Zero-Carbon Emission Aircraft Concepts Three concepts sit in the regional, narrowbody and midsize market segments and show that hydrogen aircraft can be competitive on a mission energy basis with a sustainable aviation fuel (SAF) powered aircraft using consistent 2030 technology. The FlyZero studies showed that hydrogen aircraft have the potential to address 100% of short-haul and 93% of existing scheduled long-haul flights. The midsize concept could provide global connectivity with two flights and one stop. The aircraft level design trades when using hydrogen fuel have been demonstrated to be fundamentally different to a kerosene aircraft, primarily due to the high specific energy of hydrogen, meaning much less hydrogen by weight is required in comparison with kerosene. This may drive different technology priorities. Hydrogen aircraft will require more integration than kerosene aircraft between the propulsion system and the airframe as the fuel phase change from liquid to gas and associated energy management are novel challenges for commercial aircraft design. Significant technical, safety and operational challenges remain which must be characterised and solved before a hydrogen powered aircraft could achieve certification and enter commercial service, but the FlyZero analysis has shown sufficient promise that further hydrogen technology research should be pursued. Considerable uncertainty exists around certification standards and some sustainability aspects such as contrails; further work to understand these areas should be undertaken in parallel. The design of hydrogen aircraft is inherently more integrated than for kerosene or SAF and this reinforces the need for the ATI strategic objective to maintain and develop independent whole aircraft analysis capability within the UK. The FlyZero concepts will continue to be updated by the ATI as hydrogen knowledge and technologies develop. The concepts are a critical part of the overall understanding as they are required input data for climate models to predict the overall environmental impact of a switch to hydrogen aviation.  Hydrogen Aviation   Â
