Science Fair Project Encyclopedia
An aircraft carrier is a warship whose main role is to deploy and recover aircraft. Aircraft carriers thus allow a naval force to project air power great distances without having to depend on local bases for land-based aircraft. Modern navies, who operate such ships, treat aircraft carriers as the centerpiece of the fleet, a role previously played by the battleship. The change, part of the growth of air power as a significant part of warfare, took place during World War II. Unescorted carriers are considered vulnerable to missile attack and 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 1092 ft (333 m) long and costs about $5 billion. The United States has the majority of aircraft carriers with over a dozen in service, and its aircraft carriers are a cornerstone of American power projection capability.
Nine countries maintain aircraft carriers: United States, France, India, Russia, Spain, Brazil, Italy, Thailand, and the United Kingdom. In addition 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 Varyag to learn about carrier operations for a future Chinese aircraft carrier. China, alongside Japan and Chile, also operate helicopter-carrying vessels.
Aircraft carriers have two basic configurations. The most common has a flat top deck that serves as a take-off and landing area for aircraft. A steam-powered catapult, accelerates an aircraft under full throttle, from 0 to 165 mph (265 km/h) in 2 seconds during take-off to help it reach take-off speed. To land on the carrier, incoming aircraft moving at 150 mph (240 km/h) are equipped with tailhooks to engage one of up to four arresting cables stretched across the deck, stopping the aircraft within 320 feet (100 m) after engaging a cable. The command and control superstructure of an aircraft carrier, comprising the bridge, CIC and control tower, among other systems, is concentrated in a single, relatively small structure on the starboard side of the deck called an "island," only a very few carriers have ever been designed without an island and most of those that have been, were experimental and developmental ships, and not full fleet carriers.
The second and more recent 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 35 knots (65 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 aircraft relative to the ship.
There are several basic types of aircraft carriers, some of which are obsolete:
- Seaplane tenders, such as HMS Engadine, out of use after the 1950s.
- Fleet carriers , such as USS Essex, typically 20,000 to 65,000 tons.
- Escort carriers, such as USS Barnes, were built only during World War II, and were used by the Royal Navy and US Navy.
- Light aircraft carriers, such as USS Independence, were designed to primarily carry fighters.
- CAM ships, such as SS Michael E , cargo carrying merchant ships which could launch but not retrieve fighter aircraft. These vessels were an emergency measure during World War II.
- Merchant aircraft carriers, such as MV Empire MacAlpine, another emergency measure which saw cargo-carrying merchant ships equipped with flight decks.
- Amphibious assault carriers, such as USS Tarawa, which often also serve the purpose of carrying and landing soldiers.
- Anti-submarine warfare carriers , such as HMS Invincible, also known as a "helicopter carrier."
- Supercarriers, such as USS Nimitz, typically 75,000 tons or greater.
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 capital ships of the inter-war years often carried a catapult launched seaplane for reconnaissance. It was launched by a catapult and recovered by crane from the water after landing. These were mostly removed during World War II.
Many modern warships have helicopter landing capability and helicopter assault ships represent a new form of aircraft carriers.
History and Milestones
Eugene Ely was the first pilot launch from a stationary ship in November 1910. He took off from the US armored 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 off from the Tanforan racetrack and landed on the USS Pennsylvania anchored on the San Francisco waterfront.
Commander Charles Samson, RN, 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 (19 km/h) 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 flat deck carriers
The Washington Naval Treaty of 1922 placed strict limits on the tonnages of battleships and battlecruisers for the major naval powers after World War I. Consequently, many battleships under construction (or in service) were converted into aircraft carriers. The first ship to have a full length flat deck was HMS Argus the conversion of which was completed in September 1918.
The first ship to be designed specifically as an aircraft carrier was the Japanese Hosho, commissioned in December 1922, followed by HMS Hermes which was commissioned in July 1923. Hermes' construction actually began earlier but numerous tests and experiments delayed its commission.
By the late 1930s, aircraft carriers around the world typically carried three types of aircraft: torpedo bombers, also used for conventional bombings and reconnaissance; dive bombers, also used for reconnaissance (in the US Navy this type of aircraft were known as "scout bombers"); and fighters for fleet defence and bomber escort duties. Because of the restricted spaces on aircraft carriers, all these aircraft were of small, single-engined types, usually with folding wings to facilitate storage.
The Second World War
Aircraft carriers played a significant role in World War II. Japan started the war with 10 aircraft carriers, the largest and most modern carrier fleet in the world at that time. There were 6 American aircraft carriers at the beginning of the hostilities, only 3 of them operating in the Pacific, and 3 British aircraft carriers, of which a single one operated in the Indian ocean.
Many of the major battles in the Pacific involved aircraft carriers. The most notable of them is considered to be the Japanese attack on Pearl Harbor. In addition, the sinkings of the HMS Repulse and HMS Prince of Wales who were unescorted by a carrier drove home the need for the ship class for fleet defense from aerial attack. The battle of Midway, where four Japanese carriers were sunk in a surprise attack by planes from three American carriers, is often considered the turning point of the war in the Pacific. As a result of this battle, the aircraft carrier replaced the battleship as the dominant naval vessel in the Pacific Theater.
The loss of three major carriers in quick succession in the Pacific led the US Navy to develop the light carrier (CVL) from light cruiser hulls that had already been laid down. These were intended to add fighter squadrons to a task force, and were used in the US Navy only during World War II. The Royal Navy made a similar design which served both them and Commonwealth countries after World War II. One of these carriers, India's INS Viraat, formerly HMS Hermes, is still being used.
Combat experience proved that the British invention of the sealed "hurricane bow" which protected against storms was superior to any other use for very front of the ship, be it machine-guns or a second flight deck. This became standard for British and American carriers. The Japanese carrier Taiho was the first of their ships to incorporate it.
As an emergency stop-gap to protect Atlantic convoys before sufficient escort carriers became available, the British provided air cover using CAM ships and merchant aircraft carriers. CAM ships were merchant vessels equipped with an aircraft, usually a battle-weary Hawker Hurricane, launched by a catapult. Once launched, the aircraft could not land back on the deck and had to ditch in the sea if it was not within range of land.
Merchant aircraft carriers were merchant ships equipped with a flat deck for half a dozen aircraft. They operated with civilian crews, under merchant colors, and carried their normal cargo whilst providing air support for the convoy. As there was no lift or hangar, aircraft maintenance was limited and the aircraft spent the entire trip sitting on the deck.
Escort carriers were built in the US from two basic hull designs: one from a merchant ship, and the other from a slightly larger, slightly faster tanker. Besides defending convoys, these were used to transport aircraft across the ocean. Nevertheless, some participated in the battles to liberate the Philippines, notably the battle off Samar in which six escort carriers and their escorting destroyers briefly took on five Japanese battleships and bluffed them into retreating.
Contrary to popular belief, British aircraft carriers did not carry more armor than their American counterparts. The difference in armoring instead was where the carriers held their armor: American custom held that every thing above the hangar deck was superstructure, and armored accordingly, placing the armor deck at the hangar deck level. This allowed a large, open hangar deck with high ceilings, deck-edge aircraft elevators and good ventilation. By comparison, British carriers had a small, cramped hangar deck with low ceilings, ventilation problems were hellish, and deck edge lifts were of dubious use as they would compromise the structural integrity of the ship. Additionally, the light wooden decks of American ships frequently initiated bombs, causing the explosion to be vented into the open (and usually empty) hangar deck and to mostly waste its force out the sides of the ship, while armored British ships tended to initiate bombs within the ship's structural girder, causing damage that added up and became permanent. British carriers were designed with "Bomber" Harris's maxim "The bomber will always get through" in mind, while American carrier design held that the best defense was a good offense, and their hundred-plane air groups were able to both pack a hefty offensive punch and provide a significant combat air patrol over the battlegroup, a defensive scheme that benefitted not only the carriers but all of their escorts. In the crucible of war, American carrier design doctrine succeeded and British carrier design doctrine failed; late-war American-built escort carriers carried as many aircraft as contemporary-build British full fleet carriers.
Starting with the Midway class, American carriers had grown so large that it was no longer practical to continue the hangar deck as strength deck concept, and all subsequent American carriers have the flight deck as the strength deck, leaving only the island as superstructure.
During the Second World War, aircraft would land on the flight deck parallel to the long axis of the ship's hull. Aircraft which had already landed would be parked on the deck at the bow end of the flight deck. A crash barrier was raised behind them to stop any landing aircraft which overshot the landing area because its landing hook missed the arrestor cables. If this happened, this would often cause serious damage or injury and even, if the crash barrier was not strong enough, to destruction of the parked aircraft too. An important development of the late 1940s was the British invention of the angled deck, where the runway was canted at an angle of a few degrees across the ship.
If an aircraft misses the arrestor cables, the pilot only needs to increase engine power to maximum to get airborne again and will not hit the parked aircraft because the angled deck points out over the sea. The picture of USS John C. Stennis at the top shows an angled landing deck.
The modern steam-powered catapult, powered by steam from the ship's boilers, was invented by Commander C. C. Mitchell RNVR. It was widely adopted following trials on HMS Perseus between 1950 and 1952 which showed it to be more powerful and reliable than the compressed air catapults which had been introduced in the 1930s. As now only nuclear powered carriers have boilers as part of their motive power system, the majority of aircraft carriers are now equipped with steam generating plant solely to power the catapults.
A third British invention was the glide-slope indicator. This was a gyroscopically-controlled lamp on the port side of the deck which would send a beam to the aviator who was about to land, indicating to him whether he was too high or too low or at the wrong angle of attack. It also took into account the effect of the waves on the flight deck. This also helped at night. The device became necessary as the landing speed of aircraft increased.
The US Navy prematurely attempted to become a strategic nuclear force with the project to build the United States, termed CVA, with the "A" signifying "atomic". This ship would have carried twin-propeller bombers, each of which could carry an atomic bomb. The project was cancelled under pressure from the newly-created United States Air Force, and the letter "A" was re-cycled to mean "attack." But this only delayed the growth of carriers. Nuclear weapons would put to sea despite Air Force objections in 1955 aboard USS Forrestal (CVA-59), and by the end of the fifties the Navy had a series of nuclear-armed attack aircraft.
The post-war years also saw the development of the helicopter with different capabilities to a fighter aircraft. Whereas fixed-wing aircraft are suited to air-to-air combat and air-to-surface attack, helicopters are used to transport equipment and personnel and can be used in an anti-submarine warfare role with dipped sonar and missiles.
More modern uses of aircraft carriers include the Falklands War, where the United Kingdom was able to win a conflict 8,000 miles (13,000 km) from home in large part due to the use of the carriers HMS Hermes and HMS Invincible. The Falklands showed the worthiness of a VSTOL aircraft—the Hawker Harrier.
The US has also made use of carriers in the Persian Gulf, Afghanistan and to protect its interests in the Pacific. Most recently, the 2003 invasion of Iraq featured US aircraft carriers as the primary base of US air power. Even without the ability to place significant numbers of aircraft in Middle Eastern airbases, the United States was capable of carrying out significant air attacks from carrier-based squadrons.
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 aircraft. The United Kingdom and France are both undergoing a drastic expansion in carrier capability (with a common ship class), but the United States will still maintain a very large lead.
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 Varyag to learn about carrier operations for a future Chinese aircraft carrier.
Badges of Naval Aviation
To recognize the qualification and training required for service onboard an aircraft carrier, most of the world's navies issue special badges and patches to denote those who are naval pilots or naval aviation support personnel.
- Naval Astronaut Badge
- Naval Flight Officer Astronaut Badge
- Naval Aviator Badge
- Naval Flight Officer Badge
- Naval Flight Surgeon Badge
- Naval Aviation Supply Corps Badge
- Naval Aircrew Badge
- Flight Meteorologist Badge
- Flight Nurse Badge
- Aviation Psychologist Badge
- Enlisted Aviation Warfare Specialist Badge
Aircraft carriers in fiction
- The 1980 movie The Final Countdown is about an encounter by the USS Nimitz with Japanese carriers shortly before Pearl Harbor.
- The 1986 movie Top Gun includes combat air patrol with planes launched from the carrier USS Enterprise.
- Stephen Coonts started his Jake Grafton series of aircraft carrier novels with Flight of the Intruder in 1986. Set in the Vietnam war, it was made into a movie starring Danny Glover and Willem Dafoe in 1991. Together with its first sequel Final Flight it gives an insight into flight missions and life aboard US supercarriers. All other Jake Grafton novels include at least a passing reference to carrier operations.
- Tom Clancy books often feature carrier warfare.
- The Hunt for Red October - USS John F. Kennedy and HMS Invincible aid the search for a renegade Soviet nuclear submarine
- Red Storm Rising - U.S. Navy supercarriers of various classes and allied carrier forces operate on convoy duty supplying Europe during a NATO/Warsaw Pact war.
- Clear and Present Danger - A-6E Intruders bomb houses belonging to leaders of drug cartels.
- The Sum of All Fears - USS Theodore Roosevelt's planes engage Libyan and Soviet aircraft, some which were operating off the Soviet carrier Kuznetsov
- Debt of Honor - In preparation for offensive action, Japan cripples an already depleted U.S. Navy carrier force.
- Executive Orders - US Navy carriers operate in Persian Gulf in defence of Saudi Arabia
- SSN - US Navy carriers involved in defensive and offensive action on behalf of Taiwan
- Nimitz Class by Patrick Robinson centers around the sinking of the fictional Nimitz class aircraft carrier USS Thomas Jefferson.
- The 2001 movie Behind Enemy Lines features the Nimitz-class carrier USS Carl Vinson on patrol off the Balkans
- The television show JAG frequently includes aircraft carriers in its episodes, in particular the fictional USS Seahawk, with the lead character being a former navy pilot.
- The Wing Commander series of computer games and novels takes place on spaceborne aircraft carriers in the 27th century, with the player character being a fighter pilot flying strike missions against alien opponents in an World War II-like interstellar war. Many of the carriers in the game are named for 20th century carriers; examples include Lexington, Saratoga, Intrepid, and Midway.
- The title ship of Battlestar Galactica and the current remake is another famous and massive aircraft carrier designed for space called a Battlestar. Instead of a flight deck, the fighters launch from and land into winged hanger pods positioned on the sides of the ship.
- The 1995-96 televison show Space: Above and Beyond featured a fictional USS Saratoga in 2063. She was the lead ship in the series. This Class of vessel had a designation of SCVN or Space Carrier Vehicle Nuclear.
- Haze Gray & Underway, World Aircraft Carrier Lists comprehensive and detailed listings of all the world's aircraft carriers and seaplane tenders from 1913-2001, with photo gallery.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details