EXTENDED ARM BIFILAR AND METHOD TO ELIMINATE SECOND ORDER VIBRATION EXCITATION

摘要

ABSTRACT OF THE DISCLOSUREA helicopter has a plurality of bifilar absorbersmounted on arms radially extended from the hub of the rotor.A bifilar mass of the required weight mounted at the end of anarm of required length to absorb input excitations at apendulum amplitude of approximately 30° at design forward speedis mounted on an arm twice the length without a reduction inweight of the bifilar mass to limit pendulum amplitude to 15°while maintaining the original force output. Bifilar motion inthe linear range with associated elimination of overtuning pro-duces improved bifilar operation at all flight speeds and elimi-nates second order vibration due to dissimilar motions resultingfrom overtuning.