More than a dozen nations have developed unmanned aerial vehicles (UAVs), or pilotless aircraft. But the people who design, build, and operate these vehicles today probably would be surprised to learn that the first unmanned aircraft date back more than one hundred years.
In 1915, with World War I raging in Europe, Secretary of the Navy Josephus Daniels and inventor Thomas Edison proposed a board of prominent inventors to help prepare the United States for possible entry into the conflict. Thus was formed the Naval Consulting Board.1
Among the board’s members were scientist-inventors Peter Cooper Hewitt and Elmer Sperry. Hewitt had worked in the fields of radio and aeronautics, while Sperry’s genius had brought forth the Sperry Gyroscope. Hewitt began development of an “aerial torpedo” and soon involved Sperry in the project. Sperry’s son Lawrence already had demonstrated an automatic gyrostabilizer that enabled a Curtiss flying boat to fly straight and level without human interaction. In 1914, Lawrence had won a French prize of 15,000 gold francs for these demonstrations.
Soon Sperry took the lead, and by 1916 the father-son team had produced a workable “automatic pilot” system. Could this device enable an aircraft to fly without a pilot? As far back as 1891, Sir Hiram Maxim, an American-born Briton who invented the modern machine gun, believed such flight was possible. But the technology—and genius—were not yet available.
In 1916, Lawrence Sperry filed for a patent for an “aerial torpedo”—essentially an unmanned aircraft. Beyond automation based on Sperry devices, the aircraft would have a wind-driven generator to provide power for the gyro motors and servomotors that would move the control surfaces.
The Naval Consulting Board approved the Sperry-Hewitt aerial torpedo project in April 1917—the same month the United States entered the war—and awarded their firm $200,000 to build a prototype. Aircraft designer Glenn Curtiss constructed the aircraft for the Sperry flight system. A pioneer and contemporary of the Wright brothers, Curtiss already was providing aircraft to the Navy.
A Curtiss N-9 biplane flying boat was fitted with a Sperry autopilot. The flight trials were largely successful, although a pilot was on board for takeoff and landing and to observe performance of the system. In November 1917, Curtiss delivered the first of six purpose-built airframes for the aerial torpedo. Lawrence Sperry flew flight trials of the aircraft fitted with the autopilot. It was reported to have crashed four times with the young inventor on board. Before the month was out, “piloted” 30-mile flights were being made, with an error of about 2 miles in reaching the target.
Finally, on 6 March 1918, the aerial torpedo—sans pilot—took off, climbed to a predetermined altitude, and carried out smooth, stable flight for some 1,000 yards, until the test was automatically ended. In the operational mode, the “torpedo” would dive into the target. Subsequent tests did not go as well, and the Sperry team went back to the drawing board.
The Curtiss-built aircraft had a wingspan of some 23 feet, was slightly more than 14 feet long, and had a nose-mounted radial engine turning a two-blade propeller. The performance goal called for carrying a 1,000-pound explosive a distance of some 50 miles at a speed of approximately 90 miles per hour. The aircraft would take off on a cradle from a twin-rail launcher.
Meanwhile, the U.S. Army was developing its own aerial torpedo under the leadership of Charles F. Kettering. Kettering was well-known for having developed the automobile self-starter and other vehicle-related devices.2 After observing Sperry autopilot tests in late 1917, he sought to produce a cheaper, simpler unmanned aircraft. He called on Orville Wright to help develop the airframe for his aerial torpedo. Flight tests of the “Kettering Bug” began in September 1918. Again, there were early failures, but after some successful flight tests the Army ordered 100 of the Kettering aerial torpedoes.
The war ended in November 1918, and the U.S. government decided to combine the Army and Navy programs. Competitive trials favored the Navy-sponsored Sperry-Curtiss project, and the Kettering-Wright effort was abandoned. However, government interest in even the Sperry-Curtiss project waned over the next few years. Only in the later 1930s was serious thought again given to pilotless aircraft, with the U.S. Navy developing the Naval Aircraft Factory/Interstate TDN-1 unmanned aircraft and both the U.S. Navy and German Air Force developing air-launched guided bombs.
Note: The British also began developing “aerial torpedoes” in 1915.
1. That board was progenitor of the highly successful Naval Research Advisory Committee (NRAC), established in 1946 and dissolved this year. NRAC was the principal advisory body to the Secretary of the Navy.
2. Kettering later became the first head of the General Motors Research Laboratory. His name is associated with the Sloan-Kettering Cancer Research Institute in New York.