Noise Characteristics Of Eight Helicopters
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Author | : |
Publisher | : |
Total Pages | : 170 |
Release | : 1977 |
Genre | : |
ISBN | : |
Download Noise Characteristics of Eight Helicopters Book in PDF, Epub and Kindle
This report describes the noise characteristics of Eight Helicopters during level flyovers, simulated approaches, and hover. The data was obtained during an FAA/DOT Helicopter Noise Program to acquire a data base for possible helicopter noise regulatory action. The helicopter models tested were the Bell 47G, 206L, and 212 (UHIN), the Hughes 300C and 500C, the Sikorsky S-61 (SH-3B) and S-64 (CH-54B) and the Vertol CH-47C. The acoustic data is presented as Effective Perceived Noise Level, A-weighted sound pressure level and 1/3 octave band sound pressure level with a slow meter characteristic per FAR Part 36. Selected waveforms and narrow band spectra are also shown. Proposed methods to quantify impulsive noise ('blade slap') are evaluated for a level flyover for each of the Helicopters. The tested helicopters can be grouped into classes depending upon where the maximum noise occurs during a level flyover. Helicopters with the higher main rotor tip speeds propagate highly impulsive noise ahead of the helicopter. The maximum noise for most of the helicopters occurs near the overhead position and appears to originate from the tail rotor. Unmuffled reciprocating engine helicopters appear to have significant engine noise behind the helicopter. Noise levels, when compared as a function of gross weight and flown at airspeeds to minimize 'compressibility slap' form a band 7 EPNdB wide with a slope directly proportional to gross weight. The quieter helicopters have multibladed rotors and tipspeeds below 700 fps.
Author | : Harold C. True |
Publisher | : |
Total Pages | : 172 |
Release | : 1977 |
Genre | : Helicopters |
ISBN | : |
Download Noise Characteristics of Eight Helicopters Book in PDF, Epub and Kindle
Author | : Harold C. True |
Publisher | : |
Total Pages | : 153 |
Release | : 1977 |
Genre | : Helicopters |
ISBN | : |
Download Noise Characteristics of Eight Helicopters Book in PDF, Epub and Kindle
Author | : Harold C. True |
Publisher | : |
Total Pages | : 172 |
Release | : 1977 |
Genre | : Helicopters |
ISBN | : |
Download Noise Characteristics of Eight Helicopters Book in PDF, Epub and Kindle
Author | : J. Steven Newman |
Publisher | : |
Total Pages | : 310 |
Release | : 1979 |
Genre | : Helicopters |
ISBN | : |
Download Noise Levels and Flight Profiles of Eight Helicopters Using Proposed International Certification Procedures Book in PDF, Epub and Kindle
Author | : Dwight E. Bishop |
Publisher | : |
Total Pages | : 45 |
Release | : 1965 |
Genre | : Airplanes |
ISBN | : |
Download Helicopter Noise Characteristics for Heliport Planning Book in PDF, Epub and Kindle
The report presents technical information and procedures for estimating the noise levels produced by current civil and military helicopters (piston- and turbine-powered) during varied flight and ground operations. Information and procedures are also presented for comparing helicopter noise with other vehicle noise, and with ambient noise found in typical urban and suburban areas. These procedures permit an assessment of the extent to which helicopter noise is compatible with typical land uses (residential, commercial, industrial, etc.) in areas near heliports. Noise data and procedures are presented in simplified fashion. The information may be readily used by those without specialized acoustical training but who are concerned with the location and development of a heliport, or with land planning or land zoning in the vicinity of heliports. (Author).
Author | : David Kiang |
Publisher | : |
Total Pages | : 18 |
Release | : 1971 |
Genre | : |
ISBN | : |
Download Rotational Noise Characteristics of Helicopters Book in PDF, Epub and Kindle
Author | : J. Steven Newman |
Publisher | : |
Total Pages | : 25 |
Release | : 1980 |
Genre | : Helicopters |
ISBN | : |
Download Correlations of Helicopter Noise Levels with Physical and Performance Characteristics Book in PDF, Epub and Kindle
Author | : F. H. Schmitz |
Publisher | : |
Total Pages | : 110 |
Release | : 1983 |
Genre | : |
ISBN | : |
Download Helicopter Impulsive Noise: Theoretical and Experimental Status Book in PDF, Epub and Kindle
The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanisms is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanisms of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.
Author | : M. R. P. Law |
Publisher | : |
Total Pages | : 63 |
Release | : 1982 |
Genre | : Helicopters |
ISBN | : |
Download The Influence of Helicopter Operating Conditions on Rotor Noise Characteristics and Measurement Repeatability Book in PDF, Epub and Kindle
Following on exploratory developments in flight-testing techniques and data-analysis procedures for helicopter external noise, extensive measurements of noise characteristics and associated flight-path data have been made by RAE on several helicopters in various operational modes, with repeated flight trajectories over longitudinal and lateral arrays of ground-based microphones under quiet airfield conditions. This analysis presents some experimental results from Lynx aircraft with standard rotor configurations, being concerned primarily with the influence of different operating procedures on both main-rotor and tail-rotor noise characteristics and on measurement repeatability during level-flight, oblique landing-approach, and oblique take-off. Some tail-rotor near-field noise signatures have also been derived for correlation purposes, using a microphone mounted with a forward-facing nose-cone just outside the fuselage skin on the tail-boom.