The twin-turbojet X-3, the only one built, was designed to test features of an aircraft suitable for sustained flights at supersonic speeds and high altitudes. A secondary mission was to investigate the use of new materials such as titanium and to explore new construction techniques. The X-3 made its first test flight at Edwards Air Force Base, Calif., on Oct. 20, 1952, and flew supersonically in June 1953. Unlike the X-1, X-2 and X-15, which were released in mid-air from a "mother plane," the X-3 operated in a more conventional manner by taking off from the ground. Engine development difficulties forced the use of lower powered engines than originally planned, prohibiting the X-3 program from achieving its design potential; however, data gained from the X-3 program was of great benefit in the development of the F-104, X-15, SR-71 and other high performance aircraft. The X-3 was transferred to the National Museum of the United States Air Force in 1956. SPECIFICATIONS: Span: 22 ft. 8 in. Length: 66 ft. 10 in. Height: 12 ft. 6 in. Weight: 22,400 lbs. maximum Armament: None Engines: Two Westinghouse J-34s of 3,370 lbs. thrust each (4,900 lbs. thrust with afterburner) PERFORMANCE: Maximum speed: Designed for Mach 2 Cruising speed: Not applicable Range: Not applicable Service ceiling: 38,000 ft.