A methodology for the aeroelastic analysis of bearingless main rotor helicopters in forward flight is presented. The large elastic twist experienced by the flexbeam during pitch control application can influence the nonlinear aeroelastic behaviour. Including its effects by eliminating the rigid pitch control rotation, Theta, and using an angle, Phi, to represent the spanwise distribution of cross-sectional torsional orientation would preclude the use of normal mode equations in the evaluation of blade periodic response in forward flight. In the present analysis, the elastic deformations due to pitch control are independently evaluated as the in vacuo structural response to a prescribed swashplate motion. Modified nonlinear equations of motion that include the effct of flexbeam elastic deformations due to pitch control, are used in the aeroelastic analysis. The present anlysis is robust and has good convergence behaviour in the evaluation of blade periodic response. Good correlation with experimental lag damping data is obtained for two different bearingless rotor configurations. Different types of pitch-flap coupling due to leading edge or trailing edge pitch links in a snubberless configuration are seen to have a strong effect on torsional response. The forward flight shaft-fixed and shaft-free stability characteristics are examined for the two pitch link configurations.


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    Title :

    An aeroelastic analysis methodology for bearingless main rotor helicopters


    Additional title:

    Eine aeroelastische Berechnungsmethode für Hubschrauber mit lagerlosen Hauptrotoren


    Contributors:
    Gandhi, F. (author) / Chopra, I. (author)

    Published in:

    Publication date :

    1998


    Size :

    10 Seiten, 11 Bilder, 1 Tabelle, 13 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English