26th Congress of International Council of the Aeronautical Sciences
including the 8th AIAA Aviation Technology, Integration, and Operations (ATIO) Conference
14 - 19 September 2008, Anchorage, Alaska, USA
Paper ICAS 2008-3.9.4

ON THE EFFECTS ON NOISE OF GROUND REFLECTION AND ATMOSPHERIC ATTENUATION ON THE NOISE OF HELICOPTERS

L. M. B. C. Campos, J. M. G. S. Oliveira
IST, Portugal

Keywords: Helicopter noise, ground effect, atmospheric attenuation of noise

This paper contains 6 models of helicopter noise addressing sound reflection and atmospheric absorption effects. The baseline model, a single reflection point over flat ground, is extended to include: non-flat ground including multiple paths; wide area scattering by flat ground; single scattering by mountainous ground. Atmospheric absorption effects are considered.

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