Subsonic Wing Planform Design Using Multidisciplinary Optimization

This article presents basic results from wing planform optimization for minimum drag with constraints on structural weight and maximum lift. Analyses in each of these disciplines are developed and integrated to yield successful optimization of wing planform shape. Results demonstrate the importance of weight constraints, compressibility drag, maximum lift, and static aeroelasticity on wing shape, and the necessity of modeling these effects to achieve realistic optimized planforms. Nomenclature A, = rib boom cross-sectional area A c = area enclosed by structural box cross section A,(. = rib web cross-sectional area b = span b, = stringer spacing C, = wing lift coefficient C,-,>,,,, C = chord c,, = wing box chord Cd = section drag coefficient CI = section lift coefficient CI,,,.,, E = Young's modulus G = shear modulus I = section bending inertia Ire ( = dimensionless skin bending inertia J = section torsional inertia K, = local buckling coefficient L = rib spacing it P PO = surface pressure 9 = dynamic pressure S = wing area S = line integral coordinate T,,, = ratio of smeared and actual skin thickness t = wing thickness 1, = skin thickness x, y, 2 = coordinate directions, nominally along = wing maximum lift coefficient = maximum allowable section lift coefficient = local panel unit normal vector = bending end load = bending stress times smeared skin thickness freestream, pointing to aircraft right and pointing up, respectively stress zcr = dimensionless height location of critical stringer & = jig twist 77 = coordinate direction parallel to elastic axis of A = sweep A,, V = Poisson's ratio wing = sweep of the elastic axi