Providing adequate stability and control for aircraft flying at high supersonic speeds was only one of the major difficulties facing flight researchers as they approached Mach 3. For, at speeds in that region, they knew they would also begin to encounter a "thermal barrier" severe heating effects caused by aerodynamic friction. Constructed of stainless steel and a copper-nickel alloy, and powered by a two-chamber XLR25 15,000-pound thrust throttleable rocket engine, the sweptwing Bell X-2 was designed to probe this region and to be the first aircraft to take man well above the measurable atmosphere to the very edge of space. Following 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 June 27, 1952. This aircraft was subsequently lost in an explosion during a captive flight in 1953. Lt. Col. Frank K. "Pete" Everest completed the first powered flight in the second airplane on November 18, 1955 and, by the time of his ninth and final flight in late July the following year, he had established a new speed record of Mach 2.87 (1,900 mph). The X-2 was living up to its promise, but not without difficulties. At high speeds, Everest reported that its flight controls were only marginally effective. Moreover, simulation and wind tunnel studies, combined with data from his flights, suggested that the airplane would encounter very severe stability problems as it approached Mach 3.
A pair of young test pilots, Captains Iven C. Kincheloe and Milburn G. "Mel" Apt, were assigned the job of further expanding the envelope and, on September 7, 1956, Kincheloe became the first pilot ever to climb above 100,000 feet as he flew the X-2 to a peak altitude of 126,200 feet. Just 20 days later, on the morning of September 27, Mel 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. Flying an extraordinarily precise profile, he became the first man to exceed Mach 3 that day, as he accelerated to a speed of Mach 3.2 (2,094 mph) at 65,500 feet. The flight had been flawless to this point but, for some reason, shortly after attaining top speed, Apt attempted a banking turn while the airplane was still well above Mach 3 (lagging instrumentation may have indicated that he was flying at a slower speed than he was 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 the same problem of "inertia coupling" which had overtaken Chuck Yeager in the X-1A nearly three years before. Unlike Yeager, however, Apt was unable to recover and both he and the aircraft were lost. While the X-2 had delivered valuable research data on high-speed aerodynamic heat build-up and extreme high-altitude flight conditions, this tragic event terminated the program before the National Advisory Committee for Aeronautics could commence detailed flight research with the airplane, and the search for answers to many of the riddles of high-Mach flight had to be postponed until the arrival, three years later, of the most ambitious of all the rocket planes, the North American X-15.
Flight Test Program: two aircraft completed a total of 20 flights - 7 glide and 13 powered (6/27/52- 9/27/56).
Airframe: Length 37 feet 10 inches; Wingspan 32 feet 3 inches; Gross weight 24,910 lbs; Empty weight 12,375 lbs.
Powerplant: Curtiss-Wright XLR25 rocket engine providing a max. of 15,000 lbs of static thrust.
Max. Speed Mach 3.196 (2,094 mph). Max. Altitude 126,200 feet.