Gust Response of Hingeless Rotors

Gust response of a coupled rotor-fuselage system is studied in hover as well as forward flight. Each blade undergoes flap bending, lag bending and torsional deflections. The blades are divided into beam elements and each element consists of fifteen nodal degrees of freedom. The fuselage can have three translational (vertrical, longitudinal and lateral) and two rotational (pitch and roll) degrees of freedom. The analysis considers a three-dimensional gust field wherein each gust velocity component can have an arbitrary variation in space and time. Equations governing the rotor-fuselage dynamics are linearized about the vehicle propulsive trim state and the blade steady-state deflected positions. The response equations comprising the blade equations of motions, the hub equations of motion and the dynamic inflow equations are solved by time integration. The effect of several parameters on the helicopter gust response is examined, including, dynamic inflow, lag stiffness, forward speed, gust profile, gust penetration rate and gust velocity direction.