahrenheit, was turned over to the U.S. Air Force by the Los Angeles plant in February 1964.
Design changes for the X-15A-2 included two external jettisonable fuel tanks, longer main gear, lengthened and lowered nose gear, fuselage extended 29 inches, improved windshield design, ablative material on the outer skin, a removable right-hand wingtip to accept test materials, removable lower vertical fin to permit installation of ramjet engines, and accommodations for photographic experiments.
Air Force Capt. William "Pete" Knight took the X-15A-2 to the fastest speed recorded during the program, Mach 6.7, during an Oct. 3, 1967 flight.
||June 8, 1959
||13 feet 8 inches
||Thiokol 57,000-pound thrust liquid propellant rocket engine
||Sweptback 25 degrees; area: 200 square feet
||13,000 pounds empty; 15 tons loaded with fuel
||Steel skids, nose wheel
||Inconel X nickel alloy