NACA-TN-1361

Abstract

INTRODUCTION <br>The elementary theories of bending and torsion are often not sufficiently accurate for determining the stresses in airplane wings. The bending stresses are modified by shear lag and the torsion stresses, by the so-called bending stresses due to torsion. While an appreciable amount of literature exists on these subjects, little attention has been given to the resulting effects on the bending or torsional deflections. This relative lack of attention was not accidental. The deviations of the stresses from those predicted by the elementary theories are local, and local disturbances are leveled off by the integration processes necessary to calculate deflections. The deviations of the deflections from those predicted by the elementary theories are therefore much smaller than the stress deviations, and this fact, together with the fact that deflections were only of subordinate interest in the past, accounts for the small amount of attention given to deflection calculations. However, the rapidly increasing importance of deflection calculations makes it desirable to give some discussion of the problems .