What is the term for the lift differential between the advancing and retreating main rotor blades?

The term that describes the lift differential between the advancing and retreating main rotor blades is known as dissymmetry of lift. This phenomenon occurs in rotary-wing aircraft and is a critical concept in helicopter aerodynamics.

When the rotor blades rotate, the blade that is moving forward (the advancing blade) experiences an increase in relative wind speed, generating more lift. In contrast, the blade that is moving backward (the retreating blade) experiences a decrease in relative wind speed and thus produces less lift. This difference in lift between the two blades can lead to a tendency for the helicopter to roll towards the side with lower lift.

Understanding dissymmetry of lift is essential for pilots and technicians because it influences the design and control of rotor systems and impacts flight safety. Proper management of this lift differential allows for smoother flight operations and contributes to the overall stability and maneuverability of the helicopter.