H2FLY Team Complete World’s First Piloted Flight of Liquid Hydrogen Powered Electric Aircraft
H2FLY, the German-based developer of hydrogen-electric powertrain systems for aircraft, announced this week it has successfully completed the world’s first piloted flight of an electric aircraft powered by liquid hydrogen, reports a press release. The hydrogen-electric ‘HY4’ demonstrator aircraft took off from Maribor, Slovenia, and saw safe and efficient operation throughout multiple flight tests. The H2FLY team from Stuttgart completed four separate flights as part of its test campaign, including one that lasted for over three hours.
“Results of the test flights,” explains the release, “indicate that using liquid hydrogen in place of gaseous hydrogen will double the maximum range of the HY4 aircraft from 750 km to 1,500 km, marking a critical step towards the delivery of emissions-free, medium and long-haul commercial flights.”

Professor Josef Kallo
Professor Josef Kallo, co-Founder of H2FLY, commented, “This achievement marks a watershed moment in the use of hydrogen to power aircraft. Together with our partners, we have demonstrated the viability of liquid hydrogen to support medium and long-range emissions-free flight.”
He continued, “We are now looking ahead to scaling up our technology for regional aircraft and other applications, beginning the critical mission of decarbonising commercial aviation.”
The release continues, “The successful campaign marks a significant milestone for H2FLY and reflects the extensive insights gained from the company’s research efforts. Moreover, it is the culmination of Project HEAVEN, a European-government-supported consortium assembled to demonstrate the feasibility of using liquid, cryogenic hydrogen in aircraft. The consortium is led by H2FLY and includes the partners Air Liquide, Pipistrel Vertical Solutions, the German Aerospace Center (DLR), EKPO Fuel Cell Technologies, and Fundación Ayesa.”
Beside project HEAVEN, the work has been funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK), the German Federal Ministry for Digital and Transport (BMVD) and The University of Ulm.
Compared with pressurised gaseous hydrogen storage (GH2), the use of liquified, cryogenic hydrogen (LH2) enables significantly lower tank weights and volume, therefore leading to increased aircraft range and useful payload.
Pierre Crespi, Innovation Director at Air Liquide Advanced Technologies remarked, “Air Liquide is proud to have designed, manufactured and integrated, together with H2FLY, the liquid hydrogen tank that enabled to power the HY4 aircraft. Today’s success demonstrates the full potential of liquid hydrogen for aviation. This hydrogen can be stored onboard and transported. Hydrogen is key to the energy transition and this new step proves that it’s already becoming a reality.”

Dr. Syed Asif Ansar, Head of Department Energy System Integration at the German Aerospace Center (DLR), added, “DLR boasts extensive expertise in electrified aircrafts, with a track record spanning over 15 years. Starting from the inaugural flight of the Antares DLR-H2 in 2009, consistent advancements have been made in fuel cells and their auxiliary systems.”
He continued, “This progressive journey culminates in a significant present achievement in aviation history: the utilization of cryogenic liquified hydrogen as fuel storage for a four-seater aircraft powered by fuel cells. Collaborating with H2FLY, AirLiquide and other project members, DLR is actively engaged in projects aimed at propelling the development of CS-23 and CS-25 fuel cell powered aircraft into the next phase.”
With the completion of the flight testing in project HEAVEN, H2FLY will focus on a path to commercialisation. In June, H2FLY announced the development of its new H2F-175 fuel cell systems which will be capable of providing their full power range in flight altitudes of up to 27,000 ft, marking an important step on the path from lower altitude viability flight demonstrations to real-world commercial aircraft applications.
Next year, H2FLY aims to open its Hydrogen Aviation Center at Stuttgart Airport, co-funded by the Ministry of Transport Baden Württemberg. The Center will become a focal point for the future of Europe’s aviation industry and its hydrogen economy, providing fuel cell aircraft integration facilities and liquid hydrogen infrastructure.
H2FLY was acquired in 2021 by Joby Aviation. It is viewed that in just a few years, hydrogen-electric aircraft could be transporting up to 40 passengers over distances of close to 1,240 miles.
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(Images: H2FLY)