[FF-1] Dissymmetry of Lift

There is a difference in lift between the advancing half of the rotor disk and the retreating half. In directional flight, the aircraft relative wind is added to the rotational relative wind on the advancing blade and subtracted on the retreating blade. The blade passing the tail and advancing around the right side of the helicopter has an increasing speed which reaches maximum at the 3 o'clock position. As the blade rotation continues, the speed reduces to essentially rotational speed over the nose of the helicopter. The blade speed then decreases progressively and reaches minimum airspeed at the 9 o'clock position. The blade speed then increases progressively and again reaches rotational speed as it passes over the tail.