Tiltrotor aircraft. The YO-3 was also used to measure sonic booms from the Lockheed SR-71 Blackbird. In 1997, the NASA YO-3A was transferred to the Dryden Flight Research Center (now Armstrong Flight Research Center) at Edwards Air Force Base, in California. The YO-3A remained in a flyable storage state until October 2004. Then the YO-3A was flown back to Ames to support rotorcraft research again for nearly two years before once again returning to Dryden. In 2015, the aircraft was retired by NASA and sold by the General Services Administration at auction to the Vietnam Helicopters Museum. Variants QT-1 Quiet Thruster Proposed single-seat powered glider based on the Schweizer SGS 2-32, not built. QT-2 Two modified Schweizer X-26 two-seat sailplanes for evaluation, later modified with sensor packages as the QT-2PC. QT-2PC PRIZE CREW Two QT-2s with combat sensor packages for evaluation in Vietnam theatre, one reduced to spares and the other returned to the United States Navy as the Schweizer X-26B. Q-Star Modified Schweizer SGS 2-32 for engine/propeller development. YO-3A Production aircraft for the United States Army, 11 built Operators Military operators United States Army Civil operators FBI Louisiana Department of Fish and Game NASA Surviving aircraft 69-18000 – YO-3A in storage at the United States Army Aviation Museum in Fort Rucker, Alabama. 69-18001 – YO-3A on static display at the Hiller Aviation Museum in San Carlos, California. 69-18005 – YO-3A on static display at the Museum of Flight in Seattle, Washington. 69-18006 – YO-3A on static display at the Pima Air & Space Museum in Tucson, Arizona. 69-18007 – YO-3A in storage at the Western Museum of Flight in Torrance, California. 69-18010 – YO-3A in storage at the Vietnam Helicopters Museum in Concord, California. Specifications See also References Notes Bibliography Andrade, John. U.S. Military Aircraft Designations and Serials since 1909. Hinckley, UK: Midland Counties Publications, 1979. . The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). London: Orbis Publishing, 1985. Munson, Kenneth. Bombers in Service, Patrol and Transport Aircraft Since 1960. London: The Macmillan Co., 1972. . Schnebly, F. David. A Greenhouse Anthology, Chapter 5: Taking The Night Away From Charlie (Development of the YO-3A). Xlibris Corporation, 2000 (ISBN 0-7388-3086-0) External links Lockheed's Combined Sailplane & Slow-Turning Propeller at HistoryNet.com Quiet Aircraft Association QT-2PC PRIZE CREW Lockheed YO-3A Quiet Start: The Original Stealth Aircraft of the Vietnam War YO-3A Acoustic Research Aircraft Image Gallery O-003 1970s United States military reconnaissance