Control Wing Research Articles

Control Surface and Wing Stability Problems

SummaryThis paper seeks to draw from current research work on flutter and related problems results of general design significance; and, avoiding mathematics, endeavours to set these results out in relation to past and present problems.A preliminary section of the paper indicates the main stability and allied troubles concerned and draws attention to the general similarity between wings and tailplanes in relation to these troubles. The remainder of the paper is then devoted to a discussion of the problems involved in terms of wings and ailerons.For this purpose a “ stiffness diagram ” is constructed for a typical wing, indicating the relative stiffnesses, etc., required to prevent wing-aileron flutter, wing flutter, aileron reversal, and wing divergence. By means of this diagram the course of recent history in relation to wing-aileron flutter and aileron reversal is illustrated, and attention is then given to present and future tendencies and problems. The current tendency to employ wings of high density—arisingly largely from high wing loadings—is making wing flutter the problem of immediate importance, and ways of avoiding the provision of increased stiffness as usually adopted to prevent this trouble, as well as to prevent aileron reversal and wing divergence, are discussed.Appendices are given commenting on the variation of wing flutter speed with altitude and on the modern tendency to usa wings of low flexural stiffness.