Helicopter Gust Response Including Unsteady Aerodynamic Stall Effects
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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The SikorskyUARL Normal Mode Rotor Aeroelastic Analysis Computer Program Y-200 was modified to provide the capability of predicting the gust- response characteristics of pure and compound, single-rotor helicopters, including the effects of unsteady aerodynamics on rotor blade stall. The analysis was applied to examine the effects or rotor configuration, flight condition, and gust profile variables on rotor response characteristics. Only the short-term, controls-fixed response was investigated. The results were used to assess the accuracy of the gust-alleviation factor relation given by MIL-S- 8698 ARG and USAAVLABS Technical Report 69-1 and to provide a basis for developing a more accurate relation. In addition, the impact of the gust on other quantities of interest such as blade vibratory moments and forces was briefly studied. Finally, an assessment of the relative importance of some of the assumptions in the analysis was also made.