This paper presents an approach for the simulation and evaluation of flight & mission performance of an electric powered aircraft in context of the project ELAPSED. The project is concerned with the development of a new electric powertrain for a CS23 aircraft with the focus on a novel motor and smart battery concept. In the development process a digitally linked real-time simulation of the airplane equipped with the developed powertrain is used for early validation of system requirements. Therefore, a detailed nonlinear simulation model of the aircraft and its systems (e.g., aerodynamics, motor, battery system) has been created and is under constant refinement during development. In addition to pilot-in-the-loop simulations, this model is used for estimating the flight envelope and mission performance. For flight envelope estimation, the model gets trimmed and linearized. This is done for several flight conditions and configurations. The resulting matrix of linear systems and aerodynamic derivatives can be read depending on the actual state and configuration to obtain a more realistic simulation. Sequential trimming and linearizing are inefficient. A parallelization for different flight states and configurations saves an enormous amount of time. Out of the trimpoints the flight envelope for a certain flight condition and configuration of the aircraft can be assembled. Further, mission performance evaluation is carried out via the composition of trimpoints to a defined mission.