Aircraft carrier

Sabtu, 24 Juli 2010

From bottom to top: Principe de Asturias, amphibious assault ship USS Wasp, USS Forrestal and light V/STOL carrier HMS Invincible, showing size differences of late 20th century carriers
From foreground to background: HMS Illustrious, USS Harry S. Truman, and USS Dwight D. Eisenhower

An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations. They have evolved from wooden vessels, used to deploy balloons, into nuclear powered warships that carry dozens of fixed and rotary wing aircraft.


History

The Japanese seaplane carrier Wakamiya conducted the world's first naval-launched air raids in September 1914.

Balloon carriers were the first ships to deploy manned aircraft, used during the 19th and early 20th century, mainly for observation purposes. The 1903 advent of fixed wing airplanes was followed in 1910 by the first flight of such an aircraft from the deck of a US Navy cruiser. Seaplanes and seaplane tender support ships, such as HMS Engadine, followed. In the World War I Battle of Tsingtao in 1914, the Imperial Japanese Navy seaplane carrier Wakamiya conducted the world's first naval-launched air raids[1] from Kiaochow Bay.[2] It launched four Maurice Farman seaplanes, which bombarded German communication centers and command centers and damaged a German minelayer.[3]

The development of flat top vessels produced the first large fleet ships. This evolution was well underway by the mid-1920s, resulting in ships such as HMS Hermes, Hōshō, and the Lexington-class aircraft carriers.

World War II saw the first large-scale use and further refinement of the aircraft carrier, spawning several types. Escort aircraft carriers, such as USS Bogue, were built only during World War II. Although some were purpose-built, most were converted from merchant ships as a stop-gap measure to provide air support for convoys and amphibious invasions. Light aircraft carriers, such as USS Independence, represented a larger, more "militarized" version of the escort carrier concept. Although the light carriers usually carried the same size air groups as escort carriers, they had the advantage of higher speed as they had been converted from cruisers under construction.

Wartime emergencies also saw the creation or conversion of unconventional aircraft carriers. CAM ships, like SS Michael E, were cargo-carrying merchant ships which could launch but not retrieve fighter aircraft from a catapult. These vessels were an emergency measure during World War II as were Merchant aircraft carriers (MACs), such as MV Empire MacAlpine, another emergency measure which saw cargo-carrying merchant ships equipped with flight decks. Battle carriers were created by the Imperial Japanese Navy to partially compensate for the loss of carrier strength at Midway.[citation needed] Two of them were made from Ise-class battleships during late 1943. The aft turrets were removed and replaced with a hangar, deck and catapult. The heavy cruiser Mogami concurrently received a similar conversion. This "half and half" design was an unsuccessful compromise, being neither one thing nor the other. Submarine aircraft carriers, such as the French Surcouf and the Japanese I-400 class submarine, which was capable of carrying three Aichi M6A Seiran aircraft, were first built in the 1920s, but were generally unsuccessful at war.

The Tripoli, a US Navy Iwo Jima-class helicopter carrier

Modern navies that operate such ships treat aircraft carriers as the capital ship of the fleet, a role previously played by the battleship. The change, part of the growth of air power as a significant factor in warfare, took place during World War II. This change was driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. Following the war, carrier operations continued to increase in size and importance. Supercarriers, the latest aircraft carriers, typically displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Most are powered by nuclear reactors and form the core of a fleet designed to operate far from home. Amphibious assault ships, such as USS Tarawa and HMS Ocean, serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers" or "helicopter carriers", many have a secondary capability to operate VSTOL aircraft.

Lacking the firepower of other warships, carriers by themselves are considered vulnerable to attack by other ships, aircraft, submarines, or missiles. Therefore, 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.

Before World War II international naval treaties of 1922, 1930 and 1936 limited the size of capital ships including carriers. Aircraft carrier designs since World War II have been effectively unlimited by any consideration save budgetary, and the ships have increased in size to handle the larger aircraft. The large, modern Nimitz class of United States Navy carriers has a displacement nearly four times that of the World War II–era USS Enterprise, yet its complement of aircraft is roughly the same—a consequence of the steadily increasing size and weight of military aircraft over the years.

Types of aircraft carriers

Brazilian aircraft carrier São Paulo (A12)

By role

A fleet carrier is intended to operate with the main fleet and usually provides an offensive capability. These are the largest carriers capable of fast speeds. By comparison escort carriers were developed to provide defence for convoys of ships. They were smaller and slower with lower numbers of aircraft carried. Most were built from mercantile hulls or, in the case of merchant aircraft carriers, were bulk cargo ships with a flight deck added on top. Light aircraft carriers were carriers that were fast enough to operate with the fleet but of smaller size with reduced aircraft capacity.

By configuration

There are three main configurations of aircraft carrier in service in the world's navies:

  • Catapult Assisted Take-Off But Arrested Recovery (CATOBAR)
  • Short Take-Off But Arrested Recovery (STOBAR)
  • Short Take-Off Vertical Landing (STOVL)

By size

Flight deck

Ripples appear along the fuselage of a U.S. Navy E-2C Hawkeye due to loads from landing on the USS Harry S. Truman (CVN-75).
The first carrier landing and take-off of a jet aircraft: Eric "Winkle" Brown landing on HMS Ocean (R68) in 1945
The ski-jump on Royal Navy carrier HMS Invincible (R05)

As "runways at sea," modern aircraft carriers have a flat-top deck design that serves as a flight deck for take-off and landing of aircraft. Aircraft take off to the front, into the wind, and land from the rear. Carriers steam at speed, for example up to 35 knots (65 km/h), into the wind during take-off in order to increase the apparent wind speed over the deck, thereby reducing the speed of the aircraft relative to the ship. On some ships, a steam-powered catapult is used to propel the aircraft forward, assisting the power of its engines and allowing it to take off in a shorter distance than would otherwise be required. On other carriers, aircraft do not require assistance for take off—the requirement for assistance relates to aircraft design and performance. Conversely, when landing on a carrier, conventional aircraft rely upon a tailhook that catches on arrestor wires stretched across the deck to bring them to a stop in a shorter distance than normal. Other aircraft—helicopters and V/STOL (Vertical/Short Take-Off and Landing) designs—utilize their hover capability to land vertically and so require no assistance in speed reduction upon landing.

Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, sometimes called "paddles") to control the plane's landing approach, visually gauge altitude, attitude, and speed, and transmit that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot (hence the nickname). From the late 1950s onward, visual landing aids such as mirrors provided information on proper glide slope, but LSOs still transmit voice calls to landing pilots by radio.

To facilitate working on the flight deck of a U.S. aircraft carrier, the sailors wear colored shirts that designate their responsibilities. There are at least seven different colors worn by flight deck personnel for modern United States Navy carrier air operations. Other countries carrier operations utilize similar color schemes.

Key personnel involved in the flight deck include the Shooters, the Handler, and the Air Boss. Shooters are naval aviators or Naval Flight Officers and are responsible for launching aircraft. The Handler works just inside the island from the flight deck and is responsible for the movement of aircraft before launching and after landing. The Air Boss (usually a commander) occupies the top bridge (Primary Flight Control, also called "primary" or "the tower") and has the overall responsibility for controlling takeoffs, landings, "those aircraft in the air near the ship, and the movement of planes on the flight deck, which itself resembles a well-choreographed ballet".[4] The captain of the ship spends most of his time one level below Primary on the Navigation Bridge. Below this is the Flag Bridge, designated for the embarked admiral and his staff.

Since the early 1950s it has been common to direct the landing recovery area off to port at an angle to the line of the ship. The primary function of the angled deck landing area is to allow aircraft that miss the arresting wires, referred to as a "bolter", to become airborne again without the risk of hitting aircraft parked on the forward parts of the deck. The angled deck also allows launching of aircraft at the same time as others land.

The above deck areas of the warship (such as the bridge, flight control tower) are concentrated to the starboard side of the deck in a relatively small area called an "island". Very few carriers have been designed or built without an island and such a configuration has not been seen in a fleet-sized carrier. The "flush deck" configuration proved to have very significant drawbacks, complicating navigation, air traffic control and numerous other factors.

A more recent configuration, originally developed by the Royal Navy but since adopted by many navies for smaller carriers, has a ski-jump ramp at the forward end of the flight deck. This was first developed to help launch VTOL (or STOVL) aircraft (aircraft that are able to take off and land with little or no forward movement), such as the Sea Harrier. Although these aircraft are capable of taking off vertically from the deck, using the ramp is more fuel efficient and permits a heavier launch weight. As catapults and arrestor cables are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for equipment. Russian and future Indian carriers include a ski-jump ramp for launching conventional aircraft. The disadvantage of the ski-jump is the penalty it exacts on aircraft size, payload, and fuel load (and thus range): large, slow planes such as the E-2 Hawkeye and heavily laden strike fighters like the F/A-18E/F Super Hornet and Sukhoi Su-33 cannot successfully launch using a ski-jump because their high loaded weight requires either a longer takeoff roll than is possible on a carrier deck, or catapult assistance, although the Su-33 does launch with a light fuel and weapons load from a ski jump.

F-18 - A 3-wire landing.ogv
F-18 landing

Aircraft carriers in service

Four modern aircraft carriers of various types—USS John C. Stennis, FS Charles de Gaulle, HMS Ocean and USS John F. Kennedy—and escort vessels on operations in 2002. The ships are sailing much closer together than they would during combat operations.

Aircraft carriers are generally the largest ships operated by navies. A total of 22 aircraft carriers in active service are maintained by nine navies. In addition, the People's Republic of China's People's Liberation Army Navy possesses the former Soviet aircraft carrier Varyag. Australia, Brazil, France, India, Italy, Japan, Netherlands, South Korea, Spain, United Kingdom, United States and the People's Republic of China also operate vessels capable of carrying and operating multiple helicopters.

Classes currently in service:

Brazil (1)
France (1)
India (1)
  • INS Viraat: 28,700 ton ex-British carrier HMS Hermes (launched 1953), purchased in 1986 and commissioned in 1987, scheduled to be decommissioned in 2019.[5]
Italy (2)
Japan (1)
  • Hyūga class: two helicopter destroyers (ASW carriers) planned, of which one is already in commission.
Russia (1)
Spain (1)
Thailand (1)
  • HTMS Chakri Naruebet: 11,400 ton carrier based on Spanish Principe De Asturias design. Commissioned in 1997, though remains predominantly inactive due to lack of funds.[citation needed]
United Kingdom (2)
  • Invincible class: Three STOVL carriers were originally commissioned, of which two are in active service.
United States (11)
  • USS Enterprise (CVN-65): 93,500 ton nuclear-powered supercarrier commissioned in 1961. First nuclear-powered aircraft carrier. Scheduled for decommissioning in 2013,[6] may be extended to 2014-2015.
  • Nimitz class: ten 101,000 ton nuclear-powered supercarriers, the first of which was commissioned in 1975.
A Nimitz class carrier powered by two nuclear reactors and four steam turbines is 1,092 feet (333 m) long and costs about $4.5 billion. The United States Navy has the world's largest carrier fleet, with eleven in service and one under construction (all of them supercarriers). It is also the only navy to possess operational supercarriers.

Future aircraft carriers

Several nations which currently possess aircraft carriers are in the process of planning new classes to replace current ones. The world's navies still generally see the aircraft carrier as the main future capital ship, with developments such as the arsenal ship, which have been promoted as an alternative, seen as too limited in terms of flexibility.[citation needed]

China

Varyag under tow

China bought the unfinished Soviet aircraft carrier Varyag in 2001 from Ukraine, supposedly to turn it into a floating casino. Pictures taken while in port suggest this plan has been abandoned and show that work is being carried out to maintain its military function. There is no conclusive evidence as to what role it would play in the Chinese Navy.

In late December 2008 and early January 2009, there were multiple reports of China building two conventionally powered aircraft carriers displacing 50,000–60,000 tonnes, possibly to be launched in 2015,[7] and there have been press reports suggesting China's intention to build aircraft carriers.[8]

France

The French Navy has set in motion possible plans for a second CTOL aircraft carrier, to supplement Charles de Gaulle. The design would be much larger, in the range of 65–74,000 tonnes, and would not be nuclear-powered like Charles de Gaulle. There are plans to base the carrier on the current Royal Navy design for CATOBAR operations. (The Thales/BAE Systems design for the Royal Navy is for a STOVL carrier which is reconfigurable to CATOBAR operations.)

On 21 June 2008, French President Nicolas Sarkozy decided to place France's participation in the project on hold. He stated that a final decision on the future of the French carrier would be taken in 2011 or 2012. British plans for two aircraft carriers will go ahead as planned and were in no way conditional on French participation.[9]

[edit] India

Impression of the INS Vikramaditya, which is under refit for the Indian Navy.

India started the construction of a 40,000 tonne, 260-metre-long Vikrant-class aircraft carrier in April 2005.[10] The new carrier will cost US$762 million and will operate MiG-29K, Naval HAL Tejas and Sea Harrier aircraft along with the Indian-made helicopter HAL Dhruv.[10] The ship will be powered by four turbine engines and will have a range of 8,000 nautical miles (14,000 km), carrying 160 officers, 1,400 sailors, and 30 aircraft. The carrier is being constructed by a state-run shipyard in Cochin.[10] The ship is scheduled for commissioning in 2014.[11]

As of December 2009, Navy chief Admiral Nirmal Verma said at his maiden navy week press conference that concepts currently being examined by the Directorate of Naval Design for the second indigenous aircraft carrier, the IAC-2, are for a conventionally powered carrier displacing over 50,000 tons and equipped with steam catapults (rather than the ski-jump on the Gorshkov/Vikramaditya and the IAC) to launch fourth generation aircraft.[11]

In 2004, India agreed to buy the Admiral Gorshkov from Russia for US$1.5 billion. It is named INS Vikramaditya[12], and was expected to join the Indian Navy in 2008 after a refit.[13] However, delays in the refit were announced in July 2007.

In July 2008, Russia increased the total price to US$3.4 billion because of unexpected cost overuns due to the deteriorated condition of the ship.[12] In December 2008, India finally decided in favour of purchasing Admiral Gorshkov as the best option available.[14] In February 2009, Russia asked for an additional $700 million payment for the completion of the reconstruction of the Admiral Gorshkov, bringing the total price requested by the Russians to $2.9 billion, more than three times the originally contracted price.[15] On 8 December 2009, it was reported that India and Russia ended the stalemate over Gorshkov price deal by agreeing on a price of US$2.2 billion.[16][17]

Russia

Russian Navy Commander-in-Chief Admiral Vladimir Masorin officially stated on June 23, 2007, that the Navy was considering the specifications of a new nuclear aircraft carrier design[18][19] for the class that was first announced about a month earlier. Production of the carriers is expected to start around 2010 at the Zvezdochka plant in Severodvinsk, where a large drydock, capable of launching vessels with more than 100,000 ton displacement, is now being built.[20] In his statement, Admiral Masorin said that the general dimensions of the project have already been determined. The projected carrier is to have nuclear propulsion, to displace about 50,000 tons and to carry an air wing of 30–50 air superiority aircraft and helicopters, which makes her roughly comparable with the French Charles de Gaulle. "The giants that the US Navy builds, those that carry 100–130 aircraft, we won't build anything like that", said Admiral Masorin.[19] The planned specifications reflect the role, traditional in the Russian Navy, of the aircraft carrier as an air support platform for guided missile cruisers and submarines.

The Russian naval establishment had long agreed, since the decommissioning of the Kiev-class carriers, that the only operational carrier, Admiral Kuznetsov, was insufficient, and that three or four carriers were necessary to meet the Navy's air support requirements.[citation needed] However, financial and organisational turmoil in the 1990s made even the maintenance of Admiral Kuznetsov a difficult undertaking. The improvement in Russia's economic situation after the year 2000 has allowed a major increase in defence spending. Admiral Vladimir Vysotsky announced on Navy Day 2008 that Russia plans to build five or six carriers of the new design for deployment in the Northern and Pacific fleets, starting around 2012–2013.[21] The new carrier groups are planned to be at full strength around 2050–2060.[22] According to sources from the United Shipbuilding Corporation the new carriers will carry new fifth-generation fighters as well as unmanned aerial vehicles and have a displacement of up to 60,000 metric tons.[23]

Spain

The 231-metre-long, 27,000 tonne Juan Carlos I for the Spanish Navy was approved in 2003, and its construction started in August 2005, with the shipbuilding firm Navantia in charge of the project.[24] The ship was launched on 10 March 2008,[24] and is due to be commissioned in 2011.[citation needed] Juan Carlos I is designed to operate both as an amphibious assault ship and as STOVL aircraft carrier, depending on the mission assigned.[24] The design was made keeping in mind the low-intensity conflicts in which the Spanish Navy is likely to be involved in the future. When configured for air operations the ship will displace 24,660 tonnes and will be able to carry a mixed force of up to 30 aircraft comprising AV-8B+ Matadors, F-35s and helicopters.[24] The ship is provided with a ski-jump and a three-dimensional radar-based combat system.[24]

United Kingdom

Impression of the Queen Elizabeth-class, two of which are under construction for the Royal Navy.

The Royal Navy has signed a deal to build two new larger STOVL aircraft carriers, the Queen Elizabeth-class, to replace the three Invincible-class carriers. The ships are to be named HMS Queen Elizabeth and HMS Prince of Wales.[25][26] They will be able to operate up to 40 aircraft, and will have a displacement of around 65,000 tonnes. The two ships are due to enter service in 2016 and 2018 respectively, two years later than originally planned.[27] Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 1450.[28] The two ships will be the largest warships ever built for the Royal Navy. Initially to be configured for STOVL operations, the carriers are to be adaptable to STOBAR or CATOBAR configurations to allow any type of future generation of aircraft to operate from them.

United States

Artist's impression of the US Gerald R. Ford-class aircraft carrier

The current US fleet of Nimitz-class carriers are to be followed into service (and in some cases replaced) by the Gerald R. Ford-class. It is expected that the ships will be more automated in an effort to reduce the amount of funding required to maintain and operate its supercarriers. The main new features are implementation of Electromagnetic Aircraft Launch System (EMALS) (which replace the old steam catapults) and unmanned aerial vehicles.

With the decommissioning of the USS John F. Kennedy in March 2007, the U.S. fleet comprises 11 supercarriers. The House Armed Services Seapower subcommittee on July 24, 2007, recommended seven or maybe eight new carriers (one every four years). However, the debate has deepened over budgeting for the $12–14.5 billion (plus $12 billion for development and research) for the 100,000 ton Gerald Ford-class carrier (estimated service 2015) compared to the smaller $2 billion 45,000 ton America-class amphibious assault ships able to deploy squadrons of F-35B.[29]

http://en.wikipedia.org/wiki/Aircraft_carrier

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