Lockheed YO-3 Quiet Star

The Lockheed YO-3A Quiet Star was an American single-engined, propeller-driven aircraft developed for battlefield observation during the Vietnam War and designed to be as quiet as possible so it could watch troop movements at night. It answered a United States Army specification of 1968 for an observation aircraft acoustically undetectable from the ground at 1,500 feet. Lockheed Missiles and Space Company built two prototypes in 1966 from modified Schweizer SGS 2-32 gliders, fitted with a silenced engine and a slow-turning propeller, and the production YO-3A kept the large wingspan and canopy of that glider with a pilot and observer in tandem. Eleven were produced and nine operated in South Vietnam at night from 1970 to 1971, where three were lost in crashes but none was hit by enemy fire. After the war the type served with state wildlife officers, the FBI and NASA.