Angle of Attack -- from Eric Weisstein's World of Physics

The angle of attack of an airfoil is the angle Eric Weisstein's World of Math between the airfoil and the relative wind. Ideally, the direction of the wind is measured in the free stream, i.e., far enough away that it is undisturbed by the airfoil. The angle Eric Weisstein's World of Math is measured relative to some reference on the airfoil, and common choices of reference include

1. the direction that produces zero lift, or

2. the chord line of the airfoil.

Drag, Lift, Lift Coefficient, Pitch, Roll, Yaw

References