Patent ID: 8454315

Claim:
A rotary-wing aircraft rotor system which rotates about an axis of rotation, comprising: a rotor system having an N number of blades which rotates about an axis of rotation at a rotational speed of 1P such that said main rotor system produces NP vibrations; a sensor system which senses the NP vibrations; a multiple of masses coaxially disposed with said rotor system, said multiple of masses includes a first mass and a second mass; a first drive system to spin said first mass about said axis of rotation at a first angular velocity different than an angular velocity of said rotor system; a second drive system to spin said second mass about said axis of rotation at a second angular velocity different than said angular velocity of said rotor system; and a control system in communication with said sensor system and said drive system, said control system operable to identify variations of the NP vibrations to control the angular velocity of at least one of said multiple of masses to reduce the NP in-plane vibrations.