SIFT Army Aviation Information Practice Test

When excess lift is generated by the main rotor blades, the phenomenon known as "blade flapping" occurs. This occurs because as the lift on the blades increases beyond a certain point, the rotor blades must accommodate the change in aerodynamic forces acting on them.

As the rotor blades generate more lift, the increased upward force causes them to flap upward. This is a natural response designed to maintain balance and manage the stresses acting on the rotor system. Flapping helps to equalize the lift distribution across the rotor system, preventing any one blade from encountering excessively high loads that could lead to structural failure.

In rotary-wing aircraft, this mechanism is critical for maintaining stable flight, especially in varying load conditions or during flight maneuvers where lift demands change rapidly. The ability of the blades to flap allows for adjustments in their angle of attack, promoting a more uniform lift across the rotor disk.