The Zero-length Launch, or ZEL, program was developed to launch jet fighter/bombers without a runway, using rocket boosters to get the plane from zero to flying speed. Once in flight, the rocket was dropped from the plane, which continued on its mission under jet power. On the second manned test of the system, the plane was launched from a mobile trailer platform at Edwards without a problem, but the spent rocket motor refused to detach from the plane. Since he could not land safely with the motor hanging below the wheels of the plane, test pilot Al Blackburn attempted to shake it loose for nearly an hour, circling over Harper Dry Lake. Flight test controllers eventually gave up and told him via radio to eject, and to let the plane crash. The F-100 went down on the north end of Harper Lake, and exploded on impact. Blackburn touched down safely with a parachute.
The ZEL program used modified North American Aviation F-100 fighter/bombers and Rocketdyne solid-fuel boosters. This project proved the feasibility of launching nuclear-armed bombers that had been dispersed to remote locations lacking runways, such as from mobile trailers, hardened shelters, or mountain caves. The test program moved from Edwards to Holloman Air Force Base in New Mexico, to test launching from inside small hangars. Though successful, the program was cancelled with the emergence of intercontinental nuclear missiles.
The flight was well documented, including footage filmed from a chase plane that captures the pilot ejecting. Video courtesy of Peter Merlin/NASA.