Unmanned Aerial Vehicles (UAVs) include both autonomous (capable of operating without human input) drones and remotely piloted vehicles (RPVs). The UAVs used in World War I were RPVs. Soon after its change from the Army Balloon Factory to the Royal Aircraft Factory in 1912, designers at this Farnborough base turned their thoughts to flying an unmanned aircraft. During the First World War this pioneering work resulted in trials of remotely controlled aircraft for the Royal Flying Corps and unmanned boats for the Royal Navy that were controlled from 'mother' aircraft.Low (1952) p 436 By the end of the war Britain had flown and controlled a drone aircraft and a number of fast unmanned motor boats operating in close flotilla formation that had been individually controlled by radio from operators flying in 'mother' aircraft. The work continued in the interwar years.
The Factory 1914 design There is a Royal Aircraft Factory engineering drawing of October 1914 of an unmanned powered monoplane long with a wingspan.Mills (2019) p20 This was developed as a means to counter the threat of aerial bombing from German dirigible airships. This new potential weapon was called Aerial Target (AT), a misnomer to fool the Germans into thinking it was a drone to test anti-aircraft systems.Low (1952)
Ruston Proctor Henry Folland at the Royal Aircraft Factory designed an AT powered by an ABC Gnat engine which was built by Ruston Proctor of Lincoln in 1916 and 1917.Lewis 1978, p. 101.
Sopwith With Harry Hawker, Sopwith at Kingston upon Thames built a single-bay biplane AT with a wingspan of about which was to carry a explosive charge. Stability came from pronounced dihedral and there was a four-wheel undercarriage. The aircraft was damaged during erection at Feltham and was never tested. The design was later reworked into the Sopwith Sparrow.Mills, 2019 pp. 197–198King, 1981, pp. 233–234
1917 Aerial Target The history of UAV target drones started when the Royal Flying Corps developed their prototype remote controlled aircraft and gave it the cover name Aerial Target (AT). All the 1917 Aerial Target aircraft from the various designers used the radio control system devised by Archibald Low at the RFC's Experimental Works in Feltham.Bloom (1958) p. 80Everett, H. R. 2015. Unmanned Systems of World Wars I and II. Cambridge: MIT Press p. 270 onwards One of Geoffrey de Havilland's AT aircraft powered by a Gnat engine that was launched from a pneumatically powered ramp in the RFC trials at Upavon on 21 March 1917 became the world's first powered drone aircraft to fly under radio control. The engine driven actuator applied progressively increasing deflection of the selected control (elevators or rudder) up to its limit until the selection lever was released by the ground operator. With no control demanded, the control surface was returned to its trim position by springs.IWM Q 68003 The mechanism was later exhibited by the IWM as "The original model receiving set installed in the radio controlled monoplane used in the trial flight".IWM Q 68006 along with the Selective Transmitter which the operator on the ground used to send control the control signals.IWM Q 68010
Low's system's encoded the command transmissions as a counter-measure to prevent enemy intervention. These codes could be changed daily,
By July 1917, six Aerial Targets designed by the Factory had been built and were tested at Northolt. Attempts were made to launch the first three from rails laid on the ground but they all crashed on launching and the trials were terminated.Allen (2015) pp. 31–34 The Aerial Target was later acknowledged to be a viable weapon, "...aircraft carrying high explosive charges are capable of being controlled by wireless....". The AT project was transferred to Biggin Hill, to what became the Wireless Experimental Establishment. By 1922 the work had been returned to the Royal Aircraft Establishment (RAE) at Farnborough.Allen (2015) p.36
The Royal Flying Corps 1917 Guided Rocket
Archibald Low said "...in 1917 the Experimental Works designed an electrically steered rocket... Rocket experiments were conducted under my own patents with the help of Cdr. Brock".Flight 3 October 1952, A. M. Low, "The First Guided Missile" p. 436. Like Low, Brock was an experimental officer who commanded the Royal Navy Experimental Station at Stratford; Brock was also a Director of the C.T. Brock & Co. fireworks manufacturers. The patent "Improvements in Rockets" was raised in July 1918 referring by then to the Royal Air Force but was not published until February 1923 for secrecy. Firing and guidance controls could be either wire or wireless. The propulsion and guidance rocket eflux emerged from the deflecting cowl at the nose. The 1950s IWM exhibition label states "Later in 1917, an electrically steered rocket was designed.... with the designed purpose of pursuing a hostile airman." A model of this dirigible rocket was included in this exhibition.IWM Q 68009 The model was accompanied by a note: "Exhibit that is part of Professor AM Low's exhibits. Model of the wireless controlled dirigible rocket missile designed to pursue a hostile airman".
Radio guidance and the Feltham Unit
During World War One, work started on radio guided weapons at various establishments, such as the experiments of Capt. Cyril Percy Ryan at Hawkcraig Experimental Station (H.M.S. Tarlair).Mills (2019) p251 However, as control by the Munitions Inventions Department over military research was introduced, a centre for the Royal Flying Corps radio guided weapons was established. This was the secret Experimental Works in Feltham. The focus of their work was radio guided systems but the unit also assisted with other tasks.Low (1952) p437 "Our works often had queer things sent to us for test, including 'land torpedoes,' but nothing deflected our main aim." They were involved in testing the Pomeroy bullet and George Constantinescu's synchronization gear. They provided 'distractions' for the Zeebrugge raid and its Commanding Officer Archibald Low, travelled to France and into neutral Spain during the war to debunk reports of 'fantastic' weapons.Low (1952) p. 436 "For that Mole attack I had prepared a radio-fired bomb device by which any one of a number of floating buoys could be selected and exploded by radio."Bloom (1958) p 82 "the preparation of bombs, which although successful, only just operated in time for Commander Brock to see them in the last hours of his life at Zeebrugge."Mills (2019) p. 224 Low had at least 30 specialists under his command at Feltham supported by their contractors and suppliers. They had motor transport and military and police security. Their balloon facility was used to conduct radio reception experiments and they tested their equipment using aircraft with trailing aerials. Low was a qualified RFC observer. His officers included his second in command Henry Poole, his radio engineer George Whitton, the talented inventor Ernest Bowen and the carburation specialist Louis Mantell.
Low was commended for this work by a number of senior officers including Sir David Henderson (the wartime commander of the RFC) and Admiral Edward Fitzherbert (Director of Mines and Torpedoes). Sir Henry Norman (Chairman of the War Office Committee on Wireless Telegraphy and at this time the Munitions Inventions Department's permanent attaché to the French Ministry of Inventions.) wrote to Low in March 1918, saying "I know of no man who has more extensive and more profound scientific knowledge, combined with a greater gift on imaginative invention than yourself."Mills (2019) p. 215
Their work had started in 1915 at the commercial motor garage business owned by Henry Poole, in Chiswick. During 1916 the development showed such promise that the RFC established their secret Experimental Works in premises commandeered from the Davis Paraffin Carburettor Company and the Duval Composition Company, in the old Ivory Works in Feltham. Later these Experimental Works were moved to Low's premises at 86 High Street, Feltham where all the Navy work was also carried out in 1918.Mills (2019) p. 165
The Adjutant-General investigation
Details of the Feltham Experimental Works have survived in the records of a legal claim against Archibald Low. On 5 December 1917 he was accused of plagiarism and abuse of office by a civilian inventor Clifton West. On 26 January 1918 Colonel Ernest Swinton provided his friend John Morgan with an assessment of Clifton West as "...a clever man and very ingenious, but tends towards the type of inventions 'crank'. He is also the most perfect mug in the world, as I have told him and is like a bit of toasted cheese to all the rats and crooks within a hundred miles: they smell him coming and get out their Bowie knives". The case against Archibald Low was not pursued.Mills (2019) chapter 17 page 237 Clifton's plagiarism case involved his Land Torpedo, a rolling cable drum device to snag and destroy barbed wire defences, similar to that patented under instruction from his superiors on behalf of the RFC by Archibald Low.Patent 192,093 Application date 31 August 1917 Publication date 22 February 1923 "Improvements in Apparatus for Destroying Wire or like Defensive or other Obstacles."
1918 aircraft-controlled unmanned boats
In 1917 the priority for Low's control system changed; the new imperative being to counter the submarine threat. Low and Ernest Bowen transferred into the Royal Navy to adapt the AT system to the airborne control of Royal Navy Distance Control Boats (DCB), a variant of the Coastal Motor Boat to be filled with an explosive charge. Thornycroft were contracted to design these new DCB's (and the conversions of some of the existing CMBs) to carry this large and heavy explosive payload in the bow. The resulting craft was considered to be fragile though seaworthy (but only in fair weather). The AT work was documented and transferred to Royal Flying Corps radio unit at Biggin Hill. The Feltham Works were still under Low's command and this is where the redevelopment and production of equipment was carried out, clock-driven impulse senders for DCBs being ordered on 13 March 1918. The port/starboard demand from the controller's sender units in the aircraft caused a gyroscope on the boat to change the direction of its axis by "precession" to the "new" required heading. Any "difference" between the boats current heading and the required heading (i.e. the gyroscopes alignment) started an electric motor driving a worm gear in the appropriate direction to turn the rudder. This reduced any "difference" as the boat responded and acquired the new required heading. Thus any difference caused the boat to manoeuvre to keep it on the gyroscope's "required" heading, whether that difference occurred due to wave, wind or tide deflecting the boat or to control signal demands from the "mother" aircraft precessing the gyroscope.Patent Specification 244,302 (Application date 2 April 1918, publication delayed for security Publication date 14 January 1926)
Conversions of the 40-ft CMBs Number 3, 9 and 13 were three of the five DCBs built.