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Noise Reduction Experience at Hughes Helicopter, Inc.Noise reduction is mostly limited to light helicopters whose noise signature is dominated by their tail rotors. It is primarily hardware oriented. Well known noise reduction techniques such as reduction of rotor speeds with an accompanying increase in solidity to maintain performance, engine noise reduction with the use of exhaust mufflers, and acoustic blanketing of transmission and engine compartment are used. The concept of blade phasing as a means of reducing tail rotor noise is also used. Engine noise (exhaust noise), power train noise and airframe noise becomes important at low rotor tip speeds and means must be found to reduce these noise sources if further noise reductions are desired. The use of a special test rig aids in isolating the various noise sources and arriving at the penalties (performance or payload) involved in quieting them. Significant noise reduction are achieved for the light helicopter with minimum performance or weight penalties because of the dominance of a single noise source (the tail rotor).
Document ID
19840021597
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
D S Janakiram
(Hughes Helicopters Culver City, California, United States)
Date Acquired
August 12, 2013
Publication Date
July 1, 1982
Publication Information
Publication: Proceedings of the NASA/U.S. Helicopter Industry Workshop on Aerodynamic Noise Prediction/Noise Reduction
Publisher: National Aeronautics and Space Administration
Subject Category
Acoustics
Meeting Information
Meeting: NASA/U.S. Helicopter Industry Workshop on Aerodynamic Noise Prediction/Noise Reduction
Location: Hampton, VA
Country: US
Start Date: March 29, 1982
End Date: March 31, 1982
Sponsors: Langley Research Center
Accession Number
84N29666
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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