Mxsmanic wrote in
:

Dudley Henriques writes:

AOA actually can be defined relative to any given reference datum,
but normally it's considered in the industry as being the angle
formed between the chord line of the wing and the relative wind as
you have correctly stated.

The angle of attack is the angle between the forward stagnation point
and the trailing stagnation point. The points of intersection of the
chord line with the airfoil surface are static, but the stagnation
points can change, altering the angle of attack.

If the angle of attack is not positive, there is no lift. You cannot
have lift at negative angles of attack because that is not symmetric.
If a negative angle of attack can produce positive lift, what happens
when you turn the airfoil upside down? Logically that would mean that
even a positive angle of attack would force the wing down, which makes
no sense.


Nope


Bertie