Global aviation as part of the megatrend “Mobility” has recovered from the the Covid-19 crisis much faster than expected three years ago. This creates significant pressure on all measures to realize the challenging targets on environmental protection of at least an 80% reduction in greenhouse gas emissions as set by the IPCC ot the climate neutrality goal defined by the EC, both for 2050. While other sectors, e.g. individual ground transportation do have options for reducing their carbon footprint e.g. through electrification, the very high power demands and energy densities in aviation do not allow for a direct transfer of such technologies. Even worse, fuel or energy carrier options do have opposing trends in important technical and ecological parameters. These aspects lead to two basic principles: I) Future aircraft have to be as energy efficient as possible since either the amount of energy to be stored on-board of a sustainable aircraft is limited or the costs per kWh of a sustainable fuel are significantly driving the tickets costs. II) Integration of novel energy carriers and propulsion system does always require a full developed overall aircraft design (OAD) process which most probably will lead to different configurations being each an optimal answer to their combination of operating mission and propulsion system. Multi-level overall aircraft design methods an simulations ranging from surrogate models up the full numerical fluid dynamics embedded into a design and optimisation loop allow to assess different technologies. The paper shows how different technologie integredients lead to different design solutions. On top, the contribution of individual technologies to ecological and economic key performance indicators will be analyzed.