Propeller Light Aircraft Noise at Discrete Frequencies

In-flight measurements are analyzed to study the acoustic field of a propeller-driven light aircraft. The separation of noise sources is achieved by examination of the influence on the acoustic field of the propeller and the engine. At high rotational speed, the propeller is the dominant source. Evaluating then the field due to steady/unsteady loading on the blades, one concludes that the former are acoustically the most efficient. The analysis of flyover noise measurements, using an original signal processing (Doppler effect compensation) enhances the results.