FEASIBILITY OF A ROTOR FLIGHT-DYNAMICS MODEL WITH FIRST-ORDER CYCLIC INFLOW AND MULTIBLADE MODES.

With the need of complementing the quasi-steady-inflow formulations at low advance ratios in combination with simplified rotor models, it is desirable to assess the feasibility of using only the first order forward and lateral cyclic components of multiblade modes and a time-delayed unsteady-momentum inflow. Such an approximation is appraised with reference to rigid flap-lag stability with dynamic inflow in forward flight. Three, four, and five bladed rotors are treated with and without periodic terms. For comparative purposes, that model is taken as exact which includes all the multiblade modes and a first harmonic distribution for inflow with three degrees of freedom. Numerical data are generated for trimmed and untrimmed conditions for a hierarchy of rotor-inflow models.