One difference between an actuator disk and a real rotor is that the aerodynamically active parts of real rotor blades do not extend all the way to the rotational axis -the so-called root cut-out. This is because of the need to attach the blades to the hub and also provide flap and lead-lag hinges, as well as a feathering (pitch) bearing. For a root cut-out of 25% of radius and a tip-loss factor B 0.97, estimate the S d additional effect ofthe root cut-out on the induced power factor of a hovering rotor.