H2FLY passes first integrated liquid hydrogen tank filling tests

H2FLY, the Stuttgart-based developer of hydrogen fuel cell systems for aircraft, has successfully passed liquid hydrogen on-ground filling tests with the newly developed liquid hydrogen tank which is integrated into its HY4 aircraft.

The efforts are part of the European project HEAVEN, a consortium of five partners to demonstrate the feasibility of using liquid, cryogenic hydrogen-powered fuel cell powertrain in aircraft, led by H2FLY. H2FLY has successfully passed the filling tests of the new liquid hydrogen storage system which is designed and supplied by its project partner Air Liquide based on H2FLY’s requirements. The filling procedure took place in preparation for the forthcoming coupling tests in which the liquid hydrogen storage system will be coupled with the fuel cell system to form a complete hydrogen-electric powertrain. H2FLY led the test campaign on Air Liquide’s Campus Technologies Grenoble, in Sassenage, France together with Air Liquide.

This filling milestone follows the company’s announcement in November 2022 that it had started the mechanical integration of Air Liquide’s liquid hydrogen tank into H2FLY’s fuel cell-powered aircraft HY4 after the tank passed the vibration and LH2 leakage tests in September 2022.

Prof. Dr. Josef Kallo, co-founder and CEO of H2FLY says “The successful on-ground filling tests today, mark the next milestone in our pursuit to doubling the range of our HY4 aircraft. It is a critical step for our upcoming flight test campaign this summer, which will demonstrate the feasibility of liquid hydrogen as a fuel for medium and long-haul flight.”

For more than 10 years, H2FLY has been researching, testing, and refining, resulting in the development of the HY4, a four-seat aircraft with hydrogen-electric propulsion, that first took flight in 2016. There have been several key milestones across the past three years, including:

• In 2020 H2FLY was granted a permit to fly the latest generation of the HY4 aircraft, which featured a fully redundant powertrain architecture. Across more than 100 take-offs the company successfully demonstrated the applicability of hydrogen-electric propulsion solutions in aviation
• In 2021 the company signed a strategic partnership with aircraft manufacturer Deutsche Aircraft that will see the companies work together to fly a CS25 class aircraft powered by H2FLY’s hydrogen fuel cell technology. The climate-neutral regional aircraft demonstrator is expected to fly in 2025
• Earlier last year, the company completed a cross-country flight, from Stuttgart, Germany to Friedrichshafen, covering 77 miles, marking the first time a hydrogen-powered passenger plane has flown between two commercial airports
• Also last year, the company set what is believed to be a world altitude record for a hydrogen aircraft, flying at 7,230 feet, confirming the company’s position as a leader in this new category

Why it’s important: By reaching this milestone, the consortium demonstrates world-leading experience in liquid hydrogen refueling operations and liquid hydrogen handling on board of an aircraft. H2FLY resides amongst a small collective of groups advancing the boundaries of hydrogen flight, signaling high likelihood of practical alternative energy-powered flight in the near future.