X-15, WORLD'S FIRST HYPERSONIC RESEARCH AIRCRAFT The X-15 was a small rocket-powered aircraft, 50 feet long with a wingspan of 22 feet. It had a conventional fuselage, but an unusual wedge-shaped vertical tail, thin stubby wings and unique side fairings that extended along the fuselage. The X-15 weighed about 14,000 pounds empty and approximately 34,000 pounds at launch. The rocket engine, which was controlled by the pilot, was capable of developing 60,000 pounds of thrust. The X-15 research aircraft was developed to provide inflight information and data on aero-thermodynamics, aerodynamics, structures, flight controls and the physiological aspects of high-speed, high-altitude flight. A follow-on program utilized the aircraft as a testbed to carry various scientific experiments beyond the Earth's atmosphere on a repeated basis. For flight in the dense air of the usable atmosphere, the X-15 utilized conventional aerodynamic controls. For flight outside of the appreciable Earth's atmosphere, the X-15 used a ballistic control system. Eight hydrogen peroxide thrust rockets, located on the nose of the aircraft controlled pitch and yaw. Four other rockets were located on the wings for roll control. Because of the rapid fuel consumption, the X-15 was air-launched from under the wing of a B-52 aircraft at 45,000 feet at a speed of about 500 miles per hour. Depending on the mission and engine throttle setting, the rocket engine provided thrust for the first 80 to 120 seconds of flight. The remainder of the normal 10-11 minute flight was powerless and ended with a 200 mile-per-hour glide landing. Usually, one of two types of X-15 flight profiles were flown: a high-altitude flight plan that called for the pilot to climb steeply after launch or a speed profile that called for the pilot to push over and maintain a level altitude. First flown June 8, 1959, the three X-15 aircraft made 199 powered flights, concluding with the last flight on Oct. 24, 1968. Flight maximums of 354,200 feet in altitude and a speed of 4,520 miles per hour were obtained. The airframe manufacturer was North American Rockwell, Inc. Thiokol Chemical Corp. manufactured the power plant. The program was a joint NASA-USAF-USN effort. Three X-15 aircraft were built. The number 1 aircraft now is displayed in the Smithsonian's National Air and Space Museum, Washington, D.C. Aircraft number 2 is on display at the Air Force Museum at Wright-Patterson Air Force Base, Ohio. The third aircraft was destroyed in a fatal accident in November 1967. Total cost of the X-15 program, including development of the three aircraft, was about $300 million.