Bell's Supersonic X-2 To Probe Heat Barrier -- Lt. Col Frank K. Everest, top test pilot, who has been selected to fly the aircraft, with the Bell X-2. This Picture of the Bell X-2 is an American Rocket Powered research aircraft with swept-back wings. it is partly constructed of stainless steel to resist the tremendous heat due to air friction at extreme speeds. The X-1, an earlier model with straight wings, became the world's first supersonic aircraft in 1947, when Major Charles Yeager flew it faster than the speed of sound. August 12, 1955.