Noise Detectability Prediction Method for Low Tip Speed Propellers
Final rept. 1 May 1970-1 May 1971
UNITED TECHNOLOGIES CORP WINDSOR LOCKSCT HAMILTON STANDARD DIV
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Experience in the field of quiet aircraft for reconnaissance surveillance applications indicated a need for a reliable quiet propeller design procedure. The report describes the development of a computer program intended to fulfill this need. The propeller noise detectability computer program predicts propeller harmonic rotational noise using non-steady blade loads and broad-band noise using a new integration method and compares these predictions with an appropriate aural detectability criterion to estimate the minimum undetectable flight altitude. Supporting tasks include development of aural detectability criteria, a theoretical study of the effect of airfoil section shape on vortex noise, static noise tests of several propeller configurations, correlation of unsteady blade loads corresponding to measured harmonic noise levels, design and testing of a new quiet propeller, and a propeller noise detectability trend study.
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