FORWARD FLIGHT TRIM AND FREQUENCY-RESPONSE VALIDATION OF A HELICOPTERSIMULATION-MODEL

This article describes a new trim procedure that includes the calculat ion of the steady-state response of the rotor blades and is applicable to straight flight and steady coordinated turns. This article also de scribes the results of a validation study for a high-order linearized model of helicopter flight dynamics that includes rotor, inflow, and a ctuator dynamics. The model is obtained by numerical perturbations of a nonlinear, blade element-type mathematical model. Predicted response s are compared with flight test data for two values of airspeed. The c omparison is carried out in the frequency domain. Numerical simulation s and comparisons with flight test data show that the trim algorithm i s accurate and preserve the periodicity of the aircraft states. The re sults also indicate that the predictions of the on-axis frequency resp onse are overall in good agreement with flight test data, especially a t medium and high frequencies.