In October 1945, the Army Technical Services Command asked aeronautical corporations in the United States to design a guided missile. North American Aviation proposed the MX-770, the Navaho -- a 500-mile-range missile with greater accuracy than the German-built V-2. Although the Air Force canceled the Navaho program in 1957, in its 10 years of existence, the Navaho 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. Its booster engine set a record by producing 405,000 pounds of thrust. The X-10 was the only missile to be classified as an "X" plane and completed more than 20 flights. Data from these flights led to the development of the SM-64 Navaho ground-to-ground missile system.