Ski-jump (aviation)

In aviation, a ski-jump is an upwardly curved ramp that allows a fixed-wing aircraft to take off from a runway that is shorter than the aircraft normally requires. By providing an upward vector from the ski-jump's normal force, the aircraft is launched at an elevated angle and lift-off can be achieved at a lower airspeed than that required for flat takeoff, as it allows the aircraft more time to continue accelerating while airborne after leaving the runway. Ski-jumps are commonly used to launch shipborne aircraft from aircraft carriers that lack catapults.

It is believed that the first use of the ski-jump occurred during the Second World War, when a temporary ramp was added to HMS Furious to help heavily laden Fairey Barracudas attack the German battleship Tirpitz. During the Cold War, the concept was studied as a means of reducing the length of flight decks required for aircraft carriers and to facilitate ever-heavier aircraft at sea. The Royal Navy took a particular interest in the ski-jump during the 1970s, conducting tests with the new Hawker Siddeley Harrier VSTOL fighter, then added a ramp to its next generation of aircraft carrier, the Invincible class.

Numerous naval services have since adopted the ski-jump for their own aircraft carriers and amphibious assault platforms, while land-based uses have been examined as well. Ski-jumps can be used in two ways: Short Take-Off But Arrested Recovery (STOBAR) for conventional, tailhook-equipped naval aircraft; and Short Take-Off, Vertical Landing (STOVL) for V/STOL aircraft. Catapult-equipped aircraft carriers have become a minority in the 21st century in part because ski-jump operations are simpler and cost less.