A finite-state wake model is used to investigate aeromechanical stability of hingeless-rotor helicopters in the ground-contact, hover and trimmed-flight conditions. The investigation covers three items: (1) the convergence of the damping with increasing number of wake harmonics for the lag regressing, and body pitch and roll modes; (2) a parametric study of the damping over a range of thrust level, advance ratio and number of blades; and (3) correlations, primarily with the damping and frequency measurements of these lag and body modes. The convergence and parametric studies are conducted in the hover and trimmed-flight conditions; they include predictions from the widely used dynamic inflow model. The correlations are conducted in the ground-contact conditions and include predictions from the dynamic inflow and vortex models; recently, this vortex model is proposed for the axial-flight conditions and is used to investigate the coupled free vibrations of rotor flapping and body modes. The convergence and parametric studies show that a finite-state wake model that goes well beyond the dynamic inflow model is required for fairly converged damping. Moreover, the correlations from the finite-state wake, dynamic inflow and vortex models are generally satisfactory.$


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    Title :

    Hingeless-rotor aeromechanical stability in axial and forward flight with wake dynamics


    Additional title:

    Modellierung der aeromechanischen Stabilität gelenkloser Hubschrauberrotoren unter Berücksichtigung der Dynamik der Nachlaufströmung


    Contributors:

    Published in:

    Publication date :

    1999


    Size :

    12 Seiten, 19 Bilder, 21 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English