Why is the "Nimitz" class nuclear-powered aircraft carrier the largest warship to date?

The following introduces the structure of the U.S. Navy's "Nimitz" class nuclear-powered aircraft carrier, a representative of modern large-scale nuclear-powered aircraft carriers. This class of aircraft carrier is the largest warship in history and also the most expensive.

90,000 tons, 280,000 horsepower

The "Nimitz" class aircraft carrier has a total length of 332.9 meters, a width of 48 meters, a draft of 11.3 meters, and a full load displacement of 90,940 tons (follow-up ships (91,487 tons), with a standard displacement of 81,600 tons and a combat displacement of 93,400 tons.

Generally, the full-load displacement of a ship refers to the displacement when it is filled with fuel and ammunition. However, for the "Nimitz" class, if it is fully loaded in the port, the draft will be too deep, which will hinder activities in the port. Therefore, the displacement at the deepest draft within the limit that does not hinder movement in the port is called full load displacement, and the displacement after maximum replenishment on the ocean is called combat displacement. This shows that the "Nimitz" class is so large that it is almost inconvenient to use.

The ship has 4 propellers driven by 4 steam turbines, which make this behemoth move at a speed of more than 30 knots. The maximum output power of the host is more than 260,000 horsepower according to published data, but it is said to be 280,000 horsepower. The maximum speed has not been announced, but it is generally believed that it can reach 35 knots (64.8 kilometers per hour). The propeller has a diameter of 6.4 meters and weighs 11 tons. The two rudders each weigh 45.5 tons. The two anchors each weigh 30 tons. One link of the anchor chain weighs 163 kilograms. The hull is 76 meters high from the bottom to the top of the mast, which is equivalent to the height of a 20-story building.

Steam is generated by two A4W/A1G pressurized water reactors. The earliest nuclear-powered aircraft carrier "Enterprise" has 8 reactors (A2W type), while the "Nimitz" class only uses 2 Block, this is due to advances in nuclear reactor technology. The shortest nuclear charge life is 13 years, which translates into a sailing distance of about 800,000 to 1 million nautical miles.

Aircraft Lounge - Sealed Hangar

As the name suggests, aircraft carriers have to park aircraft on the ship, so they have to have a hangar.

Before World War II, the United States had been adopting a design in which the hangar and flight deck were placed above the hull. The left and right sides of the hangar were covered only with roller curtains, allowing air to circulate freely. This was called an open design. Hangar. This design makes it easier to obtain a wider hangar space. It is easier to handle dangerous items such as gasoline and bombs, or to deal with accidents, which is called damage control. It played a considerable role during the war.

After World War II, carrier-based aircraft became more and more sophisticated. Especially after the emergence of nuclear weapons, it was necessary to improve the air tightness of ships, so it was no longer suitable to use open hangars. In addition, the open hangar deck is the strength deck that maintains the strength of the ship. However, as the aircraft carrier becomes larger, the hangar deck alone cannot maintain sufficient strength. Therefore, the U.S. Navy has adopted closed hangars since the USS Forrestal in 1955.

The "Nimitz" class aircraft carrier is a sealed hangar, which means the carrier-based aircraft hangar is sealed inside the hull. There are only 4 places on both sides (3 on the starboard side and 1 on the port side). The opening is used for aircraft lifting and landing. The ship's hangar is 209 meters long, 33 meters wide and 8.1 meters high, which is equivalent to the height of three decks.

A flight deck as big as three football fields

There is a place on an aircraft carrier for parking, take-off and landing of carrier-based aircraft, called a flight deck. The flight deck of the "Nimitz" class aircraft carrier is as big as three football fields. This is of course very narrow compared to land airports. After all, it has to accommodate 90 high-performance aircraft to park, take off and land, but as a ship deck, But no one can compare with it.

Since the "Kitty Hawk" was built in 1961, the flat flight deck has become the standard type of American aircraft carriers. On the left side of the flight deck, there are two aircraft elevators in front of the bridge, one behind the bridge, and one behind the port side. The angled flight deck from the front left to the rear right is used for aircraft landing. The take-off positions are in the front half of the flight deck and the front half of the angled flight deck, where two aircraft catapults are placed. The angled flight deck, aircraft catapults and optical landing guidance devices are called the three treasures of a modern aircraft carrier. Interestingly, these three devices were first conceived by the British Navy and put into practical use by the U.S. Navy.

Aircraft take elevator

Carrier-based aircraft need to be transported from the hangar to the flight deck using a special elevator. British and Japanese aircraft carriers are moved up and down by elevators at or near the center line of the hull. American aircraft carriers have long installed elevators on the sides of the flight decks, called side elevators. The advantages of this method are: the flight deck does not need to be dug and the strength of the flight deck will not be affected; when the elevator descends, the area of ??the flight deck will not be reduced; the disadvantage is: it is difficult to use in harsh weather.

The "Nimitz" class elevators each have an area of ??374 square meters and a load capacity of 50 tons. They can carry A-6 and A-7 attack aircraft at the same time. The trip between the hangar and flight deck takes one minute.

Sending an aircraft to the sky - catapult

The catapult is a device that ensures that the carrier-based aircraft can be ejected within a few seconds within a distance of tens of meters.

Since the flight deck of an aircraft carrier is very short, and the take-off speed of modern carrier-based aircraft is required to reach 200 to 300 kilometers per hour, the carrier-based aircraft slides on its own on the flight deck and cannot accelerate to this take-off speed, so it needs the help of a catapult accelerate.

After the carrier-based aircraft is sent to the flight deck by elevator, it stops on the parking deck on the left side of the bridge and at the front and rear, loads weapons and ammunition, completes the preparations for sortie, and then uses the front half of the flight deck or the oblique angle. Aircraft catapult on the flight deck, ejecting and taking off.

For catapults on aircraft carriers, hammers and oil pressure have been used in the past. After World War II, the British Navy invented a catapult that used steam, and it reached the practical stage in the 1950s. Most modern aircraft carriers are equipped with steam catapults.

The principle of the steam catapult is to send the high-temperature and high-pressure steam generated by the ship's boiler or nuclear reactor into a cylinder, push the piston, and use the "iron hand" extending from the piston to pull the aircraft to lift the aircraft from zero to zero. Accelerate quickly to takeoff speed. Although the principle is very simple, in order to extend the "iron hand" from the piston, it is necessary to make grooves in the cylinder while maintaining the pressure in the cylinder. This is the key to the success of the steam catapult. As a result, this problem was solved by using a soft metal band in the sealed part of the groove. The "iron wrist" extended from the piston was used to bring the convex metal piece, push the metal band close to the groove edge, and then use the metal piece behind Press back into the groove. Some steam will leak out from where the "Iron Fist" passes, producing white smoke on the flight deck.

The catapult installed on the "Nimitz" class is the C-13-I type, with a ejection force of 9.7 million meters/kg. It can launch a 30-ton aircraft within a take-off distance of 76.3 meters. The speed accelerates from zero to 256 kilometers per hour. If used to eject a 2-ton car, it can eject to a distance of 2.4 kilometers. The "Nimitz" class is equipped with 4 such catapults.

Help the aircraft brake - landing arresting device

Since the length of the aircraft carrier flight deck cannot meet the needs of the carrier-based aircraft when landing, an auxiliary facility is necessary, which is to help the ship The braking device that quickly reduces the speed of a carrier aircraft when landing on a ship is called a landing arresting device.

There are many ways for carrier-based aircraft to land on the ship. Before and after World War II, there was a method: when the aircraft entered the landing area, the landing aircraft lowered its tail hook, hooked the arresting cable, and gradually stopped taxiing while dragging the arresting cable. This method is called the standard method for hydraulic devices to absorb impulse.

The arresting cable uses a hydraulic cylinder to absorb impulse while stretching. Its absorption force is about 6.9 million meters/kg, which can make a 30-ton jet slide 100 meters and then stop. In the past, dozens of arresting cables were needed. Since the introduction of the angled flight deck, the standard on U.S. aircraft carriers is four. The arresting cables are installed in the landing area at the rear of the angled deck. Starting from 55 meters from the rear end of the flight deck, there are 4 arresting cables arranged horizontally every 12 meters. There is about 100 meters of sliding distance in front of the arresting cable, plus about 30 meters needed to turn around, so the angled flight deck needs to be about 200 meters long.

When the tailhook of the aircraft fails to hook any arresting cable, there is an arresting net made of nylon material at the stern of the ship to trap the aircraft.

Let the aircraft return home safely - landing guidance device

Landing an aircraft is much more difficult and risky than landing at a land airport. At 23:50 on May 26, 1981, when an EA-6B electronic warfare aircraft landed on the USS Nimitz, it crashed, exploded, and caught fire on the deck because it was not aligned with the center line of the runway. The Sparrow missile mounted on the previous F-14 exploded, killing 14 people, injuring 42 people, and 11 aircraft were damaged or destroyed. Therefore, the technical requirements for carrier-based aircraft pilots to control the aircraft are higher than those for land-based aircraft pilots, and the landing guidance work is also much more difficult. Naturally, landing guidance work and guidance equipment play a role in ensuring the safe landing of carrier-based aircraft.

The method of guiding carrier-based aircraft to land on the ship used to be for senior pilots to hold colored boards in both hands and direct the aircraft to land. After the carrier-based aircraft became larger, the landing speed was much faster than before. The pilots on the aircraft could not see the hand gestures of the personnel clearly. Special devices were required to allow the pilots of the aircraft to land at high speed to determine the landing route.

In order to solve this problem, the British Navy invented the reflector landing guidance system. The principle is: reflect the searchlight light with a mirror, and use the reflected light to compare with a row of lights on both sides of the mirror to make a judgment. For example, if you see reflected light from a landing aircraft above a row of lights, it means the landing route is too high, and if it is below it, it means it is too low. This method is called a reflector landing guidance system. Later, after improvements, plane lens light sources were used instead, so that even in dark nights or foggy conditions, one can still see clearly, but the basic principle remains the same.

In the late 1960s, a fully automatic landing guidance device (using radar) was developed, but carrier-based aircraft pilots still must have the driving skills for visual landing. Optical guidance devices also remain on the aircraft carrier.

The main flight control tower located on the uppermost level of the bridge controls all carrier-based aircraft takeoff and landing operations. From there, the entire flight deck can be seen at a glance, and important areas are monitored by closed-circuit television.

The next floor of the main flight control tower is the captain's navigation command bridge, and below that is the aviation battle group commander's combat bridge.

Below, the protruding part to the left is the TV camera room, which is specially used to film flight deck operations and landing situations to make video tapes. There is even a TV camera buried on the center line of the oblique flight deck to film landing aircraft. The positive image was immediately broadcast at the flight-related control tower or the preparation room of each aviation unit, and the video tape was retained for future inspection.

Beware of sneak attacks

The US aircraft carrier is equipped with 4-5 E-2C "Hawkeye" early warning aircraft, maintaining a dispatch rate of nearly 100%. In addition, the ship is also equipped with early warning radar. The main ones are SPS-48 three-coordinate air warning radar and SPS-43A long-range air search radar, as well as SPS-10F surface search radar, LN-66 navigation radar and SPN-42.43.44 air traffic control/full Automatic landing guidance radar, as well as SPS-65 low-altitude warning radar and SLQ-32 electronic warfare system. These radar antennas and receiving antennas are arranged around the bridge on the principle of not affecting the take-off and landing of carrier-based aircraft as much as possible.

Aircraft carriers cannot act alone and must be protected by a escort network of cruisers and destroyers. However, in the event that there are enemies that break through the escort network and rush in, especially anti-ship missiles, the aircraft carrier must have its own defense methods. Therefore, the aircraft carrier is also equipped with three "Sea Sparrow" short-range anti-air missile launchers and 3-4 20mm "Phalanx" short-range artillery systems. The "Sea Sparrow" missile is controlled by the SPS-65 radar. The SLQ-32 electronic warfare system can interfere with the radar guidance system of anti-ship missiles; there are also 4 MK36 interference rocket launchers used to interfere with the infrared guidance system of anti-ship missiles.

The U.S. Nimitz-class nuclear-powered aircraft carrier and the British Invincible-class light aircraft carrier

Aircraft carriers are the targets that the enemy pays most attention to. Although they are not easily sunk by the enemy, they are vulnerable to attacks from all directions. It is also not easy to deal with.