Stock Photo - After receiving a full_scale ablative coating to protect the craft from the high temperatures associated with supersonic flight, the X_15A_2 rocket_powered research aircraft was then covered with a white sealant coat. This ablative coating and sealant would help the 2 aircraft reach the record speed of 4,520 mph Mach 6.7.The basic X_15 was a rocket_powered aircraft 50 ft long with a wingspan of 22 ft. However, the X_15A_2 had been elongated to 52 ft 5 in. Like the other two X_15s, it was a missile_shaped vehicle with an unusual wedge_shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage. The X_15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR_99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was capable of developing 57,000 lb of thrust. North American Aviation built three X_15 aircraft for the program.The X_15 research aircraft was developed to provide in_flight information and data on aerodynamics, structures, flight controls, and the physiological aspects of high_speed, high_altitude flight. A follow_on program used 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 used conventional aerodynamic controls such as rudders on the vertical stabilizers to control yaw and movable horizontal stabilizers to control pitch when moving in synchronization or roll when moved differentially. For flight in the thin air outside of the appreciable Earth´s atmosphere, the X_15 used a reaction control system. Hydrogen peroxide thrust rockets located on the nose of the aircraft provided pitch and yaw control. Those on the wings provided roll control.Because of the large fuel consumption, the X_15 was air launched from a B_52 aircraft at 45,000 ft and a speed of about 500 mph. Depending on the mission, the rocket engine provided thrust for the first 80 to 120 sec of flight. The remainder of the normal 10 to 11 min. flight was powerless and ended with a 200_mph glide landing.Generally, one of two types of X_15 flight profiles was used, a high_altitude flight plan that called for the pilot to maintain a steep rate of climb, or a speed profile that called for the pilot to push over and maintain a level altitude. The X_15 was flown over a period of nearly 10 years __ June 1959 to Oct. 1968 __ and set the world´s unofficial speed and altitude records of 4,520 mph Mach 6.7 and 354,200 ft in a program to investigate all aspects of piloted hypersonic flight. Information gained from the highly successful X_15 program contributed to the development of the Mercury, Gemini, and Apollo piloted spaceflight programs, and also the Space Shuttle program.The X_15s made a total of 199 flights, and were manufactured by North American Aviation. X_15_1, serial number 56_6670, is now located at the National Air and Space Museum, Washington DC.North American X_15A_2, serial number 56_6671, is at the United States Air Force Museum, Wright_Patterson AFB, Ohio. X_15_3, serial number 56_6672, crahed on 15 November 1967, resulting in the death of Maj. Michael J. Adams.