Wing - AbsoluteAstronomy.com

A wing is an appendage

Appendage

In invertebrate biology, an appendage is an external body part, or natural prolongation, that protrudes from an organism's body . It is a general term that covers any of the homologous body parts that may extend from a body segment...

with a surface

Surface

In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...

that produces lift

Lift (force)

A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...

for flight

Flight

Flight is the process by which an object moves either through an atmosphere or beyond it by generating lift or propulsive thrust, or aerostatically using buoyancy, or by simple ballistic movement....

or propulsion

Air propulsion

Air propulsion is the generation of thrust during flight by an aircraft or a creature such as a bird, bat or insect.-Aircraft:An aircraft propulsion system must serve two purposes. First, the thrust from the propulsion system must balance the drag of the airplane when the airplane is cruising...

through the atmosphere

Earth's atmosphere

The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

, or through another gas

Gas

Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

eous or liquid

Liquid

Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...

fluid

Fluid

In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....

. A wing is an airfoil

Airfoil

An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

, which has a streamlined cross-sectional

Cross section (geometry)

In geometry, a cross-section is the intersection of a figure in 2-dimensional space with a line, or of a body in 3-dimensional space with a plane, etc...

shape producing a useful lift to drag ratio.

The word "wing" from the Old Norse vængr for many centuries referred mainly to the foremost limb

Limb (anatomy)

A limb is a jointed, or prehensile , appendage of the human or other animal body....

s of bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

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

Insect wing

Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...

s, bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s, pterosaur

Pterosaur

Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...

s, boomerangs, some sail boats

Wingsail

A wingsail is a form of marine propulsion similar to conventional sails. However, a wingsail is a built-up structure with airfoil cross-section, like an airplane wing, which shape can provide a much better lift-to-drag ratio than conventional sails....

and aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft 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 engines.Although...

.

"Wing" can also mean an inverted airfoil on a race car that generates a downward force

Downforce

Downforce is a downwards thrust created by the aerodynamic characteristics of a car. The purpose of downforce is to allow a car to travel faster through a corner by increasing the vertical force on the tires, thus creating more grip....

to increase traction.

Various species of penguin

Penguin

Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...

s and other flighted or flightless

Flightless bird

Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...

water birds such as auk

Auk

An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

s, cormorant

Cormorant

The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...

s, guillemot

Guillemot

Guillemots is the common name for several species of seabird in the auk family . In British use, the term comprises two genera: Uria and Cepphus. In North America the Uria species are called "murres" and only the Cepphus species are called "guillemots"...

s, shearwater

Shearwater

Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...

s, eider and scoter ducks and diving petrels are avid swimmers, and use their wings to propel through water.

A wing's aerodynamic quality is expressed as its lift-to-drag ratio

Lift-to-drag ratio

In aerodynamics, the lift-to-drag ratio, or L/D ratio, is the amount of lift generated by a wing or vehicle, divided by the drag it creates by moving through the air...

. The lift a wing generates at a given speed and angle of attack

Angle of attack

Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

can be one to two orders of magnitude

Order of magnitude

An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

greater than the total drag on the wing

Drag (physics)

In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

. A high lift-to-drag ratio requires a significantly smaller thrust

Thrust

Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....

to propel the wings through the air at sufficient lift.

The aerodynamics of wings

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

Aerodynamics

Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...

, which is a branch of fluid mechanics

Fluid mechanics

Fluid mechanics is the study of fluids and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion...

. The properties of the airflow around any moving object can - in principle - be found by solving the Navier-Stokes equations

Navier-Stokes equations

In physics, the Navier–Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances. These equations arise from applying Newton's second law to fluid motion, together with the assumption that the fluid stress is the sum of a diffusing viscous...

of fluid dynamics

Fluid dynamics

In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...

. However, except for simple geometries these equations are notoriously difficult to solve. Fortunately, simpler explanations can be described.

For a wing to produce "lift", it must be oriented at a suitable angle of attack

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.

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

Airfoil

An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

) These air pressure differences can be either measured directly using instrumentation or they can be calculated from the airspeed distribution using basic physical principles

Physics

Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, including Bernoulli's Principle

Bernoulli's principle

In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy...

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)

Lift (force)

Devices to change the shape of a wing

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

Francis Rogallo

Francis Melvin Rogallo was an American aeronautical engineer inventor born in Sanger, California, U.S.A.; he is credited with the invention of the Rogallo wing, or "flexible wing", a precursor to the modern hang glider and paraglider...

invented the fully limp flexible wing, which ushered new possibilities for aircraft. Near in time, Domina Jalbert

Domina Jalbert

Domina Jalbert invented the ram-air inflated flexible wing often called the "Jalbert parafoil".-Life:Settling into Boca Raton, Florida, after arriving from Quebec, Canada, he established his business Aerology....

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

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. 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 aerofoils are, in general, less efficient and lack the lift provided by cambered wings at the zero angle of attack

Angle of attack

but are used in aerobatics

Aerobatics

Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in normal flight. Aerobatics are performed in airplanes and gliders for training, recreation, entertainment and sport...

, as they provide practical performance both upright and inverted. Another example comes from sailboats, where the sail is merely a thin membrane and there is no path-length difference between one side and the other.

For flight speeds near the speed of sound (transonic flight) or above the speed of sound (supersonic 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 are called supercritical airfoil

Supercritical airfoil

A supercritical airfoil 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 cambered aft section, and greater leading edge radius compared with traditional airfoil shapes...

Other examples

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

Fixed-wing aircraft

A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...

, including:

Hang gliders, which use wings from fully flexible (paragliders, gliding parachutes
Parachutes
Parachutes is the debut album by English alternative rock band Coldplay, released by the record label Parlophone on 10 July 2000 in the United Kingdom. The album was produced by the band and British record producer Ken Nelson, excluding one track which was produced by Chris Allison...

) wings, flexible wings (framed sail wings), to rigid wings
Kites
Kite types
Kites are tethered flying objects which fly by using aerodynamic lift, requiring wind, , for generation of airflow over the lifting surfaces.-Kite types:...

, which use a vast variety of wings.
Flying model airplane
Free flight (model aircraft)
The segment of model aviation known as free flight is the original form of the aeromodeling hobby, extending back centuries.- Description :...

s
Helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

s, which use a rotating wing with a variable pitch or angle to provide directional forces
The NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

, which uses its wings only to glide during its descent to a runway. These types of aircraft are called spaceplanes
Some racing cars
Racing Cars
Racing Cars are a Welsh pop band, formed in the Rhondda Valley, Wales in 1973.-Career:They were signed to one of the biggest British record labels of the time, Chrysalis Records. Racing Cars's debut album yielded their only hit single with "They Shoot Horses, Don't They?"...

, especially Formula One car
Formula One car
A modern Formula One car is a single-seat, open cockpit, open wheel racing car with substantial front and rear wings, and an engine positioned behind the driver. The regulations governing the cars are unique to the championship...

s, which use upside-down wings (or airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

s) to provide greater traction at high speeds
Sailboat
Sailboat
A sailboat or sailing boat is a boat propelled partly or entirely by sails. The term covers a variety of boats, larger than small vessels such as sailboards and smaller than sailing ships, but distinctions in the size are not strictly defined and what constitutes a sailing ship, sailboat, or a...

s, which use sails as vertical wings with variable fullness and direction to move across water

Structures with the same purpose as wings, but designed for use in liquid media, are generally called fin

Fin

A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

s or hydroplanes, with hydrodynamics as the governing science, rather than aerodynamics

Aerodynamics

. Applications of these arise in craft such as hydrofoil

Hydrofoil

A hydrofoil is a foil which operates in water. They are similar in appearance and purpose to airfoils.Hydrofoils can be artificial, such as the rudder or keel on a boat, the diving planes on a submarine, a surfboard fin, or occur naturally, as with fish fins, the flippers of aquatic mammals, the...

s and submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. Sailboat

Sailboat

A sailboat or sailing boat is a boat propelled partly or entirely by sails. The term covers a variety of boats, larger than small vessels such as sailboards and smaller than sailing ships, but distinctions in the size are not strictly defined and what constitutes a sailing ship, sailboat, or a...

s and sailing ship

Sailing ship

The term sailing ship is now used to refer to any large wind-powered vessel. In technical terms, a ship was a sailing vessel with a specific rig of at least three masts, square rigged on all of them, making the sailing adjective redundant. In popular usage "ship" became associated with all large...

s use both fins and wings.

Design features

Aircraft wings may feature some of the following:

A rounded leading edge
Leading edge
The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one....

cross-section
A sharp trailing edge
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 rejoins. Essential control surfaces are attached here to redirect the air flow and exert a controlling force by changing its momentum...

cross-section
Leading-edge devices such as slats
Leading edge slats
Slats are aerodynamic surfaces on the leading edge of the wings of fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of angle of attack and speed, so by deploying slats an aircraft can fly at slower...

, slots
Leading edge slot
A leading edge slot is an aerodynamic feature of the wing of some aircraft to reduce the stall speed and promote good low-speed handling qualities. A leading edge slot is a span-wise gap in each wing, allowing air to flow from below the wing to its upper surface...

, or extension
Leading edge extension
A leading edge extension is a small extension to an aircraft wing surface, forward of the leading edge. Different kinds of extensions have been used for different reasons.-Leading edge slats:...

s
Trailing-edge devices such as flap
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...

s or flaperons (combination of flaps and ailerons)
Aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...

s (usually near the wingtips) to roll the aircraft clockwise or counterclockwise about its long axis
Spoiler
Spoiler (aeronautics)
In aeronautics, a spoiler is a device intended to reduce lift in an aircraft. Spoilers are plates on the top surface of a wing which can be extended upward into the airflow and spoil it. By doing so, the spoiler creates a carefully controlled stall over the portion of the wing behind it, greatly...

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
Vortex generator
A vortex generator is an aerodynamic surface, consisting of a small vane or bump that creates a vortex. Vortex generators can be found on many devices, but the term is most often used in aircraft design....

s to help prevent flow separation in transonic flow
Wing fence
Wing fence
Wing fences, also known as boundary layer fences and potential fences are fixed aerodynamic devices attached to aircraft wings. Not to be confused with wingtip fences, wing fences are flat plates fixed to the upper surfaces parallel to the airflow. They are often seen on swept-wing aircraft...

s to keep flow attached to the wing by stopping boundary layer separation from spreading
Winglets to keep wingtip vortices from increasing drag and decreasing lift
Dihedral, or a positive wing angle to the horizontal. This gives inherent stability in the roll direction. Anhedral, or a negative wing angle to the horizontal, has a destabilizing effect
Folding wing
Folding wing
A folding wing is a design feature of aircraft to save space in the airfield, and time, and is typical of naval aircraft that operate from the limited deck space of aircraft carriers. The folding allows the aircraft to occupy less space in a confined hangar because the folded wing normally rises...

s allow more aircraft storage in the confined space of the hangar deck
Hangar
A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...

of an aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
Variable-sweep wing or "swing wings" that allow outstretched wings during low-speed flight (i.e., take-off and landing) and swept back wing
Swept wing
A swept wing is a wing planform favored for high subsonic jet speeds first investigated by Germany during the Second World War. Since the introduction of the MiG-15 and North American F-86 which demonstrated a decisive superiority over the slower first generation of straight-wing jet fighters...

s for high-speed flight (including supersonic flight), such as in the F-111 Aardvark, the F-14 Tomcat
F-14 Tomcat
The Grumman F-14 Tomcat is a supersonic, twin-engine, two-seat, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental program following the collapse of the F-111B project...

, the Panavia Tornado
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...

, the MiG-23 the MiG-27, and the B-1B Lancer warplanes

External links

How Wings Work - Holger Babinsky Physics Education 2003
"Physics of flight - revisited" Weltner and Ingelman-Sundberg
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

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

The aerodynamics of wings

Devices to change the shape of a wing

A common misconception

Other examples

Design features

See also

External links