Category archives for theory of flight

Bluff Body Flow: Potential Flow with 3D Rotational Separation

            We show as part of the revelation of The Secret of Flight that slightly viscous bluff body flow, such as the flow around a wing, can be described as potential flow modified by 3d rotational separation with point stagnation. This makes slightly viscous bluff bod flow both computable and […]

Aerodynamics Text Book: Incorrect

The standard aerodynamics text book Aerodynamics for Engineering Students, 5th edition, by Houghton and Carpenter informs the students in Chapter 4: By the end of the 19th century the theory of potential flow was extremely well developed. But for the most important practical applications in aerodynamics potential flow was almost a complete failure. Flow separation and […]

Early Developments of Modern Aerodynamics: Incorrect!

We read in the opening chapter of Early Developments of Modern Aerodynamics by Ackroyd, Axcell and Ruban: Our stress on viscosity will no doubt surprise newcomers to the subject. However, it must be emphasized at the outset that, without viscosity, all flight, even in nature, would be impossible since wings would produce no lift. From this it follows that […]

The Power of Logical Fallacy

  The arguments used to motivate the Kutta-Zhukovsky circulation theory of lift of a wing (KZ-theory) represent at least two of Aristotle’s logical fallacies: Affirming the Consequent  Argument from Ignorance. These fallacies are so common in science of today that they have come to be viewed not as weak unconvincing non-logic, but rather as strong convincing […]

Scientific Revolution: New vs Old Theory

The  New Theory of Flight presented on The Secret of Flight and now being under evaluation by AIAA, can be used as a real time study of a Scientific Revolution in the sense of Thomas Kuhn as the replacement of an Old Theory of Flight developed by Kutta-Zhukovsky-Prandtl 100 years ago (KZP-theory), which has been the ruling […]

Why Kutta-Zhukovsky Lift Theory is Wrong

How to Check if a Theory is Wrong? The following criteria can be used as evidence that a certain proposed physics theory is wrong: Compare with a correct theory and notice fundamental difference. Compare with experimental observation and notice major difference. Identify a contradiction within the proposed theory. Consider as an example the classical circulation theory […]

Contradictory 2d Circulation Theory of Lift

To give perspective to the New Theory of Flight presented on the web site The Secret of Flight, let us see how the Old Theory of Flight is presented in the classical text Fundamentals of Aerodynamics by John D. Anderson. We quote from and comment on the essential Chapter 4 Incompressible Flow Over Airfoils: 2d Flow around […]

New Theory of Flight

The New Theory of Flight which I have developed together with Johan Hoffman and Johan Jansson, has now been submitted to AIAA together with a supporting article about the completely crucial issue of separation in slightly viscous flow, as a further elaboration with more computational support of the articles The Mathematical Secret of Flight, NORMAT 57 (2009) […]

Why It Is Possible to Fly

The secret of gliding flight

A new explanation is presented of how a wing generates large lift with small drag, based on computing turbulent solutions to the incompressible Euler equations. It is seen that the same mechanism which generates drag from low-pressure streamwise vorticity at the trailing edge, redistributes the pressure over the wing surface and thereby generates lift. It is shown that the classical explanation by Kutta-Zhukovsky is purely fictional and does not describe real physics of gliding flight.