Optimal control-surface locations for flexible aircraft

The basic physical relationships involved in control of a flexible aircraft disturbed by random wind gusts are used in formulating the aerodynamic surface location problem as one in optimal control of a distributed system, using a limited number of point-force controllers. The three phases of this problem-estimation, control, and surface placement-are then solved by means of the matrix minimum principle and the calculus of variations. The variational equations are greatly simplified and the order of the problem considerably reduced by the use of optimal controllers at each stage in the search for optimal surface locations. A computer program has been written which uses these equations in solving the surface location problem for winged aircraft. Results of a trial study based on a fourteenth-order model of the Lockheed C-5A transport aircraft are reported.