Occupying a place of honor in the Smithsonian Institution's National Air and Space Museum in Washington, D.C., is a black, dartlike, stubby-winged craft that resembles a cross between a rocket and an airplane. The X-15 is, in fact, just that. Tuesday, March 25, marked the 20th anniversary of the first research flight of the X-15 rocket plane, which advanced knowledge of how man and machine function in the realm of hypersonic flight and made significant contributions to the nation's space program.
The X-15 was conceived some 25 years ago and went on to fly 199 flights in a combined NASA-Air Force-Navy research program. The craft's first research flight took place March 25, 1960; its last, October 24, 1968.