Aircraft catapult

An aircraft catapult is a device used to allow aircraft to take off in a limited distance, typically from the deck of a vessel. They can also be installed on land-based runways, although this is rarely done. They are usually used on aircraft carriers as a form of assisted take off.

In the form used on aircraft carriers the catapult consists of a track, or slot, 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. Other forms have been used historically, such as mounting a launching cart holding a seaplane on a long girder-built structure mounted on the deck of a warship or merchant vessel, but most catapults share a similar sliding track concept.

Different means have been used to propel the catapult, such as weight and derrick, gunpowder, flywheel, air pressure, hydraulic, and steam power, and solid fuel rocket boosters. The U.S. Navy is developing the use of Electromagnetic Aircraft Launch Systems with the construction of the Gerald R. Ford-class aircraft carriers.

Historically it was most common for seaplanes to be catapulted, allowing them to land on the water near the vessel and be hoisted on board, although in WWII (before the advent of the escort carrier) conventional fighter planes (notably the Hawker Hurricane) would sometimes be catapulted from "catapult-equipped merchant" (CAM) vessels to drive off enemy aircraft, forcing the pilot to either divert to a land based airstrip, or to jump out by parachute or ditch in the water near the convoy and wait for rescue.