Source Noise Model for Rotorcraft Operations Planning

US warfighter safety could be improved by providing an ability to quickly and accurately assess acoustic impact of rotorcraft operations in the field to reduce the likelihood of detection.  Current mission planning tools are empirical in nature, limited to operating conditions for which flight test data exists, and challenged in predicting the acoustic impact of maneuvering flight.  Current first-principles models capable of predicting source noise beyond the range of test data cannot produce helicopter noise spheres with the accuracy required by mission planners.  The proposed solution is to develop a time-domain based hybrid method, in which a mid-fidelity, physics-based helicopter aeroacoustic model is calibrated to measured data to provide comparable accuracy to current empirical models where measured data exists and superior accuracy where measured data doesn’t exist. The new method will support accurate extrapolation from steady flight data to maneuvering flight.  Existing, validated, mid-fidelity, helicopter aeroacoustics prediction software will be calibrated to measured data using parameter identification methods tailored specifically for this application leveraging and expanding upon experience gained in Phase I and prior.  An automated, process for generating acoustic spheres from flight test data suitable for use in acoustic propagation software will be developed and delivered in Phase II.