Load prediction of hingeless helicopter rotors including drivetrain dynamics

Abstract In contrast to analyses with constrained hub speed, the present study includes dynamic response of coupled rotor-drivetrain modes in aeromechanic simulation rotor blade loads. The structural model flexible Bo105 system is aerodynamics modeled by an analytical formulation unsteady element loads combined a generalized wake or free wake, respectively. For two flight states, i. e. cruise and large loading, time-marching autopilot trim wind tunnel configuration performed. results are compared those baseline case constant speed. comparison reveals major change passage frequency harmonics lead-lag Beside full drivetrain model, reduced models shown accurately represent influence on loads, if eigenfrequency second collective lead-lag/drivetrain mode properly predicted. sensitivity analysis, this varied stiffness modification model. resulting changes correlated eigenfrequency, which serves as simple though accurate classification regarding its vibratory Finally, potential improve load predictions application demonstrated through simulated measurements from test.