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The Flutter of a Helicopter Rotor Blade in Forward Flight

Published online by Cambridge University Press:  07 June 2016

C. W. Stammers
C. W. Stammers*
Affiliation:
Westland Helicopters Ltd, Yeovil*
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Summary

The nature of flapping torsion flutter of a helicopter blade in forward flight is discussed. The essential complication in the analysis is the presence of periodic coefficients in the equations of motion; approximate solutions are obtained by use of a perturbation procedure. An unusual behaviour of the flutter equations which occurs when the fundamental frequency of flutter is a half-integer multiple of rotational speed is studied. Two different instability mechanisms can be distinguished and are related to the two energy sources in the system, namely the rotation of the rotor and the forward speed of the helicopter. It is found that forward flight can have a significant stabilising influence on flutter and that, as the tip speed ratio increases, flutter occurs predominantly at half-integer frequencies. The results are confirmed by the use of a numerical method.

Type
Research Article
Information
Aeronautical Quarterly , Volume 21 , Issue 1 , February 1970 , pp. 18 - 48
Copyright
Copyright © Royal Aeronautical Society. 1970

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References

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