An unmanned combat air vehicle (UCAV), also known as a combat drone or drone, is an unmanned aerial vehicle (UAV) that is usually armed. These aircraft hav Unmanned aerial vehicles, known variously as UAVs, drones, and remotely piloted vehicles (RPVs), have been a feature of aviation for much of its history, though often overlooked. For the purposes of this article, and to distinguish UAVs from missiles, a UAV is defined as being capable of controlled, sustained level flight and powered by a jet or reciprocating engine. The appeal of a military vehicle in which there is no risk of loss of life is quite strong, so the pace of development of UAVs has always reflected the pace of technology in general. Until recently, UAVs have tended to be small, so they depend on technology miniaturization even more than their manned siblings. In the 21st century, the technology has reached a point of sophistication that the UAV is now being given a greatly expanded role in war fighting.

The Austrian balloons

The earliest recorded use of an unmanned aerial vehicle for warfighting occurred on August 22, 1849, when the Austrians attacked the Italian city of Venice with unmanned balloons loaded with explosives. At least some of the balloons were launched from the Austrian ship Vulcano. Although some of the balloons worked, others were caught in a change of wind and blown back over Austrian lines.[1] The Austrians had been developing this system for months: "The Presse, of Vienna, Austria, has the following: 'Venice is to be bombarded by balloons, as the lagunes prevent the approaching of artillery. Five balloons, each twenty-three feet in diameter, are in construction at Treviso. In a favorable wind the balloons will be launched and directed as near to Venice as possible, and on their being brought to vertical positions over the town, they will be fired by electro magnetism by means of a long isolated copper wire with a large galvanic battery placed on a building. The bomb falls perpendicularly, and explodes on reaching the ground.'"[2] Although balloons do not generally meet today's definition of a UAV, the concept was strong enough that once winged aircraft had been invented, the effort to fly them unmanned for military purposes was not far behind.

World War I

The first pilotless aircraft were built during and shortly after World War I. Leading the way, using A. M. Low's radio control techniques, was the "Aerial Target" of 1916.[3] If developed further it was to have been used against Zeppelins. Soon after, on September 12, the Hewitt-Sperry Automatic Airplane, otherwise known as the "flying bomb" made its first flight, demonstrating the concept of an unmanned aircraft. They were intended for use as "aerial torpedoes" an early version of today's cruise missiles.[clarification needed] Control was achieved using gyroscopes developed by Elmer Sperry of the Sperry Gyroscope Company.[4]

Later, in November 1917, the Automatic Airplane was flown for representatives of the US Army. This led the army to commission a project to build an "aerial torpedo", resulting in the Kettering Bug which first flew in 1918. While the Bug's revolutionary technology was successful, it was not in time to fight in the war, which ended before it could be fully developed and deployed

Interwar period

After World War I, three Standard E-1s were converted as drones.[6] The Larynx was an early cruise missile in the form of a small monoplane aircraft that could be launched from a warship and flown under autopilot; it was tested between 1927 and 1929 by the Royal Navy. The early successes of pilotless aircraft led to the development of radio controlled pilotless target aircraft in Britain and the US in the 1930s. In 1931, the British developed the Fairey "Queen" radio-controlled target from the Fairey IIIF floatplane, building a small batch of three, and in 1935 followed up this experiment by producing larger numbers of another RC target, the "DH.82B Queen Bee", derived from the De Havilland Tiger Moth biplane trainer. Through some convoluted path, the name of "Queen Bee" is said to have led to the use of the term "drone" for pilotless aircraft, particularly when they are radio-controlled.[7] However during this period the U.S. Navy, continuing work that reached back to 1917, was also experimenting with radio controlled aircraft. In 1936 the head of this research group used the term "drone" to describe radio controlled aerial targets.[8]