Performance sensitivity of subsonic liquid hydrogen long-range tube-wing aircraft to technology developments

Liquid hydrogen (LH2) may enable the decarbonisation of long-haul aviation. However, its low volumetric energy density and subsequent tank space and weight requirements could penalise an aircraft's specific energy consumption (SEC, MJ/tonne-km). We evaluate the impacts of developments in four technology areas - aerodynamics, structures, cryo-tank gravimetric index (eta), and overall efficiency (eta(o)) - on the design-point performance of a large subsonic tube-wing LH2 aircraft. We characterise the critical value of eta, which must be exceeded to enable a given design range. For a design range of 14,000 km, eta must exceed 0.52 today but only 0.35 with expected 2030 airframe and engine efficiency improvements. Using the most optimistic technology development estimates we observe that SEC could reduce by similar to 25% via improvements in eta(o) and aerodynamics and by 33% via improvements in all four areas. Developments in technologies to improve eta(o) and reduce drag are critical to enabling zero-carbon long-haul air travel.(c) 2023 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.