Airbus’s propeller plane could look reminiscent of the golden age of air travel - Airbus
Propeller planes that once dominated the skies could again serve some of the world’s busiest flight routes under Airbus’s latest plans to slash carbon emissions.
The manufacturing giant revealed last week that it was working on a propeller model it hopes may one day take over flights currently operated by some of its most popular jets.
Images of the aircraft look at first glance like a throwback to the years immediately after the Second World War, when planes like the “four-prop” Lockheed Constellation reigned supreme.
Yet the technology behind the new model is at the cutting edge of the aviation industry’s scramble to hit net zero.
The propellers will be turned by electric motors themselves powered by hydrogen fuel cells, eliminating kerosene from the equation and delivering aviation’s holy grail: entirely zero-emission flights.
Airbus engineers had been working on the plane since 2020 as part of the company’s Zeroe project to examine hydrogen-powered aircraft.
This included initial proposals that envisaged a 100-seat turboprop able to fly for around 1,000 nautical miles (nm).
While an impressive feat, this smaller aircraft would have been limited to shorter, more regional journeys.
However, now Airbus has slammed the brakes on its larger hydrogen-powered jet engine aircraft, the company’s fuel-cell propeller option has emerged as its best bet for moving beyond fossil fuels.
Optimism is such that Airbus engineers are examining the potential for scaling up the plane to seat between 100 and 200 people.
That would allow it to take over from more mainstream aircraft the size of an Airbus A319 or even the A320, the baseline model for its most popular passenger jets.
Guillaume Faury, Airbus boss, said he sees the programme gradually expanding its scope to “longer distances and bigger planes”.
“Bigger means a market sector that is broader and larger,” he says. “It’s easier to see a return on investment in a market segment where there is more traffic and use for the plane. We think it has to go to the next step to be commercially viable.”
Airbus engineers are examining the potential for scaling up the plane to seat between 100 and 200 people - Airbus
Standing in the way are the technological challenges of extracting further efficiencies from fuel cells and developing a storage system for the hydrogen, which must be chilled to -250C in order to reduce the otherwise vast volume it would occupy.
Beyond that, the viability of the programme will be determined by access to supplies of “green hydrogen,” the chief executive said.
This means that in order to deliver zero net emissions, the energy-intensive process required to produce the hydrogen must itself be powered by renewables or small nuclear reactors, rather than fossil fuels.
He says: “We have come to the conclusion that we can make a hydrogen plane fly and work, and do it safely. We see a path to a commercially viable aeroplane with a lot of success. But some conditions are not yet there.”
In dropping the jet-powered hydrogen option, Airbus pushed back the planned date of service entry for Zeroe by at least five years beyond the original target of 2035.
The new version of the plane will instead sport four propellers, each driven by a 2 megawatt (MW) motor powered by a fuel cell system that converts hydrogen and oxygen into electrical energy, emitting only water vapour.
Glenn Llewellyn, who heads Zeroe, said that the number of propellers and motors needed for the plane reflects the fact that the technology is so early in its development.
He compared the design to early versions of jet planes such as the Boeing 707, which was powered by four engines despite carrying just 150 passengers.
He says: “That’s what aircraft looked like at the beginning of the jet age. We’re now at the beginning of the hydrogen propulsion age.
“The first iteration that we looked at had six engines [propellers]. We’ve now brought it down to four and there will be a point where we get it to two, just like we’ve seen with jet aircraft.”
People shouldn’t be deceived by appearances, he adds: “An electric car still has wheels and tyres, but it’s an electric car.”
The propeller system has been influenced by Airbus’s A400M military transport plane, “probably the most advanced propeller-powered product today”, he says.
The propeller system has been influenced by Airbus’s A400M military transport plane - Giuseppe Cacace/AFP
Andy Reynolds, head of hydrogen storage on Zeroe, says a version the size of an A319, which can carry around 150 passengers, could conceivably be possible by 2045.
That’s about 10 years after the planned introduction of a replacement for the A320, which Airbus says will be a conventional jet, albeit able to burn 100pc sustainable aviation fuel and equipped with leaner-burn engines and longer, more efficient wings.
A fuel-cell plane will require about the same amount of hydrogen as the abandoned hydrogen jet engine aircraft would have done, presenting similar storage challenges.
Airbus has now settled on two large cylindrical tanks to be accommodated in the rear of the plane, which will inevitably cannibalise space that could otherwise have seated passengers – one of the trade-offs of the transition away from jet fuel.
The company is examining whether the hydrogen should be pumped to the fuel cells as a liquid, which would require a system of chilled pipes, or be allowed to return to its gaseous form, requiring no cooling system but much larger pipes.
One major advantage of the new design is that hydrogen can be injected into fuel cells at a reasonably low pressure of five bar – around double the pressure in a home heating system or car tyre – compared with 30 bar for a jet engine.
The biggest edge, though, will be environmental, helping Airbus meet increasingly stringent net zero targets.
When asked why the propeller plane is now the priority, Faury’s answer is simple.
“If you have to go through such a deep investment in a new aircraft, why stick with the available technology if there are others that are better?”
