FltLt
Far earlier than 1930s...
[1.0] The Aerial Torpedo
[1.2] BRITISH AERIAL TORPEDOES
* The British pursued aerial torpedoes in parallel with the American effort. In late 1915, Professor A.M. Low was asked to help develop a radio-controlled aircraft to intercept Zeppelin raiders and attack ground targets. The robot aircraft was designated "AT", which was supposed to stand for "Aerial Target" as a cover to hide the true nature of the weapon.
Low built the radio control system, which, unsurprisingly considering the technology at his disposal, was crude and heavy. In the meantime, aeronautical engineers built a small monoplane airframe for the AT, powered by a 37 kW (50 HP) Gnome rotary engine. Rotary engines looked like radial piston engines, but in a rotary engine the propeller was fixed to the engine block and the engine block spun on a shaft. They leaked oil at a great rate, started small fires on the ground under an aircraft when they were cranked up, and also, as it turned out, produced a lot of electrical noise. The first AT was flown in October 1916, but the noisy engine interfered with the radio control system. The AT was obviously unworkable and was abandoned, but other aircraft manufacturers were interested in the concept and took a shot at it.
The Royal Aircraft Factory at Farnborough built a monoplane with a wingspan of 6.7 meters (22 feet) and a two-cylinder air-cooled engine providing 26 kW (35 HP). The engine was designed by a company named "ABC", and was intended to operate for a minimum of two hours, making it one of the first purpose-designed expendable engines ever built. One of these aerial torpedoes was demonstrated in March 1917, only to embarrassingly crash immediately after launch. The Sopwith company attempted to build a biplane aerial torpedo with an ABC engine, but this aircraft was never completed. The exact number of different types of aerial torpedoes developed by the British during World War I and their details is unclear. What is clear is that little came of the effort.
* Work on automated aircraft continued in Britain after the war. In 1920, a standard Bristol F.2B fighter was fitted with radio control and flown successfully, though the aircraft still carried a human pilot as a backup. A radio-guided purpose-built aerial target was also tested in 1921. These efforts led to the interesting "Long-Range Gun With Lynx Engine (LARYNX)" aerial torpedo of 1927. This was a neat little monoplane with a radial engine and a gyroscopic control system, built by the Royal Aeronautical Establishment for the Royal Navy -- one suspects the "Long-Range Gun" label was a way of selling a newfangled idea to conservative admirals. One LARYNX was successfully launched from a destroyer off the coast of England. A number of the missiles were flight-tested in the deserts of Iraq armed with a 113 kilogram (250 pound) warhead. Results of the tests were inconclusive.
Remote Piloted Aerial Vehicles : The 'Aerial Target' and 'Aerial Torpedo' in Britain
At the start of W.W.I Professor Low was actually working on the very first electronic range finder, based on the principles of radar, for the Artillery Corps but the RFC (Royal Flying Corps) had other things in mind for the good Professor. The RFC wanted Prof. Low to put his knowledge of radar to use in designing and developing remotely controlled pilot-less aircraft.
The concept was to develop a small, very simple aircraft. Pack it with explosives and then guide it into a designated target. Thus the RFC Experimental Works were born and the newly commissioned Second Lieutenant Low began his secret work in a Chiswick garage. As it turns out the aircraft design was the least of the challenges; it was the radio gear that needed to be developed first.
As Low made progress with the radio gear there was a need to relocate the operation to a more aeronautical site and Brooklands was chosen. It was here that it was discovered that the uncowled 50 hp Gnome rotary engine caused so much radio noise as to make the operation of the gear unreliable (sound familiar). In spite of the engine noise and unreliability of the aircraft it was shipped off to the Central Flying School at Upavon. It was subsequently never flown.
The key here is that the radio gear did operate as planned when the power plant was not running. As a matter of fact this remotely piloted vehicle (RPV) concept caught the interest of the great Sopwith Co. as well as Ruston Proctor & Co. Ltd who began immediate, parallel development to Low's own at the RFC. Granville Bradshaw of A.B.C. Motors Ltd. who gained fame by designing the well proven 45 hp Gnat engine subsequently designed a throwaway engine specifically for use in the RPV.
The 35 hp was a horizontally-opposed twin cylinder engine with a run life of 2 hours. It was this lightweight inexpensive engine that propelled RPV research and development into the next phase. In the mean time Sopwith had developed the 14ft wingspan "Sopwith AT" (AT = air target) which was fitted with the 35 hp ABC engine driving an ordinary wooden propeller. The radio box was further back towards the tail behind the fuel, batteries and of course the explosives.
The sensitive radio equipment was fitted into a wooden box with a glass lid, suspended on rubber supports. The box itself measured about 2ft 3in by 9in. This box contained all of the relays, receiver and the Key system which was an interference filter. An interesting note here, a shaft which was driven by the engine triggered a mechanical relay so that each contact made in the control box caused the engine power to operate the control services. The date was 1916 and the Sopwith AT was completed with full servo control. It never flew because it was subsequently damaged while in hangar and abandoned (sound familiar?).
The ironic end result was the creation of the Sopwith Sparrow which was a small, single seat aircraft which did in fact have a pilot after all. Naturally this is not the end of our story, enter Geoffrey de Havilland. De Havilland built a little mono plane around the lightweight ABC expendable engine. It is believed that it was the de Havilland monoplane which flew on a March 21st, 1917 test flight at Upavon. The rumor is that high ranking officials were invited to attend and were quickly dispersed in a rather comical fashion when the initial test flight went awry as they so often do. No more is known.
Later that year H.P. Folland the designer of the S.E.5 fighter embarked on task to build an aircraft using Low's radio equipment. By July of 1917 he had 5 aircraft ready for flight and on July 6, 1917 the first flight was conducted. The aircraft rolled smoothly along on a 150 ft launch track and became airborne mid way. The craft rose steeply, stalled and plummeted to the ground (sound familiar?). Two more tests were conducted on July 25 and 28 but the aircraft were under controlled and the entire "R/C" program slowed to a trickle until the end of the war.
Late in the War there was some research and development in the U.S. but it was relegated to gyroscopically controlled flying bombs and as such do not merit discussion here. It wouldn't be until September 3rd, 1924 when we would see the very first successful radio control flight of a lighter than air craft. From the decks of H.M.S. Stronghold a 23 ft wings span craft designated the RAE Target made a fully controlled 12 minute flight. The only reason why the flight ended was because the engine stopped (sound familiar ?). Success at last!
Subsequent flights off of the Stronghold were proving the viability of the notion of Radio Controlled flight. In fact the duration of the 10th flight was 39 minutes long. The flight was so successful that the RAE recorded a record 43 separate commands. Once the news of this reached the powers that be the RAE was given the go ahead to do what comes naturally...build it bigger and better with a larger pay load.
Thus the LARYNX was born. This mid- winged mono plane was designed to hold 250lbs of high powered explosives and travel a distance of over 300 miles. The Armstrong Siddeley Lynx - 200 hp engines was enclosed in a low drag cowling at the front end of a light weight tubular fuselage and attained the impressive speed of over 190 mph in the year - 1927.
This aircraft was years ahead of its kind and was even faster than its contemporary, manned, fighter planes. When it came time to actually replace the empty payload section with the intended explosives and field test the "flying bombs" they decided to forgo the R/C and install gyroscopes. They sent these aircraft to Iran where all of them failed miserably except one. This aircraft sailed off into the distance never to be seen or heard from again (sound familiar?). Whether the payload exploded or not, no one will ever know.