Rotor dynamic wake distortion model for helicopter maneuvering flight

Modeling of rotor dynamic wake distortion effects during helicopter transitional flight from a steady hover condition is considered in this paper. The variations of induced inflow over the rotor disk with time during transitional flight phases, such as pitching, rolling, climbing and transition to forward flight from a steady hover condition, are investigated using the vortex tube analysis. Numerical results indicate that the dynamic wake distortion effects can be approximated using first order equations for longitudinal and lateral wake curvatures, wake skew and wake spacing. The new model is implemented in a generic helicopter flight simulation program, and simulation results are compared with the Black Hawk helicopter flight test data in both the frequency domain and the time domain.