Lockheed YO-3A 'Quiet Star'

The Lockheed YO-3A "Quiet Star" was an American single-engined, propeller-driven monoplane that was developed for battlefield observation during the Vietnam war. It was designed to be as quiet as possible, and was intended to observe troop movements in near-silence during hours of darkness.

NASA took possession of one YO-3A in the late 70's. The plane was used in rotorcraft research. It is still in operation today at Moffett Field, California. (This aircraft is currently in use at Nasa's Dryden Research facility at Edwards, AFB, CA.)