Author: Michael A. Bowes
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 256
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Book Description
A study was performed to determine the noise reduction benefits and economic costs associated with applying state-of-the-art noise reduction methods to future design civil helicopters. As part of this study, a survey of the make-up of the civil fleet was performed, and this fleet make-up was projected to the 1980 time frame. Analytical methods were developed and/or adopted for calculating helicopter component noise, and these methods were incorporated into a unified total vehicle noise calculation model. Analytical methods were also developed for calculating the effects of noise reduction methodology on helicopter design, performance and cost. The analytical methods were used to calculate baseline noise and cost characteristics of several existing civil helicopters. These methods were also used to calculate changes in noise, design, performance and cost due to the incorporation of engine and main rotor noise reduction methods. All noise reduction techniques were evaluated in the context of an established mission performance criterion which included consideration of hover ceiling, forward flight range/speed/payload and rotor stall margin.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 964
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Book Description
Author: R. H. Spencer
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 132
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Book Description
Author: Wayne Johnson
Publisher: Courier Corporation
ISBN: 0486131823
Category : Technology & Engineering
Languages : en
Pages : 1122
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Book Description
Monumental engineering text covers vertical flight, forward flight, performance, mathematics of rotating systems, rotary wing dynamics and aerodynamics, aeroelasticity, stability and control, stall, noise, and more. 189 illustrations. 1980 edition.
Author: R. H. Spencer
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
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Book Description
This study investigated cost/benefit tradeoffs using the case histories of four helicopters for which design and development were complete, and in three cases, have undergone substantial flight testing. The approach to quieting each helicopter was an incremental reduction of each source as required to obtain reductions in flyover noise with modifications to other secondary systems only as necessary. The methodology used to predict the effects of the design modifications on acquisition, maintenance, and operating costs were typical of those employed by rotorcraft manufacturers. The reduction of helicopter flyover noise generally was achieved through reductions in rotor tip speed. Performance characteristics were maintained to specified minimums for each aircraft in the study. (Author).
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 48
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Book Description
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723974304
Category : Science
Languages : en
Pages : 90
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Book Description
As part of a NASA initiative to reduce helicopter main rotor noise, a Phase 1 study has been performed of candidate noise reduction concepts. Both conventional and novel design technologies have been analyzed that reduce the community impact of helicopter operations. In this study the noise reduction potential and design implications are assessed for conventional means of noise reduction, e.g., tip speed reduction, tip shapes and airfoil tailoring, and for two innovative design concepts: modulated blade spacing and x-force control. Main rotor designs that incorporate modulated blade spacing are shown to have reduced peak noise levels in most flight operations. X-force control alters the helicopter's force balance whereby the miss distance between main rotor blades and shed vortices can be controlled. This control provides a high potential to mitigate BVI noise radiation. Each concept is evaluated using best practice design and analysis methods, achieving the study's aim to significantly reduce noise with minimal performance degradation and no vibration increase. It is concluded that a SILENT main rotor design, incorporating the modulated blade spacing concept, offers significantly reduced noise levels and the potential of a breakthrough in how a helicopter's sound is perceived and judged. The SILENT rotor represents a definite advancement in the state-of-the-art and is selected as the design concept for demonstration in Phase 2. A Phase 2 Implementation Plan is developed for whirl cage and wind tunnel evaluations of a scaled model SILENT rotor.Edwards, Bryan and Cox, Charles and Booth, Earl R., Jr. (Technical Monitor)Langley Research CenterAIRCRAFT NOISE; NOISE REDUCTION; NASA PROGRAMS; ROTARY WING AIRCRAFT; AEROACOUSTICS; SOUND WAVES; WAVEFORMS; VORTICES; WIND TUNNELS; AIRFOILS; BLADE-VORTEX INTERACTION
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 850
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 244
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Book Description
"A compilation of the summary portions of each of the RTOPs used for management review and control of research currently in progress throughout NASA"--P. i.
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1090
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Book Description
