The Elementary Theory of Aero‐Elasticity: A Series of Articles Written from the Standpoint of a Structural Engineer for Students and Junior Members of Aircraft Design Teams

WE concluded Part II of this series with the remark that a different outlook is needed for problems of control surface flutter than for those of wing flutter. There are two reasons for this. Wing flutter must be investigated carefully early on in the design of an aircraft so as to provide a safe aircraft without a severe weight penalty, whereas the weight penalty of avoiding control surface flutter is usually small, although not negligible, and modifications can often be made at short notice, so it is important to make a full investigation as late as possible before flight when all the data are available in a reliable form. The second reason is that with wing flutter, as with aileron reversal and divergence, it is usual to think of safety margins in terms of forward speed or possibly wing torsional stiffness; with control surface flutter, on the other hand, quite different types of safety factor become the rule.