Wing mounted hydrogen fuel tanks: mitigating the aeroelastic penalties of dry wing configurations?

The aviation industry’s desire to mitigate its environmental impact has re-invigorated research into hydrogen-powered aircraft concepts. The transition to liquid hydrogen (LH2) fuel results in large, cryogenic fuel tanks that cannot be accommodated within the wingbox structure, leading to fuel-free or ‘dry’ wings. In traditional kerosene powered configurations fuel stored in the wings provides inertial relief, reducing the loads experienced during flight and, therefore, the required structural mass. Wing mounted fuel tanks could be used to regain this inertial relief, and this paper investigates the aerodynamic and structural implications of integrating wing-mounted hydrogen fuel tanks into medium-sized commercial aircraft with high aspect ratio wings. A multidisciplinary conceptual aircraft sizing methodology is used to explore the effect of different fuel tank configurations - where LH2 is stored within the fuselage, or in external wing-mounted tanks - on an aircraft’s geometry and performance metrics, such as fuel efficiency. The sizing of the wingbox structure includes the numerical simulation of manoeuvre, gust and turbulence loads using an aeroelastic model. The findings suggest that while wing-mounted tanks offer inertial relief, reducing wing mass by over 20%, the increased parasitic drag from the external fuel tanks outweighs the reduction in lift-induced drag. This conclusion was observed between aspect ratios of 8 and 20, suggesting that permanently attached wing-mounted fuel tanks are not viable for hydrogen-powered aircraft with high aspect ratio wings.