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Further Information

1910s & 1920s

With the Wright brothers' first flight of an airplane in 1903, and Glenn Curtis's creating the first hydroplane to take off and land from water in 1911, the aviation industry was off to a rapid start at the outset of the 20th century. Within a few years, military institutions were investigating the possibility of unmanned aircraft for use as drones, torpedoes, and bombs. These were the pioneers of unmanned aerial vehicles, working to meet brand-new challenges - namely, how to make a plane fly safely, in a specific direction, and for a specific amount of time, with no-one inside. 

RAF Aerial Target (UK, 1916-17)

The Aerial Target (AT) was a radio-controlled, unmanned airplane conceived in late 1916, designed both for defense against Zeppelins (where it would be controlled from the ground), and as a flying bomb (for which control from an accompanying manned aircraft was considered).  It was constructed in the P. Hare Royal Aircraft Factory, in Putnam. The idea for the plane was that of Captain Archibald M. Low of the RFC's wireless unit at Feltham. Although he attempted to build the plane himself, largely from spare parts, he was unsuccessful and thus requested  the assistance of the Royal Aircraft Factory. He did, however, design the wireless apparatus for the final AT. 

The design consisted of a small shoulder-wing monoplane mounted with a 2-cylinder ABC air cooled engine producing 35hp. Radio aerial wiring ran vertically down the side of its fuselage, and chord-wise across the wings, as seen below. Lateral control was achieved through wing-warping, and an extensive dihedral maintained lateral stability (vectorsite)

(below) The AT Source: http://flyingmachines.ru

Six examples were constructed (A8957 to A8962), with the first delivered to RFC Northolt. The AT's first flight, on July 6, 1917, consisted of a near-vertical take-off followed by a stall and a crash, all occurring before the radio took effect. A second example was tested on July 25th but failed to take off, simply running along the ground until its undercarriage collapsed. On a third attempt three days later, the correct angle adjustments were made to the tailplane of the AT, but the test still resulted in a crash as the engine failed shortly after take-off. (NOVA)

Even though damage was repairable, official interest began to dissipate after this final attempt, although the project was briefly resurrected in the 1920s. 

  Span 6.7m; length 6.2m; height 1.79m
  Chord 1.57m; incidence 6°; dihedral 5°
  Weight 227kg

Sperry Aerial Torpedo and Kettering Bug (USA, 1916-18)

Brothers Elmer and Lawrence Sperry were very prominent pioneers in the field of aeronautics, notably stabilizers, gyroscopes, and the like. Elmer Sperry had 350 patents to his name, and Lawrence Sperry invented an automatic gyroscope that enabled aircraft to fly level without the need for human intervention. In 1916, they incorporated a 'steering gyroscope' with the automatic gyro to create one of the first 'automatic pilot' systems in the world. That same year, Lawrence Sperry filed a patent for an aerial torpedo (unmanned aircraft) which featured:
  • A gyro-stabilizer to keep the aircraft level 
  • An automatic steering gyroscope to keep the aircraft on a specified heading
  • A barometer, indicating cruising altitude in order for the aircraft to level off
  • An engine-revolution counter to determine the point at which the aircraft should cut power and begin descent to its target.
The gyro motors and servo-motors would be powered by a wind-driven generator. (NOVA)

The US Navy awarded the Sperry Gyroscope Company $200,000 to construct this aircraft. The brothers began working with Curtis to develop it, and in 1917 Curtis delivered the first purpose-built torpedo airframe, powered by a two-cylinder engine. On March 6th, 1918, a guided missile flew for the first recorded time, successfully. Further tests of the Curtis torpedo did not go well, and Sperry engineers reverted to another design. (right: The Sperry Torpedo on its launch system)

In the meantime, Charles F. Kettering was directing the US Army's own aerial torpedo project. Kettering wanted to build a simpler, cheaper torpedo than the Sperry brothers' version. Orville Wright contributed to the building of the Kettering torpedo's airframe, and another engineering team designed the motor, a 30kW (40hp) V4 which ultimately cost about $50. A third team designed a cheap and portable launch system - a four-wheeled cradle on rails.  However, Kettering was unable to build his own autopilot system, and had to have Elmer Sperry lend his assistance. Ultimately the Kettering Aerial Torpedo consisted of a wood-reinforced papier-mache fuselage and 12-foot cardboard wings, costing about $400 per torpedo. It featured much of the same technical aspects as the Sperry torpedo (gyroscope, barometer, revolution counter...)

The first test flight, in 1918, when it was given the name 'The Bug', did not go well. Subsequent tests were more successful, to the point that the Army ordered a large amount of prototypes. As the armistice took effect, however, the Navy and Army programs were combined. Later competitive tests favored the Curtis-Sperry torpedo, and the Kettering Bug was abandoned. Over the next few years, official interest in unmanned aerial torpedoes generally decreased.

Kettering Bug Specs:
   wingspan              4.6 m          
   length                    3.8 m          
   total weight           240 kg      
   warhead weight   80 kg       
   speed                   195 KPH             
   range                    120 KM              
   source: vectorsite.net  

(right) The Kettering Bug ready for take-off

Long-Range Gun with Lynx Engine (RAE LARYNX) (UK, 1925-27)
In September 1925,  work on this new British unmanned aerial vehicle began. It featured a radial engine and a gyroscopic control engine, built by the Royal Aeronautical Establishment for the Royal Navy. It was powered by an Armstrong Siddeley Lynx IV engine producing 200Hhp; its top speed was 320kph faster than fighters of the time.  Its autopilot principles were developed by professor A. Lowe, who had already designed the autopilot apparatus for the Aerial Target (AT).
 In 1927, the LARYNX had its first test, launched from a catapult fitted on to the Destroyer HMS Stronghold.  It was tested six more times over the course of the following two years, producing few fully-successful launches. Its last test in May of 1929 was from land, and was a success. A number of LARYNX missiles were seemingly also tested in the deserts of Iraq, armed with a 113 kg warhead. Results were, however, reportedly inconclusive. 

(right)  The RAE LARYNX on the cordite-fired catapult on the HMS Stronghold. 
On the box is Dr. George Gardner, future director of  RAE