Any organisation funding the research and technology (R&T) activities necessary for aviation’s future faces a delicate balancing act as it looks to dole out investment.

Clearly the goal is to pick a winner – a piece of technology that can be exploited commercially – but there are multiple considerations informing that selection process: the maturity of the technology, the likelihood it will be deployed on an aircraft, alignment with the private sector’s priorities, and the timeframe in which it is required, for example.

On top of this, there is the pressure to balance research spending across multiple timeframes: the technology contributing to an efficiency gain in the near term may not be as relevant, if at all, to the next generation of aircraft, and will almost certainly not be applicable to the one after that.

AIRFRAMER INFLUENCE

But some of these factors are outside of a ­funding body’s control. Take hydrogen propulsion as an ­example: although there is some interest from the sub-19-seat segment, widespread use of hydrogen as a fuel for aviation will ultimately be dictated, to a greater or lesser extent, by what Airbus or Boeing do.

That is not to say the airframers have a veto on any technology, simply that if one or both say they will adopt it, the supply chain is spurred to follow suit. The opposite is also true: wavering or uncertain support, or a revised timeline, can seriously alter suppliers’ plans.

And that is exactly what has transpired.

At the turn of the year, Airbus announced it was delaying the timeline for its hydrogen-powered ZEROe airliner. Although at pains to stress it had not abandoned the concept, the airframer said – based on technology and infrastructure concerns – that service entry would slip by up to a decade.

Investment was also scaled back. In the ­medium-term, Airbus is focused on bringing its A320neo-replacing next-generation single-aisle to market, an aircraft that will achieve any environmental goals through more efficient but conventionally fuelled engines.

As might be expected, the ramifications of that decision continue to ripple through the wider sector.

Those organisations managing research funding like the UK’s Aerospace Technology Institute (ATI) have been forced to take stock. Indeed, attendees at a meeting of the body’s advisory groups earlier this year identified hydrogen as one of the topics it should now not focus on.

In some ways, by delaying but not rejecting hydrogen entirely, Airbus has simply increased some of the inherent tension between the need for investment in both mid- and long-term technology bets.

But that longer timeline for a return on investment – and pressure from other near-term needs – has also prompted industry to review its priorities.

In April, Peter Dilnot, chief executive of GKN ­Aerospace, a company that had shown notable enthusiasm for hydrogen, said talks with Airbus were continuing “to establish what does the [hydrogen] roadmap look like and where should we invest to ­support the development of the [ZEROe] aircraft”.

While he insists the company is “continuing to ­commit to hydrogen in the long term”, he concedes the delay to ZEROe “will necessarily have an impact on how much we invest and where we invest”.

The extent of that retrenchment was made clear two months later, when GKN revealed what was staying and what was not. The company has been developing multiple hydrogen propulsion systems that it hoped would find their way onto any future Airbus aircraft.

Alongside GKN’s internal R&T spending, and some investment from the Dutch government, funding for three specific projects came from the ATI.

Started in 2021, H2GEAR is a five-year project to develop a 1MW-class fuel cell powertrain, including a cryogenically-cooled motor; meanwhile, through HyFIVE – led by Marshall Aerospace – GKN was working on a hydrogen storage tank as part of a wider fuel system.

These were followed last year by the launch of H2FlyGHT, a £44 million ($60 million) project ­intended to prepare a 2MW-class cryogenic powertrain for flight testing.

Although not mentioned at the time the initiative was announced, Airbus had been lined up to carry out the flight tests.

But faced with a slower pace of development at its intended “primary customer”, GKN has had to “make some pretty difficult decisions”, says chief technology officer Russ Dunn.

“Unlike Airbus, we don’t choose when a ­programme is launched; for us, investment in ­technology is about inspiring the customer and building the confidence and credibility with the customer around our ability to exploit some of those capabilities.

“So, with that in mind, we had to look at the extended timeline and ask: ‘what should we be doing?’.”

Following an internal review and consultation with other stakeholders, GKN will “reduce [its] focus down to the things most well-aligned with Airbus’s plans”, says Dunn.

Crucially, this means an end to its involvement in HyFIVE: “We are going to stop our work around ­hydrogen storage,” he says.

That decision has had a knock-on effect on its partners in the total £37 million project: £20 million of which was to come from the ATI, alongside a £17 million contribution from industry.

Marshall and Parker Meggitt say that “after ­careful review” of GKN’s withdrawal, they “came to the conclusion that the HyFIVE project objectives can no longer be fully met”.

“Marshall, Parker Meggitt and the other partners are discussing a reduction in the scope that will likely see the project complete by the end of the year,” they add.

Marshall says it “remains in close communication” with the consortium partners, plus funding bodies Innovate UK and the ATI “to re-shape the project in a manner that preserves valuable research findings to date and enables them to be built upon in the future”.

No details on how the project will be re-scoped have been disclosed, however.

TECHNOLOGY DEVELOPMENT

HyFIVE was to cover five key technology development areas for hydrogen fuel systems: storage, conveyance, indication, fuelling and venting. The end system was intended to be suitable for “multiple aircraft classes and compatible with either hydrogen electric propulsion or hydrogen combustion powertrains”.

Due to end in 2027, the project was meant to culminate in ground tests of an integrated system at technology readiness level 6.

By that point, the partners said they would have “opened a range of flight-demonstration and ­exploitation paths with prospective customers” and “developed a customer-ready supply chain and ­industrialisation strategy”.

While HyFIVE is ending early, GKN will maintain its work on H2GEAR, which was set to wrap up in 2026 regardless: “We [will] see that through,” says Dunn.

The follow-on H2FlyGHT project will also still go ahead, although with a reduced scope as GKN has dropped the power-generation and cryogenic motor elements from the effort, partly due to those aspects being outside its area of expertise.

Airbus, notes Dunn, sees power generation as “a really core area” and has already established an aviation fuel cell joint venture, Airbus AeroStack, with Germany’s ElringKlinger.

As such, “we were unlikely to secure a route to ­exploitation on the platforms coming”, he adds.

Similarly, although GKN sees great potential from its cryogenically-cooled motor – delivering high ­efficiency and an impressive power-density – it ­cannot justify the “vast” investment required to ­develop a flight-worthy solution.

Dunn says there are other companies in the sector with more electrical motor experience who would be “better placed to exploit the concept”.

With these elements eliminated, GKN will “modify the scope of H2FlyGHT” to focus on maturing the cryogenically-cooled electrical distribution system it has developed through H2GEAR.

The system uses helium – cooled by the liquid hydrogen fuel – to bring the electrical distribution system down to -253°C (-423°F). This reduces resistance in the wiring to almost zero, allowing “high power without high voltage”, in turn enabling weight to be removed from the system by using thinner cables with less protective shielding.

Learnings from this programme – the exact shape of which is still to be agreed with the ATI – will then feed into a new Airbus UpNext-led project called ICEFlight, based in the Netherlands; the location of GKN’s centre of excellence for wiring.

LIQUID EFFECTS

Unveiled in May, ICEFlight, part-funded by the Dutch government’s Luchtvaart in Transitie (LIT) programme, is designed to explore the “use of liquid hydrogen as a fuel source as well as a cold source” to “enhance the performance of next-generation aircraft powertrains through the integration of advanced electrical technologies, superconductivity and hyperconductivity”.

These technologies will be matured “in preparation of a flight demonstration”, says Airbus.

However, another outcome of the airframer’s delayed timeline on ZEROe is that the ATI has become a target for criticism from some quarters: it was too eager to embrace an unproven technology like hydrogen, they say, and as a result too quick to allocate funds for related technology development where the outcome was uncertain.

To an extent, the ATI’s enthusiasm for hydrogen stems from its FlyZero study in 2022, which ­concluded it would be a suitable zero-emission energy source for aviation, and, crucially, one that could power both short- and long-haul aircraft.

Tom Halhead, the ATI’s head of technology – advanced systems and propulsion, told a 9 July webinar that many of the body’s “international peers” are running studies that “come to the same conclusions”.

DEPLOYMENT CHALLENGES

Although there remain some “big challenges” around hydrogen’s deployment, ongoing technical research has not thrown up any “showstoppers”, he adds.

The immediate concern, he notes, is to ensure “we maintain momentum on this” while the industry is focused on ramping-up production of current-generation jets and preparing for the likely launch of an A320neo successor before the end of the decade.

David Debney, the ATI’s head of technology – whole aircraft, says hydrogen remains a “really promising zero-carbon energy source” and although “some of the market timelines have moved to the right it doesn’t mean there aren’t things we can do now”.

The ATI’s strategy, he says, is to invest in “technology bricks” – the “critical enablers we are going to need to [unlock] the potential of hydrogen flight in the future”, including fuel distribution and storage systems.

“Development is part of the reason the ATI exists: to provide the funding to help progress the research, development and technology at pace,” he adds.

A further indication of the ATI’s direction of travel can be seen in the minutes from a recent meeting of the UK government-chaired Jet Zero Taskforce.

Released on 1 July, the minutes of the 15 May meeting of the taskforce’s ‘Expert’ group detail discussion within the Hydrogen Task & Finish Group (HTFG) – a topic-specific sub-group chaired by Debney.

In ensuring that hydrogen aircraft can be “introduced in a way that is commercially sustainable”, the group will “focus on smaller, domestic aircraft as these will be available to enter service first”, the minutes say.

To an extent, that chimes with the ATI’s recent funding awards, where the hydrogen-related projects selected were those aimed at smaller aircraft.

These include a ZeroAvia-led effort to deliver a new liquid hydrogen storage system, and an initiative led by Intelligent Energy to develop its current 300kW modular fuel cell system for use in next-generation aircraft.

Building on work carried out in GKN’s H2GEAR effort, the new three-year project, called HEIGHTS, is particularly focused on Intelligent Energy’s cooling technology, which should drive a significant reduction in heat-exchanger size and weight.

And, as a reminder that Airbus has slowed but not abandoned its work on hydrogen, the ATI also funded a project led by the airframer called the “ZEROe Development Centre Capital and Infrastructure Phase 2”.

This £35 million project will develop infrastructure for testing liquid hydrogen fuel systems and structural components to support zero-emission technologies.

It is worth remembering that the ATI is effectively a tool of government policy – it was one of the first sectors to benefit from the June launch of the UK’s Modern Industrial Strategy – so decisions made by the Jet Zero Taskforce will influence some of its priorities.

Indeed, the minutes show that outputs from the HTFG will inform the required capabilities of a ­hydrogen-powered aircraft, with a roadmap showing the timelines for their commercial operation, and ­projected demand for hydrogen from the sector.

Points raised within the group’s discussions ­included the need to “understand commercialisation barriers” and how to “bridge the economic gap for the transition to hydrogen aircraft”. There was also recognition that the ‘when’ is almost as important as the ‘how’. “There was a key question around timing and when further commitments to support zero-­emission flight can be made,” the minutes note.

With the ATI having been awarded a 10-year ­commitment worth £2.3 billion as part of the new industrial strategy, it is now firmly in delivery mode and the pressure to back a winner is ever-more acute.