Parametric Investigation of the Aerodynamic and Aeroelastic Characteristics of Articulated and Rigid (Hingeless) Helicopter Systems

摘要

This report presents results of an aeroelastic investigation to explore effects of parametric variations on blade stresses and performance of rigid (hingeless) and articulated helicopter rotor systems. The analysis considers the high-speed, steady-state flight condition and takes into account the fully coupled flatwise-edgewise-torsional response of the rotor blades. Calculated performance and one-half peak-to-peak flatwise stresses are shown to give good agreement with flight-measured values at higher airspeeds. It is found that blade twist is a significant variable for control of blade vibratory stresses and rotor performance. The sensitivity of rigid rotor flatwise and edgewise stresses to change in design of the blade root region is explored. Studies on variation of blade stiffness indicate that outboard blade stiffening is detrimental for an articulated blade, whereas inboard stiffening is detrimental for a rigid blade.. For compound helicopters, selection of rotor rpm is found to require an important compromise between blade stress and power.