AeroDelfts Phoenix ascends as the world’s first liquid hydrogen aircraft

We have written a lot about the potential of hydrogen as a transformative technology for green aviation. In gaseous form, hydrogen offers an energy density much higher than that of lithium batteries, and this offers a real avenue to decarbonize short to medium range air travel.

But the largest aircraft are the largest emitters, and to eliminate emissions from long-haul aircraft, pressurized gas-hydrogen systems – which offer about half the range of an equivalent jet-fuel powertrain – will never be able to perform this trick. For this we need liquid hydrogen systems.

Liquid hydrogen systems can store more than three times the energy of a gaseous system, meaning that a large liquid hydrogen airliner could potentially fly further than today’s fossil burners.

It’s not that easy. Liquid hydrogen has tremendous energy density by weight, but terrible density by volume. Therefore, you would have to equip your aircraft with significantly more fuel storage space and possibly deal with additional air resistance. But it could be one of the few clean fuel technologies that can bring zero-emission intercontinental aircraft into mainstream use in the medium term.

All of this makes this pioneering work by AeroDelft very exciting indeed. A team of 44 students from the TU Delft in the Netherlands has been hanging around on the “first liquid hydrogen fuel cell airplane in the world” and has now presented a prototype on a scale of 1: 3, which is planned for the first public flight in July.

Members of the 44-person AeroDelft team with the scale prototype


The Phoenix will be a hydrogen retrofitted version of the two-seater E-Genius electric glider, which was developed at the University of Stuttgart and flown for the first time in 2011. In its record, the E-Genius has flown over 400 km on battery power alone. With a gasoline-powered range extender, it can travel around 1,000 km. The full-size Phoenix will carry 10 kg of liquid hydrogen with an estimated range of 2,000 km and an endurance of up to 10 hours in the air.

The one-third scale remote-controlled prototype is not small. It has a wingspan of 5.7 m, weighs 50 kg and carries 1 kg of liquid hydrogen, which is enough for an estimated endurance of about 7 hours and a range of about 500 km). The hydrogen is held at -253 ° C (-423 ° F) in a cryotank and heated to 0 ° C (32 ° F) using a “complex tubing” system before being passed through a 1.5 kW fuel cell Charge a backup battery that powers the electric propeller motor at the tail of the aircraft.

The AeroDelft team plans to fly the Phoenix on battery power this July and on gaseous hydrogen a few months later. Finally, this fall, students will fit into the liquid hydrogen system somewhere near the northern hemisphere.

The Phoenix retrofits a hydrogen energy storage system and a fuel cell in the electric glider e-Genius

The Phoenix retrofits a hydrogen energy storage system and a fuel cell in the electric glider e-Genius


“The development of the liquid hydrogen system is going very smoothly,” said Sam Rutten, project manager for prototypes. “We’re finishing the design phase. It’s very difficult to work with liquid hydrogen. To keep it liquid, it has to be cooled to around 20 Kelvin, very close to absolute zero. Our propulsion team has developed a special tank and other support systems, too that we can fly with liquid hydrogen. We are already starting the production phase. The first steps have already been taken to design this tank in accordance with all relevant certifications. “

The full-size two-seater Phoenix is ​​also already being built. A unveiling is scheduled for July. It should fly on gaseous hydrogen by the summer of 2022, and the first full-scale flight on liquid hydrogen is planned for 2024. Both the prototype and full-size Phoenix are set to break all kinds of records, but the project is also focused on advancing hydrogen aviation by working with certification bodies to develop a framework within which a liquid hydrogen aircraft can be certified to mitigate risks in the context of liquid hydrogen aviation and to develop systems to mitigate them.

Commercialization of the Phoenix isn’t on the team’s radar right now, though it’s happy to speak to anyone who wants to take it on. However, AeroDelft has plans for a larger aircraft, including a liquid hydrogen airliner that can fly 19 passengers and pilots up to 925 km (570 mi). However, there are technical mountains that must be climbed with the Phoenix before the Greenliner project gets too far.

The Greenliner would scale things up to a 19-seat airliner running on liquid hydrogen

The Greenliner would scale things up to a 19-seat airliner running on liquid hydrogen


The Phoenix is ​​a very exciting project in an area that has truly transformative potential. The world needs liquid hydrogen to make leaps and bounds to eliminate around 2 percent of global greenhouse gas emissions from the aviation sector. It is great to see the Delft team making significant progress and we look forward to accompanying the Phoenix as the project progresses.

Check out the prototype launch presentation below.

Reveal prototype model

Source: AeroDelft via Robb Report

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