| Abstrakt: |
The influence of in-flight conditions on the community noise of propeller-driven aircraft is studied. The problem of converting the noise levels of light propeller aircraft obtained from measurements under static conditions to real flight conditions is considered. The acoustic characteristics of AN-2, YAK-18T and MAI-223M aircrafts measured under static conditions in the far field and during level flights are compared. It is found that the noise levels in the area of low and medium frequencies up to 400–630 Hz in the 1/3-octave frequency bands are determined by the acoustic radiation of the power plant and can be recalculated from the results of noise measurements of power plants under static conditions with sufficient accuracy to solve engineering problems. At frequencies above 400–630 Hz, the airframe noise becomes significant. At the same time, up to the frequency of the first tone of the propeller noise, the measured noise levels, depending on the wind speed, can be determined by ambient noise. |
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