
In computing, WinG (pronounced ''Win Gee'') was an API to provide fast graphics performance on Windows 3.1. It was later built-in to Windows 95. The original Windows GDI (Graphics Device Interface) was designed with static images in mind, making its animation capabilities very limited. The GDI provides an interface to the graphics hardware that is device independent, that is, a program written using the GDI will work on all graphics and printer hardware, provided suitable Windows GDI drivers for the hardware are installed on the system. This means that graphics cannot be written to the physical framebuffer on the graphics hardware directly and must be written to a logical graphics "device context" (DC) provided by the GDI, which is then translated by the GDI and the device drivers to suit the target hardware device and is written to its physical frame buffer in an appropriate manner. The major limitation of the GDI DC was that they were write-only. Data, once written, could not be retrieved. This was because the contents of the DC was device dependent, and data read from it would make no sense to the programmer. In order to do animation using the GDI DC, all of the animation frames needed to be manipulated in system memory and then each frame needed to be copied into a GDI DC for display on the graphics device. This was a very slow process. WinG introduced a new type of DC called a WinGDC, which allowed programmers to both read and write to it directly using Device Independent Bitmaps (DIBs). Effectively, it gave programmers the ability to do with Windows what they'd been doing without hardware access limitations in DOS for years. Programmers could write DIBs to the WinGDC, yet would still have access to the individual bits of the image data. This meant that fast graphics algorithms could be written to allow fast scrolling, overdraw, dirty rectangles, double buffering, and other animation techniques. WinG also provided much better performance when blitting graphics data to physical graphics device memory. Since WinG used the DIB format, it was possible to mix original GDI API calls and WinG calls. WinG would also perform a graphics hardware/driver profiling test on the first execution of the program in order to determine the best way to manipulate the graphics hardware. This test showed a window full of red curved lines, sections of which would wobble as performance was tested. Once WinG had determined the fastest calls that did not cause graphics corruption, a profile would be saved so that the test would not need to be performed again. WinG was largely superseded by the more advanced DirectX libraries. Microsoft Windows
This is the first revision of this page, promoting it from substub status. Please check and correct as necessary, I'm unsure of a few things here but most of it should be accurate. --User:Weevil 11:45, 6 Apr 2005 (UTC)
:''For some other uses of the word "wing" please see Wing (disambiguation)''. [[Image:Seagull wing.jpg|thumb|250px|A Laughing Gull on the beach in Atlantic City.]] A wing is a surface used to produce an aerodynamic force normal to the direction of motion by travelling in air or another gaseous medium, facilitating flight. 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. ==Use== The most common use of wings is to flight by deflecting air downwards to produce lift (force), but upside-down wings are also commonly used as a way to produce downforce and hold objects to the ground (for example racing cars). ==Artificial wings== ===Terms used to describe aeroplane wings=== * Leading edge: the front edge of the wing * Trailing edge: the back edge of the wing * Wingspan: distance from wing tip to wing tip * chord (aircraft): distance from wing leading edge to wing trailing edge, usually measured parallel to the long axis of the fuselage * aspect ratio (wing): ratio of span to chord (aircraft) ===Design features=== Aeroplane wings may feature some of the following: * A rounded leading edge cross-section * A sharp trailing edge cross-section * Leading-edge devices such as slats, slots, or leading edge extensions * Trailing-edge devices such as flaps * Ailerons (usually near the wingtips) to provide roll control * Spoiler (aeronautics)s on the upper surface to disrupt lift * Vortex generators to help prevent flow separation * Wing fences to keep flow attached to the wing * Dihedral, or a positive wing angle to the horizontal. This gives inherent stability in roll. As the aircraft rolls, the lower wing generates more lift than the upper, rolling the aircraft back into the level position. Anhedral, or a negative wing angle to the horizontal has a destabilising effect. * Swept wings are good for high-speed aircraft. The wing is at an angle to the airflow, so that the effective flow speed across the wing chord is lower. ===Wing types=== * Elliptical wings (technically wings with an elliptical lift distribution) are theoretically optimum for efficiency at subsonic speeds. * Delta wings have reasonable performance at subsonic and supersonic speeds. * Waveriders are efficient supersonic wings that take advantage of shock waves. * Rogallo wings are two hollow half-cones of fabric, one of the simplest wings to construct. * Swing-wings (or variable geometry wings) are able to move in flight to give the benefits of dihedral and delta wing. Although they were originally proposed by German aerodynamicists during the 1940s, they are currently only found on some military fighter aircraft such as the Grumman F-14, Panavia Tornado, and General Dynamics F-111. * Ring wings are optimally loaded closed lifting surfaces with higher aerodynamic efficiency than planar wings having the same aspect-ratios. Other non planar wing systems display an aerodynamic efficiency intermediate between ring wings and planar wings. ===Science of wings=== At the simplest level, a wing produces lift (force) by deflecting air downward, which propels the flying body upward with an equal and opposite force (see Newton's Laws of Motion). Bernoulli's principle has traditionally been used to explain the functioning of a wing in terms of differing pressure above and below the wing, but this model can often be misleading or depend on false assumptions. See Coanda effect for an alternative explanation of how a wing produces lift. The coefficient 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 will in fact dramatically reduce) and gives a large increase in drag. Wing design can be complex and is one of the principal applications of the science of aerodynamics. * A helicopter uses a rotating wing with a variable pitch or angle to provide a directional force. * The space shuttle uses its wings only for lift during its descent. Structures with the same purpose as wings, but designed to operate in liquid media, are generally called fins, with hydrodynamics as the governing science. ==Evolution of wings in animals== Biologists believe that animal wings evolution at least four separate times, an example of convergent evolution. Insect wings are believed to have evolved about 300 million years ago, pterosaur wings about 225 million years ago, bird wings about 150 million years ago, and bat wings about 55 million years ago. Wings in these groups are analogy (biology) structures because they evolved independently rather than being passed from a common ancestor. ''See also'' flight. ==External links== *[http://jef.raskincenter.org/published/coanda_effect.html Coanda Effect: Understanding Why Wings Work] *[http://www.av8n.com/how/ An Excellent treatment of why and how wings generate lift] *[http://www.npr.org/templates/story/story.php?storyId=3875411 Demystifying the Science of Flight] - Audio segment on NPR's Talk of the Nation Science Friday * [http://aerodyn.org/Wings/ Advanced Topics in Aerodynamics] Wings for all speeds *[http://www.nurseminerva.co.uk/adapt/evolutio.htm Evolution of flight] in animals Aerospace engineering Aerodynamics
Bernoulli versus Coanda A Contribution to the Bernoulli/Coanda Effect The entire discussion on the Bernoulli or the Coanda effect is in itself remarkable as one is familiar with some relatively simple considerations. It is correct that if one checks a series of “scientific” types of sources, there is a predominance of the Bernoulli principle, and that this predominance has been current in many years. The problem is, that it is obviously inadequate. And that the Bernoulli principle is merely a rough calculation for the Coanda effect. And that the Bernoulli effect is only one of the ways to create a change of direction and force effect of the air current. If you are interested in such wing-technical topics, you can log onto www.av8n.com/how#contents . It is a comprehensive specification on Flying Theory, which also contains a thorough discussion on the function of the wings. Initially I was impressed, but if you examine it more closely, you are to find some grave gaps. E.g. in chapter 3, which contains a number of beautiful air pictures of the air motions above and below the wing and which you at first perceive as a documentation of the Bernoulli principle. But if you are to read more carefully, it turns out that these beautiful models are made by means of computer simulation with programs that the author himself has developed. So when the author incorporate the Bernoulli principle as an important part of the wings’ function in his programs, this principle of course also appears in the turned-up models. But it does not prove anything physically – it is more suitable for deceiving its readers. Furthermore, I feel fairly confidant that the whole discussion on the Bernoulli effect is turned upside down and that the relation between cause and effect is equally turned upside down. The connection is not that the partial vacuum comes into existence because the air commences to stream faster above the wing. No, the connection is reverse; the air begins to stream faster because of the partial vacuum arisen above the wing. This goes to imply that the Bernoulli effect is only a part of the total carrying capacity and that it is practically a rough calculation of the actual effect. Namely Newton’s third law – the law of action and reaction. The Bernoulli effect merely increases the power effect which arises via Newton’s third law. In order to understand how an airplane remains in the air, one must approach the matter in a different way. Namely: How does the air change after the wing has passed through it, for this is exactly what must be measured and calculated. Because if for instance it turns out, that the directional vector for the total air mass has changed direction per second, and that this corresponds to the airplane’s gravitational acceleration per second – well, then it is proven that the Bernoulli principle at the very most, is a rough calculation of the airplane wing’s carrying capacity. And that it is Newton’s third law which bears the main responsibility. I.e. the airplane wing pushes a certain air mass downward and thereby maintains the airplane in the air. And just that is certainly worth calculating. Let me remind you, that the very same method is applied when you want to acquire knowledge of particles in the atomic area when you can neither “see, hear nor smell” the particles. You send such particles through the medium and measure to what extent it effects the medium. The issue can also be approached without all the mathematics involved. Because if the Bernoulli principle in fact has an independent carrying capacity that doesn’t result in a downward air stream behind the wing, then it must signify, that a wing could move through a medium, use this medium to stay in the air without the medium itself being significantly influenced by it. And this does sound as a physical impossibility. Nevertheless, this is how the interaction between a wing and an air mass most frequently is depicted in the models. E.g. see Lademanns Lexicon CD ROM.( a Danish Lexicon) Conclusively I will attach a model picture of a sailing boat. The sails are arched pieces in streaming fluid where its surface is made visible by means of powder. And just that shows what it is all about. Namely that the sails obtain their moving power by changing the direction of the wind. That is to say the physical law of action and reaction. Newton’s third law. The model picture is from my article from 2000 on www.maximalt.dk/Faerdigheder/sejlteori.htm May I conclusively remark This inversion between cause and effect brought on by the Bernoulli effect, may quite possibly be rooted in the following: Indeed, one has to do with an airplane and want to explain why it maintains in the air. One therefore seeks to establish the forces that keep it in the air. One ascertains that there is a partial vacuum above the wing and that the stream of air accelerates above the wing. I.e. a Bernoulli effect. As one seeks the forces that keep the airplane in the air, they yield to the psychological need, and let the effect go that way around, which apparently explain the problem that is wanted to be solved. But the coherence is false, namely that the casual connection is that the faster airstream creates the lover pressure. But as told, the connection is indeed the opposite around: the lower pressure ( arisen in a different way), creates the higher velocity above the wing. The Bernoulli principle is an energy preservation principle and it can therefor go both ways. Henning Rolapp :I doubt this is the appropriate forum for this discussion, but I will say this: Nobody seems to be suggesting that the essential principle here is not Newton - air is deflected downward and that gives rise to the lift force. What does appear to be in dispute is how this comes about. Personally I feel that the Coanda vs. Bernoulli "argument" is moot - both effects arise. What seems unclear is why the Coanda effect occurs at all (i.e. what makes air "stick" to a curved wing even though it must expend energy to do so), but maybe that problem has been solved since I last looked at the literature. To me the most important point to get across is this: there is no "catch-up" effect going on. By this I mean the explanation that an aerofoil "forces" the air over the top to go faster in order to catch up with the air below, hence lowering its pressure and sucking the wing upward. I see this explanation in book after book after book - usually those that seek to explain science to the layman. These books are wrong, they are misleading and bad. At least the site you mention above does take pains to squash this myth, and the very nice animations do help to make this clear. Incidentally nobody seems to be saying that there is no net effect on the air either - as you rightly point out, there must be, and there is. I don't think that is in dispute. As an aside, I recently heard some UFO-apologist ranting on about how UFOs might fly, by "somehow" (he was vague on this point!) displacing the air around the craft such that there was no net disturbance (hence allowing instantaneous acceleration and hypersonic flight without a shockwave, etc). If this were "somehow" possible, there would be no net lift force on the craft, so presumably it would just fall out of the sky. Of course aliens sufficiently advanced would have invented antigravity, so you can never win an argument with these people ;-) User:GRAHAMUK 00:26, 10 Sep 2004 (UTC) == Bird/insect wings missing == I missed some brief introduction to the parts of bird and insect wings. --User:213.6.97.225 09:48, 11 Nov 2004 (UTC) The disturbing thing about many of the so-called explanations of how aircraft wings generate lift rely on the SHAPE of the wing - specifically a curved upper surface and a more or less flat lower surface. However, many aerobatic and combat aircraft have fully symmetrical wing cross-sections (so they fly equally well when inverted) - and I have personally built and flown a powered radio controlled model aircraft with rectangular cross-section foam polystyrene wings specifically in order to show this theory of flight to be false. Whatever explanation wins this debate, it cannot rely entirely on the shape of the wing. If a rectangular cross-section wing can generate lift - then downward deflection of the air due to the angle of attack of the wing into the airflow is surely the key factor. This business of air moving faster over the upper surface 'because it's a longer distance' - and hence taking advantage of the Bournoulli principle - can at best only be a small part of the explanation because the distances over and under a rectangular wing are exactly the same. :rectangular wings work due to their angle of attack - they deflect air downwards, the equal and opposite reaction is lift. However they also create a great deal of drag so are not very efficient. The shape of the wing only confers efficiency - it has no "magic properties" that creates lift by virtue of its shape. The rectangular wing argument is actually very useful in explaining lift. A simple chuck glider with a flat wing works, because it has an angle of attack. If you build it so that there is no angle of attack, it doesn't fly very well (though actually achieving a totally neutral angle of attack is quite hard in practice). If you build a model with a curved aerofoil section, it can still generate lift at zero or even small negative angles of attack, because a curved aerofoil is still able to have a positive lift coefficient at these angles. It is still deflecting air downward, because of the tendency of the air to stick to it and follow its curvature - only in this sense does the shape matter, and it only has an effect on the efficiency. The "longer path over the top" argument is totally bogus, and as you say, the rectangular wing proves it. The pressure distribution above and below the wing is an EFFECT of Newton's laws operating on the air, not a CAUSE of the lift produced. You will see a similar pressure difference even with a rectangular wing, though less pronounced and disturbed by turbulence. User:GRAHAMUK 03:26, 23 Nov 2004 (UTC)
See other meanings of words starting from letter:
Words begining with Wing:
WinG
WinG
Wing
Wing
Wing,_Buckinghamshire
Wing,_ND
Wing,_North_Dakota
Wing,_Rutland
Wing-In-Ground-Effect_craft
Wing-suit
Wing.a319.750pix.jpg
Wing.bmi.a320.labelled.arp.750pix.jpg
Wing.flaps.750pix.jpg
Wing.lufthansa.arp.jpg
Wing.slat.600pix.jpg
Wing.tomcat.unswept.750pix.jpg
Wing.tomcat.vapour.arp.750pix.jpg
Wing.two.arp.600pix.jpg
Wing83
Wingate
Wingate,_County_Durham
Wingate,_IN
Wingate,_Indiana
Wingate,_NC
Wingate,_North_Carolina
Wingate,_Orde_Charles
Wingate_(computing)
Wingback
Wingback
Wingback_(soccer)
WingChun_Lawyer
WingChun_Lawyer
Wingding
Wingdings
Wingdings
Wingdings_2
Wingdings_3
Wingecarribee_River
Winged
Winged-stone
Winged-stone
Wingedbull.jpg
WingedBullPersepolis_Amiet.jpg
Winged_Bean
Winged_bean
Winged_Dragon_of_Ra
Winged_dragon_of_ra
Winged_equine
Winged_horse
Winged_Hussars
Winged_keel
Winged_kelp
Winged_Migration
Winged_Migration_movie.jpg
Winged_Nazgul
Winged_Nazgûl
Winged_unicorn
Winged_Victory
Winged_victory.jpg
Winged_Victory_of_Samothrace
Winged_Victory_of_Samothrace
Wingene
Winger
Winger
Winger,_Minnesota
Winger,_MN
Wingerode
Winger_(album)
Winger_(album)
Winger_(hockey)
Winger_(ice_hockey)
Winger_(ice_hockey)
Winger_(sport)
Winger_(sport)
Winger_Township,_Minnesota
Winger_Township,_MN
Wingfic
Wingfield_Manor
Wingfoot_Express
Wingg2
Wingham
Wingham,_Australia
Wingham,_Kent
Wingham,_New_South_Wales
Wingham,_New_South_Wales
Wingham,_NSW
Wingham,_ON
Wingham,_Ontario
Winghead_Shark
Wingles
Winglet
Winglet.a319.arp.750pix.jpg
Winglet.b737.arp.750pix.jpg
Winglet.learjet60.arp.750pix.jpg
Winglets
WingLungBank.jpg
Wingmakers
Wingmakers
Wingman
Wingman.jpg
Wingnut
Wingnut_(disambiguation)
Wingo
Wingo,_Kentucky
Wingo,_KY
WingOnHouseCentralHKG.jpg
Wingover
Wingrave
WingRoot01.jpg
Wings
Wings
Wingsandsword
Wingsandsword
Wingsatthespeedofsoundalbumcover.jpg
Wingscales.jpg
WingShot_Culpeper_Regional_Airport.JPG
Wingsofbutterfly.jpg
Wingsoveramerica.jpg
Wingspan
Wingspan.albumcover.jpg
Wingspan_(album)
Wingspr.JPG
Wingspread
Wingsuit
Wingsuit_flying
Wingsuit_flying
WingsWildLifealbumcover.jpg
Wings_(band)
Wings_(band)
Wings_(BBC_TV_series)
Wings_(BBC_TV_series)
Wings_(drama)
Wings_(movie)
Wings_(sitcom)
Wings_(television)
Wings_(TV_series)
Wings_(TV_show)
Wings_(video_game)
Wings_3D
Wings_3D
Wings_Air
Wings_albums
Wings_Alliance
Wings_at_the_Speed_of_Sound
Wings_by_nationality
WINGs_Display_Manager
Wings_Display_Manager
Wings_of_a_Butterfly_Nebula
Wings_of_Desire
Wings_of_desire.jpg
Wings_Of_Fire
Wings_of_Fire
Wings_of_Honneamise
Wings_of_Honneamise
Wings_of_Tomorrow
Wings_of_Tomorrow
Wings_Over_America
Wings_Over_Gillespie
Wings_Stadium
WingTip04.jpg
WingTip05.jpg
Wingtip_vortices
Wingtip_vortices
WingTsun
WingTsun
Wingull
Wingull
Wingville
Wingville,_WI
Wingville,_Wisconsin
Wingy_Manone
WingZ
Wing^^
Wing_(air_force_unit)
Wing_(comics)
Wing_(disambiguation)
Wing_(Singer)
Wing_(singer)
Wing_(singer)
Wing_(South_Park)
Wing_Bowl
Wing_Chun
Wing_Chun
Wing_Chun
Wing_chun
Wing_Chun_Gung_Fu
Wing_Chun_Kuen
Wing_Chun_practitioners
Wing_chun_terms
Wing_clipping
Wing_Commander
Wing_Commander
Wing_Commander
Wing_commander
Wing_Commander:_The_Secret_Missions
Wing_Commander_(computer_game)
Wing_Commander_(computer_game)
Wing_Commander_(computer_game)_images
Wing_Commander_(feature_film)
Wing_Commander_(movie)
Wing_Commander_(rank)
Wing_Commander_Academy
Wing_Commander_characters
Wing_Commander_Collectible_Trading_Card_Game
Wing_Commander_spacecraft
Wing_Commander_technology_and_vehicles
Wing_Commander_technology_and_vehicles
Wing_Commander_timeline
Wing_Gambit
Wing_Gambit
Wing_grip_controller
Wing_Hang_Bank
Wing_Han_Tsang
Wing_loading
Wing_Luke
Wing_Luke_Asian_Museum
Wing_Lung_Bank
Wing_On_Bank
Wing_On_House
Wing_Records
Wing_River
Wing_River_Township,_Minnesota
Wing_River_Township,_MN
Wing_root
Wing_Rural_District
Wing_Saber
Wing_Scout
Wing_tensing
Wing_tips
Wing_Tsun
Wing_Tsun
Wing_warping
Wing_Yee
Wing_Yee_(Singer-Songwriter)
Wing_Yip
Wing_ZERO
WinG
In computing, WinG (pronounced ''Win Gee'') was an API to provide fast graphics performance on Windows 3.1. It was later built-in to Windows 95. The original Windows GDI (Graphics Device Interface) was designed with static images in mind, making its animation capabilities very limited. The GDI provides an interface to the graphics hardware that is device independent, that is, a program written using the GDI will work on all graphics and printer hardware, provided suitable Windows GDI drivers for the hardware are installed on the system. This means that graphics cannot be written to the physical framebuffer on the graphics hardware directly and must be written to a logical graphics "device context" (DC) provided by the GDI, which is then translated by the GDI and the device drivers to suit the target hardware device and is written to its physical frame buffer in an appropriate manner. The major limitation of the GDI DC was that they were write-only. Data, once written, could not be retrieved. This was because the contents of the DC was device dependent, and data read from it would make no sense to the programmer. In order to do animation using the GDI DC, all of the animation frames needed to be manipulated in system memory and then each frame needed to be copied into a GDI DC for display on the graphics device. This was a very slow process. WinG introduced a new type of DC called a WinGDC, which allowed programmers to both read and write to it directly using Device Independent Bitmaps (DIBs). Effectively, it gave programmers the ability to do with Windows what they'd been doing without hardware access limitations in DOS for years. Programmers could write DIBs to the WinGDC, yet would still have access to the individual bits of the image data. This meant that fast graphics algorithms could be written to allow fast scrolling, overdraw, dirty rectangles, double buffering, and other animation techniques. WinG also provided much better performance when blitting graphics data to physical graphics device memory. Since WinG used the DIB format, it was possible to mix original GDI API calls and WinG calls. WinG would also perform a graphics hardware/driver profiling test on the first execution of the program in order to determine the best way to manipulate the graphics hardware. This test showed a window full of red curved lines, sections of which would wobble as performance was tested. Once WinG had determined the fastest calls that did not cause graphics corruption, a profile would be saved so that the test would not need to be performed again. WinG was largely superseded by the more advanced DirectX libraries. Microsoft Windows
WinG
This is the first revision of this page, promoting it from substub status. Please check and correct as necessary, I'm unsure of a few things here but most of it should be accurate. --User:Weevil 11:45, 6 Apr 2005 (UTC)
Wing
:''For some other uses of the word "wing" please see Wing (disambiguation)''. [[Image:Seagull wing.jpg|thumb|250px|A Laughing Gull on the beach in Atlantic City.]] A wing is a surface used to produce an aerodynamic force normal to the direction of motion by travelling in air or another gaseous medium, facilitating flight. 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. ==Use== The most common use of wings is to flight by deflecting air downwards to produce lift (force), but upside-down wings are also commonly used as a way to produce downforce and hold objects to the ground (for example racing cars). ==Artificial wings== ===Terms used to describe aeroplane wings=== * Leading edge: the front edge of the wing * Trailing edge: the back edge of the wing * Wingspan: distance from wing tip to wing tip * chord (aircraft): distance from wing leading edge to wing trailing edge, usually measured parallel to the long axis of the fuselage * aspect ratio (wing): ratio of span to chord (aircraft) ===Design features=== Aeroplane wings may feature some of the following: * A rounded leading edge cross-section * A sharp trailing edge cross-section * Leading-edge devices such as slats, slots, or leading edge extensions * Trailing-edge devices such as flaps * Ailerons (usually near the wingtips) to provide roll control * Spoiler (aeronautics)s on the upper surface to disrupt lift * Vortex generators to help prevent flow separation * Wing fences to keep flow attached to the wing * Dihedral, or a positive wing angle to the horizontal. This gives inherent stability in roll. As the aircraft rolls, the lower wing generates more lift than the upper, rolling the aircraft back into the level position. Anhedral, or a negative wing angle to the horizontal has a destabilising effect. * Swept wings are good for high-speed aircraft. The wing is at an angle to the airflow, so that the effective flow speed across the wing chord is lower. ===Wing types=== * Elliptical wings (technically wings with an elliptical lift distribution) are theoretically optimum for efficiency at subsonic speeds. * Delta wings have reasonable performance at subsonic and supersonic speeds. * Waveriders are efficient supersonic wings that take advantage of shock waves. * Rogallo wings are two hollow half-cones of fabric, one of the simplest wings to construct. * Swing-wings (or variable geometry wings) are able to move in flight to give the benefits of dihedral and delta wing. Although they were originally proposed by German aerodynamicists during the 1940s, they are currently only found on some military fighter aircraft such as the Grumman F-14, Panavia Tornado, and General Dynamics F-111. * Ring wings are optimally loaded closed lifting surfaces with higher aerodynamic efficiency than planar wings having the same aspect-ratios. Other non planar wing systems display an aerodynamic efficiency intermediate between ring wings and planar wings. ===Science of wings=== At the simplest level, a wing produces lift (force) by deflecting air downward, which propels the flying body upward with an equal and opposite force (see Newton's Laws of Motion). Bernoulli's principle has traditionally been used to explain the functioning of a wing in terms of differing pressure above and below the wing, but this model can often be misleading or depend on false assumptions. See Coanda effect for an alternative explanation of how a wing produces lift. The coefficient 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 will in fact dramatically reduce) and gives a large increase in drag. Wing design can be complex and is one of the principal applications of the science of aerodynamics. * A helicopter uses a rotating wing with a variable pitch or angle to provide a directional force. * The space shuttle uses its wings only for lift during its descent. Structures with the same purpose as wings, but designed to operate in liquid media, are generally called fins, with hydrodynamics as the governing science. ==Evolution of wings in animals== Biologists believe that animal wings evolution at least four separate times, an example of convergent evolution. Insect wings are believed to have evolved about 300 million years ago, pterosaur wings about 225 million years ago, bird wings about 150 million years ago, and bat wings about 55 million years ago. Wings in these groups are analogy (biology) structures because they evolved independently rather than being passed from a common ancestor. ''See also'' flight. ==External links== *[http://jef.raskincenter.org/published/coanda_effect.html Coanda Effect: Understanding Why Wings Work] *[http://www.av8n.com/how/ An Excellent treatment of why and how wings generate lift] *[http://www.npr.org/templates/story/story.php?storyId=3875411 Demystifying the Science of Flight] - Audio segment on NPR's Talk of the Nation Science Friday * [http://aerodyn.org/Wings/ Advanced Topics in Aerodynamics] Wings for all speeds *[http://www.nurseminerva.co.uk/adapt/evolutio.htm Evolution of flight] in animals Aerospace engineering Aerodynamics
Wing
Bernoulli versus Coanda A Contribution to the Bernoulli/Coanda Effect The entire discussion on the Bernoulli or the Coanda effect is in itself remarkable as one is familiar with some relatively simple considerations. It is correct that if one checks a series of “scientific” types of sources, there is a predominance of the Bernoulli principle, and that this predominance has been current in many years. The problem is, that it is obviously inadequate. And that the Bernoulli principle is merely a rough calculation for the Coanda effect. And that the Bernoulli effect is only one of the ways to create a change of direction and force effect of the air current. If you are interested in such wing-technical topics, you can log onto www.av8n.com/how#contents . It is a comprehensive specification on Flying Theory, which also contains a thorough discussion on the function of the wings. Initially I was impressed, but if you examine it more closely, you are to find some grave gaps. E.g. in chapter 3, which contains a number of beautiful air pictures of the air motions above and below the wing and which you at first perceive as a documentation of the Bernoulli principle. But if you are to read more carefully, it turns out that these beautiful models are made by means of computer simulation with programs that the author himself has developed. So when the author incorporate the Bernoulli principle as an important part of the wings’ function in his programs, this principle of course also appears in the turned-up models. But it does not prove anything physically – it is more suitable for deceiving its readers. Furthermore, I feel fairly confidant that the whole discussion on the Bernoulli effect is turned upside down and that the relation between cause and effect is equally turned upside down. The connection is not that the partial vacuum comes into existence because the air commences to stream faster above the wing. No, the connection is reverse; the air begins to stream faster because of the partial vacuum arisen above the wing. This goes to imply that the Bernoulli effect is only a part of the total carrying capacity and that it is practically a rough calculation of the actual effect. Namely Newton’s third law – the law of action and reaction. The Bernoulli effect merely increases the power effect which arises via Newton’s third law. In order to understand how an airplane remains in the air, one must approach the matter in a different way. Namely: How does the air change after the wing has passed through it, for this is exactly what must be measured and calculated. Because if for instance it turns out, that the directional vector for the total air mass has changed direction per second, and that this corresponds to the airplane’s gravitational acceleration per second – well, then it is proven that the Bernoulli principle at the very most, is a rough calculation of the airplane wing’s carrying capacity. And that it is Newton’s third law which bears the main responsibility. I.e. the airplane wing pushes a certain air mass downward and thereby maintains the airplane in the air. And just that is certainly worth calculating. Let me remind you, that the very same method is applied when you want to acquire knowledge of particles in the atomic area when you can neither “see, hear nor smell” the particles. You send such particles through the medium and measure to what extent it effects the medium. The issue can also be approached without all the mathematics involved. Because if the Bernoulli principle in fact has an independent carrying capacity that doesn’t result in a downward air stream behind the wing, then it must signify, that a wing could move through a medium, use this medium to stay in the air without the medium itself being significantly influenced by it. And this does sound as a physical impossibility. Nevertheless, this is how the interaction between a wing and an air mass most frequently is depicted in the models. E.g. see Lademanns Lexicon CD ROM.( a Danish Lexicon) Conclusively I will attach a model picture of a sailing boat. The sails are arched pieces in streaming fluid where its surface is made visible by means of powder. And just that shows what it is all about. Namely that the sails obtain their moving power by changing the direction of the wind. That is to say the physical law of action and reaction. Newton’s third law. The model picture is from my article from 2000 on www.maximalt.dk/Faerdigheder/sejlteori.htm May I conclusively remark This inversion between cause and effect brought on by the Bernoulli effect, may quite possibly be rooted in the following: Indeed, one has to do with an airplane and want to explain why it maintains in the air. One therefore seeks to establish the forces that keep it in the air. One ascertains that there is a partial vacuum above the wing and that the stream of air accelerates above the wing. I.e. a Bernoulli effect. As one seeks the forces that keep the airplane in the air, they yield to the psychological need, and let the effect go that way around, which apparently explain the problem that is wanted to be solved. But the coherence is false, namely that the casual connection is that the faster airstream creates the lover pressure. But as told, the connection is indeed the opposite around: the lower pressure ( arisen in a different way), creates the higher velocity above the wing. The Bernoulli principle is an energy preservation principle and it can therefor go both ways. Henning Rolapp :I doubt this is the appropriate forum for this discussion, but I will say this: Nobody seems to be suggesting that the essential principle here is not Newton - air is deflected downward and that gives rise to the lift force. What does appear to be in dispute is how this comes about. Personally I feel that the Coanda vs. Bernoulli "argument" is moot - both effects arise. What seems unclear is why the Coanda effect occurs at all (i.e. what makes air "stick" to a curved wing even though it must expend energy to do so), but maybe that problem has been solved since I last looked at the literature. To me the most important point to get across is this: there is no "catch-up" effect going on. By this I mean the explanation that an aerofoil "forces" the air over the top to go faster in order to catch up with the air below, hence lowering its pressure and sucking the wing upward. I see this explanation in book after book after book - usually those that seek to explain science to the layman. These books are wrong, they are misleading and bad. At least the site you mention above does take pains to squash this myth, and the very nice animations do help to make this clear. Incidentally nobody seems to be saying that there is no net effect on the air either - as you rightly point out, there must be, and there is. I don't think that is in dispute. As an aside, I recently heard some UFO-apologist ranting on about how UFOs might fly, by "somehow" (he was vague on this point!) displacing the air around the craft such that there was no net disturbance (hence allowing instantaneous acceleration and hypersonic flight without a shockwave, etc). If this were "somehow" possible, there would be no net lift force on the craft, so presumably it would just fall out of the sky. Of course aliens sufficiently advanced would have invented antigravity, so you can never win an argument with these people ;-) User:GRAHAMUK 00:26, 10 Sep 2004 (UTC) == Bird/insect wings missing == I missed some brief introduction to the parts of bird and insect wings. --User:213.6.97.225 09:48, 11 Nov 2004 (UTC) The disturbing thing about many of the so-called explanations of how aircraft wings generate lift rely on the SHAPE of the wing - specifically a curved upper surface and a more or less flat lower surface. However, many aerobatic and combat aircraft have fully symmetrical wing cross-sections (so they fly equally well when inverted) - and I have personally built and flown a powered radio controlled model aircraft with rectangular cross-section foam polystyrene wings specifically in order to show this theory of flight to be false. Whatever explanation wins this debate, it cannot rely entirely on the shape of the wing. If a rectangular cross-section wing can generate lift - then downward deflection of the air due to the angle of attack of the wing into the airflow is surely the key factor. This business of air moving faster over the upper surface 'because it's a longer distance' - and hence taking advantage of the Bournoulli principle - can at best only be a small part of the explanation because the distances over and under a rectangular wing are exactly the same. :rectangular wings work due to their angle of attack - they deflect air downwards, the equal and opposite reaction is lift. However they also create a great deal of drag so are not very efficient. The shape of the wing only confers efficiency - it has no "magic properties" that creates lift by virtue of its shape. The rectangular wing argument is actually very useful in explaining lift. A simple chuck glider with a flat wing works, because it has an angle of attack. If you build it so that there is no angle of attack, it doesn't fly very well (though actually achieving a totally neutral angle of attack is quite hard in practice). If you build a model with a curved aerofoil section, it can still generate lift at zero or even small negative angles of attack, because a curved aerofoil is still able to have a positive lift coefficient at these angles. It is still deflecting air downward, because of the tendency of the air to stick to it and follow its curvature - only in this sense does the shape matter, and it only has an effect on the efficiency. The "longer path over the top" argument is totally bogus, and as you say, the rectangular wing proves it. The pressure distribution above and below the wing is an EFFECT of Newton's laws operating on the air, not a CAUSE of the lift produced. You will see a similar pressure difference even with a rectangular wing, though less pronounced and disturbed by turbulence. User:GRAHAMUK 03:26, 23 Nov 2004 (UTC)
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