Higher harmonic control system for X-Wing aircraft

A system for actively reducing vibratory air-loading in the rotor blades of a rotor in an X-Wing aircraft, which includes a series of pneumatic valve control actuators, comprising:

• higher harmonic control (HHC) means associated with the rotor for alleviating vibration implemented in two forms, a scheduled HHC system and a closed loop active HHC;
• a series of sensors sensing the vibrations of the rotor blades and providing signals based thereon;
• signal processing means associated with said HHC means continuously processing vibration and HHC data from said sensors for generating signals updating the HHC based on the data a multiple number of times in each rotor revolution;
• map means associated with said scheduled HHC providing look-up maps for the second through fifth harmonic coefficients of a control equation as a function of airspeed, lift and rotor speed;
• signal processing means associated with said map means for adding the values from the look-up maps to collective and cyclic terms of the control equation and implementing them through the pneumatic control valve (PCV) actuators;
• and
• a multiple number of flight control computers managing a number of functions of the aircraft, achieving at least quadruple redundancy;
• said HHC means being located in a separate dual processor computer section associated with each of said flight control computers and being complete with its own input/output signal processing.