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Wavy-Planform Helicopter Blades Make Less NoiseWavy-planform rotor blades for helicopters have been investigated for the first time in an effort to reduce noise. Two of the main sources of helicopter noise are blade/vortex interaction (BVI) and volume displacement. (The noise contributed by volume displacement is termed thickness noise.) The reduction in noise generated by a wavyplanform blade, relative to that generated by an otherwise equivalent straight-planform blade, affects both main sources: (1) the BVI noise is reduced through smoothing and defocusing of the aerodynamic loading on the blade and (2) the thickness noise is reduced by reducing gradients of thickness with respect to listeners on the ground.
Document ID
Acquisition Source
Langley Research Center
Document Type
Other - NASA Tech Brief
Brooks, Thomas F.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 25, 2013
Publication Date
February 1, 2004
Publication Information
Publication: NASA Tech Briefs, February 2004
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
Distribution Limits
Public Use Permitted.
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