THE stiffness of an aeroplane wing is usually considered in terms of its torsional and llexural stiffnesses as measured at the “mid‐aileron” and “equivalent tip” sections(1), (2). It appears at present that the stiffness in torsion is more significant than that in flexure, partly because high torsional stiffness is necessary to prevent not only flutter but also reversal of aileron control and divergence(1), (2), both of which are independent of llexural stiff‐ness ; and partly because it is found in practice that when a wing is designed to meet minimum existing strength requirements alone, its torsional stiffness may be inadequate whereas its llexural stiffness is commonly sufficient. The more important of the two torsional stiff‐nesses (“mid‐aileron” and “equivalent‐tip”) is that at the “mid‐aileron” section. The present paper examines the effect of the various parameters on the torsional stiffness of a tapered rectangular tube of proportions representative of an aeroplane wing under a con‐centrated torque applied at a section equivalent to the average “mid‐aileron” section. The analysis of the problem is based on the stress distribution in an axially constrained tapered tube given by Williams in R. & M. 1761(3), and the stiffness obtained is compared with that for a tube with the simple shear stress distribution of the Bredt‐Batho type for a tube with free ends. The similar problem for a uniform tube has already been solved from the equations of reference (3) in R. & M. 1790(4).
Hanson, J. (1939), "Torsion of Tapered Tubes: Effect of Various Parameters on the Stiffness of Axially Constrained and Free Ended Tapered Rectangular Tubes", Aircraft Engineering and Aerospace Technology, Vol. 11 No. 4, pp. 145-160. https://doi.org/10.1108/eb030466
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