page_title: Bell X-2
section_title: Operational history
hierarchical_section_title: Bell X-2 / Operational history
caption_attribution_description: This inflight photograph of the X-2 (46-674) shows the twin set of shock-diamonds, characteristic of supersonic conditions in the exhaust plume from the two-chamber rocket engine.
context_page_description: The Bell X-2 was an X-plane research aircraft built to investigate flight characteristics in the Mach 2–3 range. The X-2 was a rocket-powered, swept-wing research aircraft developed jointly in 1945 by Bell Aircraft Corporation, the United States Air Force and the National Advisory Committee for Aeronautics to explore aerodynamic problems of supersonic flight and to expand the speed and altitude regimes obtained with the earlier X-1 series of research aircraft.
context_section_description: Following a drop launch from a modified B-50 bomber, Bell test pilot Jean "Skip" Ziegler completed the first unpowered glide flight of an X-2 at Edwards Air Force Base on 27 June 1952. Ziegler and aircraft #2 (46-675) were subsequently lost on 12 May 1953, in an inflight explosion during a captive flight intended to check the aircraft's liquid oxygen system. A B-50 crew member, Frank Wolko, was also killed during the incident. The wreckage of the aircraft fell into Lake Ontario and was not recovered.
  Lt. Col. Frank K. "Pete" Everest completed the first powered flight in the #1 airplane (46-674) on 18 November 1955. By the time of his ninth and final flight in late July 1956 the project was years behind schedule, but  he had established a new speed record of Mach 2.87 (1,900 mph, 3050 km/h). About this time, the YF-104A was demonstrating speeds of M = 2.2 or 2.3 in a fighter configuration. The X-2 was living up to its promise, but not without difficulties. At high speeds, Everest reported its flight controls were only marginally effective. High speed center of pressure shifts along with fin aeroelasticity were major factors. Moreover, simulation and wind tunnel studies, combined with data from his flights, suggested the airplane would encounter very severe stability problems as it approached Mach 3.
  A pair of less experienced but excellent pilots, Captains Iven C. Kincheloe and Milburn G. "Mel" Apt, were assigned the job of further expanding the envelope and, on 7 September 1956, Kincheloe became the first pilot ever to climb above 100,000 ft (30,500 m) as he flew the X-2 to a peak altitude of 126,200 ft (38,466 m). Just 20 days later, on the morning of 27 September, Apt was launched from the B-50 for his first flight in a rocket airplane. He had been instructed to follow the "optimum maximum energy flight path" and to avoid any rapid control movements beyond Mach 2.7. With nozzle extenders and a longer than normal motor run, Apt flew an extraordinarily precise profile; he became the first man to exceed Mach 3, reaching Mach 3.2 (2,094 mph, 3,370 km/h) at 65,500 ft (19,960 m).
  The flight had been flawless to this point, but, for some reason, shortly after attaining top speed, Apt attempted a banking turn while the aircraft was still above Mach 3 (lagging instrumentation may have indicated he was flying at a slower speed or perhaps he feared he was straying too far from the safety of his landing site on Rogers Dry Lake). The X-2 tumbled violently out of control and he found himself struggling with three sequential coupling modes, control coupling, inertial roll coupling and supersonic spinning. "Inertia coupling" and a subsonic inverted spin had overtaken Chuck Yeager in the X-1A nearly three years before. Yeager, although exposed to much higher vehicle inertial forces, as a result of extensive experience flying the X-1 was very familiar with its character, and was able to recover. Apt attempted to recover from a spin, but could not. He fired the ejection capsule, which was itself only equipped with a relatively small drogue parachute.  Apt was probably disabled by the severe release forces. As the capsule fell for several minutes to the desert floor, he did not exit so that he could use his personal parachute before ground impact, and was killed. The aircraft continued to fly in a series of glides and stalls before landing with minimal damage. A proposal to salvage the aircraft and modify it for a hypersonic test program was not approved. The aircraft was scrapped.
  While the X-2 had delivered valuable research data on high-speed aerodynamic heat build-up and extreme high-altitude flight conditions (although it is unclear how much, as the Lockheed X-7 and IM-99 were among the winged vehicles operating at comparable or higher velocities in this era), this tragic event terminated the program before the National Advisory Committee for Aeronautics could commence detailed flight research with the aircraft. The search for answers to many of the riddles of high-Mach flight had to be postponed until the arrival three years later o
caption: This shows the twin set of shock diamonds, characteristic of supersonic conditions in the exhaust plume from the two-chamber rocket engine
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