The Rotorcraft Noise Model (RNM)

Abstract

The Rotorcraft Noise Model (RNM) is a simulation program that predicts how sound will propagate through the atmosphere and accumulate at receiver locations located on flat ground or varying terrain, for single and multiple vehicle flight operations. Developed by the NASA Langley Research Center and Wyle Laboratories, RNM was initially intended to provide a tool to aid in the development of low noise terminal area operations for rotorcraft and tiltrotors, but has since been widely adopted for environmental impact studies. At the core of RNM are the vehicle source noise characteristics, input as sound hemispheres. As the vehicle flies along its prescribed flight trajectory, the source noise propagation is simulated and accumulated at the receiver locations (single points of interest or multiple grid points) in a systematic time-based manner. These sound signals at the receiver locations may then be analyzed to obtain numerous ground metrics or noise animation videos. A PC executable version of RNM is publicly available. This presentation will provide details on the theoretical framework of RNMs propagation model and the required inputs, discussion on capabilities for civil and military applications as well as details on output results. Code validation results and example outputs will be presented.