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Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
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1.a large warship that carries planes and has a long flat deck for takeoffs and landings
aircraft carrier (n.)
aircraft carrier (n.)
conveyance, transfer, transferral, transit, transport, transportation - carry - aircraft carrier, attack aircraft carrier, carrier, flattop - carrier - conveyer, conveyer belt, conveyor, conveyor belt, moving walkway, transporter, travelator - car transporter, transporter - carrier, common carrier, contract carrier, haulage business, haulage contractor, haulage firm, hauler, haulier, transit company, transport company - bearer, carrier, Carrier, toter[Dérivé]
aircraft carrier (n.)
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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 wing and rotary-wing aircraft.
Aircraft carriers are typically the capital ship of a fleet, and are extremely expensive to build and important to protect. Of the nine nations that possess an aircraft carrier, six possess only one. Twenty-one aircraft carriers are currently active throughout the world with the U.S. Navy operating 11 as of June 2011[update].
The 1903 advent of heavier-than-air, fixed-wing aircraft was closely followed in 1910 by the first experimental take-off of such an airplane from the deck of a United States Navy vessel (cruiser USS Birmingham), and the first experimental landings were conducted in 1911. On 4 May 1912 the first plane to take-off from a ship underway took place when Commander Charles Samson flew from the deck of HMS Hibernia. Seaplane tender support ships came next; in September 1914, the Imperial Japanese Navy Wakamiya conducted the world's first successful naval-launched air raids. Used against German forces during World War I, it carried four Maurice Farman seaplanes, which took off and landed on the water and were lowered from and raised to the deck by crane.
The development of flat top vessels produced the first large fleet ships. In 1918, HMS Argus became the world's first carrier capable of launching and landing naval aircraft. Carrier evolution was well underway in the mid-1920s, resulting in ships such as HMS Hermes and IJN Hōshō. Most early aircraft carriers were conversions of ships that were laid down (or had served) as different ship types: cargo ships, cruisers, battlecruisers, or battleships. The Washington Naval Treaty of 1922 affected aircraft carrier plans. The U.S. and UK were permitted up to 135,000 tons of carriers each, while specific exemptions on the upper tonnage of individual ships permitted conversion of capital ship hulls to carriers such as the Lexington-class aircraft carriers.
During the 1920s, several navies began ordering and building aircraft carriers that were specifically designed as such. This allowed the design to be specialized to their future role and resulted in superior ships. During World War II, these ships became the backbone of the carrier forces of the United States, British, and Japanese navies, known as fleet carriers.
The aircraft carrier was used extensively in World War II, and several types were created as a result. 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 built by the US, 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 since they had been converted from cruisers under construction. The UK 1942 Design Light Fleet Carrier served the Royal Navy during the war and was the hull design chosen for nearly all aircraft carrier equipped navies after the war until the 1980s.
Wartime emergencies also spurred the creation or conversion of unconventional aircraft carriers. CAM ships, like SS Michael E, were cargo-carrying merchant ships that 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. 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.
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 took place during World War II in response to air power becoming a significant factor in warfare. 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, displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Some 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.
Today's aircraft carriers are so expensive that many nations risk significant political, economic, and military ramifications if one were lost, or even used in conflict. Observers have opined that modern anti-ship weapons systems, such as torpedoes and missiles, have made aircraft carriers obsolete as too vulnerable for modern combat. Nuclear weapons would threaten whole naval carrier groups in open generalised combat. On the other hand, the proven or threatening role of aircraft carriers has an undeniably modern place in asymmetric warfare, like the gunboat diplomacy of the past. Furthermore, aircraft carriers facilitate quick and precise projections of overwhelming military power into such local and regional conflicts.
Admiral Sir Mark Stanhope, head of the Royal Navy, has said that "To put it simply, countries that aspire to strategic international influence have aircraft carriers".
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 defense 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. Soviet aircraft carriers now in use by Russia are actually called aviation cruisers, these ships while sized in the range of large fleet carriers were designed to deploy alone or with escorts and provide both strong defensive weaponry and heavy offensive missiles equivalent to a guided missile cruiser in addition to supporting fighters and helicopters.
There are three main configurations of aircraft carrier in service in the world's navies, divided by the way that aircraft take off and land:
As "runways at sea," modern aircraft carriers have a flat-top deck design that serves as a flight deck for the launch and recovery of aircraft. Aircraft launch forward, into the wind, and are recovered from astern. Carriers steam at speed, up to 35 knots (65 km/h) into the wind during flight deck operations to increase wind speed over the deck to a safe minimum. This increase in effective wind speed provides a higher launch airspeed for aircraft at the end of the catapult stroke or ski-jump, plus it makes recovery safer by reducing the difference between the relative speeds of the aircraft and ship.
On CATOBAR carriers, a steam-powered catapult is used to accelerate conventional aircraft to a safe flying speed by the end of the catapult stroke, after which the aircraft is airborne and further propulsion is provided by its own engines. On STOVL or STOBAR carriers aircraft do not require catapult assistance for take off; instead on nearly all ships of this type an upwards vector is provided by a ski-jump at the forward end of the flight deck often combined with thrust vectoring by the aircraft; though a STOVL is able to launch without a ski-jump or catapult with reduced fuel and weapon load. The form of assistance a carrier provides depends on the types of aircraft embarked and the design of the carrier itself.
Conversely, when recovering onto a CATOBAR or STOBAR carrier, conventional aircraft rely on a tailhook that catches on arrestor wires stretched across the deck to bring them to a stop in a short distance. Post WW-II Royal Navy research on safer CATOBAR recovery eventually lead to universal adoption of a landing area angled off axis to allow aircraft who missed the arresting wires to "bolt" and safely return to flight for another landing attempt rather than crashing into aircraft on the forward deck. Helicopters and vertical/short take-off and landing (V/STOL) aircraft usually recover by coming abreast the carrier on the port side and then using their hover capability to move over the flight deck and land vertically without the need for arresting gear.
Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, sometimes called paddles) to monitor the plane's approach, visually gauge glideslope, attitude, and airspeed, 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 optical landing system have provided information on proper glide slope, but LSOs still transmit voice calls to approaching 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. Carrier operations of other nations use 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 recovery. 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 launch, recovery and "those aircraft in the air near the ship, and the movement of planes on the flight deck, which itself resembles a well-choreographed ballet." 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 on conventional carriers it has been the practice to recover aircraft at an angle to port of the axial line of the ship. The primary function of this angled deck 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 forward. The angled deck also allows simultaneous launching and recovery of aircraft, and the installation of one or two "waist" catapults in addition to the two bow cats.
The superstructure of a carrier (such as the bridge, flight control tower) are concentrated to the starboard side of the deck in a relatively small area called an island, a feature pioneered on the HMS Hermes in 1923. Very few carriers have been designed or built without an island. The flush deck configuration proved to have very significant drawbacks, complicating navigation, air traffic control, and had numerous other adverse factors.
A more recent configuration, originally developed by the Royal Navy but since adopted by many navies for most smaller carriers, has a ski-jump ramp at the forward end of the flight deck. A ski jump is a fixed ramp at the end of the flight deck with a curved incline. This was first developed to help launch short takeoff and vertical landing (STOVL) aircraft. STOVL aircraft such as the Sea Harrier can take off at far higher weights than is possible with a vertical or rolling takeoff on a short flat deck on STOBAR carriers. A ski-jump works by converting some of the forward rolling motion of the aircraft into a jump into the air at the end of the flight deck, the jump combined with the aiming of jet thrust partly downwards by swiveling exhaust nozzles on aircraft with this feature allows the heavily loaded and fueled aircraft precious seconds to attain sufficient air velocity and lift to sustain normal flight. Without a ski-jump launching fully loaded and fueled aircraft such as the Harrier would not be possible on a smaller flat deck ship before either stalling out or crashing directly into the sea. Although STOVL aircraft are capable of taking off vertically from a spot on the deck, using the ramp and a running start is far more fuel efficient and permits a heavier launch weight. As catapults are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for complex steam or electromagnetic launching equipment, vertical landing aircraft also remove the need for arresting cables and related hardware. Russian and future Indian carriers include a ski-jump ramp for launching lightly loaded conventional fighter aircraft but recover using traditional carrier arresting cables and a tailhook on their aircraft.
The disadvantage of the ski-jump is the penalty it exacts on aircraft size, payload, and fuel load (and thus range); heavily laden aircraft can not launch using a ski-jump because their high loaded weight requires either a longer takeoff roll than is possible on a carrier deck, or assistance from a catapult or JATO rocket, for example the Russian Su-33 is only able to launch from the carrier Kuznetsov with a minimal armament and fuel load. Another disadvantage is on mixed flight deck operations where helicopters are also present such as a US Landing Helicopter Dock or Landing Helicopter Assault amphibious assault ship a ski jump is not included as this would eliminate one or more helicopter landing areas, this flat deck limits the loading of Harriers but is somewhat mitigated by the longer rolling start provided by a long flight deck compared to many STOVL carriers.
Unusual flight decks have been proposed for use in the jet age; from the SCADS conversion kit, to Skyhook, seaplane fighters, even a rubber flight deck. Shipborne containerized air-defense system (SCADS) was a proposed modular kit to convert a Ro-Ro or Container ship into a STOVL aircraft carrier in two days during an emergency with thirty days of jet fuel, munitions, defensive systems and missiles, ASW helicopters, crew and work areas, radar, and a ski jump, it could be quickly removed afterwards for storage, it was effectively a modern merchant aircraft carrier. Skyhook was proposed by British Aerospace and even more ambitious, a system using a crane with a top mating mechanism hung over the sea to fuel, launch, and recover a few Harriers even from ships as small as frigates. The Convair F2Y Sea Dart was a supersonic seaplane jet fighter that had skis rather than wheels, in the late 1940s the Navy feared that supersonic aircraft would not be able to land on a carrier, it would rather be lowered and raised from the sea via crane. The HMS Warrior tested a rubber coated flight deck where de Havilland Vampire fighters landed without needing landing gear or tailhook.
Aircraft carriers are generally the largest ships operated by navies. A total of 22 aircraft carriers in active service are maintained by ten navies. Australia, Brazil, France, India, Italy, Netherlands, 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:
Several nations that currently possess aircraft carriers are 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.
In 2001 China bought the unfinished hull of ex-Soviet aircraft carrier Varyag from Ukraine through a shell company with a purported intention of converting it into a floating casino. Prior to 2011, pictures taken of the carrier in port suggested that contrary to this, work was being conducted to complete construction of the vessel. On 10 August 2011, sea-trials of the re-fitted Varyag commenced with a stated purposes of training and research, i.e., for the present time it is officially assigned for non-combat activities.
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. In December 2010 China's State Oceanic Administration announced that this vessel would be finished one year earlier, in 2014. A nuclear powered carrier is planned for launch around 2020.
According to James Nolt, senior fellow at the World Policy Institute in New York, it might take China many years to develop the technology, training, and operational capability necessary for an effective carrier.
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, at 65,000–75,000 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 that can be reconfigured 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 proceed and were in no way conditional on French participation.
In 2004, India agreed to buy the Admiral Gorshkov from Russia for US$1.5 billion. It is named INS Vikramaditya, and was expected to join the Indian Navy in 2008 after a refit. However, after delays and cost overruns, the carrier is now scheduled to be handed over to India in December 2012, for an agreed price of US$2.35 billion.
India started the construction of a 40,000-tonne, 260-metre-long Vikrant-class aircraft carrier in April 2005. 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. 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. The ship is scheduled for commissioning in 2014.
In 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.
Speaking in St. Petersburg, Russia on 30 June 2011, the head of Russia's United Shipbuilding Corporation said his company expected to begin design work for a new carrier in 2016, with a goal of beginning construction in 2018 and having the carrier achieve initial operational capability by 2023. Several months later, on 3 November 2011 the Russian newspaper Izvestiya reported that the naval building plan now included (first) the construction of a new shipyard capable of building large hull ships, after which Moscow will build two nuclear-powered aircraft carriers by 2027. The spokesperson said one carrier would be assigned to the Russian Navy's Northern Fleet at Murmansk, and the second would be stationed with the Pacific Fleet at Vladivostok.
Defense analysts familiar with the Russian military speculate that while Russian Navy admirals and Russian shipyard owners want to build new aircraft carriers, it is far from certain that the Russian Parliament will authorize the spending of tens of billions of dollars it would cost to build the facilities, warships, and aircraft required to support two aircraft carrier battle groups.
The Royal Navy is constructing two new larger STOVL aircraft carriers, the Queen Elizabeth-class, to replace the three Invincible-class carriers. The ships will be named HMS Queen Elizabeth and HMS Prince of Wales. 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. Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 1450. The two ships will be the largest warships ever built for the Royal Navy.
The current US fleet of Nimitz-class and USS Enterprise carriers will 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 Kitty Hawk in May 2009, the U.S. fleet comprises 11 supercarriers. The House Armed Services Seapower subcommittee on 24 July 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 of which two are already under construction and twelve are planned.
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