Extended arm bifilar and method to eliminate second order vibration excitation

摘要

A helicopter has a plurality of bifilar absorbers mounted on arms radially extended from the hub of the rotor. A bifilar mass of the required weight mounted at the end of an arm of required length to absorb input excitations at a pendulum amplitude of approximately 30 DEG at design forward speed is mounted on an arm twice the length without a reduction in weight of the bifilar mass to limit pendulum amplitude to 15 DEG while maintaining the original force output. Bifilar motion in the linear range with associated elimination of overturning produces improved bifilar operation at all flight speeds and eliminates second order vibration due to dissimilar motions resulting from overtuning.