The X-1A, B, and D were essentially identical rocketplanes intended to reach speeds above Mach 2. The X-1A and X-1D were destroyed in in-flight explosions; the X-1B survived, training future moon lander Neil Armstrong on its last flights in 1958.
Bell flight 1. Glide flight for familiarization. Nose landing gear broken on landing. Following repairs, plane turned over to the Air Force.
AF flight 1. Launch aborted, but X-1D suffered low-order explosion during pressurization for fuel jettison. Plane jettisoned from B-50. X-1D exploded on impact with desert. Everest managed to get into B-50 bomb bay before drop.