Capt Milburn G. 'Mel' Apt 1924-1956.

Mel Apt was a US test pilot. He was killed in the destruction of the Bell X-2 during a test flight.
After having been launched from a B-50 Bomber over the Mojave Desert in California, Capt. Milburn G. Apt (USAF), flying an X-2 rocket-powered plane on its 13th powered flight, set a record speed of 3,377 km/h, or Mach 3.196 at 19,977 m (65,541 ft). Subsequent loss of control from inertia coupling led to the breakup of the aircraft and the death of the pilot.

The X-2, initially an Air Force program, was scheduled to be transferred to the civilian National Advisory Committee for Aeronautics (NACA) for scientific research. The Air Force delayed turning the aircraft over to the 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. Miburn "Mel" Apt, in the X-2 and attempt to exceed Mach 3.
After several ground briefings in the simulator, Apt (with no previous rocket plane experience) made his flight on 27 September 1956. Apt raced away from the B-50 under full power, quickly outdistancing the F-100 chase planes. At high altitude, he nosed over, accelerating rapidly. The X-2 reached Mach 3.2 (2,094 mph) at 65,000 feet. Apt became the first man to fly more than three times the speed of sound.
Still above Mach 3, he began an abrupt turn back to Edwards. This maneuver proved fatal as the X-2 began a series of diverging rolls and tumbled out of control. Apt tried to regain control of the aircraft. Unable to do so, Apt separated the escape capsule. Too late, he attempted to bail out and was killed when the capsule impacted on the Edwards bombing range. The rest of the X-2 crashed five miles away