Description: To create a viable market for full-scale electric Vertical Takeoff and Landing (eVTOL) aircraft, the Urban Air Mobility (UAM) industry must design a comfortable cabin noise environment for passengers. Although the cabin noise environment in eVTOL aircraft may share some similarities with conventional aircraft, helicopters, and automobiles, multirotor eVTOL aircraft have unique design features and operating states that differentiate them from existing vehicles. Cabin noise is a multidisciplinary acoustics, aerodynamics, propulsion, and structures problem, with noise sources generated by interactions between the airframe, rotors, and turbulence. NASA has identified a need for flight test data to validate multidisciplinary models of full-scale, multirotor eVTOL aircraft. Blue Ridge Research and Consulting (BRRC) and The Pennsylvania State University propose to deliver full-scale eVTOL cabin noise measurements and analysis to NASA. With our industry partner, Archer Aviation, our team will acquire full-scale flight test measurements during Phase I of interior and exterior noise and vibration onboard Midnight, Archer's four-passenger, multirotor eVTOL aircraft. We will develop analytical methods to quantify the vibroacoustic excitation and identify the dominant sources of cabin noise generated by the rotors, electric engines, and fluid-structure interactions onboard Midnight. Based on the results of our initial Phase I measurements, our team will develop a flight test plan to acquire more extensive cabin noise measurements during Phase II. At the end of Phase I, we will deliver the initial flight test data archive, the Phase II flight test plan, and a final technical report to NASA documenting the initial cabin noise measurements and the dominant sources of cabin noise onboard Midnight. The proposed full-scale eVTOL cabin noise measurements and analysis meet NASA's need for validation data to accelerate the development timeline of full-scale eVTOL aircraft.

Benefits: The proposed full-scale eVTOL cabin noise measurements and analysis fulfill NASA's immediate need for research-quality flight test data to validate multidisciplinary models of full-scale, multirotor eVTOL aircraft, with an emphasis on rotor-rotor and rotor-airframe interactions. Cabin noise is a multidisciplinary acoustics, aerodynamics, propulsion, and structures problem, with noise sources generated by interactions between the airframe, rotors, and turbulence. The proposed cabin noise measurements onboard Midnight, Archer's four-passenger, multirotor eVTOL aircraft, will provide the research-quality flight test data that NASA needs. The proposed research addresses the Aeronautics Research Mission Directorate (ARMD) Strategic Thrust #4 for Safe, Quiet, and Affordable Vertical Lift Air Vehicles. Research themes for Strategic Thrust #4 include minimizing noise, improving passenger comfort, and developing new measurement and analysis tools for full-scale eVTOL aircraft. The proposed cabin noise measurements and analysis will produce new tools to minimize noise and improve passenger comfort in full-scale eVTOL aircraft. These innovations meet ARMD's near-term research objectives to mitigate the noise impacts of full-scale eVTOL aircraft, validate analysis tools, and evaluate concepts to reduce noise. The proposed research directly supports active areas of research in NASA's Revolutionary Vertical Lift Technology (RVLT) project, including developing tools for full-scale eVTOL noise predictions and improving passenger comfort. The proposed cabin noise measurements and analysis will provide a rich flight-test dataset for NASA to validate multidisciplinary tools and assess passenger comfort in real-world, full-scale eVTOL aircraft. The RVLT project can apply the cabin noise and vibration measurements as inputs to the Armstrong Flight Research Center's virtual reality simulator to test passengers' physiological responses to realistic noise and vibration in eVTOL aircraft.To create a viable market for full-scale electric Vertical Takeoff and Landing (eVTOL) aircraft, the Urban Air Mobility (UAM) industry must design a comfortable cabin noise environment for passengers. Currently, the UAM industry needs measured data and analytical methods to better understand, predict, and reduce cabin noise. The proposed research will produce interior and exterior noise and vibration measurements of a full-scale eVTOL aircraft, analytical methods to identify the dominant sources of cabin noise, and potential strategies to reduce cabin noise. During the Phase I and Phase II STTR, our team will refine these proposed innovations into standardized methods to identify the dominant sources of cabin noise in any full-scale eVTOL aircraft. BRRC will market our cabin noise measurement and analysis services to help UAM manufacturers identify, understand, and reduce cabin noise for passengers, thereby accelerating the development timeline of full-scale eVTOL aircraft. Potential customers for cabin noise measurements and analysis include UAM manufacturers, UAM operators, vibroacoustic software developers, and government agencies. Our cabin noise measurement and analysis services will help UAM manufacturers design a comfortable cabin noise environment for passengers and will help UAM operators choose flight profiles that minimize cabin noise during departure and approach. Our flight test measurement capabilities will help vibracoustic software developers gather full-scale data to validate their cabin noise models and will help government agencies like the FAA gather data to develop certification procedures.