A wing is a surface used to produce an aerodynamic force normal to the direction of motion by travelling in air or another gaseous media. The first use of the word was for the foremost limbs of birds, but has been extended to include other animal limbs and man made devices.
The foremost use of wings is to fly by deflecting air downwards to produce lift, but wings are also commonly used as a way to produce downforce[?] and hold objects to the ground (for example racing cars).
Terms used to describe aeroplane wings:
- Leading edge: edge facing into wind
- Trailing edge: edge facing away from wind
- Span: distance from tip to tip
- Chord: distance from leading edge to trailing edge
- Aspect ratio: ratio of span to standard mean chord
Aeroplane wings may feature some or more of the following:
- A rounded leading edge section
- A sharp trailing edge section
- Leading-edge devices such as slats or slots
- Trailing-edge devices such as flaps
- Ailerons (usually near the wingtips) to provide roll control
- Spoilers on the upper surface to disrupt lift
Types of wings:
- Dihedral wings, which have an angle between them, have inherent stability in roll. As the aircraft rolls, one wing generates more lift, rolling the aircraft back into position.
- Swept wings are good for fast aircraft. They present the wing at an angle to the airflow, so that the wing "sees" a slower airflow.
- Elliptical wings are theoretically optimum for efficiency at subsonic speeds.
- Delta wings have reasonable performance at subsonic and supersonic speeds.
- waveriders are efficient supersonic wings.
- rogallo wings are two hollow half-cones of fabric, one of the simplest wings to construct.
The amount of lift produced by a wing increases with the angle of attack (the angle between the onset flow and the chord line) but this relationship ends once the stall angle is reached. At this angle the airflow starts to separate from the upper surface, and any further increase in angle of attack gives no more lift (it may actually reduce) and gives a large increase in drag.
Wing design is complicated and very tightly associated with the science of aerodynamics.
Examples of wing use:
- A helicopter uses a rotating wing with a varible pitch or angle to provide a directional force.
- The space shuttle uses its wings only for lift during its descent.
Constructions of the same purpose as wings, but working in liquid media instead are generally called fins with hydrodynamics as the governing science.