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A laughing gull with its wings extended in the gull wing profile
A flying bat
Several aircraft wing planform shapes: a swept wing KC-10 Extender (top) refuels a trapezoidal-wing F-22 Raptor fighter plane
The low pressure region over the wing of this A340 is clearly shown by the condensation it causes in the humid air
Internal mechanical construction of a generic monospar wing. Black = solid, red = tube used for the spar, green = foam, wood, honeycomb, or sheet metal used for the ribs. The leading edge gives torsional stiffness. The trailing edge can either have a flexible skin, which does not break under wing bending (birdlike,) or have a stiff skin (made of carbon fiber, aluminum alloy, or titanium, aircraft-like), which is prevented from buckling by span-wise "stringers."
Various trees such as maples have winged seeds that enable them to disperse, some autorotating as they fall, often catching the autumn wind as they do so.

A wing is a type of fin with a surface that produces aerodynamic force for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid. As such, wings have an airfoil shape, a streamlined cross-sectional shape producing lift.

The word "wing" from the Old Norse vængr[1] for many centuries 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.



Aerodynamics of wings[edit]

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. The properties of the airflow around any moving object can - in principle - be found by solving the Navier-Stokes equations of fluid dynamics. However, except for simple geometries these equations are notoriously difficult to solve.[3] Fortunately, simpler explanations can be described.

For a wing to produce "lift", it must be oriented at a suitable angle of attack relative to the flow of air past the wing. When this occurs the wing deflects the airflow downwards, "turning" the air as it passes the wing. Since the wing exerts a force on the air to change its direction, the air must exert a force on the wing, equal in size but opposite in direction. This force manifests itself as differing air pressures at different points on the surface of the wing.[4][5][6]

A region of lower-than-normal air pressure is generated over the top surface of the wing, with a higher pressure existing on the bottom of the wing. (See: airfoil) These air pressure differences can be either measured directly using instrumentation, or they can be calculated from the airspeed distribution using basic physical principles, including Bernoulli's Principle which relates changes in air speed to changes in air pressure.

The lower air pressure on the top of the wing generates a smaller downward force on the top of the wing than the upward force generated by the higher air pressure on the bottom of the wing. Hence, a net upward force acts on the wing. This force is called the "lift" generated by the wing.

The different velocities of the air passing by the wing, the air pressure differences, the change in direction of the airflow, and the lift on the wing are intrinsically one phenomenon. It is, therefore, possible to calculate lift from any of the other three. For example, the lift can be calculated from the pressure differences, or from different velocities of the air above and below the wing, or from the total momentum change of the deflected air. There are other approaches in fluid dynamics to solving these problems. All of these approaches will result in the same answers if done correctly. Given a particular wing and its velocity through the air, debates over which mathematical approach is the most convenient to use can be misperceived by novices as differences of opinion about the basic principles of flight.

For a more detailed coverage see lift (force).

Devices to change the shape of a wing[edit]

Usually, aircraft wings 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. In 1948, Francis Rogallo invented the fully limp flexible wing, which ushered new possibilities for aircraft. Near in time, Domina Jalbert invented flexible un-sparred ram-air airfoiled thick wings. These two new branches of wings have been since extensively studied and applied in new branches of aircraft, especially altering the personal recreational aviation landscape.

A common misconception[edit]

A common misconception is that in order to generate lift it is essential for the wing to have a longer path on the topside compared with the underside.[7] Wings with this shape are the norm in subsonic flight, but symmetrically shaped wings (above and below) can generate lift by using a positive angle of attack to deflect air downward. Symmetrical airfoils have higher stalling speeds than cambered airfoils of the same wing area[8] but are used in aerobatic aircraft as they provide practical performance whether the aircraft is upright or inverted. Another example comes from sailboats, where the sail is a thin membrane with no path-length difference between one side and the other.[9]

For flight speeds near the speed of sound (transonic flight), airfoils with complex asymmetrical shapes are used to minimize the drastic increase in drag associated with airflow near the speed of sound.[10] Such airfoils, called supercritical airfoils, are flat on top and curved on the bottom.[11]

Other examples[edit]

The science of wings applies in other areas beyond conventional fixed-wing aircraft, including:

Structures with the same purpose as wings, but designed for use in liquid media, are generally called fins or hydroplanes, with hydrodynamics as the governing science, rather than aerodynamics. Applications of these arise in craft such as hydrofoils and submarines. Sailboats and sailing ships use both fins and wings.

Design features[edit]

Aircraft wings may feature some of the following:

See also[edit]

Natural world:




  2. ^ "Swimming". Retrieved 2012-04-25. 
  7. ^

External links[edit]