The Pennsylvania State University and its industrial partner, BETA Technologies, aim to support the FAA in determining noise measurement and analysis methods that will allow the external noise radiation of a variety of Unmanned Aircraft System (UAS) and Urban Air Mobility (UAM) vehicles to be accurately characterized. The noise of these vehicles is not well understood due to a lack of available acoustic data. These vehicles often feature a number of electrically driven rotors or propellers, which vary rotor speed independently for control or in response to disturbances, resulting in variability in the radiated noise. This project aims to develop a measurement and data processing approach tailored to characterize the noise of these vehicles. This approach will then be applied to a range of vehicles across different flight conditions. It will provide: FAA and the research community with a better understanding of the noise radiation characteristics of these vehicles; industry with new experimental approaches to tailoring vehicle designs for low noise; and operators with low noise flight control systems and operational guidance. In this work, noise measurements will be collected for a wide range of UAS and UAM configurations across different operating modes, flight speeds, and altitudes. A reconfigurable multirotor UAS will be developed and tested in order to assess the effects of rotor number, blade design, and position on the radiated noise and the measurement and analysis process. The data analysis process developed through this project will allow the contributions of the individual rotor or propeller noise sources to be separated and modeled independently, allowing the variability in noise generation to be correlated to the variability in the vehicle flight state.
This project will provide FAA with timely information which can be used to inform the development of practical noise certification standards for UAS and UAM vehicles of varied configurations. The data processing methods developed under this project will enable accurate empirical noise models to be developed such that the acoustic impacts of vehicle operations can be quantified. This project will also inform the development of low noise UAS and UAM configurations and flight operations, leading to low noise designs and “acoustically aware” flight control laws for these vehicles. The data collected under this project will also enable the validation of the UAM noise prediction system currently being developed at Pennsylvania State University under a separate ASCENT Project.