A new model to account for the cyclic loading effect and the nonlinear couplings between wake curvature and wake skew on inflow across the rotor disk during maneuvering flight is developed and combined with the previously established dynamic wake distortion model. The augmented model is implemented in a generic helicopter flight simulation program in order to fully investigate various effects, such as the nonlinear couplings between wake curvature and wake skew, the cyclic loading effect, the effect of the on-axis response prediction accuracy, the blade elastic twisting motion due to gyroscopic feathering moments, etc., that contribute to the off-axis response prediction and the influence of the wake curvature parameter on response predictions. A Comparison of the simulated responses with flight test data of the Black Hawk UH-60A in hover and in 40 knots shows that the value of the wake curvature parameter needed for accurate off-axis response predictions is influenced by these nonlinear effects, which individually may be small.
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