Sunday, September 28, 2008

How Aircraft Carrrier works

Introduction:
When the U.S. Navy really needs to impress people, it flies them out to one of its super aircraft carriers. Standing 20 stories above the water and stretching 1,092 feet (333 meters) from bow to stern (about as long as the 77-story Chrysler Building is tall), the sheer bulk of these ships is awe-inspiring. But the really amazing thing about a supercarrier isn't its size; it's the intense scene on its flight deck. When the crew is in full swing, it can launch or land a plane every 25 seconds -- all in a fraction of the space available on a typical landing strip.
In this article,we'll find out what the U.S. Navy's modern Nimitz-class aircraft carriers are all about. We'll learn what's on the different decks, take a look at the amazing machines that help launch and land aircraft, and find out a little about daily life on these enormous floating bases. As we'll see, the modern aircraft carrier is one of the most amazing vehicles ever created.

USS Nimitz
Photo courtesy U.S. Dept. of Defense
The USS Nimitz, one of the U.S. Navy's super aircraft carriers. See more pictures of aircraft carriers.

At its most basic level, an aircraft carrier is simply a ship outfitted with a flight deck -- a runway area for launching and landing airplanes. This concept dates back almost as far as airplanes themselves. Within 10 years of the Wright Brothers' historic 1903 flight, the United States, the United Kingdom and Germany were launching test flights from platforms attached to cruisers. The experiments proved largely successful, and the various naval forces started adapting existing warships for this purpose. The new carriers allowed military forces to transport short-range aircraft all over the world.
USS George Washington
Photo courtesy U.S. Department of Defense
The USS George Washington, one of the U.S. Navy's nuclear-powered super aircraft carriers

Carriers didn't play a huge role in World War I, but they were central to the air combat of World War II. For example, the Japanese launched the 1941 attack on Pearl Harbor from aircraft carriers. Today, super aircraft carriers are a crucial part of almost all major U.S. military operations. While the ship itself isn't especially useful as a weapon, the air power it transports can make the difference between victory and defeat.

One of the major obstacles of using air power in war is getting the planes to their destination. To maintain an air base in a foreign region, the United States (or any other nation) has to make special arrangements with a host country, and then has to abide by that country's rules, which may change over time. Needless to say, this can be extremely difficult in some parts of the world.

Under international Freedom of Navigation laws, aircraft carriers and other warships are recognized as sovereign territories in almost all of the ocean. As long as a ship doesn't get too close to any nation's coast, the crew can carry on just like they're back home. So, while the U.S. military would have to make special arrangements with a foreign nation to set up a land military base, it can freely move a carrier battle group (an assembly of an aircraft carrier and six to eight other warships) all over the globe, just as if it were a little piece of the United States. Bombers, fighters and other aircraft can fly a variety of missions into enemy territory, and then return to the relatively safe home base of the carrier group. In most cases, the Navy can continually replenish (resupply) the carrier group, allowing it to maintain its position indefinitely.

Carriers can move in excess of 35 knots (40 mph, 64 kph), which gives them the ability to get anywhere in the ocean in a few weeks. The United States currently has six carrier groups stationed around the world, ready to move into action at a moment's notice.


Talking the Talk
Ships have their own special language, particularly when it comes to getting from point to point. Here's a quick primer, in case you don't know aft from bow.
  • Stern - the rear of the ship
  • Bow - the front of the ship
  • Starboard - the right side of the ship (if you're facing the bow)
  • Port - the left side of the ship
  • Forward - moving toward the bow of the ship (as in, "Moving forward on the flight deck" or "The hangar deck is forward of the fantail.")
  • Aft - moving toward the stern of the ship
  • Inboard - moving from the side of the ship toward the center of the ship
  • Outboard - moving from the center of the ship to the side of the ship
  • Below - on a lower deck (as in, "Going below to the hangar" -- You never "go downstairs" on a ship, you always "go below.")
  • Fantail - the stern area of the main deck (the hangar deck on a carrier)
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Air Craft Carrier


An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, 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 staging aircraft operations. They have evolved from wooden vessels used to deploy a balloon into nuclear powered warships that carry dozens of fixed and rotary wing aircraft.
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. 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 the 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 Barnes, were built only during World War II. Although some were purpose built, most were converted from merchant ships, and were a stop-gap measure in order 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 rather than civilian merchant ships.
Wartime emergencies also saw the creation or conversion of other, unconventional aircraft carriers. CAM ships, like the 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. Battlecarriers were created by the Imperial JapaneseNavy to partially compensate for the loss of carrier strength at Midway.
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, or the Japaneseclass I-400 submarines, which were capable of carrying 3 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, part of the growth of air power as a significant part of 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, the scope of carrier operations continued to increase in size and importance. Supercarriers, 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 or 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", they 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 and therefore travel as part of a carrier battle group (CVBG) for their protection. Unlike other types of capital ships in the 20th century, 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 of military aircraft over the years.

Air Craft Carrier-Architecture

Air Craft Carrier-Architecture

SUB MARINE

A submarine is a watercraft that can operate independently underwater, as distinct from a submersible that has only limited underwater capability. The term submarine most commonly refers to large manned autonomous vessels, however historically or more casually, submarine can also refer to medium sized or smaller vessels, (midget submarines, wet subs), Remotely Operated Vehicles or robots. The word submarine was originally an adjective meaning "under the sea", and so consequently other uses such as "submarine engineering" or "submarine cable" may not actually refer to submarines at all. Submarine was shortened from the term "submarine boat".
Submarines are referred to as "boats" for historical reasons because vessels deployed from a ship are referred to as boats. The first submarines were launched in such a manner. The English term U-Boat for a German submarine comes from the German word for submarine, U-Boot, itself an abbreviation for Unterseeboot ("undersea boat").
Although experimental submarines had been built before, submarine design took off during the 19th century. Submarines were first widely used in World War I, and feature in many large navies. Military usage ranges from attacking enemy ships or submarines, aircraft carrier protection, blockade running, ballistic missile submarines as part of a nuclear strike force, reconnaissance and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration and facility inspection/maintenance. Submarines can also be specialised to a function such as search and rescue, or undersea cable repair. Submarines are also used in tourism and for academic research.
Submarines have one of the largest ranges in capabilities of any vessel, ranging from small autonomous or one- or two-man vessels operating for a few hours, to vessels which can remain submerged for 6 months such as the Russian Typhoon class. Submarines can work at greater depths than are survivable or practical for human divers. Modern deep diving submarines are derived from the bathyscaphe, which in turn was an evolution of the diving bell.
Most large submarines comprise a cylindrical body with conical ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines this structure is the "sail" in American usage ("fin" in European usage). A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear and various hydrodynamic control fins as well as ballast tanks. Smaller, deep diving and specialty submarines may deviate significantly from this traditional layout.

SUB MARINE

SUB MARINE

SUB MARINE1

SUB MARINE1

SUB MARINE II

SUB MARINE II

Sailing Ships

Sailing ship is now used to refer to any large, wind-powered, vessel. In technical terms, a ship was a sailing vessel with a specific rig of at least three masts, square rigged on all of them, making the sailing adjective redundant. In popular usage ship became associated with all large sailing vessels and when steam power came along the adjective became necessary.
specification:
There are many different types of sailing ship, but they all have certain basic things in common. Every sailing ship has a hull, rigging and at least one mast to hold up the sails that use the wind to power the ship. The crew who sail a ship are called sailors or hands. They take turns to take the watch, the active managers of the ship and her performance for a period.
Watches are traditionally four hours long. Some sailing ships use traditional ship's bells to tell the time and regulate the watch system, with the bell being rung once for every half hour into the watch and rung eight times at watch end (a four-hour watch).
Ocean journeys by sailing ship can take many months, and a common hazard is becoming becalmed because of lack of wind, or being blown off course by severe storms or winds that do not allow progress in the desired direction. A severe storm could lead to shipwreck, and the loss of all hands.
Sailing ships can only carry a certain quantity of supplies in their hold, so they have to plan long voyages carefully to include many stops to take on provisions and, in the days before watermakers, fresh water.

SAILING SHIPS

SAILING SHIPS

Sailing Ships

Sailing Ships

FRIGATE CLASS SHIPS



Basically a frigate [frĭg'-ĭt] is a warship. The term has been used for warships of many sizes and roles over the past few centuries.
In the 18th century, the term referred to ships which were as long as a ship-of-the-line and were square-rigged on all three masts (full rigged), but were faster and with lighter armament, used for patrolling and escort. In the 19th century, the armoured frigate was a type of ironclad warship and for a time was the most powerful type of vessel afloat.
In modern navies, frigates are used to protect other warships and merchant-marine ships, especially as anti-submarine warfare(ASW) combatants for amphibious expeditionary forces, underway replenishment groups, and merchant convoys. But ship classes dubbed "frigates" have also more closely resembled corvettes, destroyers, cruisers and even battleships.

INS GOTHAVARI

INS GOTHAVARI

INS GOTHAVARI

TYPE 16 GODAVARI CLASS:

Vessel Type:
Guided Missile Frigate.
Names & Pennant Numbers with commission dates:
Godavari F20 (10 December 1983) INS Ganga F22 (30 December 1985)INS Gomati F21(16 April 1988)
Structure:
The Type 16 Class frigates are a modification of the original Leander Class design with an indigenous content of 72% and a larger hull.
Displacement:
3600 tons standard.............3850 tons full load.
Dimensions:
Length - 126.4 metres.................Beam - 14.5 metres.................Draught - 4.5 metres.
Main Machinery:
Two turbines with 30,000 hp motors, two 550 psi boilers and two shafts.
Maximum Speed: 27 knots.
Maximum Range: 4500 miles at 12 knots.
Complement:
313 (incl. 40 Officers & 13 Aircrew).
Radar:
Air; One Signaal radar at D-band frequency (range - 145n miles; 264 km).........Air/Surface; One MR-310U Angara (NATO: Head Net-C) radar at E-band frequency (range - 70n miles; 128 km)..........Navigation/Helo Ctrl; Two Signaal ZW06 or Don Kay radars at I-band frequency..........Fire Control; Refer to 'Weapons' sub-section.
Sonar: The Bharat APSOH; hull mounted and provides active panoramic search & attack with medium frequency. The vessels also have a Fathoms Oceanic VDS (Variable Depth Sonar) and Type 162M sonar, which provides bottom classification with high frequency. INS Ganga has a Thomson Sintra DSBV 62; passive towed array sonar with very low frequency.
Weapons:
Four P-20M (SS-N-2D Styx) AShMs, fitted in single-tube launchers, with active radar (Mod 1) or infra-red (Mod 2) homing to 45n miles; 83 km at 0.9 Mach. Becomes a sea skimmer at the end of run. Has a 513 kg warhead.
INS Ganga and INS Gomati have been refitted with the Israeli Barak SAM system, with fire control provided by an EL/M-2221 STG radar.
The latter vessel was first sighted with the Barak in December 2002 and the system was reportedly operational by March 2003. It is probable that INS Godavari also has the Barak system, but that is yet to be confirmed through official channels. Prior to the fitment of the Barak system, these vessels had a single vertical launcher with the OSA-M (SA-N-4) SAM with SAR homing to 8n miles; 15 km at Mach 2.5, with a service ceiling of 3048 meters and a 50 kg warhead. A total of 20 OSA-M missiles were carried on board and they had a limited SSM capability. Fire control was provided by a single MPZ-310 (NATO: Pop Group) radar at F/H/I-band frequency, which has since been removed from the vessels that feature the Barak system.
Two 57mm (twin) guns at 90º elevation, 120 rds/min to 4.4n miles; 8 km, for use against ship- and shore-based targets. Fire control is provided by a single MR-103 (NATO: Muff Cob) radar at G/H-band frequency. In the CIWS role, the vessels are fitted with four AK-230 30mm gunmounts with 85º elevation and 500 rounds/min to 2.7n miles; 5 km with fire control provided by two MR-123 (NATO: Drum Tilt) radars at H/I-band frequency.
Features six 324mm ILAS 3 (2 triple) torpedo tubes, which fire the Whitehead A244S anti-submarine torpedo which has active/passive homing to 3.8n miles; 7 km at 33 knots with a 34 kg shaped charged warhead. INS Godavari has tube modifications for the Indian NST 58 version of A244S.
Weapons Control:
MR 301 MFCS and MR 103 GFCS.
Combat Data System: Selenia IPN-10 action data automation and a Immarsat communications (JRC) system.
Helicopters:
Two Sea King Mk.42B or a combination of one Sea King Mk.42B and one HAL Chetak. Usually one helicopter is carried with more than one air crew. French Samahé helicopter landing equipment is fitted. The Naval ALH can also be embarked.
Countermeasures:
Selenia INS-3 (Bharat Ajanta and Elettronica TQN-2) intercept and jammer is used for ESM/ECM purposes. Two chaff/flares are used as decoys. Will have the 'Super Barricade' decoys in due course. Also has a Graesby G738 towed torpedo decoy.