A flight program was carried out to determine the variation of noise level with distance from a model high speed propeller. Noise measurements were obtained at different distances from a SR-3 propeller mounted on a JetStar aircraft, with the test instrumentation mounted on a Lear jet flown in formation. The propeller was operated at 0.8 flight Mach number, 1.12 helical tip Mach number and at 0.7 flight Mach number, 1.0 helical tip Mach number. The instantaneous pressure from individual blades was observed to rise faster at the 0.8 M flight speed, than at the 0.7 M flight speed. The measured levels appeared to decrease in good agreement with a 6 dB/doubling of distance decay, over the measurement range of approximately 16 m to 100 m distance. Further extrapolation, to the distances represented by a community, would suggest that the propagated levels during cruise would not cause a serious community annoyance.


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    Title :

    Farfield Inflight Measurement of High-Speed Turboprop Noise


    Contributors:

    Publication date :

    1982


    Size :

    19 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




    Farfield inflight measurement of high-speed turboprop noise

    Balombin, J. R. / Loeffler, I. J. | NTRS | 1982


    Farfield inflight measurements of high-speed turboprop noise

    Balombin, J. R. / Loeffler, I. J. | NTRS | 1983


    Farfield inflight measurements of high-speed turboprop noise

    BALOMBIN, J. / LOEFFLER, I. | AIAA | 1983


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    Mixson, J. S. / Farassat, F. / Leatherwood, J. D. et al. | NTRS | 1983