One of the first combat drones ever deployed in the world

Using drones for combat is nothing new, but early examples would pale in comparison to the sophistication of modern models. However, there were bright lights in the history of this technology that would reveal the potential of this technology for future generations.

One such craft was the Interstate TDR-1. Developed by the United States towards the end of World War II, this interesting craft is fascinating to briefly explore.

What is Interstate TDR-1?

The Interstate TDR was one of the first unmanned combat aerial vehicles built by the Interstate Aircraft and Engineering Corporation for use by the United States Navy during World War II. Nicknamed “attack drone” at the time, around 2,000 aircraft were ordered.

Each TDR-1 had a very simple design, with a steel tube frame built by the Schwinn Bicycle Company and a molded wood skin made by the Wurlitzer Musical Instrument Company. Two non-military flathead Lycoming 6s provided the power with 230 horsepower each. The drone was built using few strategic resources so as not to hamper the manufacture of higher priority aircraft.

The TDR-1 was capable of carrying bombs or torpedoes, but only about 200 were completed, and even fewer were used in combat. The TDR-1 saw action against the Japanese in the Pacific theater, with mixed success.

IInterstate TDR-1 assault drone in flight, circa 1944. Source: US Navy/Wikimedia Commons

Throughout their use, around 50 drones were launched in two months, with 31 hits on anti-aircraft positions, bridges, airfields and stranded ships recorded. The drone would be dropped by a ground control team and then handed over to the TBM pilot already flying above terrain, guided by a modified TBM-1C Avenger torpedo bomber. The TBM pilot would be connected to the drone and pass control to the controller in the rear cockpit. The controller would guide the drone to its target using Camera signals mounted on the nose of TDR.

Due to continued aircraft development challenges and successful operations using more conventional weapons, the attack drone program was canceled in October 1944.

Interstate TDR-1 Vital Stats

Several variants of the Interstate TDR program were built like many other aircraft. However, the only production model was the TDR-1. For this reason, we will provide the statistics for this particular model.

Seized service: July 1944

Retired: November 1944

Crew: 0–1 (optional driver)

Wingspan: 48 ft (15 m)

Gross weight: 5,900 lbs (2,676 kg)

Power plant: Lycoming O-435-2 opposed piston engines, 220 hp (160 kW) each

Cruising speed: 140mph (230kph)

Interval: 684 km (425 mi)

Armament: A 2,000-pound (907 kg) aerial bomb or torpedo

What is the history of TDR-1?

In 1942, the United States embarked on a mission to develop inexpensive, easy-to-use drones to help save their very valuable and irreplaceable human crews. With the end of the war seeming a long way off, such wacky and experimental technology was relegated to the bottom of the military’s priority list.

TDR-1 pilot variant
Interstate XBQ-4 assault drone prototype (a US Army variant). Source: US Army Air Force/Wikimedia Commons

However, enough U.S. military officials foresaw how beneficial such technology would be if successfully developed, especially in the Pacific theater against the Empire of Japan.

To that end, Interstate Aircraft was commissioned to develop the drones, which were mostly made of wood stretched over a metal frame. Each TDR had two engines and a removable cockpit, giving them the ability to be piloted by humans if and when needed. However, from the outset, their primary function was to serve as an unmanned drone.

Each drone was remotely controlled by a Grumman TBM-1C Avenger torpedo bomber master who tracked the drone and controlled it using very sophisticated technologies for the time.

What technology was added to the TDR 1 that made it different from all previous UAS?

The secret to the TDR-1 was a new type of top-secret technology called the RCA TV. Images from a camera installed in the drone’s nose were sent to a five-inch screen in the Avenger’s rear cockpit. The image quality was admittedly poor, but it was more than enough for the pilot to see large targets like enemy ships.

Once developed and built, the first batches of them were supplied to three special air groups (STAGs) specially created to operate them. However, problems with these early drones soon became apparent. For example, when they landed in the Solomon Islands, it was quickly discovered that the tropical climate and lack of sophisticated infrastructure proved to be a nightmare for drone electrical equipment.

However, these early problems were overcome and the TDRs were put into action soon after.

On June 30, 1944, they were tested against a Japanese freighter, the Yumasuki Maru, which had run aground near Guadalcanal in the Solomon Islands. A total of four drones were used, three of which collided with the ship. Two of them successfully exploded.

tdr-1 silhouette
A three-view drawing of the Interstate TDR-1 assault drone. Source: Greg Goebel/Wikimedia Commons

Another test also showed promise when four drones were launched from Bougainville in September of the same year for a mission to destroy another stranded Japanese ship. This ship, unlike the first, was a little more robust and had some Japanese defenses, such as an anti-aircraft battery. Each drone was armed with a 2,000 pound (907 kg) bomb and had to fly a total of 55 miles (88.5 km) to reach the target.

This test was a bit more mixed, with one drone lost along the way, another nearly hit the ship but didn’t explode, and a third hit the ship but didn’t explode. The last plane rammed the ship, successfully detonating its massive explosive payload.

Further tests followed, with more flights made over the next month, some of which were sent to targets over 100 miles from their base.

Drones were largely successful in attacking many military targets, but they were widely looked down upon by US Navy leaders, and in November 1944 the project was duly cancelled. This was likely due to politics, mistrust and lack of knowledge of such new and radical technology rather than serious design flaws. There had been no American lives lost as a result of their use.

After the war, some TDR-1s were converted for operation as private sport aircraft.

And that, UAV enthusiasts, is your lot for today.

The Interstate TDR-1 was a revolutionary aircraft for its time, but like most advanced technologies in history, it probably arrived a little too early to be fully appreciated. This would in part show the world how valuable unmanned aircraft could be in combat, which would ultimately lead to the development of modern combat drones that we know all too well today.

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