An Aeromechanical Stability Analysis for Bearingless Rotor Helicopters
Abstract:An analysis, developed primarily for analyzing the aeromechanical stability of bearingless rotor helicopters in hover (air resonance) and on the ground (ground resonsnce), is discussed. The flexbeam portion of the rotor blade is treated in detail while the simplicity of rigid‐body dynamics is retained for the fuselage and outboard portion of the rotor blade. The analysis is also capable of analyzing various types of pitch‐control systems and treats implicitly the aeroelastic couplings that arise from pitch‐control kinematics, the equilibrium deflected shape of the flexbeam, and the built‐in angular offsets of the blade and flexbeam. Numerical results are obtained to compare with experimental data for two small‐scale models to examine the accuracy and limitations of the analysis. One model is equipped with a simplified hingeless rotor without a pitch bearing or pitch‐control system. The correlation is excellent and serves to verify the accuracy of the rigid‐body dynamics and the aerodynamics. The other model is a 1/5.86 Froude‐scaled BO‐105 specially equipped with a bearingless main rotor; the correlation is generally good.
Document Type: Research Article
Publication date: January 1, 1979
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