Development of the SD-2 drone began in 1957 by the Rheem Manufacturing Company, and the project continued through the company's acquisition by Aerojet General in 1959. Developed as part of the
AN/USD-2 surveillance system, the SD-2 was designed for truck launch using two
solid rocket boosters; following launch, a piston engine provided propulsion. At the end of its mission, the drone would be recovered via parachute. The SD-2 was designed to use a modular sensor system, allowing equipment to be switched between missions according to requirements. Available payloads included cameras for either recovered or real-time photography, AN/AAD-2 infrared sensor, AN/DPD-2
side looking airborne radar, or equipment for the dispensing of biological or chemical warfare agents from tanks mounted under the wings of the aircraft. ==Operational history==