Aircraft carrier

An aircraft carrier is a warship whose main role is to deploy and recover aircraft—in effect acting as a sea-going airbase. 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 attack by other ships, aircraft, submarines or missiles and therefore travel as part of a carrier battle group.

Wartime innovations

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.

Related Topics:
Light cruiser - Commonwealth - INS ''Viraat'' - HMS ''Hermes''

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Combat experience proved that the British invention of the sealed "hurricane bow" which protected against storms was superior to any other use for the 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.

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To protect Atlantic convoys the escort carrier (US classifaction CVE) was developed. About a third of the size of a fleet carrier and carrying about two dozen aircraft for anti-submarine duties. Over hundred were built or converted from merchantmen. As an emergency stop-gap before sufficient became available, the British provided air cover for convoys using Catapult aircraft merchantman (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. Over two years, less than 10 launches were ever made and these flights met with some success: 6 bombers for the loss of a single pilot.

Related Topics:
Convoy - Escort carrier - CAM ship - Merchant aircraft carrier - Hawker Hurricane

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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.

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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.

Related Topics:
Philippines - Battle off Samar

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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.

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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, it would often cause serious damage or injury and even, if the crash barrier was not strong enough, destruction of parked aircraft.

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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.

Related Topics:
1940s - Pilot - Engine - USS ''John C. Stennis''

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Post-War Developments

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.

Related Topics:
Boiler - Commander - RNVR - HMS ''Perseus'' - 1950 - 1952 - 1930 - Nuclear powered

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Another British invention was the glide-slope indicator (also known as a meatball). This was a gyroscopically-controlled lamp on the port side of the deck which could be seen by 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 a necessity as the landing speed of aircraft increased.

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The US Navy prematurely attempted to become a strategic nuclear force with the project to build 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.

Related Topics:
''United States'' - United States Air Force - USS ''Forrestal''

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The US Navy took nuclear power afloat in other ways by building aircraft carriers powered by nuclear reactors. USS Enterprise was the first aircraft carrier to be powered in this way and subsequent supercarriers took advantage of this technology to increase their endurance. The only other nation to have followed the US lead is France with Charles de Gaulle.

Related Topics:
USS ''Enterprise'' - ''Charles de Gaulle''

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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.

Related Topics:
Helicopter - Anti-submarine warfare

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In the late 1950s and early 1960s, the UK converted some of its old carriers into Commando Carriers, sea-going helicopter airfields like HMS Bulwark. To militate against the expensive connotations of the term "aircraft carrier", the new Invincible Class carriers were originally designated "through deck cruisers" and were initially helicopter only craft to operate as escort carriers. The arrival of the Sea Harrier meant they could carry fixed wing aircraft despite their short flight deck.

Related Topics:
1950s - 1960s - HMS ''Bulwark'' - Invincible Class - Sea Harrier

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