1. The Aircraft carrier

The history of carries goes back almost as far as airplanes. In 1910, only seven years after Orville Wright made the first machine-powered flight, naval aviators began experiments taking off from and landing on battleships. Carriers played a small role in World War 2 and since 1945 they have been involved in almost all major US military operations.

At present, only ten countries possess carries but the super carriers, or flattops, of the US Navy are the biggest in the world. With a crew of up to 6,000 people onboard, and with a length from bow to stern the size of three football pitches, the nuclear-powered Nimitz carriers can transport up to 80 aircraft, launch or land a plane every 25 seconds and generate between 140 and 160 sorties per day. A speed of more than 35 knots per hour, approximately 700 nautical miles per day, gives the United States the ability to deploy military forces to almost anywhere in the world in less than two weeks.

Carries are open to attack from enemy ships, missiles and aircraft. From this reason, carries are always escorted by a flotilla of other ships, called the carrier battle group (GBG). The GBG is capable of carrying out anti-aircraft, anti-submarine and anti-surface defence warfare. Although the GBG is formed according to the mission, a typical formation includes: the aircraft carrier, two guided-missile cruisers; two destroyers; one frigate; two submarines and a supply ship.

2. How carriers work

An aircraft carries is a type of warships fitted with a runway or flight deck which is used to launch and recover planes. The hull of the carrier is made of extremely strong steel plates. Below the waterline the hull is rounded and narrow but above the waterline the hull gets wider and forms the flight deck. When not in use, aircraft are secured in the hangar bay, located two decks below the flight deck. The aircraft are then lifted from the hangar bay to the flight deck by the elevator.

The flight deck is not long enough for most planes to make an ordinary takeoff, so they are launched with a machine. To prepare for launching an aircraft, the carrier sails into wind. This manoeuvre reduces the plane's minimum take off the speed by getting the wind moving over the flight deck and over plane's wings. A steam- powered catapult is then used for launching the aircraft. The power for the catapult comes from the carrier's nuclear reactor and the catapult is able to accelerate the aircraft from 0 to 240 kph in two seconds.

The flight deck only has about 150 metres of runway space for launching which is not enough for high-speed jets, so aircraft land in process known as an arrested landing. Thick metal cables, or arresting wires are stretched across the deck and the pilot's arm when he lands is to catch the cable with the tailhook - a long hook attached to the plane's tail. This system can stop 24.5 -ton aircraft travelling at 241 kph in a 96-metre landing area in only two seconds.