Re: Misconceptions: Physics of Flight

[William Beaty <billb@ESKIMO.COM>]

On Fri, 13 Aug 1999, Glenn A. Carlson wrote:

> Redefining angle of attack to make the point reminds me of the
> conversation between Alice and Humpty Dumpty:


LOL!

Maybe I should just attempt to redefine the method used to choose the
zero-reference for angle of attack, rather than attacking angle-of-attack
itself?  :)


Changing the shape of an airfoil can alter the AOA at which the
lifting force goes to zero.  Does this fact support the argument that
wing-shape is the source of the lifting force?  Or does it simply mean
that the zero-reference for AOA can be pushed around a bit depending upon
how the shape of the wing has changed?

Again here's that diagram which shows what I mean:

   http://www.eskimo.com/~billb/wing/airfoil2.gif


Suppose that the overall angle of the trailing half of the airfoil is a
major determinant of air-deflection and of lifting force.  If this is the
case, then the usual method of setting the zero-angle for AOA would *not*
give us the angle of zero lift, except when the airfoil happened to be
symmetrical and have zero camber.


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