Main rotor

There are three configurations of main-rotor system – fully articulated, semi-rigid and rigid. These describe the relative degrees of freedom between the blades and the rotor hub.

The rigid rotor system is the simplest configuration, in which the blades are effectively rigid in relation to the centre of rotation.The semi-rigid rotor system has the blades fixed in relation to “lead/lag”, but still allows the blade to “flap”. These terms are defined below in relation to the fully articulated rotor.

The fully articulated rotor system allows the blades the highest degrees of freedom in relation to the centre of rotation. Freedom of pitch allows rotation of the blade along its axis. Freedom to “flap” allows the blade to move perpendicular to the rotor disc. Freedom to lead/lag allows the blade to move within the plane of the rotor disc as it rotates through a cycle.
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