Effect of Crashworthiness on the Design of Hydrogen Aircraft

Hydrogen aircraft are strong candidates in the fight to reduce climate emissions in aviation. The main challenge in designing hydrogen aircraft lies in the storage of hydrogen, which requires four times more volume compared to kerosene alternatives. Furthermore, to ensure crashworthiness, it is desirable to prevent damage to the hydrogen tank during a crash landing by reducing its diameter via the crashed diameter coefficient. This requires a longer tank, which snowballs into larger, less efficient aircraft. The objective of this research is to quantify the effect of the crashed diameter coefficient on aircraft performance. This has been done by modifying a hydrogen aircraft design framework to include crashworthiness and performing multidisciplinary design optimizations that minimize mission energy. Additionally, a number of design variables were varied to study how different design parameters affect the tendencies, such as changing the span limit, seats abreast or the payload-range requirement. It was found that accounting for the crashed diameter coefficient can increase the fuselage length and maximum take-off mass by 17% and 6%, respectively, for a medium range aircraft like the Airbus A320. Alternatively, if the length of the fuselage is kept fixed, a 20% reduction in payload or a 60% reduction in range would be required. Overall, it has been found that crashworthiness needs to be considered in the preliminary stage of hydrogen aircraft design.