Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-24T04:06:54.793Z Has data issue: false hasContentIssue false
  • English
  • Français

Counter-Rotating Propellers* †

Published online by Cambridge University Press:  28 July 2016

H. M. McCoy
H. M. McCoy*
Affiliation:
U.S. Army Air Corps, Wright Field, Dayton, Ohio
Get access Rights & Permissions [Opens in a new window]

Abstract

This paper is concerned mainly with that application of counter-rotating propellers referred to as “ dual-rotation ” propellers. This term is here defined to apply to a pair of oppositely-rotating propellers operating in close tandem, mounted on concentric shafts. Only the application to aeroplanes is discussed herein, for the application of these principles to helicopter design is considered another subject.

This paper presents a summary of the development and background of dual-rotation propellers and the benefits that can be derived from their use. Complete references are furnished for designers, no attempt being made to reproduce the somewhat involved theory and lengthy reference data.

A short history of the three applications of counter-rotating propellers is presented. The applications include multi-motored aeroplanes with oppositely-rotating propellers, aeroplanes with engines mounted in tandem (back to back) so that the propellers revolve in opposite directions, but primarily, aeroplanes with dual-rotation propeller installations.

Most present-day aeroplanes with maximum velocities of 350 m.p.h. and over have single-rotation propellers. At this velocity the single propeller is operating past the peak of its efficiency. The loss in efficiency increases rapidly with increasing forward velocity. Dual-rotation propellers offer an excellent means of maintaining peak propeller efficiencies up to aeroplane velocities of about 450 m.p.h. by absorbing the rotational energy losses in the propeller slipstream. At velocities above 450 m.p.h. up to the limiting velocity there will be only a small reduction from the peak in dual-rotation propeller efficiencies.

Sustained level flight aeroplane velocities appear to be limited to about 550 m.p.h. when propellers are used as the means of propulsion. The efficiency of a conventional single-rotation propeller will be so low, however, that this limiting velocity can be approached with such a propeller only at a prohibitive cost in engine horse-power. Any given velocity above 300 m.p.h. can be obtained with less horse-power if dual-rotation propellers are used to replace a single-rotation propeller with the same total number of blades. The percentage gain in performance will increase with increasing forward velocity when dual-rotation propellers are used.

It is possible that single-rotation propellers with more than four blades will never be commonly used. Instead, dual-rotation propellers with a total of four, six or perhaps even eight blades, will be used in the next decade on many high performance aeroplanes, especially those operating at high altitudes. The types of aeroplanes will include small single-seater racers and fighters and high performance, long range bombers and transports, particularly those with supercharged cabins.

The discussion brings forth the fact that there are few experimental data available in this country to allow a quantitative engineering evaluation to be made of the worth of dual-rotation propellers. Sufficient substantiated theory exists, however, to permit the general statements made above. An outline of the experimental tests that are required to check the theory is presented.

Following the discussion of tests made by the U.S. Air Corps on a pursuit type aeroplane equipped with a dual-rotation propeller system, comments are made on the relative advantages and disadvantages of dual and single-rotation propellers as they affect aeroplane design. Hub design problems associated with dual-rotation propellers are discussed.

Because of the increasing importance of dual-rotation propellers, additional pertinent references other than those used in this paper are presented in the Appendix.

Type
Research Article
Information
The Aeronautical Journal , Volume 44 , Issue 354 , June 1940 , pp. 481 - 498
Copyright
Copyright © Royal Aeronautical Society 1940

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

The views expressed in this report are those of the author and not necessarily those of the War Department.

†

Printed by courteous permission of the U.S. War Department, the author, and the Editorial Board of the Institute of Aeronautical Sciences.

References

1. Heinkel, Dr. Ernst, The Increase in Aeroplane Speed During the Last Few Years, The Aeroplane, pages 502–507, October 26, 1938.Google Scholar
2. Watts, H. C., Airscrew Development, R.Ae.S. Journal, Volume 40, pages 483–523, 1936.Google Scholar
3. Watts, H. C., The Design of Screw Propellers for Aircraft, Chapter 12, Longmans, Green and Co., London, 1920.Google Scholar
4. Weick, Fred E., Aircraft Propeller Design, Chapter 13, McGraw-Hill, New York, 1930.Google Scholar
5. Lanchester, F. W., Investigation of the Efficiency of Reverse Rotating Propellers in Tandem, A.C.A.R. and M. No. 540, May, 1918.Google Scholar
6. Star-Telegram, Fort Worth, Texas, June 29, 1931.Google Scholar
7. Rice, G. E., One Prop or Two, Western Flying, pages 20 and 22, March, 1938.Google Scholar
8. Dr.Vandone, , On Producing a Racing Aero-motor, The Aeroplane, pages 627–630, May 29, 1935.Google Scholar
9. Photographs, The Aeroplane, page 43, July 13, 1938.Google Scholar
10. Anonymous, Double Propeller Drive, Automotive Industries, page 279, September 15, 1939.Google Scholar
11. Lock, C. N. H., Problems of High Speed Flight as Affected by Compressibility, R.A.S. Journal, March, 1938.Google Scholar
12. Losch, F., Calculations of the Induced Efficiency of Heavily Loaded Propellers having Infinite Number of Blades; Kramer, K. N., The Induced Efficiency of Optimum Propellers having Finite Number of Blades; Bock, G., and Nikodemus, R., Prospects of Propeller Drive for High Flying Speeds, Luftfahrtforschung, Vol. 15, No. 7, July 6, 1938 (N.A.C.A. Technical Memorandum No. 884, January, 1939).Google Scholar
13. Biermann, D., and Hartman, E. P., Tests of Two Full-Scale Propellers with Definite Pitch Distributions at Blade Angles up to 60°, N.A.C.A. Technical Report No. 658, 1939.Google Scholar
14. Biermann, D., and Hartman, E. P., Tests of Five Full-Scale Propellers in the Presence of a Radial and a Liquid-Cooled Engine Nacelle, Including Tests of Two Spinners, N.A.C.A. Technical Report No. 642, 1938.Google Scholar
15. Eiffel, G., Tandem Propellers, L'Aerophile, November, 1919, (Translation “ Paris Office,” N.A.C.A., March, 1920.)Google Scholar
16. Durand, W. F., and Lesley, E. P., Experimental Research on Air Propellers, II, N.A.C.A, Technical Report No, 30, 1919.Google Scholar
17. Glauert, H., The Elements of Aerofoil and Airscrew Theory, Cambridge University Press, London, 1930.Google Scholar
18. Durand, W. F., Aerodynamic Theory, Vol. 4, pages 169–360, Julius Springer, Berlin, 1935.Google Scholar
19. Panetti, N., About the Output of Tandem Propellers, L'Aerotecnica, December, 1934 (Translation available, Wright Field Library).Google Scholar
20. Weinig, F., Propellers for High Speed Aeroplanes, pages 168–172, Luftfahrtforschung, April 20, 1937 (Wright Field Translation No. 320).Google Scholar
21. Lesley, E. P., Tandem Air Propellers, N.A.C.A. Technical Notes No. 689, February, 1939.Google Scholar
22. Lesley, E. P., Propeller Tests to Determine the Effect of Number of Blades and Two Typical Solidities, N.A.C.A. Technical Notes No. 698, April, 1939.Google Scholar
23. Lock, C. N. H., Bateman, H., and Nixon, H. L., Wind Tunnel Tests of High Pitch Airscrews (Part I), A.C.A.R. and M. No. 1,673, October, 1930.Google Scholar
24. Hartman, E. P., and Biermann, D., The Aerodynamic Characteristics of Full-Scale Propellers having 2, 3, and 4 Blades of Clark Y and R.A.F. 6 Aerofoil Sections, N.A.C.A. Technical Report No. 640, 1938.Google Scholar
25. McHugh, J. G., and Derring, E. H., The Effect of Nacelle-Propeller Diameter Ratio on Body Interference and on Propeller and Cooling Characteristics, N.A.C.A., Report No. 680, 1939.Google Scholar
26. Anonymous, Photograph and Description of the Fairey “ Contra ” Airscrew, Flight, pages 551 and 552, May 25, 1939.Google Scholar
27. Caldwell, F. W., Propellers for Aircraft Engines of High Power Output, Journal of the Aeronautical Sciences, Vol. 5, December, 1937.Google Scholar
28. Kearns, C. N., Vibration Characteristics of Aircraft Engine Propeller System, Paper presented at the World Automotive Engineering Congress, Soc. of Automotive Eng., New York City, May 25, 1939.Google Scholar