Capts. Iven C. Kinchloe (left) and Mel Apt pose with the Bell X-2 rocket-powered aircraft. Captain Kinchloe climbed to 126,200 feet altitude in the X-2 Sept. 7, 1956. Captain Apt reached a speed of Mach 3.2 — three times the speed of sound — in the aircraft before it tumbled out of control and he was killed attempting to bail out on Sept. 27, 1956. (U.S. Air Force photo)