Lockheed’s Combined Sailplane & Slow-Turning Propeller

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The payload carried by the YO-3A consisted of the night-vision system–a horizon-stabilized image-intensifier unit with a wide-angle objective lens mounted in a turret in the bottom of the fuselage. The viewing scope was located in the observer’s cockpit. Since no suitable night-observation system was available off the shelf, a Lockheed engineer designed one for subcontract fabrication.

All of those changes boosted the YO-3A’s empty weight to 3,129 pounds (almost twice the QT-2’s), so Lockheed once again went to a larger engine: the 210-hp air-cooled, 6-cylinder Continental IO-360D. That power plant gave a top speed of 138 mph and a cruising speed of 110–or as slow as 70 mph for maximum noise reduction. Endurance was six hours of flight time. The company used a constant-speed three-bladed propeller because it was found to be nearly as quiet at slow cruise as the six-bladed unit, but much more efficient at higher speeds.

A final question was whether the plane could be armed. For a while, gravity-dropping a load of flechettes seemed feasible, but the laws of physics and probability combined to decree that the YO-3A would go to war without a weapon.

Lockheed anticipated an initial multiservice production contract for at least 50 aircraft when DARPA pronounced Prize Crew a success. However, time had already begun to run out for American involvement in Vietnam. Tet had been the turning point. Lockheed received its initial–and final–production contract in late 1968, a $2 million order for 14 aircraft for the U.S. Army.

The YO-3As passed their acceptance tests in the fall of 1969, and the Army immediately shipped 13 of them to the 1st Army Security Agency (ASA) Company in Vietnam. (The Army Aviation Agency at Fort Rucker, Ala., got the remaining airplane for advanced testing.) Based at Long Binh, a few miles northeast of Saigon, the YO-3As proved valuable for night reconnaissance of enemy troop movements during the next two years. But on April 30, 1972, as part of its phased withdrawal from Vietnam, the Army deactivated the 1st ASA Company and returned the aircraft to the United States.

Earlier, DARPA had returned the QT-2s (redesignated the X-26A/Bs) to the Naval Test Pilot School at Patuxent River, Md. The Navy cannibalized one to provide spares for the other, and eventually sent the surviving aircraft to the Army Aviation Museum at Fort Rucker. Lockheed donated the Q-Star to the privately owned Flying Lady Museum at Morgan Hill, Calif. Of the 14 YO-3As built in 1969, only six could still be accounted for 11 years later. Four had gone to law enforcement agencies (a market that Lockheed tried without success to exploit): two each to the FBI field office in Oxnard, Calif., and the Louisiana Department of Wildlife and Fisheries. A fifth was registered to a private owner in Connecticut. In 1980, the sixth plane was serving as an airborne microphone platform in a helicopter rotor-blade research program at the NASA Ames Research Center at Moffett Field in Sunnyvale, Calif.–just across the field from its builder, the Lockheed Missiles & Space Company.

This article was written by Ronald R. Gilliam and originally published in the July 1996 issue of Aviation History.

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