Developed by the Interstate Aircraft and Engineering Corporation during the Second World War for use by the United States Navy, the Interstate TDR was an early unmanned combat aerial vehicle referred to at the time as an 'assault drone.' Capable of being armed with bombs or torpedoes, the type saw some service in the Pacific Theatre against the Japanese.
Interstate TDR-1 on display at Naval Aviation Museum
Powered by two Lycoming O-435 engines of 220 horsepower (160 kW) each, the TDR-1 used a remarkably simple design, with a steel-tube frame covered with a moulded wood skin thus making little use of strategic materials so as not to impede production of higher priority aircraft. Control of the TDR-1 would be conducted from either a control aircraft, usually a Grumman TBF Avenger, with the operator viewing a television screen showing the view from a camera mounted aboard the drone along with the radar altimeter's readout.
The first operational test against a naval target was conducted in April 1942. Following trials Interstate Aircraft received a contract from the Navy for two prototypes and 2000 production aircraft but only around 200 were built.
The TDR's was first deployed operationally on 27 September 27, conducting bombing operations against Japanese ships. On 27 October the last TDR missions were flown. In all 50 drones were lost on operations with 31 successfully striking their targets. Despite this success, the assault drone program had already been cancelled due to a combination of continued technical problems and the fact that more conventional weaponry was proving adequate for the defeat of Japan.