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. Phase two of the nuclear Navaho development program was the G-26 drone missile, 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), built by North American's Autonetics Division.