Simulation of Complete Helicopter Noise in Maneuver Flight using Aeroacoustic Flight Test Database

This paper reports recent developments conducted at the DLR to set up a tool able to compute the ground noise footprint created by a complete helicopter in an arbitrary flight (including maneuvers). The computational tool relies on a hybrid approach: generation of an arbitrary trajectory, checks of flyability and comfort and propagation of noise down to the ground are performed numerically whereas noise emission characteristics are provided by an aeroacoustic database. The underlying idea is that the instantaneous noise emission of the whole helicopter can be characterized by the instantaneous value of few aerodynamic parameters. The aeroacoustic database relates those quantities via postprocessing of the DLR flight campaign PAVE 2004. Its generation and extent is explained. When computing the noise of an arbitrary flight, interpolations within the aeroacoustic database are used. The whole method has been successfully validated versus experimental data, including ground noise footprint. The tool is used within the European project Friendcopter and the DLR project PAVE2 to minimize the ground noise footprint of flyable and comfortable flight procedures including arbitrary maneuvers, landing and take-off.