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It is possible for a constant span to obtain better aerodynamic performance from a wing with a nonplanar outboard wing form than from a wing with a planar outboard form, despite the added drag from the increased wetted area. Furthermore, the semispan rolling-moment characteristics indicate the lower wing-root bending moment for some nonplanar configurations. These conclusions are based on an experimental and computational investigation of the aerodynamic characteristics of planar and nonplanar outboard wing forms. Seven different configurations-planar rectangular, nonplanar rising arc, nonplanar drooping arc, planar sheared, sheared with dihedral, sheared with anhedral, and planar elliptical-were investigated for two different spans. Flowvisualization photographs indicate that there are three vortex systems associated with the sheared forms. The lower induced drag coefficients of nonplanar wings are believed to accrue from the movement of vorticity away from the center-of-span line, resulting, in some instances, in induced efficiencies higher than that of a planar elliptical wing. Flow surveys indicate that the effective span, as determined by the location of the tip vortex, might not be a sufficient yardstick of the induced performance of a nonplanar wing. Nomenclature& -aspect ratio, = b 2 /S b =span c = reference chord C D = drag coefficient, = drag/qs Ci = rolling-(or root-bending) moment coefficient, = moment/qSb C L = lift coefficient, = lift/qS C L a. = lift slope per degree C m = pitching-moment coefficient, = moment/gSc e = induced (or span) efficiency factor K = profile drag magnification factor q -freestream dynamic pressure RN = Reynolds number, wrt c S =planform area a = angle of attack Subscripts s = stall 0 = zero-lift condition

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