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Comparison of acoustic performance of five muffler configurations on a small helicopter. [acoustic properties of modified helicopter exhaust system
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Hilton, D. A. Pegg, R. J. |
| Copyright Year | 1974 |
| Description | A field noise measurement program has been conducted on a standard Bell 47 series helicopter and on one that had been modified with specially designed, airframe-mounted mufflers to reduce the engine exhaust noise. The purpose of the study was to evaluate the acoustic performance of five experimental exhaust muffler configurations for a helicopter reciprocating engine in an operational environment. All muffler configurations produced beneficial engine exhaust noise reductions but some configurations were markedly better than others. Flyover noise results indicated that maximum overall noise reductions of approximately 8 db were obtained with the various mufflers. The rotor noise was judged to be the dominant noise component for the muffler-equipped helicopters whereas the engine noise was the dominant component for the basic configuration. |
| File Size | 3157464 |
| Page Count | 37 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19740013539 |
| Archival Resource Key | ark:/13960/t6m08w91b |
| Language | English |
| Publisher Date | 1974-05-01 |
| Access Restriction | Open |
| Subject Keyword | Aircraft Equipment Specifications Acoustic Measurement Acoustic Properties Mufflers Engine Noise Noise Reduction Helicopters Exhaust Gases Bell Aircraft Aircraft Equipment Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
