Thus C Lα is a function of wing aspect ratio, mid-chord sweep angle Λ c/2, Mach number, and airfoil section (defined parallel to the free stream) lift curve slope.The factor κ in Equation (5.18) is the ratio of the experimental two-dimensional (i.e., airfoil) lift curve slope (per radian) at the appropriate Mach number (c la) M to the theoretical value at that Mach number, 2π/β, or κ. Airfoil is not available for Windows but there are some alternatives that runs on Windows with similar functionality. The most popular Windows alternative is Stream What You Hear, which is both free and Open Source. Airfoil Alternatives. For our design alternatives we decided to invest our research into changing the airfoil used in the bladeless fan. The airfoil is the cross section of the fans outer and inner rings. We decided to concentrate on the outlet of where the air exits the ring and how this outlet can affect the dispersion of air. NACA airfoils are used still used in aircraft, though most of the airfoils used are modified in some way. For example, the Cessa uses either pure or modified NACA airfoils in most of its Cessna Citation jets, though newer models tend to use Cessna's own airfoils.
Alternatives To Airfoil
But in the 2D world of the wind-tunnel, there is no such downward-moving wake behind the wing. Instead, the 2D upwash must always be exactly equal to the 2D downwash, and the wing does not push upon the air. Instead, all the momentum is injected directly and instantly into the distant floor/ceiling. Even more important, 3D wings have finite dimensions, while 2D wings act as if they have infinite span. An infinite wingspan gives some exceeding strange results; odd results never produced by finite 3D wings in the real world.
For example, if a 2D infinitely-wide wing should ever deflect even a tiny portion of the oncoming air downwards (deflecting a streamline,) it would deflect an infinite amount of air, and produce an infinite lifting force. As a result, a 2D infinite airfoil does an odd thing: it applies a finite force to an infinite mass of air. In response, a net amount of air does NOT move downwards (since it has infinite mass.) The incoming and outgoing streamlines remain horizontal. The wing doesn't deflect any air at all, on average. The wing acts like a weird reaction engine, a strange engine where the 'exhaust gasses' have zero velocity and infinite mass. This strange effect only applies to 2D airfoils and to infinitely-wide wings, and obviously is never encountered with real 3D airplanes flying through 3D air.
Airfoil Alternatives
The controversy about 'Bernoulli versus Newton' is probably a controversy about two-D wings versus three-D. It's a fight between the reaction- motor-like flight of real wings, versus the instant-forces of ground-effect flight seen in airfoil diagrams and in 2D wind tunnels. It's a controversy over fluid propulsion versus venturi-effect, between the the physics of short 3D wings in a 3D world, versus flight in strange a two-dimensional 'flatland' or 'Dewdney Planiverse' world.In other words, flight of airplanes in the real world is an example of reaction engines and propulsion, same as with hovering helicopters and hovering rocket engines. Real wings are reaction engines. But the flight of a 2D airfoil is not propulsion, and doesn't inherently require any fuel. Real 3D airplanes require fuel, even when flying in an idealized zero-friction environment. (Real helicopters and rocket engines are the same. But a rocket engine with an infinitely-wide engine-bell does not need fuel and is not a reaction engine. The same is true of a helicopter with infinitely-wide rotor blades ...and true for a two-dimensional airfoil in a world of 2D streamlines.)
I attempt to explain the problem in words, but words are easilymisunderstood (especially on hot-button issues where emotions run high.) A visual analogy works much better. Below is my explanation for how athree-dimensional airplane flies through 3D air. It is very differentthan the typical 2D explanations found in most textboooks. My'circulation' is flipped ninety degrees!
Take a look at my animated crude GIF diagram, and also see the green smoke laser-scanned video segment of a model 747 producing a downwash pattern.