Why is hunting necessary in the articulated/rigid rotor system?

Why is hunting necessary in the articulated/rigid rotor system?

• A. Increases rotor RPM
• B. Improves lift at high speeds
• C. Relieves the stress forces on the blade caused by flapping
• D. Reduces drag

Answer: (C)

In articulated and rigid rotor systems, blades are allowed to move in the flap direction to respond to changing aerodynamic loads. This motion, often labeled as hunting, is the blade’s natural adjustment to lift variations across the rotor disk. By flapping, a blade can relieve the bending moments and peak stresses that would otherwise occur at the root when lift changes rapidly or gusts hit the rotor. That load-relief role is the central reason hunting is built into these systems. The other choices miss this key function: rotor speed is controlled by the engine and governor, not by hunting; lifting capability at high speeds and overall drag reduction aren’t the primary purposes of this flap/lead-lag behavior.

In articulated and rigid rotor systems, blades are allowed to move in the flap direction to respond to changing aerodynamic loads. This motion, often labeled as hunting, is the blade’s natural adjustment to lift variations across the rotor disk. By flapping, a blade can relieve the bending moments and peak stresses that would otherwise occur at the root when lift changes rapidly or gusts hit the rotor. That load-relief role is the central reason hunting is built into these systems. The other choices miss this key function: rotor speed is controlled by the engine and governor, not by hunting; lifting capability at high speeds and overall drag reduction aren’t the primary purposes of this flap/lead-lag behavior.