TDR Assault Drone 

and 

TBM Avenger Control Aircraft

by Thomas Conte

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Smart bombs and cruise missiles of the present day can trace their ancestry back to World War Two and even earlier.

The Interstate TDR assault drone was the result of testing done by the U.S. Navy during the late thirties. At this time a group of officers began experiments with radio control aircraft for the use as a target for practice by the fleet. These test evolved into an aircraft that could be remotely controlled to attack a ship or other type of targets. The world 's first guided missile attack was accomplished on September 14th, 1938 against the USS Utah using a N2C-2 drone. It is interesting to note that this was completed a full two years earlier than the German's projects which used an unpowered gliding bomb. The N2C-2 was a converted Navy biplane trainer.

Following this success, plans were considered to convert obsolete aircraft into target and assault drones. The outbreak of WW II changed this and now a requirement for a specially built aircraft was created. Two aircraft came out of this specification - the Interstate's TDR and the Naval Aircraft Factory's TDN. Both aircraft were designed to accept a number of low power piston engines and roughly the same dimensions; a 50 ft. wingspan and about 36 ft. long. The TDN differed from the TDR by having a shoulder mounted wing. Both were made from subcontracted parts so there could be a number of manufactures that can claim having a hand in their construction. Each aircraft could be flown by a pilot onboard during testing, ferrying, or when checking out newly installed hardware.

As crude as these aircraft appeared, they were packed with the latest hardware of their time. They had the capability to hold a heading, fly a set pattern, and maintain a specific altitude besides being controlled by a ground or airborne transmitter from a good distance. They also carried a television transmitter whose images were sent to the controlling aircraft. The drone controller pilot onboard the Avenger used the TV images to acquire the target and fly the drone into it. With all of this equipment the drone could takeoff with up to 2000 lbs. of explosives and either drop it or be flown directly into the target.

During the War in the Pacific nearly four dozen of these aircraft, mostly the TDR was used against the Japanese during 1944 in the Rabaul area. They were used by a Special Task Air Group One, Special Air Task Force (STAG ONE SATFOR).

Much more information can be found on their website, http://www.stagone.org or in the book by James J. Hall American Kamikaze.

The model came about because references to this type of aircraft kept coming up during my research into similar type used by the other combatants during WW II.

Finally I learned that one was, at the time, on display at the U.S. Naval Museum at Pensacola, Florida, US. I made the trip to take photos and to find more leads. From more detective work I was able to come into contact with a Mr. Newton who was involved with them during the war and who kindly provided me with more details. With this information I later discovered from old magazines from the 40's, I created a set of working drawings to make a master model in 1/72 scale so that I could make a number of resin cast models.

Remember I mentioned that these aircraft were designed to be powered by a number of different engines and to be piloted? Well I was planning to build a number of models to represent the variants and that meant that if I did not want to build each one separately, I had to make a master and molds to create my fleet of assault drones. The one in the photo is the first out of the molds.

The model was assembled from parts taken from molds made from RTV and the master and then using available urethane cold casting resin for the production of the final pieces. After removal from the molds the parts were cleaned with alcohol and super glued together. After everything was checked it was given a coat of primer and airbrushed with Testor's paint and given a flat final coat. The landing gear is made from small brass and aluminum tubing that was also super glued into place.

Since the major difference between the TDR type were their engines, the center section of the wing master was made with no fairings for any type of engine. The first model, the one in the photos, shows a TDR with two horizontally opposed engines, no pilot, and carryings two 1000 lbs. bomb under the wing racks. The next project will a version with two radial engines and piloted. The model has a wingspan of 8.33 inches and is 6 inches long.

While it is not hard to create a model like this, it takes time to describe how to do it. If there are a number of people who are interested, when I build the next TDR I will photograph the steps and write a more detail description. If you let Brett or myself know I would be glad to put something together.

The Grumman TBM drone controller aircraft was built to give a sense of size to the TDR. It started out as a Hasagawa TBF Avenger model since my information indicated that the first batch of Grumman aircraft built by General Motors (the M in TBM ) were identical to the ones built by Grumman (the F in TBF ). The major external change was the addition on the retractable radar dome on the bottom of the fuselage behind the bomb bay doors. In the photo, it is extended more than it should while the aircraft was on the ground, this was done in the photo to make it more noticeable. The other modification was in the cockpit area behind the pilot seat. An additional seat and instruments were added in the position the drone control pilot occupied, which was behind the original pilot's seat. The rest of the model was completed normally and finished in Testor's solvent base paints.

The models make a very interesting addition to my collection of WW II aircraft and are something different from what's being offered by the model manufactures.