|TDR-1 in flight with aerial torpedo.|
|National origin||United States|
|Primary user||United States Navy|
The Interstate TDR was an early unmanned combat aerial vehicle — referred to at the time as an "assault drone" — developed by the Interstate Aircraft and Engineering Corporation during the Second World War for use by the United States Navy. Capable of being armed with bombs or torpedoes, 2000 aircraft were ordered, but only around 200 were built. The type saw some service in the Pacific Theater against the Japanese, but continuing developmental issues affecting the aircraft, along with the success of operations using more conventional weapons, led to the decision being made to cancel the assault drone program in October 1944.
Design and development
In 1936, Lieutenant Commander Delmar S. Fahrney proposed that unpiloted, remotely controlled aircraft had potential for use by the United States Navy in combat operations. Due to the limitations of the technology of the time, development of the "assault drone" project was given a low priority, but by the early 1940s the development of the radar altimeter and television made the project more feasible, and following trials using converted manned aircraft, the first operational test of a drone against a naval target was conducted in April 1942. That same month, following trials of the Naval Aircraft Factory TDN assault drone, Interstate Aircraft received a contract from the Navy for two prototype and 100 production aircraft to a simplified and improved design, to be designated TDR-1.
Control of the TDR-1 would be conducted from either a control aircraft, usually a Grumman TBF Avenger, with the operator viewing a tv screen showing the view from a camera mounted aboard the drone along with the radar altimeter's readout, or via a pilot on board the TDR-1 for test flights. 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 constructed by the Schwinn bicycle company covered with a molded wood skin, thus making little use of strategic materials so as not to impede production of higher priority aircraft. Capable of being optionally piloted for test flights, an aerodynamic fairing was used to cover the cockpit area during operational missions. The TDR-1 was equipped with a fixed tricycle landing gear that would be jettisoned in operation after takeoff for improved performance. The TDR-1s were manufactured by the Wurlitzer Company.
Under the code-name Operation Option, the Navy projected that up to 18 squadrons of assault drones would be formed, with 162 Grumman TBF Avenger control aircraft and 1000 assault drones being ordered. However technical difficulties in the development of the TDR-1, combined with a continued low priority given to the project, saw the contract modified with the order reduced to only around 300 aircraft. A single TDR-1 was tested by the U.S. Army Air Forces as the XBQ-4, however no production contract resulted from this testing.
In 1944, under the control of the Special Air Task Force (SATFOR), the TDR-1 was deployed operationally to the South Pacific for operations against the Japanese. TDR-1 aircraft equipped a single mixed squadron (Special Air Task Group 1) along with TBM Avenger control aircraft, and the first operational mission took place on September 27, conducting bombing operations against Japanese ships. Despite this success, the assault drone program had already been canceled after the production of 189 TDR-1 aircraft, due to a combination of continued technical problems, the aircraft failing to live up to expectations, and the fact that more conventional weaponry was proving adequate for the defeat of Japan. The final mission was flown on October 27, with 50 drones having been expended on operations, 31 aircraft successfully striking their targets, without loss to the pilots of STAG-1.
Following the war, some TDR-1s were converted for operation as private sportsplanes.
Variants and operators
- XTDR-1 – Two prototypes.
- TDR-1 – Production version of XTDR-1, 189 aircraft produced.
- XTD2R-1 – Variant with two Franklin O-805-2 engines, two prototypes ordered, canceled in favor of TD3R.
- XTD3R-1 – Variant with Wright R-975 radial engines, three prototypes.
- XTD3R-2 – Variant of XTD3R-1, one prototype.
- TD3R-1 – Production version of XTD3R-1, 40 aircraft ordered but cancelled.
- XBQ-4 – Army designation for TDR-1. One aircraft converted from TDR-1.
- XBQ-5 – Army designation for XTD2R-1. Designation reserved but no aircraft ordered.
- XBQ-6 – Army designation for XTD3R. No aircraft produced.
- BQ-6A – Army designation for TD3R-1. No aircraft produced.
Aircraft on display
Data from Parsch
- Crew: 0–1 (optional pilot)
- Wingspan: 48 ft (15 m)
- Gross weight: 5,900 lb (2,676 kg)
- Powerplant: 2 × Lycoming O-435-2 opposed piston engines, 220 hp (160 kW) each
- Cruise speed: 140 mph (225 km/h; 122 kn)
- Range: 425 mi (369 nmi; 684 km)
- One 2,000-pound (910 kg) bomb or one aerial torpedo
Aircraft of comparable role, configuration and era
- Parsch 2005.
- "TDR-1 Edna III". National Naval Aviation Museum. 2016. Retrieved 2017-12-07.
- Zaloga 2008, p.8.
- Newcome 2004, p.68.
- Goebel 2010
- Newcome 2004, p.69.
- Goebel, Greg (2010). "The Aerial Torpedo". Cruise Missiles. VectorSite. Retrieved 2010-11-18.
- Newcome, Lawrence R. (2004). Unmanned Aviation: A Brief History of Unmanned Aerial Vehicles. Reston, Virginia: American Institute of Aeronautics and Astronautics. ISBN 978-1-56347-644-0.
- Parsch, Andreas (2005). "Interstate BQ-4/TDR". Directory of U.S. Military Rockets and Missiles, Appendix 1: Early Missiles and Drones. designation-systems.net. Retrieved 2010-11-17.
- Zaloga, Steven (2008). Unmanned Aerial Vehicles: Robotic Air Warfare 1917–2007. New Vanguard. 144. New York: Osprey Publishing. ISBN 978-1-84603-243-1.
Media related to Interstate TDR at Wikimedia Commons