Acoustic Self-Noise Measurement of a Quadcopter (UAV) in Flight with Focus on Data Acquisition, Microphone Position, and Microphone Wind Protection

The use of UAVs (Unmanned Aerial Vehicles), mostly quadro-, hexa- or octacopters, is becoming increasingly common across various industries. Despite the numerous advantages of these aircraft, the self-noise generated during flight remains an unresolved challenge. The noise emitted by UAVs is perceived as annoying, leading to a decline in public acceptance of these devices. One approach to reduce the inherent noise of UAVs is flight path optimization. For successful implementation, it is essential to be able to accurately measure the UAV's self-noise during flight. This paper describes the development of a data acquisition system for accurate measurement of self-noise during various flight maneuvers. It also discusses the challenges of microphone encapsulation against airflow influences and the optimal positioning of the microphone on the research quadrocopter. The data acquisition system allows the simultaneous recording of microphone signals and data from the flight controller. Additionally, it integrates a direct evaluation of the sound pressure data in the air and their real-time transmission to the pilot on the ground. Another focus is the minimization of the hydrodynamic pressure effects on the acoustic measurement. The sound from the drone can be superimposed by ambient wind and propeller flow, leading to measurement errors without proper precautions. The results highlight how the importance of the right equipment and methodology are for precise and undistorted acoustic measurements in the UAV sector.