Early unmanned aircraft research in the United Kingdom

The RAE Larynx (Long Range Gun with Lynx Engine) missile on cordite-fired catapult of destroyer HMS Stronghold, July 1927. The man on the box is Dr. George Gardner; later Director of RAE.

British interest in the use of unmanned aircraft had a slightly different starting point. How to deal with the Zeppelin raids? At the Royal Aircraft Establishment (RAE) at Farnborough in England research efforts were under way into how to fly an unmanned aircraft.

Zeppelin raids over London and the south-east of England were a huge problem. They were affecting the morale of the people. What was needed urgently was a means of attacking the Zeppelins that would result in the airships being shot down. At the time British air defences, such as anti-aircraft fire, were not that effective. At first they were divided between the Royal Navy and the British army. In February 1916 the British army took full control. Some guns were converted to an anti-aircraft role with 271 being installed by the middle of 1916 alongside 258 searchlights.

The air defence element of the defence of the United Kingdom was also fragmentary. It was divided between the Royal Flying Corps and the Royal Naval Air Service (RNAS). The latter took responsibility for engaging the Zeppelins before they crossed the coast over the North Sea. The RFC then took on the task when the Zeppelin had crossed the coastline. In February 1916 fighter strength for the defence of the south-east of England was just ten squadrons and many of these were underequipped.

The main issue, however, was the armament on the fighter. The Vickers-Challenger interrupter mechanism that allowed bullets to be fired through the propeller was still several months away from becoming operational. Experimentation had proved it could work but it was not yet ready to be fitted to the B.E.12 fighters trying to bring down the Zeppelins. Initial trials with incendiary bullets were also unimpressive. There was also some uncertainty over the structure of the air bags on the Zeppelin. This led to suggestions that the airships were fitted with an outer envelope of inert gas to avoid ignition by incendiary bullets. Other more innovative approaches were therefore needed.

While it is difficult to be certain how many Zeppelins were destroyed by British air defences in the First World War, at least three incidents are documented. The first Zeppelin was brought down over Ghent in Belgium on 7 June 1915 by Sub-Lieutenant Reggie Warneford from the Royal Naval Air Service. During his flying training Warneford developed a reputation for aggressive flying. His first encounter with a Zeppelin had been less successful. On 17 May 1915 he tried to bring down Zeppelin LZ.39 as it approached the United Kingdom. Despite using a machine gun loaded with incendiary ammunition he failed to destroy the target. The airship simply ascended out of range by jettisoning ballast.

Days later Warneford brought down Zeppelin LZ.37, dropping six 20lb incendiary devices on the airship from above. It was a very brave and novel attack delivered with his customary panache in the face of a barrage of defensive fire from the Zeppelin. The last bomb succeeded in setting the target on fire. Of the crew of Zeppelin LZ.37 only one man survived, the helmsman, after it crashed in Sint-Amandsberg in Belgium.

The drama of the engagement was not over yet. The updraft from the explosion caught Warneford by surprise and flipped his Morane-Saulnier Type L aircraft onto its back in the air. His engine also cut out. Showing incredible calm in what was a very difficult situation, Warneford regained control of his aircraft and glided to land behind enemy lines. Repairs to the engine took him thirty-five minutes before he re-started it and took off to return to his base. For this Warneford was awarded the Victoria Cross. Sadly, he was to die only days later when the aircraft he was flying suffered a major structural collapse.

Just over a year later on 24 September 1916 Second Lieutenant Sowrey of 39 Squadron shot down the German navy Zeppelin L.32 over Great Burstead. In a more famous incident on 2 October 1916 Second Lieutenant Tempest of 39 Squadron shot down German navy Zeppelin L.31 over Potters Bar. Zeppelin L.48 was also destroyed by a B.E.12 on 17 June 1917. The fighter aircraft deployed at the time were simply inadequate. As the Zeppelins improved and were able to operate at higher altitude they simply became out of reach of the fighters which had a ceiling of 12,500 feet. Their rate of climb was also poor, taking eleven minutes to reach 5,000 feet.

But the idea of flying an unmanned aircraft carrying a warhead into a Zeppelin offered an alternative solution. The first generation of such a device was constructed at the P. Hare Royal Aircraft Factory in Putnam. The idea had come from Captain Archibald M. Low of the Royal Flying Corps signals unit at Feltham. It was called the AT: aerial torpedo. Years later at the end of the Second World War a manned version of this same idea was to appear over the Pacific Ocean. This was the fabled kamikaze.

The design of the AT was quite simple. It was a shoulder-wing monoplane driven by a two-cylinder ABC air-cooled engine that was able to produce 35hp. The radio antenna designed to allow it to be remotely controlled was affixed down the side of the fuselage. The overall weight of the aircraft was 500lb (227 kilos).

To achieve lateral control the wings were bent (warped) and stability was achieved by them being shaped at a dihedral angle. Six test aircraft were built. Its first flight occurred on 6 July 1917. The aircraft took off almost vertically, entered a stall and crashed. All of this occurred before the radio could have any effect on the controls. The second aircraft never left the ground, simply running along until its undercarriage collapsed. The third test also came to a quick end when the engine failed shortly after take-off.

In 1922 the RAE started testing its RAE 1921 Target aircraft. The results were not encouraging. All of the test aircraft flown from an aircraft carrier simply crashed into the sea. Controlling the aircraft at low speeds was clearly a problem. To resolve this issue a small radio system was added to provide control inputs from the point of take-off. What had up until then been a string of failures was halted. In 1924 the RAE Target 1921 flew for thirty-nine minutes at speeds of up to 100 mph. It flew for a distance of 65 miles.

The second generation of the design was quickly forthcoming. A monoplane called the Larynx was designed that could operate over a range of 100 miles. Its name was derived from a highly-contrived acronym that read Long Range Gun with Lynx Engine (LARYNX). Work on it started in 1925. It was capable of flying at a speed of 200 mph. This was surprisingly quick for the period and showed what was possible when the weight of a pilot was removed from a flying machine.

Its first test flight took place on 20 July 1927 in the Bristol Channel. It was launched from the S-class destroyer HMS Stronghold located in Swansea Bay. The aim was for the vehicle to fly to a point around 10 nautical miles north of Cape Cornwall. This was a distance of 200 kilometres (108 nautical miles). At the end point of the flight a drifter was anchored to observe the final moments before the aircraft hit the water. To help the observers at the target point pick up the aircraft, titanium tetrachloride was to be ejected from the platform in the last 5 miles of the flight.

The outcome of the flight was to be somewhat disappointing. When the engine was opened to full throttle a junior member of the team from Farnborough was due to make some final adjustments before it was released. At this point the trolley carrying the Larynx collapsed and the aircraft crashed forward onto the catapult causing the propeller to disintegrate. To compound matters the container carrying the titanium tetrachloride burst open and the unwitting junior scientist from the RAE was projected by the tailplane over the edge of a packing case onto the steel floor of the destroyer. It was an ignominious start to a career that would eventually see Dr Gardiner appointed as Director of RAE in 1955.

Other tests, however, produced more positive results. Five of the aircraft were then sent out to the RAF airbase at Basrah in Iraq. Testing was to involve live warheads each weighing 250lb (113 kilos). The first four tests again were inconclusive before the fifth crashed, having flown successfully in May 1929. Arguably this was the first cruise missile to fly over Iraq. It set a precedent that was to be repeated sixty-two years later at the outbreak of the First Gulf War.

Building on the developments made during the Larynx programme, the Royal Navy was anxious to develop a new series of target drones to help train naval gunnery teams. They needed a target that could manoeuvre to simulate the kind of airborne attack that might now occur on warships. The result of this saw the development of the De Havilland Queen Bee.

On his return to the United States Admiral Standley asked his research teams to develop a similar capability. In his book Unmanned Aviation: A Brief History of Unmanned Aerial Vehicles Laurence Newcome details the admiral’s requirements. What he was after was a radio-controlled seaplane that could fly at 100 knots to a ceiling of 10,000 feet.

Importantly, given the developments in dive-bombers, the unmanned aircraft should be capable of not only flying straight and level but also climbing, turning, gliding and descending into a 45˚ dive before pulling out. Throttle controls were to be fully under remote control by radio out to a range of 10 miles from the host vessel. Take-off was to be conducted either conventionally or using a catapult-assisted mechanism. Within a year the United States had developed its first target drone. Its control surfaces and throttles were manipulated through twelve radio channels.

In March 1937 the target drone and its controlling aircraft flew for the first time. A year later Adolf Hitler sent his German troops to occupy the Sudetenland. War in Europe was now almost inevitable. While in Britain the development of unmanned aircraft was being driven by the need to develop target drones for the Royal Navy, across the North Sea in Germany a far more advanced set of ideas had been traced out on the drawing board. This was the design concept for the world’s first cruise missile, the V-1 flying bomb or ‘doodlebug’. In June 1944 as the Allied landings started in France it was to make an appearance over the skies of England as the Third Reich tried to bomb the Allies to the negotiating table. It was a plan that would not succeed.

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