Interstate TDR

The Interstate TDR was an early unmanned combat aerial vehicle, known at the time as an "assault drone," built by the Interstate Aircraft and Engineering Corporation for the U.S. Navy during World War II. It could carry bombs or torpedoes. Although the Navy ordered 2,000 of these drones, only about 200 were actually built. The TDR saw limited action in the Pacific Theater against Japanese forces, but ongoing technical problems and the effectiveness of conventional weapons led to the program being canceled in October 1944.

Design and development

The idea for a remotely controlled combat aircraft came from Lieutenant Commander Delmar S. Fahrney in 1936. Early technology limited progress, but advances in radar altimeters and television made the concept more practical by the early 1940s. After tests with converted manned planes, the first operational drone strike against a naval target occurred in April 1942. That same month, following trials of the Naval Aircraft Factory TDN, Interstate received a contract for two prototypes and 100 production aircraft of a simplified, improved design called the TDR-1.

The TDR-1 was controlled from a nearby aircraft, usually a Grumman TBF Avenger, whose operator watched a television screen showing the drone’s camera view and radar altimeter reading. For test flights, a pilot could also fly the drone from an onboard cockpit. The drone was powered by two 220-horsepower Lycoming O-435 engines.

Its design was remarkably simple: a steel-tube frame built by the Schwinn bicycle company, covered with molded wood skin, using little strategic material to avoid slowing production of higher-priority aircraft. During operational missions, the cockpit was covered with an aerodynamic fairing. The TDR-1 had fixed tricycle landing gear that was jettisoned after takeoff to improve performance.

In September 1942, the Navy chose DeKalb, Illinois, as the manufacturing site for the TDR-1 and built an airport on the city’s east side, complete with a guarded airfield and large hangar. DeKalb was selected because Wurlitzer, a piano maker skilled in wood products, was located there. Interstate Aircraft and Engineering Corporation, based in El Segundo, California, assembled the planes at the new DeKalb Airport. About 200 drones were built, tested, boxed, and shipped to the South Pacific for use against the enemy.