Lockheed’s Missile and Space Division designed the YO-3A as a
nearly silent observation aircraft. The United States Army used
the plane to spot nighttime enemy activity and direct artillery
fire during the war in Vietnam. A downward-facing periscope
equipped with night vision and infrared (heat sensing)
capabilities allowed the aircraft’s forward observer to spot
activity on the jungle floor, even in nearly complete darkness.
The YO-3A and it's prototype, the QT-2 represent represented the
first use of aerial stealth technology in combat. Unlike the
stealth aircraft we know today, the QT-2 and YO-3A were not
designed to hide from radar, but to hide from human detection.
The plane’s muffler-equipped engine drove a special slow
propeller that eliminated the buzzing sound typical of propeller
aircraft. This let the YO-3A operate almost unheard by people on
the ground. Lockheed project manager, Stanley Hall described the
aircraft’s noise as “the gentle rushing sound of the ocean
surf”. The Museum’s aircraft, 69-1