Definition of blade angle. : the angle between the chord of a propeller or rotor blade and a plane normal to the axis of rotation, its value varying along the span and decreasing from root to tip because of blade twist.
The angle the face of the propeller blade makes at any particular place with its plane of rotation. It is also the angle subtended by the chord of the propeller blade with the horizontal plane when the propeller is laid flat on its boss on this horizontal plane, its axis being vertical.
The angular difference between the chord of the rotor blade and the plane of rotation. This angle may be altered by the pilot through movement of the collective lever or through the cyclic control.