NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Press Enter or click the Search button to begin your search.

Back to Results
Forward sweep, low noise rotor bladeA forward-swept, low-noise rotor blade includes an inboard section, an aft-swept section and a forward-swept outboard section. The rotor blade reduces the noise of rotorcraft, including both standard helicopters and advanced systems such as tiltrotors. The primary noise reduction feature is the forward sweep of the planform over a large portion of the outer blade radius. The rotor blade also includes an aft-swept section. The purpose of the aft-swept region is to provide a partial balance to pitching moments produced by the outboard forward-swept portion of the blade. The rotor blade has a constant chord width; or has a chord width which decreases linearly along the entire blade span; or combines constant and decreasing chord widths, wherein the blade is of constant chord width from the blade root to a certain location on the rotor blade, then decreases linearly to the blade tip thereafter. The noise source showing maximum noise reduction is blade-vortex interaction (BVI) noise. Also reduced are thickness, noise, high speed impulsive noise, cabin vibration and loading noise.
Document ID
20080004855
Acquisition Source
Headquarters
Document Type
Other - Patent
Authors
Brooks, Thomas F.
Date Acquired
August 24, 2013
Publication Date
December 17, 1996
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
Patent Application Number: US-PATENT-APPL-SN-498807
Patent Number: US-PATENT-5,584,661
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-PATENT-5,584,661
Patent Application
US-PATENT-APPL-SN-498807
No Preview Available