A wing is a type of

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

that produces

lift Lift or LIFT may refer to: Physical devices * Elevator, or lift, a device used for raising and lowering people or goods ** Paternoster lift, a type of lift using a continuous chain of cars which do not stop ** Patient lift, or Hoyer lift, mobil ...

while moving through air or some other fluid. Accordingly, wings have

streamlined Streamlines, streaklines and pathlines are field lines in a fluid flow. They differ only when the flow changes with time, that is, when the flow is not steady. Considering a velocity vector field in three-dimensional space in the framework of ...

cross-sections that are subject to

aerodynamic force In fluid mechanics, an aerodynamic force is a force exerted on a body by the air (or other gas) in which the body is immersed, and is due to the relative motion between the body and the gas. Force There are two causes of aerodynamic force: ...

s and act as airfoils. A wing's

aerodynamic Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

efficiency is expressed as its

lift-to-drag ratio In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under gi ...

. The lift a wing generates at a given speed and angle of attack can be one to two

orders of magnitude An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic dis ...

greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that sys ...

to propel the wings through the air at sufficient lift. Lifting structures used in water include various foils, such as hydrofoils. Hydrodynamics is the governing science, rather than aerodynamics. Applications of underwater foils occur in hydroplanes,

sailboat A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture. Types Although sailboat terminolo ...

s and submarines.

Etymology and usage

For many centuries, the word "wing", from the Old Norse ''vængr'', referred mainly to the foremost

limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, ...

s of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s (in addition to the architectural aisle). But in recent centuries the word's meaning has extended to include lift producing appendages of

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 ...

boomerangs A boomerang () is a thrown tool, typically constructed with aerofoil sections and designed to spin about an axis perpendicular to the direction of its flight. A returning boomerang is designed to return to the thrower, while a non-returning b ...

, some sail boats and

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...

, or the inverted airfoil on a race car that generates a downward force to increase traction.

Aerodynamics

The design and analysis of the wings of aircraft is one of the principal applications of the science of

aerodynamics Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dy ...

, which is a branch of

fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics of fluids ( liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical and ...

. 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. 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."The cause of the aerodynamic lifting force is the downward acceleration of air by the airfoil..."

Cross-sectional shape

An ''airfoil'' (

American English American English, sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. English is the most widely spoken language in the United States and in most circumstances i ...

) or ''aerofoil'' (

British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...

) is the shape of a wing, blade (of a propeller,

rotor Rotor may refer to: Science and technology Engineering * Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator *Helicopter rotor, the rotary wing(s) of a rotorcraft ...

, or

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating ...

), or sail (as seen in cross-section). Wings with an asymmetrical cross section are the norm in

subsonic flight Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

. Wings with a symmetrical cross section can also 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 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."...consider a sail that is nothing but a vertical wing (generating side-force to propel a yacht). ...it is obvious that the distance between the stagnation point and the trailing edge is more or less the same on both sides. This becomes exactly true in the absence of a mast—and clearly the presence of the mast is of no consequence in the generation of lift. ''Thus, the generation of lift does not require different distances around the upper and lower surfaces.''" Holger Babinsky ''How do Wings Work?'' Physics Education November 2003
PDF
/ref> 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. Such airfoils, called

supercritical airfoil A supercritical airfoil (supercritical aerofoil in British English) is an airfoil designed primarily to delay the onset of wave drag in the transonic speed range. Supercritical airfoils are characterized by their flattened upper surface, highly ...

s, are flat on top and curved on the bottom.

Design features

Aircraft wings may feature some of the following: * A rounded

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

cross-section * A sharp

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...

cross-section * Leading-edge devices such as

slats Super Low Altitude Test Satellite (SLATS) or Tsubame was a JAXA satellite intended to demonstrate operations in very low Earth orbit (VLEO, below 200 km), using ion engines to counteract aerodynamic drag from the Earth's atmosphere which i ...

, slots, or extensions * Trailing-edge devices such as

flap Flap may refer to: Arts, entertainment, and media * ''Flap'' (film), a 1970 American film * Flap, a boss character in the arcade game ''Gaiapolis'' * Flap, a minor character in the film '' Little Nemo: Adventures in Slumberland'' Biology and he ...

s or flaperons (combination of flaps and ailerons) *

Winglets Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft' ...

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 *

Spoiler Spoiler is a security vulnerability on modern computer central processing units that use speculative execution. It exploits side-effects of speculative execution to improve the efficiency of Rowhammer and other related memory and cache attacks. Ac ...

s 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 generator A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (or airfoil, such as an aircraft wing) or a rotor blade of a wind turbine.

s mitigate flow separation at low speeds and high angles of attack, especially over control surfaces. * Wing fences to keep flow attached to the wing by stopping boundary layer separation from spreading roll direction. *

Folding wing A folding wing is a wing configuration design feature of aircraft to save space and is typical of carrier-based aircraft that operate from the limited deck space of aircraft carriers. The folding allows the aircraft to occupy less space in a con ...

s allow more aircraft storage in the confined space of the

hangar deck A hangar is a building or structure designed to hold aircraft or spacecraft. Hangars are built of metal, wood, or concrete. The word ''hangar'' comes from Middle French ''hanghart'' ("enclosure near a house"), of Germanic origin, from Frankish ...

of an aircraft carrier *

Variable-sweep wing A variable-sweep wing, colloquially known as a "swing wing", is an airplane wing, or set of wings, that may be swept back and then returned to its original straight position during flight. It allows the aircraft's shape to be modified in fli ...

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 General Dynamics F-111 Aardvark is a retired supersonic, medium-range, Multirole combat aircraft, multirole combat aircraft. Production variants of the F-111 had roles that included attack aircraft, ground attack (e.g. Air interdiction, i ...

, the

F-14 Tomcat The Grumman F-14 Tomcat is an American carrier-capable supersonic, twin-engine, two-seat, twin-tail, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental (VFX) program after the ...

, the

Panavia Tornado The Panavia Tornado is a family of twin-engine, variable-sweep wing multirole combat aircraft, jointly developed and manufactured by Italy, the United Kingdom and West Germany. There are three primary Tornado variants: the Tornado IDS ( in ...

, the

MiG-23 The Mikoyan-Gurevich MiG-23 (russian: Микоян и Гуревич МиГ-23; NATO reporting name: Flogger) is a variable-geometry fighter aircraft, designed by the Mikoyan-Gurevich design bureau in the Soviet Union. It is a third-generati ...

, the

MiG-27 The Mikoyan MiG-27 (russian: Микоян МиГ-27; NATO reporting name: Flogger-D/J) is a variable-sweep ground-attack aircraft, originally built by the Mikoyan-Gurevich design bureau in the Soviet Union and later licence-produced in India ...

, the

Tu-160 The Tupolev Tu-160 (russian: Туполев Ту-160 Белый лебедь, translit=Belyj Lebeď, translation=White Swan; NATO reporting name: Blackjack) is a supersonic, variable-sweep wing heavy strategic bomber designed by the Tupolev Desi ...

and the

B-1B Lancer The Rockwell B-1 Lancer is a supersonic variable-sweep wing, heavy bomber used by the United States Air Force. It is commonly called the "Bone" (from "B-One"). It is one of three strategic bombers serving in the U.S. Air Force fleet along with ...

warplanes *

Strake On a vessel's hull, a strake is a longitudinal course of planking or plating which runs from the boat's stempost (at the bows) to the sternpost or transom (at the rear). The garboard strakes are the two immediately adjacent to the keel on ea ...

s to improve flight characteristics *

Chine A chine () is a steep-sided coastal gorge where a river flows to the sea through, typically, soft eroding cliffs of sandstone or clays. The word is still in use in central Southern England—notably in East Devon, Dorset, Hampshire and the Is ...

, which may blend into the wing *

Leading-edge droop flap The leading-edge droop flap is a device on the leading edge of aircraft wings designed to improve airflow at high pitch angles (high angle of attack). The droop flap is similar to the leading-edge slat and the Krueger flap, but with the differen ...

, 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.

Applications and variants

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

Hang glider Hang gliding is an air sport or recreational activity in which a pilot flies a light, non-motorised foot-launched heavier-than-air aircraft called a hang glider. Most modern hang gliders are made of an aluminium alloy or composite frame cover ...

s, which use wings ranging from fully flexible (

paraglider Paragliding is the recreational and competitive adventure sport of flying paragliders: lightweight, free-flying, foot-launched glider aircraft with no rigid primary structure. The pilot sits in a harness or lies supine in a cocoon-like ' ...

s, gliding parachutes), flexible (framed sail wings), to rigid *

Kites A kite is a tethered heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create lift and drag forces. A kite consists of wings, tethers and anchors. Kites often have a bridle and tail to guide the face ...

, which use a variety of surfaces to attain lift and maintain stability * Flying model airplanes *

Helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

s, which use a rotating wing with a variable pitch angle to provide directional forces * Propellers, whose blades generate lift for propulsion. * The

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program ...

, which uses its wings only to glide during its descent to a runway. These types of aircraft are called

spaceplane A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes te ...

s. * Some

racing cars Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport involving the racing of automobiles for competition. Auto racing has existed since the invention of the automobile. Races of various sorts were organise ...

, especially

Formula One car A Formula One car (also known as an F1 car) is a single-seat, open-cockpit, open-wheel formula racing car with substantial front and rear wings, and an engine positioned behind the driver, intended to be used in competition at Formul ...

s, which use upside-down wings (or '' airfoils'') to provide greater traction at high speeds. *

Sailboat A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture. Types Although sailboat terminolo ...

s, 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.

In nature

In nature, wings have

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

s, dinosaurs (

s), and mammals (

s) as a means of

locomotion Locomotion means the act or ability of something to transport or move itself from place to place. Locomotion may refer to: Motion * Motion (physics) * Robot locomotion, of man-made devices By environment * Aquatic locomotion * Flight * Locomo ...

. Various species of penguins and other flighted or

flightless Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

water birds such as

auk An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...

s, cormorants,

guillemot Guillemot is the common name for several species of seabird in the Alcidae or auk family (part of the order Charadriiformes). In British use, the term comprises two genera: '' Uria'' and ''Cepphus''. In North America the ''Uria'' species ...

shearwater Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and are pelagic outside the breeding season. Description These tub ...

eider Eiders () are large seaducks in the genus ''Somateria''. The three extant species all breed in the cooler latitudes of the Northern Hemisphere. The down feathers of eider ducks, and some other ducks and geese, are used to fill pillows and quil ...

and scoter ducks and diving

petrel Petrels are tube-nosed seabirds in the bird order Procellariiformes. Description The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group (all except the albatross f ...

s are avid swimmers, and use their wings to propel through water.

;Wing forms in nature

File:PSM V19 D181 Various seeds of trees.jpg, Winged tree seeds that cause

autorotation Autorotation is a state of flight in which the main rotor system of a helicopter or other rotary-wing aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. Bensen, Ig ...

in descent File:Seagull wing.jpg, A

laughing gull The laughing gull (''Leucophaeus atricilla'') is a medium-sized gull of North and South America. Named for its laugh-like call, it is an opportunistic omnivore and scavenger. It breeds in large colonies mostly along the Atlantic coast of North Am ...

, exhibiting the "

gull wing The gull wing is an aircraft wing configuration, known also as ''Pulaski wings'', with a prominent bend in the wing inner section towards the wing root. Its name is derived from the seabirds which it resembles. Numerous aircraft have incorpora ...

" outline File:PikiWiki_Israel_11327_Wildlife_and_Plants_of_Israel-Bat-003.jpg, Bat in flight

Tensile structures

In 1948,

Francis Rogallo Francis Melvin Rogallo (January 27, 1912 – September 1, 2009) was an American aeronautical engineer inventor born in Sanger, California, U.S. Together with his wife, he is credited with the invention of the Rogallo wing, or "flexible w ...

invented a kite-like tensile wing supported by inflated or rigid struts, which ushered in 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.

References

External links

How Wings Work - Holger Babinsky Physics Education 2003

Demystifying the Science of Flight
– Audio segment on NPR's Talk of the Nation Science Friday

Flight of the StyroHawk wing
{{Authority control Aerodynamics Aerospace technologies Aircraft wing components Bird anatomy Bird flight Insect anatomy Mammal anatomy es:Ala (zoología)

Etymology and usage

Aerodynamics

Cross-sectional shape

Design features

Applications and variants

In nature

Tensile structures

See also

References

External links