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Aeroelastic stability of coupled flap-lag motion of hingeless helicopter blades at arbitrary advance ratiosEquations for large amplitude coupled flap-lag motion of a hingeless elastic helicopter blade in forward flight are derived. Only a torsionally rigid blade excited by quasi-steady aerodynamic loads is considered. The effects of reversed flow together with some new terms due to radial flow are included. Using Galerkin's method the spatial dependence is eliminated and the equations are linearized about a suitable equilibrium position. The resulting system of homogeneous periodic equations is solved using multivariable Floquet-Liapunov theory, and the transition matrix at the end of the period is evaluated by two separate methods. Computational efficiency of the two numerical methods is compared. Results illustrating the effects of forward flight and various important blade parameters on the stability boundaries are presented.
Document ID
19740017436
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Friedmann, P. (California Univ. Los Angeles, CA, United States)
Silverthorn, L. J. (California Univ. Los Angeles, CA, United States)
Date Acquired
September 3, 2013
Publication Date
February 1, 1974
Subject Category
Aircraft
Report/Patent Number
UCLA-ENG-7406
NASA-CR-132431
Accession Number
74N25549
Funding Number(s)
CONTRACT_GRANT: NGR-05-007-414
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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