Measurement and characterization of helicopter noise at different altitudes

Michael E. Watts, Eric Greenwood, James H. Stephenson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Scopus citations


This paper presents an overview of a flight test campaign performed at different test sites whose altitudes ranged from 0 to 7000 feet above mean sea level (AMSL) between September 2014 and February 2015. The purposes of this campaign were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. In addition to describing the test campaign, results of the acoustic effects of altitude variation for the AS350 SDI and EH-60L aircraft are presented. Large changes in acoustic amplitudes were observed in response to changes in ambient conditions when the helicopter was flown at constant indicatcd airspccd and gross weight at thc three test sites. Howcvcr, acoustic amplitudcs were found to scale with ambient pressure when flight conditions were defined in terms of the non-dimensional parameters, such as the weigh1 coemcient and effective hover tip Mach number.

Original languageEnglish (US)
Title of host publication72nd American Helicopter Society International Annual Forum 2016
Subtitle of host publicationLeveraging Emerging Technologies for Future Capabilities
PublisherAmerican Helicopter Society
Number of pages15
ISBN (Electronic)9781510825062
StatePublished - 2016

Publication series

NameAnnual Forum Proceedings - AHS International
ISSN (Print)1552-2938

All Science Journal Classification (ASJC) codes

  • General Engineering


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