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Aircraft catapult

 
Aircraft Catapult

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Aircraft catapult



 
 
An aircraft catapult is a device used to launch aircraft
Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
 from ship
Ship

A ship is a large watercraft that floats on water. Ships are generally distinguished from boats based on size. Ships may be found on lakes, seas, and rivers and they allow for a variety of activities, such as the ferry or cargo ships, fishing, cruise ship, Coast guard, and warship....
s—in particular aircraft carrier
Aircraft carrier

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 navy force to project air power great distances without having to depend on local bases for staging aircraft operations....
s—as a form of assisted take off
Assisted take off

Assisted take off is any system for helping aircraft into the air . The reason it might be needed is due to the aircraft's weight exceeding the normal Maximum Takeoff Weight, insufficient power, or the available runway length may be insufficient, or a combination of all three factors....
. It consists of a track built into the flight deck
Flight deck

The flight deck of an aircraft carrier is the Deck from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the flight deck....
, below which is a large piston or shuttle that is attached through the track to the nose gear
Undercarriage

In aviation, the undercarriage or landing gear is the structure that supports an aircraft on the ground and allows it to taxiing....
 of the aircraft.

Older aircraft did not have a launch bar integrated in the nose gear; instead, a wire rope called a catapult bridle was attached to the aircraft and the catapult shuttle.






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F 18 Release
An aircraft catapult is a device used to launch aircraft
Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
 from ship
Ship

A ship is a large watercraft that floats on water. Ships are generally distinguished from boats based on size. Ships may be found on lakes, seas, and rivers and they allow for a variety of activities, such as the ferry or cargo ships, fishing, cruise ship, Coast guard, and warship....
s—in particular aircraft carrier
Aircraft carrier

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 navy force to project air power great distances without having to depend on local bases for staging aircraft operations....
s—as a form of assisted take off
Assisted take off

Assisted take off is any system for helping aircraft into the air . The reason it might be needed is due to the aircraft's weight exceeding the normal Maximum Takeoff Weight, insufficient power, or the available runway length may be insufficient, or a combination of all three factors....
. It consists of a track built into the flight deck
Flight deck

The flight deck of an aircraft carrier is the Deck from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the flight deck....
, below which is a large piston or shuttle that is attached through the track to the nose gear
Undercarriage

In aviation, the undercarriage or landing gear is the structure that supports an aircraft on the ground and allows it to taxiing....
 of the aircraft.

Older aircraft did not have a launch bar integrated in the nose gear; instead, a wire rope called a catapult bridle was attached to the aircraft and the catapult shuttle. The ramps at the catapult ends on older carriers were used to catch these ropes so they could be reused; bridles have not been used on aircraft since the end of the Cold War
Cold War

The Cold War was the continuing state of conflict, tension and competition that existed between a number of world powers, including the United States, the Soviet Union, People's Republic of China, France, United Kingdom and those countries' respective allies from the mid-1940s to the early 1990s....
 and all carriers commissioned since then have not had the ramps. The last carrier commissioned with a bridle catcher was USS Carl Vinson
USS Carl Vinson (CVN-70)

The USS Carl Vinson is a United States Navy Nimitz class aircraft carrier supercarrier named after Carl Vinson, a Congressman from Georgia ....
; starting with Theodore Roosevelt
USS Theodore Roosevelt (CVN-71)

USS Theodore Roosevelt is the fourth Nimitz class aircraft carrier supercarrier and her call sign is Rough Rider, the name of President Theodore Roosevelt's Rough Riders during the Spanish-American War....
 the ramps were deleted. During Refueling and Comprehensive Overhaul refits in the late 1990s-early 2000s, the bridle catchers were removed from the first three Nimitz class aircraft carrier
Nimitz class aircraft carrier

The Nimitz-class supercarriers, a line of Nuclear reactor technology aircraft carriers in service with the United States Navy, are the largest capital ships in the world, and are considered to be a hallmark in the United States' superpower status....
s. USS Enterprise
USS Enterprise (CVN-65)

USS Enterprise , formerly CVA-65, is the world's first nuclear-powered aircraft carrier and the eighth U.S. naval vessel to USS Enterprise. Like USS Enterprise of World War II fame, she is nicknamed the "Big E." At 1,123 feet , she is the longest naval vessel in the world, though her 93,500 tons displacement places her as t...
 is the last operational carrier with the ramps still attached.

At launch, a release bar holds the aircraft in place as steam pressure builds up, then breaks (or "releases"; older models used a pin that sheared), freeing the piston to pull the aircraft along the deck at high speed. Within about four seconds, aircraft velocity plus apparent wind speed (ship's speed plus "natural" wind) will be sufficient to allow an aircraft to fly away, even after losing one engine.

History


First record flight using a catapult


Aviation pioneer Samuel Langley used a spring operated catapult to launch his successful flying models and his failed aerodrome of 1903 Likewise the Wright Brothers
Wright brothers

The Wright brothers, Orville and Wilbur , were two United States who are generally credited with inventing and building the world's first successful fixed-wing aircraft and making the first controlled, powered and sustained heavier-than-air Flight#Mechanical flight, on December 17, 1903....
 beginning in 1904 used a weight
Weight

In the physical sciences, weight is a measurement of the gravitational force acting on an object. Near the surface of the Earth, the Earth's gravity is approximately constant; this means that an object's weight is roughly proportional to its mass....
 and derrick
Derrick

A derrick is a lifting device composed of one mast or pole which is hinged freely at the bottom. It is controlled by lines powered by some means such as man-hauling or motors, so that the pole can move in all four directions....
 styled catapult to assist their early aircraft with a takeoff in a limited space.

On 31 July 1912, Theodore Gordon Ellyson
Theodore Gordon Ellyson

Commander Theodore Gordon "Spuds" Ellyson, USN was the first United States Navy officer designated as an aviator . Ellyson served in the experimental development of aviation in the years before and after World War I....
 ("Spuds") as he was known, became the first person to be launched from the experimental catapult system. The U.S. Navy had perfecting an air-compressed catapult system and mounted it on the Santee Dock in Annapolis. The first attempt nearly killed Lt. Ellyson when the plane left the ramp with its nose pointing upward and it caught a crosswind, pushing the plane into the water. Ellyson was able to escape from the wreckage unhurt. On 12 November 1912, Lt. Ellyson made history as the Navy’s first successful catapult launch, from a stationary coal barge. On 5 November 1915, Lt. Cdr. H. C. Mustin made the first catapult launch from a moving ship

Catapults during WWII


Up to and during World War II
World War II

World War II, or the Second World War , was a global military conflict which involved a Participants in World War II, including all of the great powers, organised into two opposing military alliances: the Allies of World War II and the Axis powers....
 most catapults were hydraulic, and there were a number of armed merchantmen
Armed merchantmen

An Armed Merchantman has come to mean a merchant vessel equipped with guns, usually for defensive purposes, either by design or after the fact. In the days of sail, Maritime Piracy and privateers, many merchantmen would be routinely armed, especially those engaging in long distance and high value trade....
, known as CAM ship
CAM ship

A CAM ship was a World War II-era United Kingdom merchant ship used in convoys as a quick emergency solution to the shortage of escort aircraft carriers....
s ("catapult armed merchantmen"), that had rocket-driven catapults. Some carriers were completed before and during World War II with catapults on the hangar deck that fired athwartships, but they were unpopular due to their short run, low clearance of the hangar decks, inability to add the ship's forward speed to the aircraft's airspeed for takeoff, and lower clearance from the water (conditions which afforded pilot
Aviator

An aviator is a person who flies aircraft for pleasure or as a profession.The feminine word aviatrix is sometimes used and is the correct term to refer to all women pilots....
s far less margin for error in the first moments of flight). They were mostly used for experimental purposes, and their use was entirely discontinued during the latter half of the war.

Steam catapult


The steam catapult was a British
United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
 invention.The use of steam to launch aircraft was suggested by Commander
Commander

Commander is a military rank which is also sometimes used as a military title depending on the individual customs of a given military service. Commander is also used as a rank or title in some organizations outside of the military, particularly in police and law enforcement....
 Colin C. Mitchell RNVR, and trials on HMS Perseus
HMS Perseus (R51)

HMS Perseus was a Colossus class carrier light fleet aircraft carrier of the Royal Navy. She was laid down by Vickers Armstrong on the Tyne on 1 January 1943, launched on 26 March 1944, and commissioned on 19 October 1945, thus missing World War II....
 from 1950 showed its effectiveness. Navies
Navy

A navy is the branch of a nation's military forces principally designated for naval warfare and amphibious warfare; namely, lake- or ocean-borne combat operations and related functions....
 introduced steam catapults, capable of launching the heavier jet
Jet aircraft

A jet aircraft is an aircraft propelled by jet engines. Jet aircraft fly much faster than propeller-powered aircraft and at higher altitudes -- as high as 10,000 to 15,000 meters ....
 fighters
Fighter aircraft

A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets by dropping bombs....
, in the mid-1950s. Powder-driven catapults were also contemplated, and would have been powerful enough, but would also have introduced far greater stresses on the airframes and may have been unsuitable for long use.

Nations that have retained large aircraft carriers and high performance CATOBAR
CATOBAR

CATOBAR is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier. Under this technique, aircraft launch using a Aircraft catapult assisted take off and land on the ship using arrestor wires....
 (Catapult Assisted Take Off But Arrested Recovery) (the United States Navy
United States Navy

The United States Navy is the navy of the United States Armed Forces. It is one of the seven uniformed services of the United States. The U.S. Navy currently has approximately 331,682 personnel on active duty as of 31 December 2008 and 124,000 in the United States Navy Reserve....
, Brazilian Navy
Brazilian Navy

The Brazilian Navy is the navy of Brazil and forms part of the Brazilian Armed Forces. It is the largest navy in Latin America, with a 27,307-ton aircraft carrier, the NAe S?o Paulo , some American and British-built frigates, a few locally-built corvettes, coastal diesel-electric submarines and many other river and coastal patrol craft....
, and French Navy
French Navy

The French Navy, officially the Marine nationale and often called La Royale , is the maritime arm of the French military. It consists of a full range of vessels, from patrol boats to guided missile frigates, and includes one nuclear aircraft carrier and ten nuclear submarines ....
) are still, out of necessity, using catapults. Other navies operate STOVL
STOVL

STOVL is an acronym for Short Take Off and Vertical Landing.This is the ability of some aircraft to take off from a short runway or take off vertically if it does not have a very heavy payload and land vertically ....
 aircraft, such the Sea Harrier
BAE Sea Harrier

The BAE Systems Sea Harrier is a Navy VTOL/STOVL jet fighter, reconnaissance and attack aircraft, a development of the Hawker Siddeley Harrier. It first entered service with the Royal Navy in April 1980 as the Sea Harrier FRS1....
 or AV-8B Harrier II
AV-8B Harrier II

The McDonnell Douglas AV-8B Harrier II is a family of second-generation vertical/short takeoff and landing or V/STOL ground-attack aircraft of the late 20th century....
, which do not require catapult assistance, from smaller and less costly ships. The Russian Su-33 "Flanker-D"
Sukhoi Su-33

The Sukhoi Su-33 is a aircraft carrier multi-role fighter aircraft produced by Russian firm Sukhoi beginning in 1982. It is a derivative of the Sukhoi Su-27 and was initially known as the Su-27K....
 can take off from aircraft carriers without a catapult, albeit at a reduced fuel and armament load. U.S. Navy tactical aircraft use catapults to launch with a heavier warload than would otherwise be possible. Larger planes, such as the E-2 Hawkeye
E-2 Hawkeye

The Grumman E-2 Hawkeye is an United States all-weather, aircraft carrier-based tactical Airborne Early Warning aircraft. The twin turboprop aircraft was designed and developed in the 1950s by Grumman for the United States Navy as a replacement for the E-1 Tracer....
 and S-3 Viking
S-3 Viking

The Lockheed S-3 Viking is a jet aircraft originally used by the United States Navy to identify, track, and destroy enemy submarines. In the late 1990s, the S-3B's mission focus shifted to surface warfare and aerial refueling....
, require a catapult shot, inasmuch as their thrust-to-weight ratio is too low for a conventional rolling takeoff on a carrier deck.

Operation


The commonly-used steam catapult relies on the availability of large quantities of high-pressure steam- found in the vast majority of 20th century capital ships. The steam charges a steam accumulator
Steam accumulator

A Steam accumulator is an Thermal insulation steel pressure tank containing hot water and steam under pressure. It is a type of energy storage device which is used to smooth out peaks and troughs in demand for steam in a factory....
 so that it may be released faster than it can be produced by the ship.

The steam catapult consists of two slotted cylinders similar in principle to those used by the Clegg & Samuda atmospheric railway
Atmospheric railway

An atmospheric railway is a railway that uses air pressure to provide power for propulsion. A pneumatic tube is laid between the rails, with a piston running in it suspended from the train through a sealable slot in the top of the tube....
. The cylinders—typically 18 inches in diameter—contain free pistons connected to a shuttle which protrudes through a slot in the flight deck. The nosewheel of the aircraft to be launched is attached to the shuttle by a launch bar.

On completion of the launch the piston is travelling at high speed and would cause damage if not stopped in a controlled fashion. This is done by a water brake, which is a horizontal dashpot
Dashpot

A dashpot is a mechanical device, a damper which resists motion via viscous friction. The resulting force is proportional to the velocity, but acts in the opposite direction, slowing the motion and absorbing energy....
 into which sea water is pumped with a swirling action as fast as it can flow out of the open end. The combination of the slight compressibility of the aerated water, the restriction as the water is expelled from the dashpot and the force produced by the expelled water hitting the front of the piston assembly itself serves to absorb the energy of the piston without damage. At that point a bring-back mechanism returns the piston and shuttle for the next launch.

Future


The size and manpower requirements of steam catapults place limits on their capabilities. A newer approach is the Electromagnetic Aircraft Launch System (EMALS). Electromagnetic catapults place less stress on the aircraft, require less manpower, and offer substantially more control during the launch. At the beginning of the 21st century, navies started experimenting with catapults powered by linear induction motors and electromagnetic
Electromagnetic

Electromagnetic may refer to:* Electromagnetic radiation* Electromagnetism...
s. These electromagnetic catapults
Electromagnetic Aircraft Launch System

Electromagnetic Aircraft Launch System is a system under development by the United States Navy to launch aircraft from carriers using a linear motor drive instead of steam pistons used in conventional aircraft catapults....
 would be more energy efficient on nuclear powered
Nuclear marine propulsion

Nuclear marine propulsion is propulsion of a ship powered by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships ....
 aircraft carriers and would alleviate some of the dangers posed by using pressurized steam. On gas-turbine
Gas turbine

A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between....
 powered ships, an electromagnetic catapult would eliminate the need for a separate steam boiler for generating catapult steam. The U.S. Navy's upcoming Gerald R. Ford class carrier includes electric catapults in its design.

See also

  • Modern US Navy carrier operations