‘Zero P’ Active Rotor Control for Performance Enhancement and Vibration/Noise Mitigation

The vertical flight community faces a continuing need for improved performance and reduced vibration and noise on full scale helicopter and tiltrotor systems, beyond those achievable with a single fixed design. While past and ongoing efforts have defined Individual Blade Control (IBC) and Higher Harmonic Control (HHC) strategies based on high frequency root pitch control that promise substantial improvement in these metrics, such systems in general require qualification and fielding main rotor control mechanisms with very challenging specifications for actuator bandwidth. Past and recent work has defined alternative, high-payoff, reduced-risk method for active rotor control that focuses on satisfaction of target metrics by deployable surfaces actuated in a quasi-steady manner. This ‘zero per rev’ (‘Zero P’) approach builds on demonstrated results from wind tunnel testing and validated models; it also incorporates insights into methods for providing a substantial fraction of the improvements available via IBC with greatly reduced development risk. Moreover, this ‘adaptive blade’ approach takes advantage of several decades of rotor system analysis by the lead authors, who were among the very first investigators of IBC at its origins in the 1980s. This ‘Zero P’ approach is judged to hold substantial continuing promise for both conventional vertical lift aircraft and new-generation Advanced Air Mobility (AAM) vehicles.