Effects of analytical modeling assumptions on the predicted stability of a model hingeless rotor

The HELSA aeroelastic stability analysis developed by Sikorsky Aircraft is applied to a stiff inplane hingeless rotor model tested in hover at the Ames Research Center by the U.S. Army. The analysis was evaluated on six configurations achieved by adjusting precone, droop, and pitch flexure stiffness. The comparisons illustrate the ability of a state-of-the-art industry-developed analysis to predict flap-lag-torsion stability for a range of design parameter variations. Significant sensitivities to equilibrium deflections, torsional representations, and aerodynamic assumptions were shown. Predictions show the influences of elastic torsion-bending coupling and emphasize the need for careful examination in applications of factors contributing to the couplings.