Quote Originally Posted by scottmm73 View Post
Okay, two things to seperate here for a more better understanding. Both definitions apply to Rotor wing as opposed to fixed wing. However both a loosely related.

Angle of Attack(AOA) - is the angle between the airfoil(rotorblade) chord line and resultant relative wind or otherwise an aerodynamic angle.

Angle of Incidence (AOI) - is the angle between the chord line of a main or tail rotor blade and the rotational relative wind of the rotor system (tip-path plane(or the rotor disk)) or otherwise a mechanical angle.

Collective input and cyclic feathering(or cyclic input) changes AOI, which in turn changes AOA somewhat. However, AOA can change, without collective or cyclic input, due to the integral part of travel of the rotor blade through the rotor disc arc, caused by the flapping or flexing of the rotor blade, and gusty or turbulent air.

Remember cyclic input changes the attitude of the rotor disc but does not produce more lift, therefore the blade flapping alone counteracts dissymetry of lift.
Ok Thanks, I think that makes alot more sence....