Wikipedia on Lack of Theory of Flight

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Let us see how Wikipedia handles the fact that there is no convincing explanation of how a wing generates large lift at small drag, which makes it possible to fly for both birds and airplanes.

We quote from Lift Force:

  • There are several ways to explain how an airfoil generates lift. Some are more complicated or more mathematically rigorous than others; some have been shown to be incorrect. For example, there are explanations based directly on Newton’s laws of motion and explanations based on Bernoulli’s principle. 
  • Both principles can be used to explain lift, but each appeals to a different audience.
  • While the theory correctly reasons that deflection implies that there must be a force on the wing, it does not explain why the air is deflected. Intuitively, one can say that the air follows the curve of the foil, but this is not very rigorous or precise.
  • Explaining lift while considering all of the principles involved is a complex task and is not easily simplified. Lift is generated in accordance with the fundamental principles of physics.
  • In attempting to explain why the air flows the way it does (e.g. why the flow follows the upper surface of the airfoil and why the streamtubes change size), the situation gets considerably more complex. It is here that many simplifications are made in presenting lift to various audiences.
  • Many other alternative explanations for the generation of lift by an airfoil have been put forward, of which a few are presented here. Most of them are intended to explain the phenomenon of lift to a general audience.
  • Several theories introduce assumptions which proved to be wrong, like the equal transit-time theory.
  • In accordance with Bernoulli’s principle, where the fluid is moving faster the pressure is lower, and where the fluid is moving slower the pressure is greater. The fluid is moving faster over the upper surface, particularly near the leading edge, than over the lower surface so the pressure on the upper surface is lower than the pressure on the lower surface. The difference in pressure between the upper and lower surfaces results in lift.

Examining these statements we understand that the generation of lift by a wing is not understood. What we see is a cover up seeking to give the impression that there is a scientific explanation known by the experts of aerodynamics,  but that this explanation is so complicated that it cannot be told to a general audience, to which only fairytales known to be incorrect can be offered.

But there is no such explanation to be found in the scientific literature. If there was one, it could be told in suitable form also to a general audience. If there is a correct theory, there is no need of incorrect theories.

If there is no correct theory, then an incorrect theory is better than nothing, at least to scientists supposed to deliver theory.There is thus a genuine need of an explanation, and this is now available as New Theory of Flight submitted to AIAA in final form on June 7 2012 also presented at The Secret of Flight with a wider perspective.

The New Theory of Flight connects to the resolution of d’Alembert’s paradox by Johan Hoffman and myself published in 2008 in Journal of Mathematical Fluid Mechanics, which Wikipedia refuses to acknowledge as part of the scientific literature.

3 Comments

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  1. David Philip

    I am not sure Wikipedia is always a good place to start. I think I found a better reference on Applied Aerodynamics (Digital Textbook provided by Desktop Aeronautics at Stanford University). They don’t seem to have the same starting position that is the key to your presentation. I could not find any reference to some of what is presented by yourselves as “current theories” such as Kutta-Zhukovsky-Prandtl.

    I quote from their preface the following :- “The aerodynamics of bumble bees, disk heads, weather, and many other things is not a solved problem. While it is impressive that the methods in use today do so well, we are still not able to predict many flows.”

    My question how does your new theory of flight deal with any or all of the remaining problems of air flow?

  2. claesjohnson

    If you read the presentation on The Secret of Flight you will find that many questions are answered by the New Theory.

  3. David Philip

    I read the “New Theory of Flight” but the link to “The Secret of Flight” seems to have a problem. Thats when I started looking elsewhere.

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