Helicopter Gust Response Characteristics Including Unsteady Aerodynamic Stall Effects
Abstract:The results of an analytical study to evaluate the general response characteristics of a helicopter subjected to various types of discrete gust encounters are presented. The analysis employed was a nonlinear coupled, multi‐blade rotor‐fuselage analysis including the effects of blade flexibility and unsteady aerodynamic stall. Only the controls‐fixed response of the basic aircraft without any aircraft stability augmentation was considered. A discussion of the basic differences between gust sensitivity of fixed and rotary wing aircraft is presented. The effects of several rotor configuration and aircraft operating parameters on initial gust‐induced load factor are discussed. The results are used to assess the accuracy of the gust alleviation factor given by MIL‐S‐8698. Finally, a brief assessment of the relative importance of possible assumptions in gust response analyses is made and a brief comparison of gust and maneuver load experiences in Southeast Asia is presented. The results confirm that current gust alleviation factors are too conservative and that the inclusion of unsteady stall effects result in higher initial load factors than predicted using a steady stall aerodynamic analysis.
Document Type: Research Article
Affiliations: Sikorsky Aircraft Division of United Aircraft Corporation, Stratford, Connecticut
Publication date: October 1, 1974
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