Parametric investigation has been performed including unsteady effects. In a first method, variation in mass properties and flight conditions are investigated. Trajectory simulations are conducted including unsteady effects and surrogate models are constructed based on their results. In a second method, intermediate data such as unsteady grid loads are formulated based on the results of lower fidelity analyses. In both cases, parametric studies are performed establishing relationships between store parameters and the occurrence of trajectory variations.