This paper presents an overview of a flight test campaign performed at different test sites whose altitudes ranged from 0 to 7000 feet above mean sea level (AMSL) between September 2014 and February 2015. The purposes of this campaign were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. In addition to describing the test campaign, results of the acoustic effects of altitude variation for the AS350 SD1 and EH-60L aircraft are presented. Large changes in acoustic amplitudes were observed in response to changes in ambient conditions when the helicopter was flown at constant indicated airspeed and gross weight at the three test sites. However, acoustic amplitudes were found to scale with ambient pressure when flight conditions were defined in terms of the non-dimensional parameters, such as the weight coefficient and effective hover tip Mach number.


    Access

    Access via TIB

    Check availability in my library


    Export, share and cite



    Title :

    Measurement and Characterization of Helicopter Noise at Different Altitudes


    Contributors:

    Conference:

    American Helicopter Society (AHS) Annual Forum ; 2016 ; West Palm Beach, FL, United States


    Publication date :

    2016-05-17


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English


    Keywords :


    Measurement and Characterization of Helicopter Noise at Different Altitudes

    M. E. Watts / E. Greenwood / J. Stephenson | NTIS | 2016


    Helicopter operations at high altitudes

    Engineering Index Backfile | 1957




    Numerical characterization of helicopter noise hemispheres

    Gennaretti, M. / Serafini, J. / Bernardini, G. et al. | BASE | 2016

    Free access