An aircraft catapult is a device used to launch aircraft from ships, most
commonly used on aircraft carriers,as a form of assisted take off. It consists
of a track built into the flight deck, below which is a large piston or shuttle
that is attached through the track to the nose gear of the aircraft, or in
some cases a wire rope, called a catapult bridle, is attached to the
aircraft and the catapult shuttle. There have been different means of which have
been used to propel the catapult, such as weight and derrick, gunpowder,
flywheel, air pressure, hydraulic, steam power, and also in development to use
electromagnets. History
= First recorded flight using a catapult Aviation pioneer and Smithsonian
Secretary Samuel Langley used a spring-operated catapult to launch his
successful flying models and his failed aerodrome of 1903. Likewise the Wright
Brothers beginning in 1904 used a weight and derrick styled catapult to assist
their early aircraft with a takeoff in a limited space.
On 31 July 1912, Theodore Gordon Ellyson became the first person to be launched
from the experimental catapult system. The U.S. Navy had been perfecting a
compressed-air catapult system and mounted it on the Santee Dock in
Annapolis, Maryland. 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, LCDR Henry C. Mustin made the first catapult launch from a ship
underway. = Interwar and World War II =
The US Navy experimented with other power sources and models, including
catapults that utilized gunpowder and flywheel variations. On 14 December
1924, a Martin MO-1 observation plane flown by Lt. L. C. Hayden was launched
from USS Langley using a catapult powered by gunpowder. Following this
launch, this method was used aboard both cruisers and battleships.
Up to and during World War II, most catapults were hydraulic. Some carriers
were completed before and during World War II with catapults on the hangar deck
that fired athwartships, but they were unpopular because of 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. They were mostly used for experimental purposes, and their use was
entirely discontinued during the latter half of the war.
Many naval vessels apart from aircraft carriers carried float planes, seaplanes
or amphibians for reconnaissance and spotting. They were catapult-launched
and landed on the sea alongside for recovery by crane. There were submarine
aircraft carriers, and some Japanese submarines used them for offensive
operations also. The first launch off a Royal Navy battlecruiser was from HMAS
Australia on 8 March 1918. Subsequently many RN ships carried a catapult and
from one to four aircraft; battleships or battlecruisers like the HMS Prince of
Wales carried four aircraft and HMS Rodney carried two, while smaller
warships like the cruiser HMNZS Leander carried one. The aircraft carried were
the Fairey Seafox or Supermarine Walrus. Some like HMS Nelson did not use a
catapult, and the aircraft was lowered onto the sea for takeoff. Some had their
aircraft and catapult removed during WWII e.g. HMS Duke of York, or before.
During World War II a number of ships were fitted with rocket-driven
catapults, first the Fighter catapult ships of the Royal Navy, then armed
merchantmen known as CAM ships from "catapult armed merchantmen." These were
used for convoy escort duties to drive off enemy reconnaissance bombers. CAM
ships carried a Hawker Sea Hurricane, dubbed a "Hurricat" or "Catafighter",
and the pilot bailed out unless he could fly to land.
While imprisoned in Colditz Castle during the war, British prisoners of war
planned an escape attempt using a falling bathtub full of heavy rocks and
stones as the motive power for a catapult to be used for launching the
Colditz Cock glider from the roof of the castle.
= Steam catapult = Following World War II, the Royal Navy
was hard at work developing a new catapult system for their fleet of
carriers. Commander Colin C. Mitchell, RNV, recommended a steam-based system as
an effective and efficient means to launch the next generation of naval
aircraft. Trials on HMS Perseus, flown by pilots such as Eric "Winkle" Brown,
from 1950 showed its effectiveness. Navies introduced steam catapults,
capable of launching the heavier jet fighters, 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 might have been unsuitable for long use.
The way the steam catapult works is at launch, a release bar holds the aircraft
in place as steam pressure builds up, then breaks, freeing the piston to pull
the aircraft along the deck at high speed. Within about two to four seconds,
aircraft velocity by the action of the catapult plus apparent wind speed is
sufficient to allow an aircraft to fly away, even after losing one engine.
Nations that have retained large aircraft carriers and high performance
CATOBAR which the United States Navy, Brazilian Navy, and French Navy, are
still using catapults for their superior power and flexibility. The Royal Navy
operates STOVL aircraft, such as the imminent F-35B on the HMS Queen
Elizabeth Class Carriers and US Carrier/Expeditionary Strike Groups,
others employ the Sea Harrier or AV-8B Harrier II, which do not require
catapult assistance and take off vertically from STOVL configuration
carriers which are less expensive and generally smaller in size compared to
CATOBAR carriers. The Russian Su-33 "Flanker-D" 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 and S-3 Viking,
require a catapult shot, since their thrust-to-weight ratio is too low for a
conventional rolling takeoff on a carrier deck.
= Steam catapults types = Presently or at one time operated by the
U.S. Navy include: = Bridle catchers =
The ramps at the catapult ends on some aircraft carriers are used to catch the
ropes so they can be reused; bridles have not been used on U.S. aircraft
since the end of the Cold War, and all U.S. Navy carriers commissioned since
then have not had the ramps. The last U.S. carrier commissioned with a bridle
catcher was USS Carl Vinson; starting with USS Theodore Roosevelt the ramps
were deleted. During Refueling and Complex Overhaul refits in the late
1990s–early 2000s, the bridle catchers were removed from the first three
Nimitz-class aircraft carriers. USS Enterprise was the last U.S. Navy
operational carrier with the ramps still attached before her inactivation in
2012. Future
The size and manpower requirements of steam catapults place limits on their
capabilities. A newer approach is the Electromagnetic Aircraft Launch System.
Electromagnetic catapults place less stress on the aircraft and offer more
control during the launch by allowing gradual and continual acceleration.
Electromagnetic catapults are also anticipated to require significantly
less maintenance through the use of solid state components.
Linear induction motors have been experimented with before, such as
Westinghouse's Electropult system in 1945. However at the beginning of the
21st century, navies again started experimenting with catapults powered by
linear induction motors and electromagnets. EMALs would be more
energy efficient on nuclear-powered aircraft carriers and would alleviate
some of the dangers posed by using pressurized steam. On gas-turbine
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 electromagnetic catapults in its design.
Civilian use From 1929, the German Norddeutscher
Lloyd-liners SS Bremen and Europa were fitted with catapults to launch
mail-planes. These ships served the route between Germany and the United
States. The aircraft, carrying mail–bags, would be launched while the
ship was still many hundreds of miles from its destination, thus speeding mail
delivery by about a day. Initially, Heinkel HE 12 aircraft were used before
they were replaced by Junkers Ju 46, which were in turn replaced by the
Vought V-85G. The catapults were powered by compressed air.
After World War II, Supermarine Walrus amphibian aircraft were briefly operated
by a British whaling company, United Whalers. Operating in the Antarctic,
they were launched from the factory ship FF Balaena, which had been equipped with
an ex-navy aircraft catapult. See also
Arresting gear Jet blast deflector
Modern US Navy carrier operations Naval aviation
References Citations
Bibliography London, Peter. British Flying Boats.
Stoud, UK: Sutton Publishers Ltd., 2003. ISBN 0-7509-2695-3.
External links