Fuel cell aircraft developer H2FLY says it has started final preparations for the integration of liquid hydrogen tanks into the HY4 test aircraft. An intensive programme of ground tests is then scheduled to start in early 2023.
So far, the HY4, which was last exhibited at the AERO trade fair in Friedrichshafen and then at the Farnborough Air Show in the UK, is being operated with gaseous compressed hydrogen. In a few weeks, the pressurised tanks will be replaced by tanks for liquid hydrogen. According to H2FLY, this should double the range of the HY4.
Before the HY4 and the new tanks take to the air, extensive ground tests are scheduled. After all, the storage technologies used – sometimes with several hundred bar pressure, sometimes at -253 degrees Celsius – differ enormously from each other. If problems arise during integration or commissioning, they are to be sorted out on the ground – and not at a height of several hundred metres.
According to the company, which is the result of a partnership between the German Aerospace Center (DLR) and the University of Ulm, the integration of the liquid hydrogen system is another important step towards H2FLY’s goal of developing the world’s first fully hydrogen-electric powertrain that integrates fuel cells and liquid hydrogen. The switch from pressurised to liquid hydrogen is a “decisive step” on the way to realising emission-free medium- and long-haul flights, he said.
Liquid hydrogen has the advantage that it has a significantly higher energy density than compressed hydrogen. Moreover, it can be refuelled like a liquid, which makes it easier to handle on the ground. But: for hydrogen to remain liquid, it must be cooled to at least 253 degrees Celsius below zero.
The HY4 with pressurised tanks has completed more than 90 take-offs and landings since 2020, including a 124-kilometre, non-stop flight from its home airport of Stuttgart to Friedrichshafen for the AERO. In addition, this year the HY4 has reached a flight altitude of 7,230 feet or more than 2,200 metres, which the company says is a “presumed world altitude record for a hydrogen aircraft”.
“An aircraft that uses liquid hydrogen has the potential to transform the way we travel between cities, regions and countries, delivering true zero-emissions flight on medium and long-haul flights,” said Josef Kallo, co-founder and CEO of H2FLY. ““Liquid hydrogen has huge advantages over the alternative pressurised hydrogen gas, not least because it becomes possible to carry a far greater quantity on board an aircraft. The result is that significantly longer ranges are possible.”
h2fly.de (PDF)
Keyword: H2FLY is getting ready for hydrogen-powered flight