H2FLY, the Ger­man-based devel­op­er of hydro­gen-elec­tric pow­er­train sys­tems for air­craft, announced this week it has suc­cess­ful­ly com­plet­ed the world’s first pilot­ed flight of an elec­tric air­craft pow­ered by liq­uid hydro­gen, reports a press release. The hydro­gen-elec­tric ‘HY4’ demon­stra­tor air­craft took off from Mari­bor, Slove­nia, and saw safe and effi­cient oper­a­tion through­out mul­ti­ple flight tests. The H2FLY team from Stuttgart com­plet­ed four sep­a­rate flights as part of its test cam­paign, includ­ing one that last­ed for over three hours. 

“Results of the test flights,” explains the release, “indi­cate that using liq­uid hydro­gen in place of gaseous hydro­gen will dou­ble the max­i­mum range of the HY4 air­craft from 750 km to 1,500 km, mark­ing a crit­i­cal step towards the deliv­ery of emis­sions-free, medi­um and long-haul com­mer­cial flights.” 

Pro­fes­sor Josef Kallo

Pro­fes­sor Josef Kallo, co-Founder of H2FLY, com­ment­ed, “This achieve­ment  marks a water­shed moment in the use of hydro­gen to pow­er air­craft. Togeth­er with our part­ners, we have demon­strat­ed the via­bil­i­ty of liq­uid hydro­gen to sup­port medi­um and long-range emis­sions-free flight.”

He con­tin­ued, “We are now look­ing ahead to scal­ing up our tech­nol­o­gy for region­al air­craft and oth­er appli­ca­tions, begin­ning the crit­i­cal mis­sion of decar­bon­is­ing com­mer­cial avi­a­tion.” 

The release con­tin­ues, “The suc­cess­ful cam­paign marks a sig­nif­i­cant mile­stone for H2FLY and reflects the exten­sive insights gained from the company’s research efforts. More­over, it is the cul­mi­na­tion of Project HEAVEN, a Euro­pean-gov­ern­ment-sup­port­ed con­sor­tium assem­bled to demon­strate the fea­si­bil­i­ty of using liq­uid, cryo­genic hydro­gen in air­craft. The con­sor­tium is led by H2FLY and includes the part­ners Air Liq­uide, Pip­istrel Ver­ti­cal Solu­tions, the Ger­man Aero­space Cen­ter (DLR), EKPO Fuel Cell Tech­nolo­gies, and Fun­dación Ayesa.” 

Beside project HEAVEN, the work has been fund­ed by the Ger­man Fed­er­al Min­istry for Eco­nom­ic Affairs and Cli­mate Action (BMWK), the Ger­man Fed­er­al Min­istry for Dig­i­tal and Trans­port (BMVD) and The Uni­ver­si­ty of Ulm. 

Com­pared with pres­surised gaseous hydro­gen stor­age (GH2), the use of liqui­fied, cryo­genic hydro­gen (LH2) enables sig­nif­i­cant­ly low­er tank weights and vol­ume, there­fore lead­ing to increased air­craft range and use­ful pay­load.

Pierre Crespi, Inno­va­tion Direc­tor at Air Liq­uide Advanced Tech­nolo­gies remarked, “Air Liq­uide is proud to have designed, man­u­fac­tured and inte­grat­ed, togeth­er with H2FLY, the liq­uid hydro­gen tank that enabled to pow­er the HY4 air­craft. Today’s suc­cess demon­strates the full poten­tial of liq­uid hydro­gen for avi­a­tion. This hydro­gen can be stored onboard and trans­port­ed. Hydro­gen is key to the ener­gy tran­si­tion and this new step proves that it’s already becom­ing a real­i­ty.”

Dr. Syed Asif Ansar, Head of Depart­ment Ener­gy Sys­tem Inte­gra­tion at the Ger­man Aero­space Cen­ter (DLR), added, “DLR boasts exten­sive exper­tise in elec­tri­fied air­crafts, with a track record span­ning over 15 years. Start­ing from the inau­gur­al flight of the Antares DLR-H2 in 2009, con­sis­tent advance­ments have been made in fuel cells and their aux­il­iary sys­tems.”

He con­tin­ued, “This pro­gres­sive jour­ney cul­mi­nates in a sig­nif­i­cant present achieve­ment in avi­a­tion his­to­ry: the uti­liza­tion of cryo­genic liqui­fied hydro­gen as fuel stor­age for a four-seater air­craft pow­ered by fuel cells. Col­lab­o­rat­ing with H2FLY, AirLiq­uide and oth­er project mem­bers, DLR is active­ly engaged in projects aimed at pro­pelling the devel­op­ment of CS-23 and CS-25 fuel cell pow­ered air­craft into the next phase.”

With the com­ple­tion of the flight test­ing in project HEAVEN, H2FLY will focus on a path to com­mer­cial­i­sa­tion. In June, H2FLY announced the devel­op­ment of its new H2F-175 fuel cell sys­tems which will be capa­ble of pro­vid­ing their full pow­er range in flight alti­tudes of up to 27,000 ft, mark­ing an impor­tant step on the path from low­er alti­tude via­bil­i­ty flight demon­stra­tions to real-world com­mer­cial air­craft appli­ca­tions.  

Next year, H2FLY aims to open its Hydro­gen Avi­a­tion Cen­ter at Stuttgart Air­port, co-fund­ed by the Min­istry of Trans­port Baden Würt­tem­berg. The Cen­ter will become a focal point for the future of Europe’s avi­a­tion indus­try and its hydro­gen econ­o­my, pro­vid­ing fuel cell air­craft inte­gra­tion facil­i­ties and liq­uid hydro­gen infra­struc­ture.

H2FLY was acquired in 2021 by Joby Avi­a­tion. It is viewed that in just a few years, hydro­gen-elec­tric air­craft could be trans­port­ing up to 40 pas­sen­gers over dis­tances of close to 1,240 miles.  

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(Images: H2FLY)