Tailplane sizing for LH2 aircraft families

Abstract

Liquid hydrogen (LH2) aircraft concepts with rear-fuselage tanks often necessitate a larger horizontal tailplane (HTP) due to the increased centre of gravity longitudinal travel. However, most studies focus on point designs of individual aircraft. In contrast, conventional kerosene aircraft are typically developed as families that share a common empennage across multiple variants. Whether such empennage commonality is feasible for LH2 families remains largely unexplored. This paper therefore investigates the performance trade-offs associated. A preliminary design methodology is developed to size an aircraft, influencing the design of its tailplane, based on the definition of two potential shorter family variants. All aircraft are sized simultaneously, resulting in a family with a common empennage. When maintaining fuel capacity across a kerosene aircraft family, the smallest member serves as the design driver for tailplane dimensions, as its shorter fuselage results in a reduced tailplane lever arm. For LH2 families using the same strategy, the results revealed that the fuel penalty due to tailplane commonality is halved when compared to an analogous kerosene family. The effect of the shorter lever arm on the HTP area in the case of the smallest variant is compensated by a reduced centre of gravity longitudinal range resulting from the placement of the tanks. However, family design strategies that do not assume tank commonality, now present significant design challenges.