Tail Shake Vibration: Objective Comparison of Aerodynamic Configurations in a211 Subjective Environment

摘要

Extensive computational fluid dynamic analysis and wind tunnel testing form part211u001eof the design of any new helicopter. Nevertheless, the so-called 'tail shake' 211u001ephenomenon is often encountered during early flight testing. A method is 211u001epresented to characterize this wake related phenomenon in a tractable fashion. It 211u001eis substantiated how a crew-correlated tail shake indicator was extracted from a 211u001esubjective environment and developed into an objective characterization. Amongst 211u001eother rotorcraft, it was applied to the NH90 helicopter, used in this paper to 211u001edemonstrate the method. The differences between two early aerodynamic 211u001econfigurations tested are quantified and wake behavior highlighted, using the so-211u001ecalled 'gamma-alpha plot'. It is concluded that the proposed method allows 211u001eobjective comparison and gives insight into wake behavior, supporting engineering 211u001edecisions during development flight testing.