Aerojet SD-2 Overseer

The Aerojet SD-2 Overseer was an unmanned aircraft built by Aerojet General and Rheem Manufacturing Co. for the U.S. Army during the late 1950s. Only a small number were produced, and the type never entered active service.

Development of the SD-2 drone started in 1957 under Rheem Manufacturing, continuing after Aerojet General acquired the company in 1959. It was part of the AN/USD-2 surveillance system.

The drone launched from a truck using two solid rocket boosters, then switched to a piston engine for flight. At the end of its mission, it returned by parachute. A translateration navigation system—similar in principle to later differential GPS—allowed the aircraft to follow a pre-programmed route.

The SD-2 carried modular sensors that could be swapped between missions. Payload options included cameras for either recovered or real-time imagery, an AN/AAD-2 infrared sensor, an AN/DPD-2 side-looking airborne radar, or wing-mounted tanks for dispensing biological or chemical agents.

Thirty-five production SD-2s were built. The navigation system performed poorly, leading to the program’s cancellation in 1966, with no Overseers ever used operationally. In 1963, the drone was redesignated MQM-58A under the new naming system.