SAFTu - a versatile noise mapping software for UAS or piloted flying vehicles

The civil UAS market is expected to grow significantly in the coming years resulting in a more intense and conceptually different air-traffic with new noise challenges. Existing aircraft noise regulations and standards, like ECAC Doc29, do not apply to this emerging air-traffic. Therefore, appropriate computational tools and plausible noise scenario studies ahead of this new air-traffic becoming a reality is crucial. A tool aimed for this purpose is the SAFTu software, a versatile software that simulates UAV noise emissions, developed within the KTH/CSA-project APIS. New vehicles, ranging from smaller multicopters to larger VTOLs are incorporated using flight mode conditions and sound source data sets. In a typical run, the ground track is defined by waypoint input in Google Earth. Flight profiles are established by providing altitude and speed at the waypoints. Ground noise is computed onto an adaptive grid using raytracing. The plotting of noise contours in dBAmax, or other metrics, requires only some CPU minutes. Frequency dependent time histories can be presented for selected positions. Other output includes histograms representing nof. inhabitants exposed to various noise levels. Refractive noise propagation due to wind and temperature gradients are planned to be implemented to enable acoustically optimised flights in sensitive areas