Fuel cell developer H2Fly has completed initial ground tests to refuel its hydrogen-electric HY4 aircraft with liquid hydrogen. On April 5, the German company conducted the test in Grenoble in France at a facility operated by its partner, the industrial gas group Air Liquide as part of preparations for the start of a new round of flight testing this summer.
The tests for what H2Fly calls the filling procedure are part of the European Union-funded Project Heaven which is contributing to the European Commission’s Horizon 2020 research and development initiative to demonstrate the feasibility of using a liquid, cryogenic hydrogen-powered fuel cell powertrain in an aircraft. Since December 2022, H2Fly, which is based in Stuttgart, has been responsible for reporting the project’s results.
During the tests, a new cryogenic hydrogen storage system designed by Air Liquide was filled with liquid hydrogen. In the next stage of the joint project, the partners will couple the storage tank to the fuel cell component of the HY4’s powertrain.
“The successful on-ground filling tests mark the next milestone in our pursuit of doubling the range of our HY4 aircraft,” said H2Fly CEO and co-founder Josef Kallo. “It is a critical step for our flight test campaign this summer, which will demonstrate the feasibility of liquid hydrogen as a fuel for medium- and long-haul flight.”
In November 2022, H2Fly started the mechanical integration of Air Liquide’s liquid hydrogen tank into the HY4 technology demonstrator after the tank had passed earlier vibration and leakage tests in September. Since 2020, H2Fly has conducted more than 100 takeoffs with the HY4 during flight testing that used an earlier version of the powertrain. Currently, the aircraft’s range is around 750 kilometers (469 miles), and H2Fly aims to increase this to 1,500 kilometers.
H2Fly is already working with Munich-based Deutsche Aircraft and has agreed to collaborate on plans to convert a 1990s-vintage Dornier 328 regional airliner to hydrogen power. The partners hope to start flight testing the former twin turboprop in 2025 as part of a timeline that H2Fly founder and CEO Josef Kallo told FutureFlight could lead to an aircraft being certified under EASA’s Part CS-25 rules (equivalent to FAA's Part 25) in about seven to eight years.
Earlier this year, the HY4 made a cross-country flight of 77 miles between Stuttgart and Friedrichshafen in Germany. It has also set what the company believes is a world altitude record for a hydrogen-powered aircraft by cruising at 7,230 feet.