A consortium led by Collins Aerospace will later this year complete the initial design of a new high-voltage electrical distribution system suitable for a future regional aircraft under an EU-backed project.

Kick-off meetings for the initiative – called HECATE, or hybrid-electric regional aircraft technologies – were held in January, on the back of the project’s selection last November by the EU’s Clean Aviation body for funding.

Clean Aviation-c-DLR

Source: DLR

Future regional aircraft will require novel power distribution systems

Collins’ Applied Research and Technology unit in Cork, Ireland, is coordinating HECATE, with the manufacturer’s sites in Nordlingen, Germany and Solihull in the UK also contributing expertise on power conversion and secondary distribution.

Other consortium members include Diehl Aerospace, Safran Electrical & Power, and Thales, plus Airbus Defence & Space and Leonardo who will provide an airframer perspective.

Todd Spierling, principle technical fellow for electrification at the US-headquartered aerospace giant, says preliminary design activities for the system will be completed this year, followed by a critical design review milestone in 2024, ultimately leading to full testing of the 500kW-plus system at technology readiness level 5 in 2025.

Spierling says the project will seek to develop and mature both the individual components or sub-systems – power switches, protection and power conversion systems – and the overall integrated distribution system.

“It’s not just a component programme, it’s not just an architectural programme – it’s a combination of the two,” he says.

That approach will be key, he notes, given the lack of clarity on which configurations will be employed by future regional aircraft. “There’s a lot of fluidity still in what these architectures are going to look like for the different platforms.”

Any development programme will likely “take some of these, some of those and a bit of that and combine them in the particular configuration for the real aircraft”, he argues.

Although the power requirements for future electric powertrains – likely to be at least 1MW for regional aircraft – are an important consideration, Marc Holme, Collins senior director for electric power systems, says the project will look at “power distribution across the entire aircraft” – and the voltage conversions needed to run different systems.

With the likely change to alternative power sources on an aircraft there will also be a need to develop DC-DC converters, and to cope with the move to higher voltages for secondary systems, says Spierling, potentially enabling another efficiency gain.

“If we go to higher voltage we can go to smaller wire and take significant weight out of the platform,” he adds.

But as Holme points out, that “brings fresh challenges in terms of insulation systems, and then protection of the system – particularly when we are operating at altitude”.

HECATE’s development scope includes neither a generator at one end, nor a motor at the other, however. “We will process the power and flow the power, but we won’t really create or use it,” says Spierling.

Besides, Collins is already working on such technologies within its North American unit where it is undertaking the partial electrification of a De Havilland Canada Dash 8-100 through a Canadian-funded project. The electric motor for that project has been developed at the Solihull site.

In addition, there is no flight test envisaged as part of HECATE, although Holme says this may be pursued as part of Clean Aviation’s second phase.

This, says Spierling, would provide valuable insights: “You can try as well as possible to simulate those environments on the ground, but an actual flight test gives you the combination of things – the temperature, the altitude, the vibrations – all those things you see on real aeroplanes that are difficult to simulate in labs.”

Others developing higher-voltage distribution systems for aviation – notably Airbus – are exploring the potential efficiency gains that could be realised through the use of cryogenics and super-conductive materials. While not being pursued by HECATE, Spierling thinks such technology will find a role – although not for all applications.

“I think for certain aircraft, certain missions, certain configurations [super-conductivity] will make sense – the trade offs will work. But for some of the other smaller platforms the potential weight savings or efficiency gains you get might not be worth it,” he says.

For their part, Airbus Defence & Space and Leonardo will bring “the airframer view”, about “what they think the future looks like”, says Spierling: “They will be the ones who will be creating the ultimate end vehicles.”

With future aircraft power requirements likely to be higher than that of the system on test, Holme points out that there will be growth potential in its design.

“I think some of the design scope [of the system] is looking at that scalability – how do you take these building blocks and scale them effectively together to give you the higher power capability as that’s required,” he says.

HECATE will receive €34 million ($36.7 million) from Clean Aviation, while the UK’s Research & Innovation body – which is involved due to Brexit – is contributing €6 million; the total will be at least matched by industry.

Those with a passing knowledge of ancient mythology will recognise HECATE as the name of a Greek godess, variously associated with witchcraft, magic night and crossroads. The choice was deliberate – and is nodded to in the project’s logo – explains Collins, given that the aviation industry finds itself at a crossroads in terms of emerging technologies and the imperative to slash CO2 emissions. 

“Her association with magic thus represents the groundbreaking solutions needed to address these challenges and the innovative technologies the HECATE consortium will work to develop.”