Acoustic measurements of full-scale electric vertical takeoff and landing aircraft

The Advanced Air Mobility industry is progressing rapidly towards the goal of revolutionizing transportation by connecting urban and underserved communities with electric vertical takeoff and landing (eVTOL) aircraft. To achieve widespread use, eVTOL aircraft must generate acceptable noise in surrounding communities. Many eVTOL aircraft currently under development have novel configurations of rotors, propellers, and wings that may produce rotor-rotor and rotor-airframe interaction noise at certain flight conditions. Acoustic measurements of full-scale eVTOL aircraft are critical to understand the complex noise-generation mechanisms and to validate aeroacoustic models for these novel aircraft designs. In this presentation, we present acoustic measurements of Hexa, an 18-rotor, single-passenger eVTOL aircraft developed by LIFT Aircraft, Inc. We apply acoustic source characterization techniques using simultaneous acoustic measurements and vehicle telemetry data to provide a better understanding of the noise-generation mechanisms. One such analysis technique is the Vold-Kalman filter, which we apply to auralize the tonal waveforms of individual rotors. Finally, we discuss plans for upcoming acoustic measurements of a full-scale, multi-passenger eVTOL aircraft. These measurements and analyses provide the data and tools required to better understand the noise-generation mechanisms and to validate aeroacoustic models for full-scale eVTOL aircraft