The Bell X-2 was a swept-wing, rocket-powered research aircraft designed to fly three times faster than the speed of sound. It was flown to investigate the problems of aerodynamic heating, stability, and control effectiveness at high speeds and altitudes. On each mission, a Boeing B-50 bomber carried the X-2 to launch altitude and released it.

Two X-2 aircraft, serial numbers 46-674 and 46-675, were built. While Bell technicians fitted 674 with its Curtis-Wright XLR25-CW-1 rocket engine, the second X-2 began glide tests at Edwards AFB, California. Lt. Col Frank "Pete" Everest piloted 674 on its first unpowered flight on 5 August 1955. He also flew the aircraft on its first rocket-powered flight on 11 November 1955. Everest made the first supersonic X-2 flight in 674 on 25 April 1956, achieving a speed of Mach 1.4. In July he reached Mach 2.87, just short of the Mach 3 goal.

The other X-2 (675) was written off prior to making any powered flights. The first X-2 (46-674) made a total of 17 flights. On 7 September 1956, Capt. Iven Kincheloe attained an altitude of 126,200 feet in this aircraft. It was the first manned fight beyond 100,000 feet.

Initially an Air Force program, the X-2 was to be transferred to the civilian National Advisory Committee for Aeronautics (NACA) for scientific research. The Air Force delayed turning the aircraft over to NACA in the hope of attaining Mach 3 in the airplane. The service requested and received a two-month extension to qualify another Air Force test pilot, Capt. Milburn "Mel" Apt, in the X-2 and attempt to exceed Mach 3.