Coupled Pitch Links for Multi-Harmonic Isolation Using Fluidic Circuits

Replacing rigid pitch links on rotorcraft with coupled fluidic devices has the potential to reduce the aerodynamic blade loads transmitted through the pitch links. Analytical models of two fluidic devices coupled with three different fluidic circuits are derived. These passive fluidlastic systems are tuned, by varying the fluid inertances and capacitances of each fluidic circuit, to reduce the transmitted pitch-link loads for up to three main-rotor harmonics. The simulation results show loads reduction at the targeted odd and even harmonics of at least 95% and 72%, respectively.