Aircraft

Squirrel-cheeked liquid H2 airliner will take you anywhere in two hops

Squirrel-cheeked liquid H2 air...
FlyZero's midsize liquid H2 concept will fly as fast as current airliners and nearly as far, linking any two airports on Earth with a maximum of one stop
FlyZero's midsize liquid H2 concept will fly as fast as current airliners and nearly as far, linking any two airports on Earth with a maximum of one stop
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FlyZero's midsize liquid H2 concept will fly as fast as current airliners and nearly as far, linking any two airports on Earth with a maximum of one stop
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FlyZero's midsize liquid H2 concept will fly as fast as current airliners and nearly as far, linking any two airports on Earth with a maximum of one stop
The FlyZero project has selected cryogenic liquid H2 as the current optimal fuel source for clean aviation
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The FlyZero project has selected cryogenic liquid H2 as the current optimal fuel source for clean aviation
The FlyZero midsize concept would carry 279 passengers up to 5,250 nautical miles between fuelling stops
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The FlyZero midsize concept would carry 279 passengers up to 5,250 nautical miles between fuelling stops
The FlyZero team evaluated a range of zero-emissions energy sources before settling on cryogenic liquid H2 in a combustion powertrain
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The FlyZero team evaluated a range of zero-emissions energy sources before settling on cryogenic liquid H2 in a combustion powertrain
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Long-haul aviation presents a tough challenge for decarbonization, but a group of 100 aerospace experts working on the UK government's FlyZero project says 279-seat liquid hydrogen airliners will connect any two points on the globe with just one stop.

The FlyZero team, led by the UK's Aerospace Technology Institute but featuring talent seconded from a range of aviation companies, was put together to to examine all promising paths to zero-carbon intercontinental aviation, and propose solutions that can be put into service by the end of the decade. With experts from across the aviation and clean fuels spectrum, the approach is holistic, and covers technology, design, manufacturing, operational and marketing elements of possible solutions.

The team examined the pros and cons of batteries, gaseous hydrogen, ammonia, liquid hydrogen as a combustion fuel and liquid hydrogen used in fuel cells. Batteries were off the table pretty much immediately, being too heavy and bulky for the job. Ammonia was dropped due to excessive harmful NOx emissions and the heavy weight of the required fuel and propulsion systems – although it could come back into the discussion at some point when the technology to extract energy from ammonia evolves.

The FlyZero team evaluated a range of zero-emissions energy sources before settling on cryogenic liquid H2 in a combustion powertrain
The FlyZero team evaluated a range of zero-emissions energy sources before settling on cryogenic liquid H2 in a combustion powertrain

That left hydrogen. Gaseous H2, while promising for shorter flights, takes up too much space, and the heavy tanks and fuel cell systems make it inappropriate for long-range planes. Cryogenic liquid H2, the team decided, offers the best path forward, burned as a combustion fuel in large turbofan engines. Combustion beat out liquid H2 fuel cells and electric propulsion systems simply on weight.

Using liquid H2, the team has put together a concept mid-size airliner it says can fly at the same speeds as today's airliners, carrying up to 279 passengers and delivering range figures up to 5,250 nautical miles (6,040 miles, 9,723 km) in a single hop. That's not quite Dreamliner level – those can cover 7,532 nautical miles (8,668 miles, 13,950 km) on a tank of kerosene jet fuel, carrying around 242 passengers. But these hydrogen airliners would still make very practical long-haulers, capable of linking any two airports on the planet with just one refueling stop.

It's a chubby-looking thing; liquid hydrogen powertrains will take up more space than conventional ones, so the FlyZero team has supplemented the cryogenic fuel tanks in the aft fuselage with a pair of smaller "cheek" tanks that expand the lower forward fuselage and give the plane its signature "squirrel with its cheeks stuffed full of nuts" look. These tanks also help balance the plane as fuel loads dwindle during flight.

The FlyZero midsize concept would carry 279 passengers up to 5,250 nautical miles between fuelling stops
The FlyZero midsize concept would carry 279 passengers up to 5,250 nautical miles between fuelling stops

The team also projects that these machines will "have superior operating economics than conventional aircraft from the mid-2030s onwards," as hydrogen prices fall.

There's still some technological and logistic mountains to climb, though. "The challenges of realizing liquid hydrogen," reads FlyZero's energy source comparison and selection report, "include, but are not limited to; the storage and distribution of a cryogenic fuel onboard an aircraft, developing sustainable technologies for stable and reliable hydrogen combustion in gas turbines, efficient energy conversion and thermal management of hydrogen fuel cells and hybrids thereof, minimizing the generation of other climate impacts i.e., NOx and contrails, minimizing the impact on aircraft structural mass and drag, and developing a sustainable hydrogen fuel production infrastructure."

The team is preparing a detailed report for early 2022, including three final aircraft concepts for regional, narrowbody and mid-size airliners, technology roadmaps, economic and marketing reports and sustainability assessments.

Source: Aerospace Technology Insititute via FutureFlight

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18 comments
18 comments
HokenPoke
So much for all the clowns preaching hydrogen systems was not possible.
Well Done FlyZero. Looking forward to the first flight !
Steven Clarkson
A pity they had to drop the electric motor system... Lets hope they get it right next time.
Sergo Kalandadze
Funny - humanity damped dirigibles early in the twentieth century - because hydrogen is dangerous, too flammable - only to use this substance as fuel now. Cheap flights anyone?
paul314
Are those tanks part of the structure? Because there's a reason companies stick to the same fuselage (with minor stretches or enhancements) for decades at a time.
Catweazle
"As hydrogen prices fall"...Hmmm....
JasonBurr
@Steven Clarkson - I very much want to see if GE or Rolls Royce and engineer a hybrid gas/electric turbine. Have a combustion turbine turning the fan for take off and electric motor turning it at cruise. Biggest issue would be decoupling the turbine and fan in flight. OR recouping in flight to restart a turbine.
FB36
Our world already always have countless people keep burning to death alive (after traffic accidents), because of using gasoline (which easily starts fires) as fuel!
(Diesel fuel, for example, does NOT easily starts fires (& that is why POTUS car is specifically chosen to be a diesel, for example)!)
Hydrogen, on the other hand, does NOT start fires but EXPLODES like a bomb!!!
If there are hydrogen vehicles around, do you seriously think their tanks would never leak or rapture, because of an accident, for example???

Not to mention, there is actually no need at all to use hydrogen as fuel!

All light/small vehicles are already becoming fully electric & all heavy/big land/sea/air vehicles just need us to start producing biodiesel/biofuel at large scales!
(From all possible industrial/agricultural/forestry waste/biomass & trash & sewage!)
Smokey_Bear
FB36 - The main reason POTUS use diesel is because of the torque, It's not called "the tank" because it's light.
MQ
So much fear and misinformation in the peanut gallery.

If the ignorant got educated they would talk sense. L9l

Here they have a research and development team provide their conclusions with existing technoligy and they all cry for unicorn tears and narwal Ambergris. Listen to experts at least in the field of materials energy and transport.. (if not climate and medicine)

Energy balances and lifetime cost analysis rules over wishes and hope of Elysium...

Cheers to a rational future - maybe we will see some sort of incorporation of LOx in the combustion to reduce NOx output somewhat.

PS. a fast flying airliner with a hydrogen leak - unlikely but possible - will have the mild onconvenience of an earlier landing rather than fiery deflagration. Sorry folks the fears don't stack up.
-dphiBbydt
The idea of combusting liquid hydrogen is a poor choice. Polluting nitrogen compounds will still be created in a hydrogen jet if the combustion temperatures are the same as with aviation fuel. H2 is explosive, not just flammable; when one of these planes crashes at an airport not only will there be no remains to be identified but the runway will probably have to be rebuilt. Far better would be to use 'green electrons' from renewable resources to suck CO2 out of the air and make regular aviation fuel (like the US army/navy are considering). In this way there's no need to change the planes or engines and we don't have to go down the disastrous hydrogen rabbit hole.
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