INTEGRATED SIMULATION MODEL FOR PRELIMINARY AERODYNAMIC, STRUCTURAL, AND CONTROL-LAW DESIGN OF AIRCRAFT

An integrated model is developed for aerodynamic, structural, and control simulation of flexible aircraft in extreme flight situations. The structure consists of joined nonlinear beams allowing arbitrarily large deformations. The aerodynamic model is a compressible vortex/source-lattice with wind-aligned trailing vorticity. Full unsteady terms with flight dynamics are included. Model forcing is via gusts or control inputs. The overall nonlinear equation set is solved by a full Newton method. The Newton Jacobian matrix is also used for frequency-domain computations to investigate flight stability, control-response behavior, and flutter. Nonlinear performance of control laws can be examined. The numerical problem is small enough for interactive computation, allowing rapid diagnosis of local aerodynamic stall, structural failure, or control system saturation for a wide range of flight conditions. The overall approach allows quick generation of a robust multi-disciplinary preliminary design which can serve as a good basis for subsequent detailed design.