Importance of engine as a source of helicopter external noise

Janakiram, Ram D.; Smith, Michael J.; Tadghighi, H.

doi:10.2514/6.1989-1147

Cited by 4 publications

(2 citation statements)

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“…Because engine noise has a broad band character it is often not immediately observed either subjectively, or in the spectral analysis. Papers by Damongeot et aH 1T > and JanakiRam et a/< 73 ) give practical examples of cases where engine noise has been found to be dominant is some flight conditions. Fortunately, if desired, engine noise can be reduced in many ways.…”

Section: Other Sourcesmentioning

confidence: 99%

Progress towards quieter civil helicopters

Lowson¹

1992

Aeronaut. j.

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A review of recent developments in helicopter noise reduction is presented. The paper includes a discussion of the present state of understanding of helicopter noise radiation mechanisms and a review of actual noise reductions achieved by the manufacturers over the past decade. An analysis of progress achieved in meeting certification limits is given, together with an evaluation of the impact on design. Future trends in helicopter noise reduction based on current noise research programmes are discussed and suggestions advanced for possible additional areas of study.

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Section: Other Sourcesmentioning

confidence: 99%

Progress towards quieter civil helicopters

Lowson¹

1992

Aeronaut. j.

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“…Turboshaft engines can become the main source of helicopter noise around heliports at takeoff. 1,2 Inlet radiation mainly comes from the compressor tones, but aft radiation is more intricate. Turbine tones usually are above the audible frequency range and do not contribute to the weighted sound levels.…”

Section: Introductionmentioning

confidence: 99%