A discrete potential element approach to nonsteady subsonic lifting surface theory
Breckon, Richard Louis
Schmidt, L. V.
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A discrete potential element approach to subsonic numerical lifting surface theory has been developed and shown to be practical in predicting the non-steady loading on harmonically oscillating, medium to low aspect ratio wings. A unique method of including the wake effect in the wing kernel function matrix prior to the solution of the singular internal downwash equation was devised, thus greatly simplifying the velocity potential formulation. In addition, termination of the effective wake a finite distance downstream of the wing was investigated, with wing loading found to converge to within one per cent in an effective wake length of four root chords. This discrete element method has also been extended to the case of an oscillating wing, cantilevered from a cylindrical fuselage, to investigate non-planar interference effects. This interference is wing loading, while of relatively small magnitude, does exist in both pressure amplitude and phase angle distributions, and is, therefore, of importance in three-dimensional stability analysis of wing/body configurations.
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