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Encyclopedia > Aspect ratio (wing)
The low aspect ratio wing of a Piper PA-28 Cherokee
The low aspect ratio wing of a Piper PA-28 Cherokee

In aerodynamics, the aspect ratio is an airplane's wing's span divided by its standard mean chord (SMC). It can be calculated more easily, however as span squared divided by wing area: The low aspect ratio wing of a Piper PA-28 Cherokee (G-MKAS) at Bristol Airport, England. ... The low aspect ratio wing of a Piper PA-28 Cherokee (G-MKAS) at Bristol Airport, England. ... Cherokee is the common name for the Pipers PA-28 family of aircraft models, which received its type certificate from the FAA in 1960 and is still under production by The New Piper Aircraft Company. ... Aerodynamics is a branch of fluid dynamics concerned with the study of gas flows, first analysed by George Cayley in the 1800s. ... Fixed-wing aircraft is a term used to refer to what are more commonly known as aeroplanes in Commonwealth English (excluding Canada) or airplanes in North American English. ... A Laughing Gull on the beach in Atlantic City. ... The wingspan (or just span) of an airplane is the distance from the left wingtip to the right wingtip. ... In reference to aircraft, chord refers to the distance between the front and back of a wing, measured in the direction of the normal airflow. ...


Informally, a "high" aspect ratio indicates long, narrow wings, whereas a "low" aspect ratio indicates short, stubby wings.


Aspect ratio is a powerful indicator of the general performance of a wing. Wingtip vortices greatly deteriorate the performance of a wing, and by reducing the amount of wing tip area, making it skinny or pointed for instance, you reduce the amount of energy lost to this process, and increase the lift generated by the wing. This is why high performance gliders have very long, skinny wings; with no engine power, they must be as efficient as possible in every respect in order to stay aloft. Wingtip vortices stream from an F-15 as it disengages from a KC-10 Extender following midair refueling. ... Gliders are un-powered heavier-than-air aircraft. ...


High aspect-ratio wings reduce the amount of induced drag relative to the amount of lift produced. In aerodynamics, lift-induced drag, or more simply, induced drag, is a drag force arising from the generation of lift by wings or a lifting body during flight. ... Lift consists of the sum (technically the negative product) of all the fluid dynamic forces on a body normal (i. ...


Why don't all aircraft have high aspect-ratio wings? There are several reasons:

  • Structural: the deflection along a high aspect-ratio wing tends to be much higher than for one of low aspect ratio, thus the stresses and consequent risk of fatigue failures are higher - particularly with swept-wing designs.
  • Maneuverability: a high aspect-ratio wing will have a lower roll rate than one of low aspect ratio, due to higher drag and greater moment of inertia, thus rendering them unsuitable for fighter aircraft.
  • Stability - low aspect ratio wings tend to be more naturally stable than high-aspect ratios. This confers handling advantages, especially at slow speeds.
  • Practicality - low aspect ratios have a greater useful internal volume, which can be used to house the fuel tanks, retractable landing gear and other systems.
The high aspect ratio wing of a USAF B52 bomber
The high aspect ratio wing of a USAF B52 bomber

It is interesting to note that as with many discoveries in science and engineering, nature got there first. Most birds have wings with a high aspect ratio, and with tapered or elliptical tips. This is particularly noticeable on soaring birds such as the albatross and eagle. In addition, the V-formation (echelon) often seen in flights of geese, ducks and other migratory birds can be considered to act as a single swept wing with a very high aspect ratio - the vortices shed by the lead bird are smoothly transferred to the next and so on. This confers a huge efficiency advantage to the flight as a whole - perhaps as much as a 100% improvement compared to a single bird in flight. Note that the usual common explanation of the V-formation - that following birds are "shielded" from air resistance by the bird in front - may be misleading. While birds do "take turns" at being the lead bird, it is probably to give those at the tips a rest - they are the ones that will experience the most drag when the vortices are finally shed. However, the full explanation of this behaviour is still the subject of research and debate; scientists still do not claim to have fully understood the phenomenon. The swept wing of an airliner: British Midland Airbus A320-200 A swept-wing is a wing planform used on high-speed aircraft that spend a considerable portion of their flight time in the transonic. ... Moment of inertia quantifies the resistance of a physical object to angular acceleration. ... A fighter aircraft is a military aircraft designed primarily for attacking other aircraft, as opposed to a bomber, which is designed to attack ground targets, primarily by dropping bombs. ... The high aspect ratio wing of a USAF B52 bomber. ... The high aspect ratio wing of a USAF B52 bomber. ... Seal of the Air Force. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Genera Diomedea Thallasarche Phoebastria Phoebetria The albatrosses are seabirds in the family Diomedeidae, which is closely allied to the petrels, storm-petrels and diving-petrels in the order Procellariiformes, or tubenoses. ... Genera Several, see below. ... Four OS2U Kingfisher airplanes flying in right echelon formation. ... Other uses: Goose (disambiguation) Genera Anser Branta Chen Cereopsis Cnemiornis (extinct) † see also: Swan, Duck Anatidae Goose (plural geese) is the general English name for a considerable number of birds, belonging to the family Anatidae. ... Subfamilies Dendrocygninae Oxyurinae Anatinae Merginae Drake Mallard Duck is the common name for a number of species in the Anatidae bird family. ... // Long-distance land bird migration Many species of land birds migrate very long distances, the most common pattern being for birds to breed in the temperate or arctic northern hemisphere and winter in warmer regions, often in the tropics or the southern hemisphere. ... The swept wing of an airliner: British Midland Airbus A320-200 A swept-wing is a wing planform used on high-speed aircraft that spend a considerable portion of their flight time in the transonic. ...


See also

The wetted aspect ratio is a good indication of the aerodynamic efficiency of an aircraft. ... The aspect ratio of a two-dimensional shape is the ratio of its longest dimension to its shortest dimension. ...

External links

  • Scientific paper discussing V-formations in migratory birds
  • discussion about low aspect-ratio designs

 
 

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