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A tailhook, also arresting hook or arrestor hook, is a device attached to the empennage (rear) of an aircraft. It is used to achieve rapid deceleration after landing, usually aboard an aircraft carrier.
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Description
The tailhook is a strong metal bar, with its free end flattened out, thickened somewhat, and fashioned into a claw-like hook. The pilot is capable of raising this bar to its inflight position or lowering it ("Hook Down") for landing. Helicopters and other aircraft that are able to land vertically are not equipped with tailhooks.
Aircraft land on the flight deck of an aircraft carrier on a short "landing area", towards the aft end of the ship. A number (usually four) of very greasy and very strong thick flexible cables called arrestor cables, "arresting wires" or "cross deck pendandts" are stretched across the landing area. When an aircraft lands properly, the tailhook should catch one of the cables and the cable will transfer the energy of the aircraft, through a "purchase cable," to the belowdecks arresting gear engines, stopping the aircraft. Both the hook and cables have to be very strong: jet aircraft land on carriers just above stall speed. Once contact is made with the deck, the pilot advances the throttle(s) to the full military setting to generate enough available power in the event of a "bolter" (where the hook fails to catch any of the cross-deck pendants).
The term "hooked" is sometimes used to describe aircraft fitted with a tailhook. "Trapped" is often-used slang for an arrested landing. An aircraft which misses a landing by failing to catch the arresting cables is said to have "boltered." Occasionally, the tailhook bounces over one or more of the wires, resulting in a "hook skip bolter."
Every carrier landing is graded by the LSO (landing signals officer), "3-OK" being the highest rating. The "3" indicates the cross-deck pendant on which the aircraft trapped.
Land-based tailhooks
Most land-based fighters also have tailhooks. In case of a brake malfunction, an aborted takeoff, a tire explosion, or a related problem, a tailhook can stop the aircraft in a departure-end or approach-end cable arrestment. Since it is an emergency equipment, the tailhook is deployed with nitrogen pressure instead of using the aircraft's hydraulic system. Additionally the tailhook can only be repositioned by ground crew.
The presence of a tailhook is not evidence of an aircraft's suitability for carrier operations. Typical carrier aircraft are built to withstand the tremendous stresses endured during launch and recovery operations.
Gallery
Tail hooks
 Detail of a tailhook. |
 F/A-18E Super Hornet with hook, from below. |
 FH1 Phantom with tail hook down |
 Tailhook down on an A4D approaching its ship for recovery |
 Super Etendard with V-shaped tail hook. |
Landings on carrier
 Landing of a Fairey 3F on HMS Furious in the 1930's |
 F-4 Phantom lands on USS John F. Kennedy |
 F/A-18 on USS John C. Stennis |
 A6 Intruder |
 A successfully landed F/A-18. Note the engines are at full throttle. |
 F/A-18 successfull landing |
 A missed landing (bolter). |
 A USAF F-16 hooks an arresting cable during a test at Shaw Air Force Base. |
References
- United States Air Force. [1]. Guide To Mobile Aircraft Arresting System Installation. Retrieved on 3 November 2007.
See also
External links
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Wikimedia Commons has media related to: Tail hook |
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