Stringent sustainability goals are set for the next generation of aircraft. A promising novel airframe concept is the ultra-high aspect ratio Strut-Braced Wing (SBW) aircraft. Hydrogen-based concepts are active contenders for sustainable propulsion. The study compares a medium-range Liquid Hydrogen (LH2) to a kerosene-based SBW aircraft designed with the same top-level requirements. For both concepts, overall design, operating costs, and emissions are evaluated using the tool SUAVE. Furthermore, aerostructural optimizations are performed for the wing mass of SBW aircraft with and without wing-based fuel tanks. Results show that the main difference in the design point definition results from a higher zero-lift drag due to an extended fuselage housing the LH2 tanks, with a small reduction in the required wing loading. Structural mass increases of the LH2 aircraft due to additional tanks and fuselage structure are mostly offset by fuel mass savings. While the fuel mass accounts for nearly 25% of the kerosene design’s Maximum Take-Off Mass (MTOM), this reduces to 10% for the LH2 design. The LH2 aircraft has 16% higher operating costs with emission levels reduced to 57–82% of the kerosene aircraft, depending on the LH2 production method. For static loads, the absence of fuel acting as bending moment relief in the wing results in an increase in wing structural mass. However, the inclusion of roll rate requirements causes large wing mass increases for both concepts, significantly outweighing dry wing penalties.

Strict sustainability objectives have been established for the upcoming generation of aircraft. A promising innovative airframe concept is the ultra-high-aspect-ratio Strut-Braced-Wing Aircraft (SBWA). Hydrogen-powered concepts are strong candidates for sustainable propulsion. The study investigates the influence of Liquid Hydrogen (LH2) propulsion on the optimal wing geometry of medium-range SBWA for minimum-cost and minimum-emission objectives. Multiobjective optimizations are performed in two optimization frameworks of differing fidelity for both kerosene- and LH2-propelled SBWA concepts. Furthermore, a range of Pareto-optimal designs show the changes in the optimized planform for variable weighting of the two objectives. The results show that the differences in the optimal wing geometry between the kerosene- and LH2-powered results for each respective objective function are small. For both aircraft, the minimum-emission objective optimizes for lower fuel burns and hence lower emissions, albeit at an increase in wing structural mass. The minimum-cost objective balances the reductions in structural and fuel masses, resulting in a lighter design at lower aspect ratios. Other wing-shape parameters only have minor contributions. Although the wing aspect ratios for both objectives differ by ca. 50%, the actual changes are only 2.5% in fuel and 1.5% in Direct Operating Cost (DOC). Due to a larger set of design variables used in the higher-fidelity optimizations, further parasite and wave drag reduction opportunities result in increased optimal aspect ratios.

Research on electric aviation energy networks tends to focus on either detailed studies of individual subsystems, or full-aircraft analyses that use highly simplified network (component) models. This paper aims to bridge that gap by performing sensitivity studies for various network parameters (HVDC cables, power converters, and motors), evaluating their effect on both the system and aircraft level. This is achieved through a combination of higher-fidelity explicit modeling of the network components and conceptual aircraft design software. This analysis is applied to a parallel-electric regional jet and a fully-electric commuter aircraft. The effects of parameter variations within literature-supported ranges are evaluated on component, network and aircraft mass for a given mission profile. Results show that the most influential parameters are the level of DC voltage in power transmission, the cable material, and the achievable mission-average efficiency of the electric motor. Individual component mass variations of over 100% can be observed within the investigated ranges; with variations of up to 10% of the aircraft mass for the parallel-electric jet. Aircraft mass variations for the fully-electric aircraft are up to 5%, with the required battery size due to component efficiency changes as driving factor. Results show that for large aircraft, the network is highly sensitive to power requirements. For small aircraft the network is more sensitive to mission energy requirements.