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The multipurpose aircraft carriers of the Nimitz class are the largest warships ever built that are in service. The USS Nimitz (CVN 68) is
the leading unit of these "supercarriers"; her keel was laid down in June 1968, her hull was launched in May 1972 and she entered service in
May 1975. The USS Nimitz is a nuclear-powered vessel; her propulsion plant comprises two nuclear reactors General Electric A4W/AIG, cooled by
pressurized water, linked to four steam turbines able to provide 260000 horsepower, enough to propel the ship at speeds over 30 knots
(almost 60 kilometers/hour).
The true advantage of nuclear propulsion is the huge increment in operational range, for the resupply of atomic fuel is only required at
very large time intervals. In fact, the first supply of uranium bars was enough to navigate during 13 years, during which the USS Nimitz would
travel a distance between 1.5 and 1.9 millions of kilometers without requiring to refuel. Or said with other words, a single series of uranium
bars could provide the same energy than 11 millions of oil barrels (1.22 millions of tonnes). But, unlike the vessel, the crew and the aircraft
onboard need to be fed daily, so the aircraft carrier has space for provisions and aviation fuel to supply during 15 days only.
Based on the theory that the best defense of the aircraft carrier are her aircraft, the USS Nimitz was fitted with a very limited armament:
three octuple launchers for surface-to-air missiles Sea Sparrow, for air defense in a radius of about 14.6 kilometers, and three Vulcan Phalanx
CIWS mountings with a six-barrel 20-millimeter cannon each, for antimissile defense at very close range. Apart from the active armament, the
aircraft carrier is fitted with diverse radars and a bow sonar, electronic war devices and launchers for chaff or flares, to detect and divert
incoming missiles and torpedoes.
The airborne air defense is formed by twenty F-14 Tomcat which, with their air-to-air missiles AIM-7 or AIM-54, provide combat air patrols (CAP)
in a radius of up to 570 kilometers around the aircraft carrier (since the F-14 was retired from US Navy service in 2006 the F-18 took its
role). While the F-14 perform their mission, the turboprop aircraft E-2C Hawkeye, fitted with a long-range search radar (AEW), explore the sky and the
sea surface to detect any relevant activity. In case of contact, they would guide the patrolling F-14 to control the matter.
The air wing on the USS Nimitz also comprises a part of antisubmarine aircraft (ASW), this is, ten S-3A Viking, as well as six helicopters SH-3 Sea King
for antisubmarine defense at close range (since the S-3A was retired from US Navy service in 2009 and the Sea King in 2006 other aircraft took their
role). Both aircraft types are fitted with sonar devices for submarine detection and are able to launch self-guided torpedoes to the chosen
targets.
To perform offensive actions, the USS Nimitz would make exclusive use of her aircraft. The attack squadron is formed by 40 aircraft: twenty
A-6E Intruder and twenty F/A-18 Hornet. These latter are very adaptable aircraft, which can be used against land or sea targets. By contrast,
the Intruder is a naval bomber, able to fly in the most adverse atmospheric conditions, and which can launch twenty-eight 226.8-kilogram bombs against
targets located in a radius of 1670 kilometers around the aircraft carrier and then return.
The model A-6 comprises also an electronic warfare version (EW), the EA-6B Prowler, suitable to cause tactical electronic interferences, and a
tanker version, the KA-6D (since the A-6 was retired from US Navy service in 1997 other aircraft took its diverse roles). The air wing on the
USS Nimitz includes six Prowler and four KA-6D.
The following photograph, taken in 1997, shows all of the aforementioned aircraft parked in the flight deck. In the image are visible a total of
46 aircraft: eight F-14 Tomcat with retracted wings, twenty-four F/A-18 Hornet, three E-2C Hawkeye, five S-3A Viking, three helicopters and
three A-6E Intruder. Note also the Sea Sparrow and the Vulcan Phalanx installed astern.
About half of the aircraft onboard can be allocated in the hangar beneath the flight deck, using for the transfer one of the four elevators;
the rest of the aircraft has to remain in the flight deck. Elevators have their shape adapted to that of the aircraft onboard and, with an area over
300 square meters and a lift power of 58500 kilograms, they are able to harbor two units on each transfer.
The required speed for take off is provided by steam catapults which, literally, throw the aircraft into the air. To land onboard, the aircraft must
be hooked in one of the four arresting wires distributed across the landing area, maneuver not easy for an F-14, which during landing still advances with
a speed of about 250 kilometers/hour. On the flight deck the personnel wears different colors to differentiate their diverse roles.
As 2016 goes by, and with the aircraft carriers of the Gerald R. Ford class in the horizon, the ten components of the Nimitz class still conform the aircraft
carrier fleet of the United States Navy, over fourty years after the commissioning of the USS Nimitz. A number of upgrades have been effectuated in the
electronics, the armament and the aircraft since then, but these aircraft carriers are still the best ones in the world and they will be serving
for many years coming.
The USS Nimitz in detail
The 3rd May 1975, the USS Nimitz entered service with the United States Navy, being the second aircraft carrier in the world fitted with nuclear
propulsion. At the same time she was the largest warship in existance, surpassing the USS Enterprise, which was precisely the first aircraft
carrier powered by nuclear energy. The construction cost of the USS Nimitz reached 1881 millions of dollars. The assembly of the diverse components,
not counting the design nor the production time, occupied about 40 millions of hours/person.
With a complement of around 6000 persons, a library, a supermarket and her own radio and television stations, the USS Nimitz is truly a floating city,
and one gifted with exceptional warlike power, integrated by an air wing of around 90 aircraft, among which are always present some of the most modern
models in existance. Of the 6000 persons onboard about 60 percent belongs to the ship's crew and the rest to the air wing. Inside such a ship there
are about 3400 rooms of every type (offices, salons, cabins, storages, etc...), all of them gifted with air conditioning. For the large population
onboard, every day the kitchens prepare about 18000 meals and 2000 cubic meters of salt water are potabilized.
With an overal length of 332.8 meters and a maximum beam of 76.8 meters, the USS Nimitz has a standard displacement over 91000 tonnes and a flight deck
with an area of about 18200 square meters. There is such a multitude of systems onboard the ship, and of such complexity, that if all the manuals required
to operate them were stacked together, they would form a column over 170 meters tall. These systems require so much energy that the power plant has
capacity to provide electric energy for a city of 100000 habitants. The network of electric cables of every type onboard would measure, if put in line
each one of them, more than 1500 kilometers. And there are more than 30000 lightpoints and 2000 telephones onboard.
When the aircraft carrier is operating, the operations post is not the command bridge, located on the isle and therefore too exposed, but the Combat
Information Center (CIC) located deep inside the hull. This room contains every electronic device required to fight against an "invisible" enemy located
beyond the horizon, while being protected from the effects of nuclear, biological and chemical warfare (NBC). The electronic equipment onboard the
USS Nimitz includes the air surveillance radar SPS-49 with a range of 457 kilometers and the three-dimensional radar SPS-48 with a range of 402
kilometers. She also has radars for surface surveillance and navigation, and for controlling the aircraft and the launching of surface-to-air missiles.
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