History of unmanned aerial vehicles

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 in limited or secondary roles, and 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.

Early development

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 [ [http://www.ctie.monash.edu/hargrave/rpav_home.html#Beginnings Monash University UAV history] ] . 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 the shore. The bomb falls perpendicularly, and explodes on reaching the ground.'" ["Scientific American", March 1849] Although balloons don't 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 1

The first pilotless aircraft, intended for use as "aerial torpedoes" or what would now be called "cruise missiles", were built during and shortly after World War I. Leading the way was A. M. Low's "Aerial Target" of 1916. [Taylor, A. J. P. "Jane's Book of Remotely Piloted Vehicles".] 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. Control was achieved using gyroscopes developed by Elmer Sperry of the Sperry Gyroscope Company. [ [http://www.history.navy.mil/download/ww1-10.pdf Pearson, Lee: "Developing the Flying Bomb"] ]

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. [ [http://www.daviddarling.info/encyclopedia/K/Kettering_Bug.html Encyclopedia of Astrobiology, Astronomy, and Space Flight: Kettering Bug] ] After WW1, three Standard E-1s were converted as drones, also. [Donald, David, ed. "Encyclopedia of World Aircraft" (Etobicoke, Ontario: Prospero Books, 1997), p.854, "Standard aircraft".]

British drones

The early successes of pilotless aircraft led to the development of radio controlled (RC) 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. [ [http://www.vectorsite.net/twuav_01.html#m1 Unmanned Aerial Vehicles by greg goebel] ]

World War 2

Reginald Denny and the Radioplane

The first large-scale production, purpose-built drone was the product of Reginald Denny. He served with the British Royal Flying Corps during World War I, and after the war emigrated to the United States to seek his fortunes in Hollywood as an actor. Denny had made a name for himself as an actor, and between acting jobs, he pursued his interest in radio control model aircraft in the 1930s. He and his business partners formed "Reginald Denny Industries" and opened a model plane shop in 1934 on Hollywood Boulevard known as "Reginald Denny Hobby Shops". [ [http://www.ctie.monash.edu.au/hargrave/dennyplane.html Reginald Denny Hobby Shops] ]

The shop evolved into the "Radioplane Company". Denny believed that low-cost RC aircraft would be very useful for training anti-aircraft gunners, and in 1935 he demonstrated a prototype target drone, the RP-1, to the US Army. Denny then bought a design from Walter Righter in 1938 and began marketing it to hobbyists as the Dennymite, and demonstrated it to the Army as the RP-2, and after modifications as the RP-3 and RP-4 in 1939. In 1940, Denny and his partners won an Army contract for their radio controlled RP-4, which became the OQ-2 Radioplane. They manufactured nearly fifteen thousand drones for the army during World War II.

It was at the Van Nuys Radioplane factory that in 1944 that Army photographer David Conover saw a young lady named Norma Jeane, and thought she had potential as a model. This "discovery" led to fame for Jeane, who soon changed her name to Marilyn Monroe.

Aerial torpedoes

The US Navy began experimenting with radio-controlled aircraft during the 1930s as well, resulting in the Curtiss "N2C-2" drone in 1937. The N2C-2 was remotely controlled from another aircraft, called a TG-2. N2C-2 anti-aircraft target drones were in service by 1938.Fahrney, Delmar S., RADM USN "The Birth of Guided Missiles" "United States Naval Institute Proceedings" December 1980 pp.54-60]

The US Army Air Forces (USAAF) adopted the N2C-2 concept in 1939. Obsolescent aircraft were put into service as "A-series" anti-aircraft target drones. Since the "A" code would be also used for "Attack" aircraft, later "full-sized" targets would be given the "PQ" designation. USAAF acquired hundreds of Culver "PQ-8" target drones, which were radio-controlled versions of the tidy little Culver Cadet two-seat light civil aircraft, and thousands of the improved Culver "PQ-14" derivative of the PQ-8. The US also used RC aircraft, including modified B-17 and B-24 bombers, in combat on a small scale during World War II as aerial torpedoes, though with no great success.

The Naval Aircraft Factory assault drone "Project Fox" installed an RCA television camera in the drone and a television screen in the TG-2 control aircraft in 1941. In April 1942 the assault drone successfully delivered a torpedo attack on a destroyer at a range of 20 miles from the TG-2 control aircraft. Another assault drone was successfully crashed into a target moving at eight knots. The Navy Bureau of Aeronautics then proposed a television-assisted remote control assault drone program of 162 control planes and 1000 assault drones. Disagreements arose within the Navy concerning the relative advantages of the proposed program for full scale combat implementation versus a small scale combat test with minimum aircraft resource expenditure which might reveal the concept to the enemy and allow development of countermeasures prior to full production. Assault drones remained an unproven concept in the minds of military planners through major allied advances of 1944. Utilization was limited to a 4-drone attack on a beached Japanese merchant ship in the Russell Islands at the end of July followed by expenditure of 46 drones in the northern Solomon Islands. Two hits and two near-misses were scored on the stationary ship. Several of the later drones failed to reach their targets, but most were effective.

Pulsejets

Although small piston engines were the normal powerplant for target drones in this era, there was something of a fad for pulsejet propulsion as well, though it doesn't appear that the US military ever acquired any pulsejet-powered targets in more than modest numbers.

McDonnell built a pulsejet-powered target, the T2D2-1 Katydid, later the KDD-1 and then KDH-1. It was an air-launched cigar-shaped machine with a straight mid-mounted wing, and a vee tail straddling the pulsejet engine. The Katydid was developed in mid-war and a small number were put into service with the US Navy.

After the war, the Navy obtained small numbers of another pulsejet-powered target, the KD2C Skeet series, built by Curtiss. It was another cigar-shaped machine, with the pulsejet in the fuselage and intake in the nose. It featured straight, low-mounted wings with tip tanks, and a triple-fin tail.

Korea and Vietnam

Target drone evolution

In the post-World War II period, Radioplane followed up the success of the OQ-2 target drone with another very successful series of piston-powered target drones, what would become known as the Basic Training Target (BTT) family (the BTT designation wasn't created until the 1980s, but is used here as a convenient way to resolve the tangle of designations), including the OQ-19/KD2R Quail, the MQM-33/MQM-36 Shelduck and the MQM-57 Falconer. The BTTs remained in service for the rest of the 20th century.

The US military acquired a number of other drones similar in many ways to the Radioplane drones. The Globe company built a series of targets, beginning with the piston-powered "KDG Snipe" of 1946, which evolved through the "KD2G" and "KD5G" pulsejet-powered targets and the "KD3G" and "KD4G" piston-powered targets, to the "KD6G" series of piston powered targets. The KD6G series appears to have been the only one of the Globe targets to be built in substantial numbers. It was similar in size and configuration to the BTT series, but had a twin-fin tail. It was redesignated "MQM-40" in the early 1960s, by which time it was generally out of service.

The use of drones as decoys goes back at least to the 1950s, with the Northrop Crossbow tested in such a role. The first operational decoy drone was the McDonnell Douglas "ADM-20 Quail", which was carried by Boeing B-52 Stratofortress bombers to help them penetrate defended airspace.

By the late 1950s combat aircraft were capable of Mach 2, and so faster targets had to be developed to keep pace. Northrop designed a turbojet-powered Mach 2 target in the late 1950s, originally designated the Q-4 but later given the designation of AQM-35. In production form, it was a slender dart with wedge-shaped stubby wings, swept conventional tail assembly, and a GE J85 turbojet engine, like that used on the Northrop F-5 fighter.

Reconnaissance platforms

In the late 1950s, along with the Falconer, the US Army acquired another reconnaissance drone, the Aerojet-General "MQM-58 Overseer". It had a similar configuration to the Falconer, but featured a vee tail and was about twice as heavy. It does not appear to have been built in large quantities, and may have never been much more than an experimental platform to evaluate more sophisticated reconnaissance sensors than could be carried by the Falconer.

The success of drones as targets led to their use for other missions. The well-proven Ryan Firebee was a good platform for such experiments, and tests to evaluate it for the reconnaissance mission proved highly successful. A series of reconnaissance drones derived from the Firebee, the Ryan Model 147 Lightning Bug series, were used by the US to spy on Vietnam, China, and North Korea in the 1960s and early 1970s.

The Lightning Bugs were not the only long-range reconnaissance drones developed in the 1960s. The US developed other, more specialized reconnaissance drones: the Ryan "Model 154", the Ryan and Boeing "Compass Copes", and the Lockheed "D-21", all of which were more or less cloaked in secrecy.

ecret projects

The USSR also developed a number of reconnaissance drones, though since everything the Soviets did was cloaked in secrecy, details of these aircraft are unclear and contradictory.

Cold war era

The usefulness of robot aircraft for reconnaissance was demonstrated in Vietnam. At the same time, early steps were being taken to use them in active combat at sea and on land, but battlefield UAVs would not come into their own until the 1980s.

Modern target drones are usually launched by aircraft; or off a rail using solid-fuel rocket assisted takeoff (RATO) boosters; or hydraulic, electromagnetic, or pneumatic catapult. Very small target drones can be launched by an elastic bungee catapult. Few target drones have landing gear, and so they are generally recovered by parachute or, in some cases, by a skid landing.

Era of the robot warrior

Battlefield UAVs

After some fumbling, the US military now seems to be acquiring an effective fleet of battlefield UAVs. The US military is entering a new era in which UAVs will be critical to SIGINT payloads, or ECM systems should be in widespread use following 2010, with the UAVs controlled and relaying data back over high-bandwidth data links in real time, linked to ground, air, sea, and space platforms. The trend had been emerging before the American war in Afghanistan began in 2001, but was greatly accelerated by the use of UAVs in that conflict. The Predator RQ-1L UAV (General Atomics)was the first deployed UAV to the Balkans in 1995 Iraq in 1996 and was proved very effective in OIF as well as Afganistan.

Micro UAVs

Another growth field in UAVs are miniature UAVs, ranging from "micro air vehicles (MAVs)" that can be carried by an infantryman to man-portable UAVs that can be carried and launched like an infantry anti-aircraft missile.

Endurance UAVs

The idea of designing a UAV that could remain in the air for a long time has been around for decades, but only became an operational reality in the 21st century. Endurance UAVs for low-altitude and high-altitude operation, the latter sometimes referred to as "high-altitude long-endurance (HALE)" UAVs, are now in full service.

On August 21, 1998, an Insitu Aerosonde named "Laima" becomes the first UAV to cross the Atlantic Ocean, completing the flight in 26 hours.

U.S. domestic use

The U.S. Customs and Border Protection agency has experimented with several models of UAVs, and has begun purchasing a fleet of unarmed MQ-9 Reapers to survey the U.S. border with Mexico. "In more than six months of service, the Predator's surveillance aided in the arrest of nearly 2,000 illegal immigrants and the seizure of four tons of marijuana, border officials say." cite web |url=http://www.mail-archive.com/[e-mail]/msg12701.html |title="Drones in Domestic Skies? They're in Demand for Rescue And Surveillance Missions, But Critics Question Safety" |accessdate=2006-11-07 |author=Jonathan Karp and Andy Pasztor |authorlink= |coauthors= |date=2006-08-07 |year= |month= |format= |work=Wall Street Journal |publisher= |pages= |language= |archiveurl= |archivedate= |quote= ]

On March 20, 2007, an unmanned Border Protection agency UAV detected and led agents to six suspected aliens, including Mexican national Leopoldo Aparicio-Lopez, who had been wanted in Washington state on charges of third-degree rape of a child. Aparicio-Lopez was one of six suspected illegals in the group, and 395 pounds of marijuana were also seized during the arrest, federal officials said. [ [http://www.cnn.com/2007/US/03/22/plane.border/index.html Unmanned plane finds child sex abuse suspect] , "cnn.com", 22 March 2007. Accessed 23 March 2007.]

On May 18, 2006, the Federal Aviation Administration (FAA) issued a certificate of authorization which will allow the M/RQ-1 and M/RQ-9 aircraft to be used within U.S. civilian airspace to search for survivors of disasters. Requests had been made in 2005 for the aircraft to be used in search and rescue operations following Hurricane Katrina, but because there was no FAA authorization in place at the time, the assets were not used. The Predator's infrared camera with digitally-enhanced zoom has the capability of identifying the heat signature of a human body from an altitude of 10,000 feet, making the aircraft an ideal search and rescue tool. [ [http://www.af.mil/news/story.asp?storyID=123024467 SSgt Amy Robinson, "FAA Authorizes Predators to seek survivors," August 2, 2006] ]

According to a 2006 Wall Street Journal report, "After distinguished service in war zones in recent years, unmanned planes are hitting turbulence as they battle to join airliners and weekend pilots in America's civilian skies. Drones face regulatory, safety and technological hurdles -- even though demand for them is burgeoning. Government agencies want them for disaster relief, border surveillance and wildfire fighting, while private companies hope to one day use drones for a wide variety of tasks, such as inspecting pipelines and spraying pesticides on farms."

mall-player use

At one time the cost of miniature technology limited the usage of UAVs to larger and better funded groups such as the US military, but due to falling costs of UAV technology, including vehicles and monitoring equipment in their simpler forms, it has become available to groups that before wouldn't have had the funding to utilize it. Beginning in 2004, the Lebanese Shi'ite militia Hezbollah began operating the Mirsad-1 UAV, with the stated goal of arming the aircraft for cross-border attacks into Israel. [http://www.armscontrol.ru/UAV/mirsad1.htm Moscow Institute of Physics and TechnologyCenter for Arms Control Energy and Environmental Studies]

Late US Target Drones

*Beech MQM-107 Streaker / CEI BQM-167 Skeeter
*US Army FQM-117 Targets / MQM-170A Outlaw / BATS
*Full-scale aircraft targets

ee also

* US Battlefield UAVs (1)
* International Battlefield UAVs (1)
* International Battlefield UAVs (2)
* List of unmanned aerial vehicles
* The prehistory of endurance UAVs
* Modern US endurance UAVs
* History of Unmanned Combat Air Vehicles
* Miniature UAVs

References

*Fahrney, Delmer S. (RAdm ret): "History of Radio-Controlled Aircraft and Guided Missiles"
*McDaid, Hugh & Oliver, David.: "Robot Warriors. The Top Secret History of the Pilotless Plane". Orion Media, 1997.
*This article contains material that originally came from the web article [http://www.vectorsite.net/twuav.html "Unmanned Aerial Vehicles"] by Greg Goebel, which exists in the Public Domain.