This paper shows how simulation-based optimization can be used to investigate the impact of technologydevelopment on the feasibility and performance of electric aircraft. This work investigates the design of anelectric/hydrogen-powered commuter aircraft (certified according to CS/FAR23) based on a dynamic missionsimulation including a 6DOF flight dynamics aircraft model. The electric/hydrogen hybrid propulsion system isbeing optimized to realize a design missions of 500km and 1000km, respectively, based on present technologylevels with a scenario with technology improvement of batteries and fuel cells. By the optimization-basedsizing of the propulsion train components, automated morphological and topological changes on the propulsionsystem are realized. The results cover a spectrum from pure electric to pure hydrogen fuel cell aircraft includingall possible hybrid solutions in between. In this way, simulation-based optimization is demonstrated also for itsuse for concept selection and system architecture optimization.