Rolls-Royce is redesigning its UltraFan jet engine to burn hydrogen instead of kerosene, aiming for a 2035 entry into service. The HEAVEN project will evolve the existing UltraFan architecture—already designed for high bypass ratio and scalability—into the UltraFan H2, targeting a 20% fuel burn reduction by combining hydrogen combustion, hybrid electric technology, and numerous efficiency innovations already at technology readiness level 3. This matters because small and medium-range aircraft produce roughly half of aviation’s current CO₂ emissions, and no drop-in battery or fuel-cell solution can match the power density of a gas turbine for these routes. Hydrogen offers net-zero carbon combustion, but existing engines cannot simply be retrofitted—they must be fundamentally re-engineered to handle hydrogen’s different flame speed, storage, and thermal properties. If successful, the UltraFan H2 could become the first commercially viable hydrogen-powered gas turbine for the SMR market, cutting aviation’s carbon footprint without sacrificing range or payload. The consortium includes easyJet, Europe’s largest operator of SMR aircraft, ensuring the design meets real-world operational demands. The project validates the architecture to TRL6, bridging the gap between laboratory concepts and flight-ready hardware.
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Climate-neutral aviation will require the use of alternative fuels such as Green Hydrogen and Sustainable Aviation Fuel (SAF) combined with the power density of an ultra-efficient gas turbine engine for the Small and Medium Range (SMR) market which corresponds to approximately 50% of the current share of air transport emissions. Rolls-Royce (represented within the HEAVEN project by RR-UK, RR-D and ITP) supported by key UK and European academia, industry and research centres are currently developing a new generation of very high bypass ratio geared engine architecture called UltraFan® which was started in 2014. From the beginning this ducted engine architecture has been designed to be scalable and meet the needs both of widebody and SMR markets. To achieve the necessary 20% fuel burn reduction Rolls-Royce proposes to significantly evolve the UltraFan design into UltraFan H2. The evolved engine architecture design will take the next steps in improving the efficiency of the gas turbine, take advantage of the properties of net zero carbon fuels such as Hydrogen to improve efficiency, combining this with Hybrid electric technology to reduce wasted energy. Numerous innovative enabling technologies already at TR3 will be incorporated into this new architecture to improve the gas turbine efficiency. Together with work proposed on Hydrogen in CAVENDISH (HRA-01) and Hybrid Electric in HE-ART (HER-01) Clean Aviation proposals in conjunction with activities in national and regional programmes, this will be synergistically combined to validate up to TRL6 the highly innovative UltraFan H2 design to support a 2035 EIS. HEAVEN brings together a highly specialised European industrial and academic consortium already strongly involved and familiar with the UltraFan programme. Additionally, the partner easyJet, European airline operator who have the largest fleet of European manufactured SMR aircraft operating in Europe will bring an in depth knowledge of operational requirements.
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