Flaps are hinged surfaces on the trailing edge of an airplane wing which, when deployed, increase the lift (and drag) of a wing. They are usually used while landing to allow the aircraft to fly more slowly and to steepen the approach to the landing site.

Wing trailing-edge flaps extended on an aircraft approaching London (Heathrow) airport

Types include:

• Plain flap - rotates on a simple hinge
• Split flap - upper and lower surfaces are separate, the lower surface operates like a plain flap, but the upper surface stays immobile or moves only slightly
• Fowler flap - slides backwards before hinging downwards, thereby increasing both camber and chord, creating a larger wing surface better tuned for lower speeds
• Slotted flap - systems made up of several individual Fowler flaps, which combine to form a single, much more powerful, flap
• Blown flaps - systems that blow engine air over the upper surface of the flap at certain angles to improve lift characteristics.

See also

• Flight controls