High Offset Flapping Pin Rotor Analysis

High Offset Flapping Pin Rotor Analysis The theory of rotor dynamics given in Ref. 1 is extended to include the effects of coupling between feathering and flapping 3 angle and flapping hinge offset. Both introduce considerable modification to the classic equations, and instead of simple explicit equations for flapping amplitudes, coning angle, collective pitch and inflow angles, five simultaneous equations have now to be solved. Data sheets have been constructed which enable this to be done quickly and accurately for any design of linearly tapered and twisted blade. It is suggested that the intelligent use of such data sheets is of great assistance in a design office, not only because of the very considerable time savings achieved, but also because they eliminate the most fruitful sources of error in numerical calculation. It is shown that a high offset rotor enables much higher speeds to be achieved with a conventional helicopteran effect which has already been fairly well publicized. A penalty is paid for this in the form of hub pitching moments which have to be balanced out externally either by the use of two rotors, offset C.G., aerodynamic surfaces, or inclination of the mechanical axis. These effects will be considered in detail in a further article. Finally, equations are developed for a convenient method of calculating blade elemental angle of attack which is claimed to be superior to classic methods for design office purposes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

High Offset Flapping Pin Rotor Analysis

Aircraft Engineering and Aerospace Technology, Volume 26 (11): 5 – Nov 1, 1954

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb032490
Publisher site
See Article on Publisher Site

Abstract

The theory of rotor dynamics given in Ref. 1 is extended to include the effects of coupling between feathering and flapping 3 angle and flapping hinge offset. Both introduce considerable modification to the classic equations, and instead of simple explicit equations for flapping amplitudes, coning angle, collective pitch and inflow angles, five simultaneous equations have now to be solved. Data sheets have been constructed which enable this to be done quickly and accurately for any design of linearly tapered and twisted blade. It is suggested that the intelligent use of such data sheets is of great assistance in a design office, not only because of the very considerable time savings achieved, but also because they eliminate the most fruitful sources of error in numerical calculation. It is shown that a high offset rotor enables much higher speeds to be achieved with a conventional helicopteran effect which has already been fairly well publicized. A penalty is paid for this in the form of hub pitching moments which have to be balanced out externally either by the use of two rotors, offset C.G., aerodynamic surfaces, or inclination of the mechanical axis. These effects will be considered in detail in a further article. Finally, equations are developed for a convenient method of calculating blade elemental angle of attack which is claimed to be superior to classic methods for design office purposes.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Nov 1, 1954

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