An aircraft carrier is a military ship whose main function is to deploy and recover aircraft. which allows a nation to project power great distances without having to depend on local bases for land-based aircraft. At the same time, carriers may be vulnerable to missile attack and must therefore travel as part of a carrier battle group.
Aircraft carriers are generally the largest ships operated by navies; a Nimitz-class carrier powered by two nuclear reactors and four steam turbines is over 1,000 feet long and costs about $4.5 billion. The United States has the vast majority of aircraft carriers with over a dozen in service, and its aircraft carriers are a cornerstone of American military power.
Besides the United States, only eight other countries maintain aircraft carriers: France, India, Russia, Spain, Brazil, Italy, Thailand, the United Kingdom. The People's Republic of China's People's Liberation Army Navy possesses the former Soviet aircraft carrier Varyag, but most naval analysts believe that they have no intention to operate it, but instead are using them to learn about carrier operations for a future Chinese aircraft carrier.
US Navy aircraft carrier USS Harry S. Truman alongside Military Sealift Command Oiler USNS John Lenthall in the Mediterranean Sea.
USS Harry S. Truman anchors outside Portsmouth, England, while her crew
enjoy a port visit.
Aircraft carriers have two basic configurations. The most common has a flat top deck that serves as a take-off and landing area for airplanes. A steam-powered catapult accelerates an aircraft under full throttle, from 0 to 165 mph in 2 seconds during take-off to help it reach take-off speed. To land on the carrier, incoming airplanes moving at 150 mph are equipped with tailhooks to engage one of up to four arresting cables stretched across the deck, stopping the aircraft within 320 feet after engaging a cable.
The second configuration, developed for the Royal Navy, has a 'ski-jump' at one end of the flat deck, that helps launch the aircraft. This arrangement is designed for use with VTOL or STOVL aircraft that are able to take off and land with little or no forward movement. These aircraft do not require catapult facilities or arrestor cables to be deployed across the flight deck.
In either case the ship steams at up to 30 knots (56 km/h) straight into the wind during take-off and landing operations in order to increase the apparent wind speed, thereby reducing the required speed of the plane relative to the ship.
Aircraft carriers are generally accompanied by a number of other ships, to provide protection for the relatively unwieldy carrier, to carry supplies, and to provide additional offensive capabilities. This is often termed a battle group or carrier group, sometimes a carrier battle group.
Cruisers and other ships of the early twentieth century often carried a few catapult launched seaplanes that could be recovered by crane after landing on the water. These planes were often used for reconnaissance. Many modern warships have helicopter landing capability and helicopter assault ships represent a new form of aircraft carriers.
Eugene Ely was the first pilot launch from a stationary ship in November 1910. He took off from the US Cruiser USS Birmingham at Hampton Roads, Virginia and landed nearby on Willoughby Spit after some five minutes in the air. On January 18, 1911 he became the first pilot to land on a stationary ship. He took of from the Tanforan racetrack and landed on the USS Pennsylvania achored on the San Francisco waterfront.
Commander Charles Samson became the first airman to take off from a moving warship on May 2, 1912 He took off in a Shorts S27 from the battleship HMS Hibernia while she steamed at 10.5 knots in during the Royal Fleet Review at Weymouth.
The first strike from a carrier against a land target took place on July 19, 1918. Seven Sopwith Camels launched from HMS Furious attacked the German Zeppelin base at Tondern. Several airships and balloons were destroyed.
The first ship to have a full length flat deck was HMS Argus the conversion of which was completed in September 1918.
Aircraft carriers played a large role in World War II including the Japanese attack on Pearl Harbor. The Battle of Midway where 4 Japanese carriers were sunk by planes from 3 American carriers is often considered the turning point of the war in the Pacific.
More modern uses of aircraft carriers include the Falklands War, where the United Kingdom was able to win a conflict some 8,000 miles from home in large part due to the use of the carriers HMS Hermes and HMS Invincible. The US has also made use of carriers in the Persian Gulf, Afghanistan and to protect its interests in the Pacific.
In the early 21st century, worldwide aircraft carriers were capable of carrying about 1250 aircraft. US carriers accounted for over 1000 of these; the second leading country, the United Kingdom fielded over 50 planes.
See also: Escort aircraft carrier; amphibious assault ship