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Tilt rotor aircraft aeroacousticsThis paper studies the state of knowledge and the needed improvement in noise methodology and measurements for tilt rotor aircraft. Similarities and differences between tilt rotor aeroacoustic conditions and helicopter and propeller experience are identified. A discussion of the possible principal noise mechanisms throughout the flight envelope shows a need for further experimental and analytical investigations to develop an adequate understanding of the important sources and influencing factors. Existing experimental data from flight tests suggest terminal area noise reduction by operating within certain portions of the conversion flight envelope. Prediction methods are found to provide approximate indications only for low frequency harmonic and broadband noise for several of the tilt rotor's operating conditions. The acoustic effects of the hover case 'fountain' flow are pronounced and need further research. Impulsive noise and high frequency harmonic noise remain problems, as on helicopters, pending major improvements in wake, unsteady aerodynamics, and acoustics methodology.
Document ID
19900041183
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
George, Albert R.
(Cornell University Ithaca, NY, United States)
Smith, Charles A.
(NASA Aerodynamics Div. Washington, DC, United States)
Maisel, Martin D.
(NASA Ames Research Center; U.S. Army, Research and Technology Activity, Moffett Field CA, United States)
Brieger, John T.
(Bell Helicopter Textron, Inc. Fort Worth, TX, United States)
Date Acquired
August 14, 2013
Publication Date
May 1, 1989
Subject Category
Aircraft Design, Testing And Performance
Accession Number
90A28238
Funding Number(s)
CONTRACT_GRANT: NAG2-554
Distribution Limits
Public
Copyright
Other

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