Development of a Rapid Acoustic Prediction Methodology for Conceptual Electric Aircraft

The rapid growth of electric vertical takeoff and landing (eVTOL) concepts has amplified the need for fast, reliable acoustic prediction tools that can inform early-stage aircraft design. Planned operations in close proximity to densely populated areas makes the acoustic signature of eVTOL aircraft vitally important, but current acoustic prediction tools are too time consuming to inform rapid iteration on a conceptual design. This work evaluates NASA's Aircraft NOise Prediction Program 2 (ANOPP2) as a low-fidelity, rapid prediction method by comparing its rotor noise estimates against a comprehensive set of laboratory acoustic measurements for varying blade counts, pitch angles, and tip speeds. Results show that ANOPP2 reliably captures tonal content and the relative trends associated with key design variables, typically within a few decibels, despite notable underprediction of high-frequency broadband noise and an inability to capture high-order harmonics. The model also reproduces the primary directivity features observed in experiments. ANOPP2's accuracy in predicting changes in acoustic behavior suggests it can serve as an effective component of a rapid conceptual design toolchain for early eVTOL noise assessment.