Measurement and characterization of helicopter noise in steady-state and maneuvering flight

Fredric H. Schmitz, Eric Greenwood, Richard D. Sickenberger, Gaurav Gopalan, Ben Wel C. Sim, David Conner, Ernesto Moralez, William A. Decker

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

15 Scopus citations


A special acoustic flight test program was performed on the Bell 206B helicopter outfitted with an in-flight microphone boom/array attached to the helicopter while simultaneous acoustic measurements were made using a linear ground array of microphones arranged to be perpendicular to the flight path. Air and ground noise measurements were made in steady-state longitudinal and steady turning flight, and during selected dynamic maneuvers. Special instrumentation, including direct measurement of the helicopter's longitudinal tip-path-plane (TPP) angle, Differential Global Positioning System (DGPS) and Inertial Navigation Unit (INU) measurements, and a pursuit guidance display were used to measure important noise controlling parameters and to make the task of flying precise operating conditions and flight track easier for the pilot. Special care was also made to test only in very low winds. The resulting acoustic data is of relatively high quality and shows the value of carefully monitoring and controlling the helicopter's performance state. This paper has shown experimentally, that microphones close to the helicopter can be used to estimate the specific noise sources that radiate to the far field - if the microphones are positioned correctly relative to the noise source. Directivity patterns for steady, turning flight were also developed, for the first time, and connected to the turning performance of the helicopter. Some of the acoustic benefits of combining normally separated flight segments (i.e. an accelerated segment and a descending segment) were also demonstrated.

Original languageEnglish (US)
Title of host publicationAHS International 63rd Annual Forum - Proceedings - Riding the Wave of New Vertical Flight Technology
Number of pages17
StatePublished - 2007
Event63rd American Helicopter Society International Annual Forum 2007 - Virginia Beach, VA, United States
Duration: May 1 2007May 3 2007

Publication series

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


Other63rd American Helicopter Society International Annual Forum 2007
Country/TerritoryUnited States
CityVirginia Beach, VA

All Science Journal Classification (ASJC) codes

  • General Engineering


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