North American Aviation ... Star Tracker
North American's Navaho test vehicle, the X-10, used the North American-developed XN-2 star tracker inertial navigation unit guidance system. The X-10 also included the PIX10 autopilot, telemetry system transmitters and a cooling system. The X-10 could cruise at Mach 2 and, without an afterburner, could climb to 35,000 feet in 6.7 minutes. Its automatic landing system included the radio-controlled lateral optical tracker, or Hero Scope, operated by a human at the end of the runway to guide final approach and landing.
Takeoff and flight were controlled from the ground or, in an emergency, by the chase plane. X-10 test flights at Edwards Air Force Base proved its structure could stand speeds up to Mach 1.84 and proved reliability of the PIX10 autopilot for stable, level flight at supersonic speeds while implementing ground-control-directed course and speeds. The flights also tested the X-10 telemetry system, fuel-transfer system and glide brakes.
In October 1950, North American successfully flew the X-10, powered by its Rocketdyne-built 75,000-pound-thrust engine. The U.S. Army quickly selected the engine for its Redstone missile, launched in 1953.
The next Navaho vehicle was the G-26, powered by ramjet engines. The G-26 tested the vertical launch system and the piggyback booster arrangement. It used a new guidance system called NAVAN (North American Vehicle Auto Navigation), developed in 1952. NAVAN had six gyros connected to a digital N-6 computer. The computer adjusted discrepancies and tremendously increased accuracy. In 1954, the N-6 evolved into a transistorized digital computer to reduce weight and size and improve reliability.
The Navaho program was canceled in 1957, but the technologies it developed helped make American military systems the most powerful in the world.
The following year, NASA awarded North American's Missile Division the contract to build the Little Joe booster, a low-cost launcher designed to test the escape system and heat shield for the manned Mercury spacecraft.
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