In October 1945, the Army Technical Services Command asked U.S. aeronautical corporations to design a guided missile. North American Aviation proposed the MX-770, the Navaho -- a 500-mile-range missile, which made many key technological breakthroughs. The X-10 Navaho test drone was the first turbojet-powered vehicle to reach Mach 2, and the first aircraft to fly a complete mission under inertial (computerized) guidance. Phase two of the nuclear Navaho development program was the G-26 drone missile (shown here), which would prove the vertical launch system. The G-26 required the development of the largest ramjet engines built, an auxiliary power unit to power the missile's electronics and hydraulics, and a more effective autonavigator unit, the N-6 or NAVAN (North American Vehicle Auto Navigation). The Navaho program was canceled in July 1957 when, after extensive testing at Cape Canaveral, Florida, the Atlas ICBM was chosen over winged missile designs.