The TDR-1 was one of the earliest unmanned cruise missiles manufactured at the behest of the US Navy. An innovative projectile that was remotely guided using television screens and radio, the TDR-1 was so ahead of its time that it was misunderstood by many in the top echelons of Navy leadership, and unjustly cancelled after only a month of operational service.
After decades of failed projects dating back to the earliest era of aviation, the 1930s witnessed a revolution in cruise missile technology following the emergence of radio. Sophisticated advances in radio communications would lead to the creation of one of the earliest remote-controlled aircraft, dubbed the ‘Queen Bee’, which was developed by the British Royal Navy to combat a new wave of high-performance aircraft that were increasingly outmatching shipboard anti-aircraft weapons with their speed.
Essentially an overhauled de Haviland biplane equipped with radio controls connected to small servo motors, the Queen Bee was a breakthrough craft that could be operated remotely by a pilot sitting in another plane or standing on the deck.
In 1936 the America Chief of Naval Operations, Admiral William H. Standley witnessed the Queen Bee in action firsthand and was so impressed by its performance that he determined that the US Navy had to develop a similar device.
Unperturbed by the past failures of the World War One era ‘Flying Bomb’, the brainchild of inventor Elmer Sperry, or the postwar ‘Flying Bug’ conceived by Charles Kettering, Standley was certain that if the Navy took advantage of many of the breathtaking advances in vacuum tubes, the broadcasting of modulated signals, gyroscopes, and auto-pilot software, that it could finally produce a reliable cruise missile.
After communicating his wishes to his colleague Rear Admiral Earnest J.King, head of the Bureau of Aeronautics, Lieutenant Commander Delmar S. Fahrney, widely regarded today as the ‘Father of the Guided Missile’, was chosen to lead the project, which resulted in the Curtiss drone.
In 1938 the drone took part in a series of tests where it acted as a moving target for naval anti-aircraft weapons to shoot down. In a damning inditement of the efficacy of such armaments, the Curtiss plane survived several volleys of fire to the disappointment of Navy officials.
But while the incident forced the Navy to confront the fleet’s weaknesses, it also illustrated that the unmanned missile could be an effective offensive weapon against ships, which would be powerless to stop it.
At the time the concept certainly had its detractors, who pointed out that such a weapon was still lethal for pilots since the remote control operators had to be uncomfortably near the target to keep it within eyesight.
On the other hand, with the advent of television technology in the mid-1930s, it was now theoretically possible to completely remove the pilot from the danger zone. This concept would be explored more deeply in the TDN-1 and TDR-1 programs to follow.
As early as 1934 Dr Vladimir Zworykin, an immigrant from Russia, had hypothesized that a flying missile could be fitted with a television screen to act as an electronic eye in the sky. It was this man, an early television scientist, that Fahrney approached about making his television-aided drone a reality.
Although initially greeted with some scepticism, in the wake of the devastating Japanese assault on Pearl Harbor in December 1941 and the American entry into World War Two the idea was popularized. Supervised by Commodore Oscar Smith and Fahrney himself, in February 1942 a classified program known only as ‘Project Option’ was commenced.
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The development of a ‘Torpedo Drone’ guided by radio and television screens soon became a top priority. In April 1942, with the operator 8 miles distant and out of sight, the device illustrated its merits after successfully hitting the US destroyer Aaron Ward, which was unable to dodge the projectile despite travelling at a speed of nearly 15 knots and performing a range of evasive manoeuvres.
Project Option was now even more vigorously pursued by the Navy top brass, who ordered a Special Air Task Force (SATFOR) made up of 5000 assault drones or TDN-1s in 18 squadrons to be assembled.
The resulting contraption that rolled off the production line at the Naval Aircraft Factory was a twin-engined monoplane with a high wing, tricycle landing gear, and a removable cockpit which was only used by pilots to transport the drone to another location.
On the other hand with resources scarce, the airframe was found to be far too expensive to manufacture in the numbers the Navy wanted, and so only 114 TDN-1s were ever completed, none of which ever saw combat.
With the leftover airframes rather ignominiously employed as anti-aircraft training targets, the future of the project, which had promised so much and delivered so little, now looked bleak. Luckily Fahrney and Smith had recognized early on that the TDN-1 was doomed, and had already prepared a backup plan to take its place.
Employing the services of the Interstate Aircraft Company based in California, Fahrney and Smith now set about creating a cheaper and simpler version of the TDN-1 given the moniker TDR-1, with ‘R’ representing the manufacturing code ‘Interstate’.
As well as teaming up with American Aviation, surprisingly Interstate also thought it wise to contact the Wurlitzer Musical Instrument Company, whose expertise in crafting complicated wooden contraptions such as pianos would come in handy for many of the TDR-1’s trickiest components.
Consequently, the development of the TDR-1 would largely take place in a piano factory located in Dekalb, Illinois. Of Wurlitzer, Local historian Roger Keys notes how:
“They had several patents on unique assembly processes. And when they were approached by the Navy to make the TDR, they were extremely enthusiastic about it. In the span of about six months they completely converted all their tooling to build them”.
The piano company was so eager to be involved they even transformed a furniture factory adjacent to their facility into an assembly line, while a runway was built nearby. Like its predecessor, the project was enshrouded in a veil of secrecy, with Wurlitzer employees made to believe that they were working only on training planes.
The TDR-1 had a fuselage that was composed of moulded wood that was supported by a sturdy central metal framework manufactured by the bicycle company Schwinn.
The drone was powered by two 220-horsepower flat six-cylinder Lycoming engines that provided a cruise speed of 125 knots. Its wings were long and low with a span of 48 feet, and weighing in at only 5,900 pounds its lightweight construction ensured smoothness in take-off as well as a landing speed of 60 knots.
For maximum impact, the TDR-1 also had a landing gear that could be jettisoned to increase the craft’s terminal dive velocity to over 150 knots, upon which it detonated a 2,000-pound payload of explosives.
Like the TDN-1 before it, the TDR-1 featured a fully detachable cockpit for ferrying operations, which had an instrument panel that had an airspeed indicator, a ball and turn indicator, an altimeter, and a compass.
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It also had an engine gauge replete with an oil pressure monitor and tachometer, which were built into the sides of the engines to save money, meaning that the pilot would have to turn his head four feet to the left or right to get a reading.
TDR-1 operators were initially trained using radio-augmented Beechcraft civilian craft, before being taught how to control ‘Avenger Torpedo Bombs’ which were made by General Motors and codenamed TBM-1C. This craft, which had space for a pilot, radioman, gunner, and control pilot, would act as the mobile remote station where the TDN-1 was manoeuvred.
In a typical operation, the remote control team first took off in a TBM-1C with the TDN-1 flying close by. Flying in a loose formation, once the target location had been reached the control pilot immediately ducked under a black drape to block out the sun so that he could use the Block television screen developed by Dr Vladimir Zworykin in combination with a radar scope to guide the TDN-1 to its intended mark.
The control pilot used a joystick to determine the TDR-1 position, which worked in tandem with a telephone box mounted on the left side of the cockpit and could be inputted with numbers to change the behaviour of the missile.
For example, dialling in ‘one’ made it fly at 50 feet, and ‘two’ at 100 feet, while other numbers could signal the wheels to drop, the torpedo to launch, or the internal bombs to detonate.
Following a great amount of pushback from some Navy officers, who believed that unmanned missile technology was too untried to be properly debuted in a combat situation, the TDR-1 was finally given a chance to prove its worth after being deployed to the Russell Islands in the Pacific, nearby Guadalcanal.
Here on July 30th 1944 squadrons VK-11 and VK-12 were assigned their first operational capability test, which would involve firing 4 TDRS at the grounded Japanese freighter Yamazuki Maru situated near Cape Esperance. In a bid to impress unconvinced Navy officers, the action would also be filmed.
The mission was of mixed success, with the first TDRS landing a direct hit, the second missing the ship by 30 feet and failing to detonate, the third hitting near the ship but also failing to explode, and the fourth rather dramatically smashing into the hull and producing an enormous fireball. Nevertheless, Smith was delighted at the results and was soon on his way to deliver the film to Navy commanders in Hawaii.
However, upon his arrival, Smith learnt that the VK-11 and VK-12 had already been recalled by Admiral Towers, who had advocated for the project’s cancellation from the very beginning.
Nevertheless, Smith, who believed wholeheartedly that these drones were the future of warfare, persevered and was able to secure a 30-day extension and permission to attack targets of opportunity around the Solomon Islands.
Between September 27 to October 26th, the VK-11 and VK-12 crews would perform the earliest recorded cruise missile assaults. Among the victims was a Japanese merchant vessel that had previously downed a C-47 transport plane, while bridges, anti-aircraft installations, and supply dumps became the main focus of the mission.
However, the limitations of the system soon came apparent. With many Japanese vessels hidden behind jungle cover, it was incredibly hard to accurately hit them, leading to the conclusion that the TDRS was only effective if the target was in the open sea.
On October 26th, after a volley of missiles obliterated a lighthouse at Cape St. George on the island of New Ireland, the deployments of VK-11 and VK-12 officially came to an end. Overall, a total of 46 TDRS were fired, with 37 reaching their target zones and a further 21 successfully pulling off a precision strike.
In 1944 the control squadrons were disbanded, yet the experiment had certainly left a significant legacy, with a successor missile, the nuclear-capable Regulus being used throughout the Cold War as a submarine-based nuclear deterrent.
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Block 3 television systems would also be used in the Korean War, where they were fitted to six F6F-5K aircraft that took down a North Korean power plant, railway tunnel, and bridge.
Today only a single TDR missile, exhibited in the Naval Aircraft Museum in Pensacola, Florida, survives.
- 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 (230 km/h, 120 kn)
- Range: 425 mi (684 km, 369 nmi)
- One 2,000-pound (910 kg) bomb or one aerial torpedo