Unmanned Aerial Vehicle

I

Introduction

Unmanned Aerial Vehicle, also known as a drone, an aircraft without a human operator on board. The largest modern unmanned aerial vehicles (UAVs) have a wingspan of more than 30 m (100 ft); the smallest UAVs can be carried in a backpack. UAVs originated during World War I (1914-1918), but modern UAVs were first developed in the 1970s.

Almost all UAVs are military aircraft. Most of them are used for reconnaissance (exploration to gather information), although a few UAVs are armed with missiles. UAVs are employed when a piloted reconnaissance aircraft would run a high risk of being attacked or for very long missions that would exceed a pilot’s physical endurance. Often, a UAV is smaller and cheaper than a piloted aircraft designed to do the same job.

In the near future, UAVs are expected to be used for civilian missions as well. The United States Coast Guard planned to use UAVs for search, rescue, and patrol operations. UAVs could also be used for aerial surveys and to inspect pipelines and power lines—jobs done today by piloted airplanes.

II

How UAVs Operate

UAVs are flown and navigated by onboard computers and operated by humans on the ground. Software code containing the entire mission plan is downloaded to the UAV’s computers before it is launched. The operator on the ground does not “fly” the UAV, but can change the mission plan by sending new software instructions to the computers via radio, so that the UAV will change course, circle a target, or return to base. The UAV will continue to fly even if it loses radio contact with the operator, who may be hundreds or even thousands of kilometers away.

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The most widely used UAV in the United States military is the Predator, made by General Atomics Aeronautical Systems, Inc., based in San Diego, California. The Predator weighs about as much as a small private airplane, such as a Cessna 172. It has a 110-horsepower (hp) engine, similar to a snowmobile motor, and a wingspan of 15 m (48 ft). It can remain airborne for 14 hours and travel 740 km (460 mi) from its base, while flying at up to 8,000 m (25,000 ft) above sea level.

Under the Predator’s nose is a rotating turret that houses a video and an infrared camera. The video camera provides the clearest daytime picture. The infrared camera, which detects heat radiation, provides a daylike picture at night. The infrared camera can visualize people and vehicles because they are warmer than their surroundings. The Predator also carries a small radar system. The radar sends radio signals to the ground and receives those signals after they are reflected back from the ground. The radar can detect small objects on the ground despite cloud or smoke cover.

Above the Predator’s nose is a radome, an object that covers a satellite antenna dish. The satellite dish sends images from the video and infrared cameras to the operators’ control station on the ground. The Predator has two operators: One controls the airplane and the other works the cameras and the radar.

With the satellite dish, images from the cameras can be sent “live” to video monitors at the operators’ control station and from there can be transmitted directly to senior commanders or even national leaders. Data revealing the type of target and the location of the target can be linked by radio to computers onboard a fighter aircraft, a process known as data-linking. The fighter aircraft can then find and attack the target easily.

Predators can also be equipped to attack a target. Some Predators carry a laser designator that can mark a target for laser-guided bombs or missiles. A laser produces a beam of intense light that can light up a target many kilometers away. The Predator can carry under its wings a pair of Hellfire missiles, designed to destroy tanks. The Predator aims its laser at the target, and the missiles home in on the reflected laser energy.

The Predator has limitations. Minor mechanical failures can lead to a crash when there is no pilot on board to correct a problem. Some Predators have crashed after they blundered into bad weather that the operators could not see. Also, the UAV is defenseless and can be easily shot down.

III

Sizes of UAVs

Many armies prefer to use UAVs smaller than the Predator, such as the French-made Sagem Sperwer or the Israeli-made IAI Searcher. Weighing around 270 kg (600 lbs) and with wingspans from 4 to 5 m (14 to 17 ft), these UAVs can be carried near a battlefield on cross-country trucks, launched from a catapult, and quickly recovered by parachute. Unlike the Predator, which is relatively slow and may have a launch site located several hours from the battlefield, these UAVs can respond quickly if a battlefield commander needs images immediately.

The biggest UAV in use today is the Global Hawk, made by Northrop Grumman Corporation of Los Angeles. With a 35-m (114-ft) wingspan, the jet-powered Global Hawk can cruise at 20,000 m (65,000 ft) for 24 hours, up to 2,220 km (1,400 mi) from its base. In 2001 a Global Hawk flew from Edwards Air Force Base in southern California to Australia, the longest flight ever by a UAV.

IV

History of UAVs

The first unmanned aircraft were cruise missiles built to destroy themselves along with their targets, such as the Kettering Aerial Torpedo, a 240-kg (530-lb) flying bomb developed for the United States Army in 1918. The first radio-controlled UAVs were “target drones,” used during World War II (1939-1945) to train antiaircraft gunners.

The first reconnaissance UAV was a modification of the U.S. Air Force’s jet-powered target drone, the Firebee. The Air Force used camera-carrying Firebees for spy flights over North Vietnam and China during the Vietnam War (1959-1975).

The modern UAV originated in the early 1970s. Designers in the United States and Israel started experimenting with smaller, slower, cheaper UAVs. These UAVs resembled large model airplanes, powered by motorbike or snowmobile engines. Their most important feature was that they used new, small video cameras that could send pictures to the operator in real time.

Israel was the first nation to use these “mini-UAVs” in combat. In 1982 Scout and Pointer UAVs probed Syrian air defenses in Lebanon in advance of Israel’s air attack, helping achieve a crushing victory. Nine years later, in the 1991 Persian Gulf War, the only UAV used by allied forces was the Israeli-designed Pioneer.

In the 1999 Kosovo war, the use of UAVs became more widespread. The United States and four allied nations employed various UAVs to help commanders identify possible targets in difficult terrain and poor weather.

During the war against the Taliban in Afghanistan in 2001 and 2002, the U.S. Air Force used Predators and a number of the prototype Global Hawks. Predators transmitted streaming video images of a target directly to AC-130 “gunship” airplanes as they flew over the target, while the Predator operators told the gunship crews exactly where to aim the aircraft’s guns. The Central Intelligence Agency (CIA) used armed Predators in attempts to kill senior leaders of the al-Qaeda terrorist network based in Afghanistan, the group believed to have been involved in the September 2001 terrorist attack on the United States. In one instance a Predator pinpointed a building believed to house al-Qaeda leaders, relayed live images to senior commanders who called in air attacks on the building, and then fired missiles when al-Qaeda officials fled the attack.

Predators were used extensively during the 2003 U.S.-British invasion of Iraq that ousted the regime of President Saddam Hussein. The low-flying Predators were used primarily to draw antiaircraft fire so that antiaircraft positions could be pinpointed and then bombed. The military’s Joint Chiefs of Staff cited the higher-flying Global Hawk for its ability to provide 24-hour, all-weather surveillance of an area the size of the state of Illinois. Altogether, ten different types of UAVs were used by the Air Force, the Army, and the Marines during the war.

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