How does dissymmetry of lift affect the rotor disk?

Dissymmetry of lift causes an unequal distribution of lift across the rotor disk in forward flight, requiring compensation to maintain stability and control. Dissymmetry of lift occurs because the advancing blade (the blade moving in the same direction as the helicopter) experiences a higher relative wind speed than the retreating blade (the blade moving against the direction of flight). This difference in relative wind speed causes the advancing blade to generate more lift than the retreating blade. If left uncorrected, this unequal lift distribution would cause the helicopter to roll towards the retreating blade side. To compensate for dissymmetry of lift, the cyclic pitch control is used to decrease the angle of attack of the advancing blade and increase the angle of attack of the retreating blade. This equalizes the lift distribution across the rotor disk, allowing the helicopter to maintain level flight.