Aircraft performance assessment based on nonlinear constraints imposed on complex flight simulation models

The paper describes the development and implementation of a MATLAB tool for executing performance calculations on the basis of complex high-fidelity simulation models featuring a high level of automation and a high computation speed. The tool is utilized for a large range of applications, including performance chart generation, automated checking of certification cri teria, parameter sensitivity studies or flight perf ormance optimizations. The basic concept is that the desire d system condition is expressed by a set of nonline ar constraints imposed on the nonlinear SIMULINK simulation model. The approach also accounts for differential algebraic systems, i.e. the case when the nonlinear simulation model is only available as implicit model and not explicitly solved for the state derivatives. The se t of nonlinear constraints is programmed in a templ ate with an embedded call to the simulation model. As the size of the nonlinear equation system could significantl y increase for complex simulation models when compared to a system only consisting of the rigid-body aircraft, it can be chosen between an integral, a nested or a staged ap proach to optimize the computational performance of the system based on the actual application case. The system also features a high numeric efficiency due to a large number of algorithmic optimizations, like a custom-tailored nonlinear equation solver or a high-level trim strategy for multi-point and grid trimming.