Wing

For many centuries, the word "wing", from the Old Norse vængr,[1] referred mainly to the foremost limbs of birds (in addition to the architectural aisle). But in recent centuries the word's meaning has extended to include lift producing appendages of insects, bats, pterosaurs, boomerangs, some sail boats and aircraft, or the inverted airfoil on a race car that generates a downward force to increase traction.

Condensation in the low pressure region over the wing of an Airbus A340, passing through humid air

Flaps (green) are used in various configurations to increase the wing area and to increase the lift. In conjunction with spoilers (red), flaps maximize drag and minimize lift during the landing roll.

The design and analysis of the wings of aircraft is one of the principal applications of the science of aerodynamics, which is a branch of fluid mechanics. In principle, the properties of the airflow around any moving object can be found by solving the Navier-Stokes equations of fluid dynamics. However, except for simple geometries these equations are notoriously difficult to solve and simpler equations are used.[2]

For a wing to produce lift, it must be oriented at a suitable angle of attack. When this occurs, the wing deflects the airflow downwards as it passes the wing. Since the wing exerts a force on the air to change its direction, the air must also exert an equal and opposite force on the wing.[3][4][5][6]

The wing of a landing BMI Airbus A319-100. The slats at its leading edge and the flaps at its trailing edge are extended.

Aircraft wings may feature some of the following:

• A rounded leading edge cross-section
• A sharp trailing edge cross-section
• Leading-edge devices such as slats, slots, or extensions
• Trailing-edge devices such as flaps or flaperons (combination of flaps and ailerons)
• Winglets to keep wingtip vortices from increasing drag and decreasing lift
• Dihedral, or a positive wing angle to the horizontal, increases spiral stability around the roll axis, whereas anhedral, or a negative wing angle to the horizontal, decreases spiral stability.

Aircraft wings may have various devices, such as flaps or slats that the pilot uses to modify the shape and surface area of the wing to change its operating characteristics in flight.

• Ailerons (usually near the wingtips) to roll the aircraft clockwise or counterclockwise about its long axis
• Spoilers on the upper surface to disrupt the lift and to provide additional traction to an aircraft that has just landed but is still moving.
• Vortex generators mitigate flow separation at low speeds and high angles of attack, especially over control surfaces.[12]
• Wing fences to keep flow attached to the wing by stopping boundary layer separation from spreading roll direction.
• Folding wings allow more aircraft storage in the confined space of the hangar deck of an aircraft carrier
• Variable-sweep wing or "swing wings" that allow outstretched wings during low-speed flight (i.e., take-off and landing) and swept back wings for high-speed flight (including supersonic flight), such as in the F-111 Aardvark, the F-14 Tomcat, the Panavia Tornado, the MiG-23, the MiG-27, the Tu-160 and the B-1B Lancer warplanes
• Strakes to improve flight characteristics
• Chine, which may blend into the wing
• Leading-edge droop flap, a high-lift device
• Fairings, structures whose primary function is to produce a smooth outline and reduce drag. For example, flap track fairings

Wings may have other minor independent surfaces.

Besides fixed-wing aircraft, applications for wing shapes include:

• Hang gliders, which use wings ranging from fully flexible (paragliders, gliding parachutes), flexible (framed sail wings), to rigid
• Kites, which use a variety of surfaces to attain lift and maintain stability[13]
• Flying model airplanes
• Helicopters, which use a rotating wing with a variable pitch angle to provide directional forces[14]
• Propellers, whose blades generate lift for propulsion.
• The NASA Space Shuttle, which uses its wings only to glide during its descent to a runway. These types of aircraft are called spaceplanes.[15]
• Some racing cars, especially Formula One cars, which use upside-down wings (or airfoils) to provide greater traction at high speeds.[16]
• Sailboats, which use flexible cloth sails as vertical wings with variable fullness and direction to move across water.
• Hydrofoils, which use rigid wing shaped structures to lift a vessel out of the water to reduce drag and increase speed.

• Flight

Natural world

• Bat flight
• Bird flight
• Flight feather
• Flying and gliding animals
• Insect flight
• List of soaring birds
• Samara (winged seeds of trees)

Aviation

• Aircraft
• Blade solidity
• FanWing and Flettner airplane (experimental wing types)
• Flight dynamics (fixed-wing aircraft)
• Kite types
• Ornithopter – Flapping-wing aircraft (research prototypes, simple toys and models)
• Otto Lilienthal
• Wing configuration
• Wing root
• Wingsuit flying

Sailing

• Sails
• Forces on sails
• Wingsail

Wikimedia Commons has media related to Wings.

• How Wings Work - Holger Babinsky Physics Education 2003
• How Airplanes Fly: A Physical Description of Lift
• Demystifying the Science of Flight – Audio segment on NPR's Talk of the Nation Science Friday
• NASA's explanations and simulations
• Flight of the StyroHawk wing
• See How It Flies