Subsonic flutter characteristics for seven swept and unswept wings have been calculated by the kernel-function method and by a modified strip method. Comparisons of the results from the approximate strip method, from the more rig¬orous lifting-surface method, and from flutter experiments indicated that all calculated flutter speeds were in good agreement with measured values with the exception of those given by the kernel-function method for two swept wings that had ballast weight distributed along leading or trailing edges. The latter results were unconservative over most of the subsonic range and, within the limits of this investigation, were not significantly improved by changes in the number or type of vibration modes (coupled or uncoupled) nor by increasing the number of downwash collocation points. No appreciable changes were encountered in kernel-function results when uncoupled (rather than coupled) vibration modes were employed for homogeneous wings whose natural modes involved a high degree of bending-torsion coupling.
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