Stock Photo - One of three X_15 rocket_powered research aircraft being carried aloft under the wing of its B_52 mothership. The X_15 was air launched from the B_52 so the rocket plane would have enough fuel to reach its high speed and altitude test points. For flight in the dense air of the usable atmosphere, the X_15 used conventional aerodynamic controls. 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. The X_15s made a total of 199 flights over a period of nearly 10 years and set world´s unofficial speed and altitude records of 4,520 miles per hour Mach 6.7 and 354,200 feet. Information gained from the highly successful X_15 program contributed to the development of the Mercury, Gemini, and Apollo manned spaceflight programs and also the Space Shuttle program.