Selection Criteria for a Fuel-Cell-Based Propulsion Architecture of a Regional Box-Wing Aircraft

To reduce the impact of aviation on the environment, a multitude of concepts must be evaluated to enable subsequent targeted developments. The reduction of on-board energy requirements through the aero-propulsive coupling of a box-wing configuration can represent one possible approach. It enables a decreased environmental impact by cutting the energy required and—in the configuration under consideration—by using hydrogen fuel cells as power generators. To fully exploit the advantages of such a concept, different propulsion system architectures were analyzed. Decision criteria were developed to select the most sensible powertrain architecture for the box-wing regional aircraft considering component and aircraft-level effects in a two-phased approach; following a qualitative preselection, a multi-criteria decision analysis was employed. Fuselage, fairing and nacelle-bound architecture options for the 70-passenger aircraft with a projection of its powertrain characteristics into the year 2045 are shown and compared. The placement of propulsion system components as well as their characteristics play a major role in the downselection of propulsion architecture options, especially considering the requirements placed by the liquid hydrogen energy storage. Due to low aerodynamic interference with the specific aero-propulsive arrangement, its high safety characteristics, synergistic potential with other systems, and not least, ease of integration, a compact propulsion system placement forward of the front hydrogen tank is considered most beneficial on aircraft level.