Uninhabited aerial vehicles Summary

  • Last updated on November 10, 2022

An airborne vehicle that operates without a pilot by either a preprogrammed system or an overriding command system operated from the ground.

Development of Uninhabited Aerial Vehicles

During World War II, Germany developed and deployed the first uninhabited aerial vehicle (UAV) known as the V-1. Built to attack a specific target, the V-1 was used once and was destroyed along with its target. The United States began developing uninhabited aircraft during the 1950’s to supplement crewed aircraft under Strategic Air Command (SAC). Capable of achieving intercontinental-range flight, the UAV, like its predecessor, also destroyed itself on contact with the target. After the Soviet Union launched Sputnik and then shot down a U-2 spy plane in the early 1960’s, the United States embarked on a reconnaissance program developed around the use of uninhabited aircraft. Ryan Aeronautical Company flew the first of these remote-controlled aircraft under the code name of “Red Wagon” and effectively demonstrated the ability to use UAVs for aerial photographic missions. In addition to being flown over the Soviet Union and Cuba, these vehicles were also deployed over China.

By 1962, Lockheed and the Central Intelligence Agency (CIA) developed the supersonic reconnaissance D-21, known as the Tagboard. Launched from the A-12 or the B-52H airplane, the Tagboard was capable of achieving a speed of Mach 3.3 and could fly at high altitudes over 90,000 feet for a distance of 3,000 miles. After photographs were taken of the targeted area, the film was released and recovered by another aircraft. The Tagboard was retired in 1971 due to several mission failures and high costs.

During the Vietnam conflict, the United States Air Force relied on the Ryan BQM-34 Lightning Bug for both high- and low-altitude missions. High-altitude flights operated at heights of 60,000 feet and above, while low-altitude sorties flew at an altitude below 500 feet. Capable of flying for 7.8 hours without landing, the Lightning Bug was used for photographic reconnaissance, leaflet dropping, picking up enemy signals, and providing assistance to crewed aircraft by releasing chaff corridors as a decoy maneuver. On an average, each Lightning Bug flew just over seven missions, for a total of 3,435 missions between 1964 and 1975. In 1971 and 1972, Ryan Aeronautics experimented with the use of the Lightning Bug as an armed vehicle capable of dropping an electro-optically guided bomb. Several of these modified UAVs flew with crewed aircraft on missions over Vietnam. After the United States withdrew from Vietnam, interest in the use of drone aircraft diminished but other countries, such as Israel, continued to develop the technology.

The rebirth of the UAV in the United States occurred during the Persian Gulf War of 1991 when the Navy and the Army deployed the Pioneer uninhabited aerial vehicle. Based on the designs of the Israeli Scout and the Mastiff UAV, six Pioneers were deployed during Desert Storm. The three systems used by the Marines assisted AV-8B Harriers during air strikes while the systems deployed by the Navy provided gunfire spotting for the battleships, located mines in the Persian Gulf, and pinpointed antiship missile sites in Kuwait and Iraq. Used for targeting, reconnaissance, and battle damage assessment, the Pioneer flew 533 missions and logged over 1,688 hours in the air. After the war, the Pioneer was used for reconnaissance in Bosnia and Kosovo beginning in 1993. In the Western Hemisphere, the Pioneer has been used during Operation Uphold Democracy in Haiti and in conjunction with the U.S. Customs Service to spot illegal immigrants crossing the border and to combat the smuggling of illegal drugs. The Pioneer provides real-time video within line-of-sight and flies low- to medium-altitude missions. The aircraft is capable of operating on totally preprogrammed instructions or can receive commands while in flight. After the mission is over, the Pioneer can land in one of three different ways: by using an arresting cable across the runway, much like the type used on an aircraft carrier; flying the aircraft into a recovery net; or a traditional landing. Measuring 14 feet in length and weighing 460 pounds, the Pioneer can fly for five hours at speeds of up to 100 knots with a payload of 55 pounds.

Endurance UAVs

The usefulness of the uninhabited aerial vehicles prompted the United States to enhance the technology, making the aircraft capable of longer flight times for increased coverage during periods of conflict. The Predator is a medium-range altitude endurance uninhabited aerial vehicle (MAE UAV) capable of remaining in flight at loitering speed for twenty-four hours at a time at its 500-nautical-mile range. The cost per unit is $3.5 million. Each Predator system consists of four aircraft, one ground station, and one Trojan Spirit II SATCOM system. The aircraft is designed like the Gnat 750, with a slender fuselage 320 inches in length and 72 inches high, with a span of 580.8 inches. Manufactured by General Atomics, the Predator operates within line-of-sight of GSC (ground control station) and virtually anywhere by satellite. The midwing monoplane, powered by a four-cylinder Rotax engine, carries an electro-optic/infrared (EO/IR) Versatron Skyball Model 18 and a zoom and spotter lens, as well as a Westinghouse 783R234 synthetic aperture radar. The Predator is easily recognized because of its inverted-V tails. Transportation of the Predator by C-5, C-141, and C-130 aircraft allows the system to be highly mobile and its easy assembly allows the UAV to be operational within six hours of arrival. Data is gathered through the Trojan Spirit II (TS II) SATCOM system that transmits and receives messages simultaneously from a variety of sources including satellites, joint surveillance target attack radar system (Joint-STARS), U-2’s, Rivet Joint, and airborne warning and control system (AWACS).

The first deployment of the Predator occurred in Gjader, Albania, in 1995. After Serb air-defense gunners shot down one of the aircraft and another was destroyed as a result of ground fire, the Predators were removed from the European theatre. The second deployment occurred in Taszar, Hungary, in March, 1996, when U.S. European Command engaged in Operation Nomad Endeavor. That same year, the Air Force ordered thirteen Predator systems with four aircraft each, scheduled for delivery between 1996 and 2002 at a cost of approximately $118 million. All of the systems are operated by the Eleventh and Fifteenth Reconnaissance Squadrons located at Indian Springs Air Force Auxiliary Field, 40 miles northwest of Las Vegas. The Joint Requirements Oversight Council has issued a requirement for several system upgrades, which will be retrofitted on existing Predators, including a deicing capability, a UHF radio link, and Mode IV IFF transponders. In addition, a contract has been signed with General Atomics Aeronautical Systems to expand operations from line-of-sight to beyond-line-of-sight capability, using a Predator as a communications relay.

The effectiveness of the Predator for intelligence gathering and the reduction of human risk led the United States military to explore the possibility of arming the Predator. General John P. Jumper, Air Combat Command’s top commander, proposed equipping Predator with weapons, and in February, 2001, the first successful live missile test took place at Nellis Air Force Base Range, Nevada. The armed Predator, controlled through a Ku-band satellite link and traveling beyond the controllers’ line of sight, flew to 2,000 feet before identifying its target and launching a live Hellfire missile, blowing a track off a tank. Air Combat Command and Aeronautical Systems Center continue to evaluate and analyze the test results with the goal of achieving the capability of firing missiles from the Predator at heights between 10,000 to 15,000 feet.

Although the Predator fulfilled medium-range altitude requirements, the Air Force required an uninhabited aircraft that could conduct high-altitude reconnaissance for longer periods of time. Teledyne Ryan Aeronautics developed the conventional high-altitude endurance uninhabited aerial vehicle (CHAE UAV) and flew the aircraft for the first time in 1997. The aircraft, commonly referred to as the Tier II+ or the Global Hawk, flies at altitudes above 60,000 feet at speeds of up to 340 knots. The Global Hawk performs high-resolution reconnaissance over a 40,000-square-mile area in twenty-four hours at loitering speed at a range of 3,000 miles. With a payload of 2,000 pounds, the Global Hawk can operate from conventional 5,000-feet runaways. Cost per unit is $10 million.

Rounding out the endurance vehicles is the DarkStar. Manufactured by Lockheed Martin and Boeing, the DarkStar flies low observable high-altitude endurance (LOHAE) missions above 45,000 feet and is capable of loitering for eight hours and can travel 5,000 miles from its base of operation. Equipped with either high-resolution synthetic aperture radar (SAR) or electro-optical (EO) sensors, the DarkStar images well-protected, essential targets. The first flight of a DarkStar occurred in March, 1996, and each aircraft costs $10 million. Operation requires the use of runways under 4,000 feet in length and the aircraft is able to fly in all types of weather conditions. The aircraft is half the span of the Global Hawk and one-third the length. The development program of the DarkStar, administered by Defense Advanced Research Projects Agency (DARPA), was cancelled in 1999 due to budget cuts, with the Department of Defense opting for longer range as opposed to the stealth of the DarkStar.

The latest development of an uninhabited aerial vehicle is the Cypher aircraft, manufactured by Sikorsky Aircraft Corporation. Designed to meet military needs such as reconnaissance, communication relay, and countermeasure missions, the Cypher also meets civilian needs in areas such as counternarcotics, ordinance disposal, forestry, utilities, law enforcement, and search-and-rescue. The use of a differential Global Positioning System (GPS) allows the Cypher to navigate autonomously. The aircraft is capable of vertical takeoff or landing (VTOL), is 6.5 feet in diameter, carries a payload of 50 pounds, and cruises at 80 knots. The rotor system is shrouded to prevent damage to the high-speed rotors and possible risks to personnel. Equipped with a 50-horsepower engine, the Cypher has a ceiling altitude of 8,000 feet and can fly for three hours without landing. The onboard sensors relay information to control stations on land, sea, or in the air via digital telemetry uplink. Information about flight status, data gathered during the mission, as well as video images are downloaded simultaneously.

The development of uninhabited aerial vehicles continues to advance with new capabilities and systems continuously being added or modified to increase the performance of the aircraft. The intelligence gathering designed to assist tactical commanders remains the primary function of the uninhabited aerial vehicles, but as the industry develops lower-cost units, the number and variety of applications have increased.

  • Clark, Richard M. Uninhabited Combat Aerial Vehicles: Airpower by the People, for the People, but Not with the People. Maxwell Air Force Base, Ala.: Air University Press, 2000. Clark examines the use of uninhabited aerial vehicles for the defense of the country. The future of UAVs with armaments raises new questions about their use.
  • Fredriksen, John C. Warbirds: An Illustrated Guide to U.S. Military Aircraft, 1915-2000. Santa Barbara, Calif.: ABC-Clio, 1999. Complete with photographs, dimensions, weight, power plant, performance, and weapons on American fighters, bombers, transports, flying boats, helicopters, and uninhabited reconnaissance aircraft. Invaluable source of technical information.
  • Gerken, Louis C. UAV: Unmanned Aerial Vehicle. Chula Vista, Calif.: American Scientific, 1991. The author describes the development and uses of uninhabited aerial vehicles. A good general introduction to the subject.

Air Force, U.S.


Gulf War



Rescue aircraft


Strategic Air Command

Vietnam War

World War II

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