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The Sound of Rotorcraft

Published online by Cambridge University Press:  04 July 2016

J. W. Leverton
J. W. Leverton*
Affiliation:
Westland Helicopters Ltd, andInstitute of Sound and Vibration Research, University of Southampton
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Extract

The sound of a rotorcraft is very complex in nature since it is a combination of the sound produced by several individual sources, which in the main generate acoustic energy by more than one mechanism. Externally, the important sources are rotor noise and engine noise; while internally transmission system (gear) noise is an additional source. The frequency ranges associated with the various sources on a rotorcraft are summarised on the narrowband spectrum shown in Fig. 1. Main rotor noise is treated as two separate entities, rotational and broadband noise, while the tail rotor noise (if applicable) is dominated by its rotational components.

The following discussion is limited to gas-turbine-engined rotorcraft as, except for some of the small light-weight helicopters, the majority are powered by this type of engine. It is worth noting that on a piston-engined helicopter, the engine itself is the main noise generator, with the primary source being the exhaust noise emanating from the periodic expulsion of the hot gases of combustion. This produces harmonics at the engine firing frequency as indicated on Fig. 1, and in addition to being of high amplitude is very annoying since it occurs in the 200-1000 Hz range.

Type
Rotorcraft Section
Information
The Aeronautical Journal , Volume 75 , Issue 726 , June 1971 , pp. 385 - 397
Copyright
Copyright © Royal Aeronautical Society 1971 

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References

1. Leverton, J. W. Helicopter Noise, ISAV Memo 194, July 1967.Google Scholar
2. Arndt, R. E. A. and Boroman, D. C., Noise Radiation frorn Helicopters Rotors Operating at High Tip Mach Number. Proceedings of 26th Annual National Forum of American Helicopter Society, May 1966.Google Scholar
3. Wright, S. E. and Leverton, J. W., Helicopter Rotor Noise Generation. Proceedings: Third CAL/AVLABS Symposium. June 1969.Google Scholar
4. Tanna, H. K. and Morfey, C. L., Sound Radiation from a point force in circular motion. Proceedings: Symposium on Aerodynamic Noise, Loughborough University of Technology. September 1970.Google Scholar
5. Davidson, I. M. and Hargest, T. J., Helicopter Noise. Journal of the Royal Aeronautical Society. Vol 69, May 1965.Google Scholar
6. Lowson, M. V. and Ollerhead, J. B., Studies of Heli copter Rotor Noise, USAAVLABS Technical Report 68-60 Wyle Research Staff Report WR.68-9, 1968.Google Scholar
7. Stainer, N. J. An experimental investigation into rotational noise—for a low solidity rotor. M.Sc. Thesis; ISVR, Uni versity of Southampton, 1969.Google Scholar
8. Dodson, A. An investigation into rotor Rotational Noise of Helicopters in the Single and Tandem Rotor Con figuration. M.Sc. Thesis; ISVR University of Southampton, 1969.Google Scholar
9. Schlegel, R. G. and Bausch, W. E., Helicopter Rotor Rotational Noise Prediction and Correlation. Sikorsky Aircraft Report, 1968.Google Scholar
10. Wright, S. E. Sound Radiation from a Lifting Rotor Generated bv Asymmetric Disc Loadings. ISVR Tech nical Report No 5, April 1968.Google Scholar
11. Tanna, H. K. Private Communications (ISVR: Oct. 1970).Google Scholar
12. Wright, S. E. Theoretical Study of Rotational Noise. ISVR Technical Report No 14, May 1969.Google Scholar
13. Cook, C. V. A method of predicting the trajectory of the tip vortex issuing from a helicopter rotor blade in the forward flight mode. Westland Note CVC/EW/862: October 1970.Google Scholar
14. Leverton, J. W. Helicopter Noise—Blade Slap Part I: Review & Theoretical Study. NASA CR-1221. October 1968.Google Scholar
15. Simons, I. A. Some objectives and problems associated with model testing. The Aeronautical Journal of the Royal Aeronautical Society. Vol 74, July 1970.Google Scholar
16. Cook, C. V. Rotor performance prediction in hover Westland Research Paper RP 387. November 1968.Google Scholar
17. Burpo, F. B. and Lynn, R. R. Measurement of Dvnamic Airloads on a Full Scale Semi-Rigid Rotor, TCREC Tech. Report 62-42. December 1962.Google Scholar
18. Scheimen, J. A Tabulation of Helicopter Rotor Blade Differential Pressures. Stress and Motions as measured in Flight. NASA Tech Memo TMX-952.Google Scholar
19. Leverton, J. W. Noise of Rotorcraft. Westland Research Paper RP365. March 1969.Google Scholar
20. Schlegfl, R., King, R. and Mull, H. Helicopter Rotor Noise Generation and Propagation. USAAVLABS Tech. Report 66-4, 1966.Google Scholar
21. Leverton, T. W. and Taylor, . Helicopter Blade Slap. J of S & Vib. Vol 4, November 1966.Google Scholar
22. Whatmore, A. R. A Studv of Transient Rotor Noise. M.Sc. Thesis; ISVR University of Southampton. 1969.Google Scholar
23. Goddard, J. O. and Stuckey, T. J. Investigation and Prediction of Helicopter Rotor Noise. Westland Report No AAD.4/1. November 1964. 10.Google Scholar
24. Widnaix, S. E. A Correlation of Vortex Noise Data from Helicopter Main Rotors: AlAA Journal. Vol 6, May-June 1969.Google Scholar
25. Leverton, J. W. Helicopter Noise. Proceedings: AGARD Conference, Ottawa, June 1968.Google Scholar
26. Shilladay, J. D. Helicopter and Convertible Rotorcraft Noise Estimation. Westland Research Paper No 387, August 1970.Google Scholar
27. Robinson, D. W. and Copeland, W. C. T. Interim Pro posal for Air Attenuation Aircraft Values for Aircraft Noise. NPL Aero Report AC28, July 1967.Google Scholar
28. Bishop, D. E. Helicopter Noise Characteristics for Heli port Planning. Tech Report ADS-40, March 1965.Google Scholar
29. Trillo, R. L. An Empirical Study of Hovercraft Pro peller Noise. J Sound Vib. 1965.Google Scholar
30. Leverton, J. W. The Reduction of the Aircraft Noise Nuisance by the use of Rotorcraft. Westland Research Paper 391, January 1971.Google Scholar
31. Leverton, J. W. Helicopter Noise—Blade Slap Part II— Experimental Results. (To be published as NASA CR Report). Google Scholar
32. Spencer, R. H. Application of Vortex Visualization Test Techniques to Rotor Noise Research. Proceedings: 26th Annual National Forum of American Helicopter Society, June 1970.Google Scholar
33. Sternfeld, H. Influence on the tip vortex on helicopter rotor noise. AGARD Conference Proceedings No 22; Sep tember 1967.Google Scholar
34. Cox, C. R. Rotor Noise Measurement in Wind Tunnels. 3rd CAL/AVLAB Symposium on V/STOL Aero dynamics, Buifalo, June 1969.Google Scholar
35. Schlegel, R. G. Helicopter Noise Generation. Sikorsky Aircraft, 1965.Google Scholar
36. Noak, M. Wake Measurements on Helicopter Rotors, University of Southampton. (Report to be prepared in 1971).Google Scholar
37. Spivey, W. A. and Morehouse, G. G. New insights into the design of swept-tip rotor blades. Proceedings: 26th Annual National Forum of American Helicopter Society. June 1970.Google Scholar
38. Leverton, J. W. Special Instrumentation Requirements. Westland Research Paper 370, November 1969.Google Scholar