1. Partners’ progress concerning the Heaven project (October 2022 – March 2023)
  2. HEAVEN Project meeting
  3. Relevant upcoming events about hydrogen, fuel cells and aviation


This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 826247. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation programme, Hydrogen Europe and Hydrogen Europe Research.


  1. Partners’ progress concerning the Heaven project (October 2022 – March 2023)


In this phase of the project, all the developments from the various work packages were brought together to demonstrate the applicable technological advances achieved in the previous project years.

After the completion of the integration of all subsystems into H2FLY’s owned and operated HY4 demonstrator aircraft, with the support of our partner PVS end of last year, the aircraft has been delivered to Air Liquide premises to initiate the coupling activities and thereby validate the functionality of the FC-System together with the fuel system using liquid, cryogenic hydrogen on board of the aircraft.This LH2 storage system was developed and tested on functionality and structural durability by our partner Air Liquide.

LH2 coupling and integration in the HY4

H2FLY then has successfully, and with the support of ALAT, passed first filling tests with LH2 in preparation for the coupling tests. After the coupling tests, H2FLY will prepare its HY4 aircraft for the upcoming ground- and flight test programme that is expected to be held at an airport in Slovenia in early Q3 this year and will be the world’s first passenger aircraft to fly on a liquid hydrogen-powered fuel cell system.

H2FLY experts during coupling test at Air Liquide facilities


Over the past year, EKPO has worked extensively on the anode loop functionality of the NM12 single and twin stack modules. The focus was on the pre-heating of the hydrogen supply, which is particularly important in combination with the LH2 storage. With the package and volume optimized integration of an anode heat exchanger, the heat from the coolant outlet is used to pre-heat the hydrogen feed gas. This is critical to avoid condensation when mixing the water-saturated hydrogen from the stack with the cold hydrogen from the LH2 tank.

Left: P&ID scheme – Anode Heat Exchanger (AHE) integration into the fuel cell stack module. Right: Heat Exchanger
(AHE) – First prototype.


DLR continued the work on the system modelling. A Modelica model was created, which is being validated against the measurement data. After the completion of the validation process, further operation procedures can be analyzed by simulation. The model represents cathode, anode and thermal management subsystems by their individual components. The layout and connection of the induvial components is illustrated in Figure 1. Dynamic operation can be simulated and is validated against existing results. Controllers and set points are being fine-tuned.

Figure 1: Layout of the fuel cell system model


To extrapolate the technology for small-scale UAV applications and been able to analyse the viability of this technology in UAVs, FAY is working on the analysis of a dynamic model of an aircraft that simulates an UAV application, for a conceptual design. The model is developed with Matlab Simulink, the goal of this one is to emulate the behaviour of the system in a controlled scenario. For that end, the Matlab model is integrated with Gazebo to emulate a flight and test the whole system and obtain the correspond conclusions.

UAV Gazebo model


Pipistrel Vertical Solution’s (PVS) team has been working together with colleagues from H2FLY and Air Liquide in finalising the mechanical integration of the LH2 tank in light of the anticipated ground tests.

Furthermore, the team has been working actively on the process for the obtainment of the Permit-To-Fly with the Slovenian Civil Aviation Authority, with the support of all partners. This process will ensure that the test aircraft meets local standards of safety for experimental flight test operations.


During the last three months, Air Liquide has prepared the test area for the coupling tests. A Ground Refuelling Equipment was installed in order to fill the tank with LH2 coming from a LH2 trailer, and the permit for LH2 filling operations was received from French Authorities.

The LH2 tank was installed inside the HY4 aircraft. H2FLY and Air Liquide teams worked together in this period to prepare filling operations and coupling tests. The HY4 aircraft is now ready for coupling tests.


  1. HEAVEN Project meeting

As the end of the of the European project HEAVEN is slowly approaching the project partners met in Sassenage, in the premises of the partner Air Liquide, for two days of intensive collaboration. All 7 partners from industry and research have been able to share the results of the last years and to set the basis for the upcoming final works steps. The challenge in this last phase of the project will be the ground testing of the plane and the obtainment of the Permit-To-Fly which will allow the resulting fly test that will take place in Slovenia. At the meeting the members took a tour of the Ai Liquid facility and could observe the HY4 aircraft on which the LH2 coupling and integration was being done by the H2FLY and Air Liquide teams. The tames successfully integrated the tank and the HY4 aircraft is now ready for coupling tests. The members discussed the future exploitation and dissemination activities that will be focusing on social media appearance and the demonstration video that will be shot during the flight test which is one of the final milestones of the project activities.

  1. Relevant upcoming events about hydrogen, fuel cells and aviation

Hannover Messe (17 – 21 April 2023):
HANNOVER MESSE is the most important international platform and hot spot for industrial transformation – with excellent innovations or unusual products. Here you will find all the facts that make one thing even clearer: participation is an absolute “must”!

Aero Friedrichshafen 2023 (19 – 22 April 2023, Friedrichshafen, Germany):
Discover what direction developments in the General Aviation industry are going at the AERO Friedrichshafen. With more than 600 exhibitors from 35 countries, 33,000 visitors and 600 journalists from all over the world, the AERO Friedrichshafen is the international community’s annual meeting place. At Lake Constance, numerous companies will be displaying their latest products and innovations, covering the whole industry from ultralights and gliders to business jets, helicopters and electric aircraft as well as avionics and maintenance.

Hydrogen Online Workshop 2023 (9-10 May 2023):
The Hydrogen Online Workshop (HOW) is a unique interactive event that provides a global platform for discussing the most important issues of the hydrogen industry. 150+ world-class experts in Keynotes and Workshops, interactive virtual Exhibition, 10000+ Hydrogen Pioneers, 110+ countries. The World’s Largest Interactive Hydrogen Event.

World Hydrogen Summit 2023 (9-11 May 2023):
The Sustainable Energy Council with partners the Port of Rotterdam, the City of Rotterdam and the Province of Zuid-Holland are delighted to renew their commitment to enhance the event as the official global springboard for hydrogen deals and project developments where real action is displayed to inspire and motivate the rest of the world. Welcoming 8000 decision makers, Energy Ministers, and CEOs from over 100 countries, it’s a truly global gathering of minds where key priorities are set, bold announcements are made, and new partnerships are forged.

Hydrogen Expo Italy (17-19 May 2023):
First Italian exhibition & conference entirely dedicated to the technological sector for the development of the hydrogen supply chain. The decarbonisation policy aimed at reducing global pollution sees hydrogen as a sustainable energy source since it can be generated using renewable energy and, therefore, it can be transported, stored and used as a gas; Italy can be an extremely interesting market for the development of hydrogen, thanks to the widespread presence of renewable energy sources and a capillary network for the transport of gas.

Paris Airshow (SIAE) (19 – 25 June 2023):
The 54th edition of the Show will take place at the Le Bourget Parc des Expositions in June 2023, and once again will bring together all the players in this global industry around the latest technological innovations. The first four days of the Show will be reserved for trade visitors, followed by three days open to the general public.