Lockheed YO-3 Quiet Star


1st Flight 1969

Crew: 2

Length: 29 ft 4 in (8.94 m)

Wingspan: 57 ft (17 m)

Wing area: 213.1 sq ft (19.80 m2)

Aspect ratio: 1:7 at 80kts IAS

Max takeoff weight: 3,800 lb (1,724 kg)

Powerplant: 1 × Continental Model No. I0-360D engine , 210 hp (156 kW) at 2800 rpm

Propellers: 3-bladed laminated wood, constant-speed propeller.


Maximum speed: 103 mph (166 km/h, 90 kn)

Cruise speed: 80.6 mph (129.7 km/h, 70.0 kn)

Stall speed: 64.4 mph (103.6 km/h, 56.0 kn)


The Lockheed YO-3 Quiet Star is an American single-engined, propeller-driven aircraft that was developed for battlefield observation during the Vietnam War.

Designed to be as quiet as possible, it was intended to observe troop movements in near-silence during the hours of darkness.

QT-1 Quiet Thruster

Proposed single-seat powered glider based on the Schweizer SGS 2-32, not built.


Two modified Schweizer X-26 two-seat sailplanes for evaluation, later modified with sensor packages as the QT-2PC.


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.


Modified Schweizer SGS 2-32 for engine/propeller development.


Production aircraft for the United States Army, 11 built.

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