Contrail-Aware Aircraft Design Optimization: A Comparative Study of Kerosene and LH2 Aircraft

Aviation is one of the most rapidly growing contributors to anthropogenic climate change, driven not only by carbon emissions but also by non-carbon effects such as contrail-induced cirrus clouds. Traditional aircraft design optimization frameworks primarily minimise fuel consumption or direct operating costs, typically neglecting the coupled effects of aerodynamic configuration, local meteorology, and resulting contrail formation. Consequently, aircraft that are ”fuel-optimal” may not be ”climate-optimal.” Aircraft parameters and atmospheric conditions influence both overall performance and the altitude-specific conditions under which contrails form. To explore these trade-offs, a comprehensive contrail-aware aircraft design and optimization framework is developed by integrating an in-house clean-sheet aircraft sizing methodology with the Stanford University Aerospace Vehicle Environment (SUAVE) and the PyContrails–CoCiP framework. The integrated framework enables simultaneous aircraft sizing, mission analysis, aerodynamic and propulsion performance assessment, direct operating cost (DOC) estimation, and evaluation of both CO2 and non-CO2 climate impacts, including contrail-induced energy forcing (EF). Two case studies based on a kerosene-fueled aircraft and a liquid hydrogen (LH2)-powered aircraft are performed to systematically quantify the differences between the two propulsion technologies under identical mission and atmospheric conditions. The results show that the LH2-powered aircraft consistently produces substantially lower contrail climate impact compared to the kerosene configuration despite higher water vapour emissions. For the minimum-EF optimized configurations, the hydrogen aircraft achieves approximately 44% lower EF compared to thecorresponding kerosene aircraft. However, this reduction is accompanied by increased aircraft weight and direct operating cost, highlighting a clear trade-off between climate-optimal and economically-optimal aircraft designs.