Anti-resonance system for variable speed rotors

A helicopter rotor assembly, comprising:

• (a) a main rotor hub;
• (b) a plurality of blades extending from the main rotor hub, each of the plurality of blades defining an elongated channel therein, wherein each of the plurality of blades includes:
• (i) an elongated cradle that runs along the length of the elongated channel;
• (ii) an elongated threaded rod disposed within the elongated channel and supported by the elongated cradle;
• (iii) a moveable mass disposed around both the elongated cradle and the elongated threaded rod within the elongated channel, the moveable mass including a threaded portion that is engaged with the elongated threaded rod so that rotation of the threaded rod causes lateral movement of the moveable mass;
• and
• (iv) an actuator that rotates the elongated threaded rod to move the moveable mass to the selected position;
• and
• (c) a controller configured to cause each actuator to move the moveable mass in the blade corresponding to the actuator to a selected position within the elongated channel so as to avoid resonance vibrations of the blade during a rotor speed change;
• wherein changing a position of the moveable mass changes the blade natural frequency so as to move resonance points actively out of rotor operating speed, thereby reducing blade vibrations.