Bell X - 2 The Bell X - 2 ( nicknamed " Starbuster " ) was a 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 U . S . Air Force and the National Advisory Committee for Aeronautics ( NACA ) 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 . Design and development . The Bell X - 2 was developed to provide a vehicle for researching flight characteristics in excess of the limits of the Bell X - 1 and D - 558 II , while investigating aerodynamic heating problems in what was then called the " thermal thicket " . The Bell X - 2 had a prolonged development period due to the advances needed in aerodynamic design , control systems , high - temperature resistant materials to be used , and other technologies that had to be developed . Not only did the X - 2 push the envelope of manned flight to speeds , altitudes and temperatures beyond any other aircraft at the time , it pioneered throttleable rocket motors in U . S . aircraft ( previously demonstrated on the Me 163B during World War II ) and digital flight simulation . The XLR25 rocket engine , built by Curtiss - Wright , was based on the smoothly variable - thrust JATO engine built by Robert Goddard in 1942 for the Navy . 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 , K - Monel , and powered by a liquid propellant ( alcohol and oxygen ) two - chamber XLR25 2 , 500 to 15 , 000 lbf ( 11 to 67 kN ) sea level thrust , continuously throttleable rocket engine , the swept - wing Bell X - 2 was designed to probe the supersonic region . Operational history . 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 . 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 the same problem of " inertia coupling " which 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 , was able to recover . Apt attempted to recover from a spin , but could not , and 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 emerge so that he could use his personal parachute . 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 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 of the most advanced of all the experimental rocket aircraft , the North American X - 15 . Flight test program . Two aircraft completed a total of 20 flights ( 27 June 1952 - 27 September 1956 ) .