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National Advisory Committee for Aeronautics, Technical Notes - A Method for Calculating the Subsonic Steady State Loading on an Airplane with a Wing of Arbitrary Plan Form and Stiffness

The inclusion of the effects of flexibility in the solution of the
spanwise airload distribution applied to a wing of arbitrary plan form
and stiffness distribution has increased the complexity of analysis over
that for a rigid wing. The methods that are available at the present
time are generally concerned with the calculation of loading on an iso—
lated flexible wing rather than the more practical case not only where
the effects of fuselage and nacelles on the spanwise loading must be
taken into account but also where the total lift on each of the major
components must be considered simultaneously in order to determine the
wing loading at a specified load factor. A method for including such
effects without recourse to iterative procedures for steady—state flight
conditions and subcritical mach numbers is presented in this paper. The
equations are derived so that the spanwise airload distribution can be
expressed in matrix form in terms of influence coefficients for aero—
dynamic induction and structural deflection in a manner similar to that
employed in reference 1.

The basic method is outlined in the body of the paper. Included
in appendixes are details of the various derivations, the expansion of
the basic equations to include fuselage interference and store load
effects, the modifications for tailéboom.and tailless configurations,
a method for determining divergence dynamic pressures for swept wings
with large external stores, a method for reducing wind-tunnel data to
obtain effective aerodynamic coefficients which are free of model flexi—
bility effects, and a method for Obtaining compressibility corrections.