Sound exposure level (SEL) data from three Army helicopters were used to test a proposed method for calculating sideline decay developed for fixed-wing aircraft. The Federal Aviation Administration (FAA) and the U.S. Air Force (USAF) have adopted this method for use with fixed-wing aircraft, and it was desired to know if the same method could predict rotary-wing aircraft sideline decay with distance or if a more complex computer model is necessary. The procedure was found accurate for limited altitudes and slant distances. In addition, the sideline decay data were studied using variables known to affect sound attenuation. The purpose was to gain further insight into the mechanisms of sideline decay with distance. Variations in the results suggest an unknown mechanism is contributing to this attenuation. (Author)


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    Title :

    Prediction and modeling of helicopter noise


    Additional title:

    Vorberechnung und Modellerstellung fuer die Geraeuschentstehung bei Hubschraubern


    Contributors:
    Raspet, R. (author) / Kief, M. (author) / Daniels, R. (author)

    Published in:

    Publication date :

    1984


    Size :

    54 Seiten


    Type of media :

    Report


    Type of material :

    Print


    Language :

    English




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