The Anonymous Widower

ZEROe – Towards The World’s First Zero-Emission Commercial Aircraft

The title of this post, is the same as that of this Press Release from Airbus.

This is the introductory paragraph.

At Airbus, we have the ambition to develop the world’s first zero-emission commercial aircraft by 2035. Hydrogen propulsion will help us to deliver on this ambition. Our ZEROe concept aircraft enable us to explore a variety of configurations and hydrogen technologies that will shape the development of our future zero-emission aircraft.

Overall, the Press Release discloses a lot and gives details of three different aircraft, which are shown in this Airbus infographic.

I have some thoughts that apply to all three concepts.

Hydrogen Hybrid Power

The Press Release says this about the propulsion systems for the three aircraft.

All three ZEROe concepts are hydrogen hybrid aircraft. They are powered by hydrogen combustion through modified gas-turbine engines. Liquid hydrogen is used as fuel for combustion with oxygen.

In addition, hydrogen fuel cells create electrical power that complements the gas turbine, resulting in a highly efficient hybrid-electric propulsion system. All of these technologies are complementary, and the benefits are additive.

There is a Wikipedia entry which is entitled Hydrogen Fuel, where this is said.

Once produced, hydrogen can be used in much the same way as natural gas – it can be delivered to fuel cells to generate electricity and heat, used in a combined cycle gas turbine to produce larger quantities of centrally produced electricity or burned to run a combustion engine; all methods producing no carbon or methane emissions.

It looks like the aircraft will be powered by engines that are not too different to the current engines in today’s aircraft.

This must be a big advantage, in that much of the research done to improve the current gas-turbine powered by aviation fuel will apply.

Liquid Hydrogen

It appears all three aircraft will use liquid hydrogen.

Liquid Hydrogen Storage

I believe the major uses for hydrogen will be aircraft, buses, cars, rail locomotives and multiple units and heavy trucks.

All will need efficient storage of the hydrogen.

Some applications, will use it in liquid form, as it is a more dense form, but it will need to be kept cold.

As aviation will probably be the most demanding application, will it drive the storage technology?

Oxygen

This will be atmospheric oxygen, which is used by any combustion engine.

Fuel Cells

Will the fuel cells be used to provide power for the plane’s systems, rather than to power the aircraft?

Most airlines do this with an auxiliary power unit or APU, which is just a small gas-turbine engine with a generator. The A 320 family use one made by Pratt & Whitney, which is described on this page of their web site. It is the third one on the page and is called a APS3200. This is said about its function.

Pratt & Whitney APS3200 is the Airbus baseline APU of choice for the Airbus A320 family of aircraft. It is designed to meet performance and environmental requirements for modern day, single-aisle aircraft. The APU comprises a single-shaft, fixedspeed, high-pressure ratio core driving a load compressor that provides bleed air for cabin conditioning and main engine starting, concurrent with 90kVA of electrical power.

The APU is usually located in the tail.

In the ZEROe family will there be a fuel-cell powered compressor to provide bleed air for cabin airconditioning and main engine starting?

Slippery Aerodynamics

Airbus seem to be the masters of slippery aerodynamics, which will help make the planes very fuel efficient.

Lightweight Composite Structures

Like the latest Airbus airliners, these planes will be made from lightweight composite structures and I wouldn’t be surprised to see weight saving in other parts of the aircraft.

Carbon Emissions And Pollution

There will be no carbon dioxide produced, as where’s the carbon in the fuel?

But there could be small amounts of the oxides of nitrogen produced, by the combustion, as nitrogen will be present from the air.

Noise

As the aircraft are powered by gas-turbine engines, there will be some noise.

The Mathematics Of Hydrogen-Powered Aviation

The mathematics for these three aircraft must say, that the designs are feasible.

Otherwise Airbus wouldn’t have published a detailed Press Release, only for it to be torn to pieces.

Pressures Driving Aviation In The Next Ten Years

Aviation will change in the text ten years and it will be driven by various competing forces.

Environmental Issues

Pollution, Carbon Emissions and Noise will be the big environmental issues.

Hydrogen will go a long way to reducing the first two issues, but progress with noise will generally be made by better engineering.

COVID-19 And Future Pandemics

These could have a bigger effect, as to make flying safe in these troubled times, passengers will need to be given more space.

But I do wonder, if there is an administrative solution, backed up, by innovative engineering.

Could a very quick test for COVID-19, that would stop infected passengers boarding, coupled with high quality automatic cleaning and air purification, ensure that passengers didn’t get infected?

Entry Into Service

Airbus are quoting 2035 in the Press Release and this YouTube video.

Is that ambitious?

Thoughts On The Three Designs

My thoughts on the three designs, follow in the next three sections.

The ZEROe Turboprop

This is Airbus’s summary of the design for the ZEROe Turboprop.

Two hybrid hydrogen turboprop engines, which drive the six bladed propellers, provide thrust. The liquid hydrogen storage and distribution system is located behind the rear pressure bulkhead.

This screen capture taken from the video, shows the plane.

It certainly is a layout that has been used successfully, by many conventionally-powered aircraft in the past. The De Havilland Canada Dash 8 and ATR 72 are still in production.

The Turboprop Engines

If you look at the Lockheed-Martin C 130J Super Hercules, you will see it is powered by four Rolls-Royce AE 2100D3 turboprop engines, that drive 6-bladed Dowty R391 composite constant-speed fully-feathering reversible-pitch propellers.

These Rolls-Royce engines are a development of an Allison design, but they also form the heart of Rolls-Royce’s 2.5 MW Generator, that I wrote about in Our Sustainability Journey. The generator was developed for use in Airbus’s electric flight research program.

I wouldn’t be surprised to find the following.

• , The propulsion system for this aircraft is under test with hydrogen at Derby and Toulouse.
• Dowty are testing propellers suitable for the aircraft.
• Serious research is ongoing to store enough liquid hydrogen in a small tank that fits the design.

Why develop something new, when Rolls-Royce, Dowty and Lockheed have done all the basic design and testing?

The Fuselage

This screen capture taken from the video, shows the front view of the plane.

From clues in the picture, I estimate that the fuselage diameter is around four metres. Which is not surprising, as the Airbus A320 has a height of 4.14 metres and a with of 3.95 metres.

So is the ZEROe Turboprop based on a shortened Airbus A 320 fuselage?

As the aircraft has a capacity of less than a hundred passengers and an Airbus A320 has six-abreast seating, could the aircraft have sixteen rows of seats.

With the seat pitch of an Airbus A 320, which is 81 centimetres, this means just under thirteen metres for the passengers.

The Technical Challenge

I don’t feel there are any great technical challenges in building this aircraft.

• The engines appear to be conventional and could even have been more-or-less fully developed.
• The fuselage could be a development of an existing design.
• The wings and tail-plane are not large and given the company’s experience with large composite structures, they shouldn’t be too challenging.
• The hydrogen storage and distributing system will have to be designed, but as hydrogen is being used in increasing numbers of applications, I doubt the expertise will be difficult to find.
• The avionics and other important systems could probably be borrowed from other Airbus products.

Given that the much larger and more complicated Airbus A380 was launched in 2000 and first flew in 2005, I think that a prototype of this aircraft could fly around the middle of this decade.

The Market Segment

It may seem small at less than a hundred seats, but it does have a range of greater than a 1000 nautical miles or 1150 miles.

Consider.

• It compares closely in passenger capacity, speed and range, with the De Havilland Canada Dash 8/400 and the ATR 72/600.
• The ATR 72 is part produced by Airbus.
• The aircraft is forty percent slower than an Airbus A 320.
• It is a genuine zero-carbon aircraft.
• It looks like it could be designed to have a Short-Takeoff-And Landing (STOL) capability.

On the other hand, a lot of busy routes, like London and Edinburgh and Berlin and Munich are less than or around 400 miles.

These short routes are being challenged aggressively by the rail industry, as over this sort of distance, which typically takes four hours by train, rail has enough advantages, that passengers may choose not to fly.

Examples of cities with a range of between 400 and 1000 miles from London include.

• Berlin – 571 miles
• Cork – 354 miles
• Inverness – 445 miles
• Lisbon – 991 miles
• Madrid – 781 miles
• Palma – 835 miles
• Rome – 893 miles
• Stockholm – 892 miles
• Warsaw – 900 miles

This aircraft would appear to be sized as an aircraft, that can fly further than passengers are happy to travel by train. But because of its cruising speed, the routes, where it will be viable would probably be limited in duration.

But important routes to, from and between secondary locations, like those that used to be flown by FlyBe, would surely be naturals for this aircraft.

It looks to be an aircraft that could have a big future.

The ZEROe Turbofan

This is Airbus’s summary of the design.

Two hybrid hydrogen turbofan engines provide thrust. The liquid hydrogen storage and distribution system is located behind the rear pressure bulkhead.

This screen capture taken from the video, shows the plane.

This screen capture taken from the video, shows the front view of the plane.

The aircraft doesn’t look very different different to an Airbus A320 and appears to be fairly conventional. It does appear to have the characteristic tall winglets of the A 320 neo.

The Turbofan Engines

These would be standard turbofan engines modified to run on hydrogen, fuelled from a liquid hydrogen tank behind the rear pressure bulkhead of the fuselage.

If you want to learn more about gas turbine engines and hydrogen, read this article on the General Electric web site, which is entitled The Hydrogen Generation: These Gas Turbines Can Run On The Most Abundant Element In the Universe,

Range And Performance

I will compare range, performance and capacity with the latest Airbus A 320.

ZEROe Turbofan

• Range – 2300 miles
• Cruising Speed – Mach 0.78
• Capacity – < 200 passengers

Airbus A 320

• Range – 3800 miles
• Cruising Speed – Mach 0.82
• Capacity – 190 passengers

There is not too much difference, except that the A 320 has a longer range.

The Cockpits Of The ZEROe Turboprop And The ZEROe Turbofan

This gallery puts the two cockpit images together.

Are they by any chance related?

Could the controls and avionics in both aircraft be the same?

A quick look says that like the Boeing 757 and 767, the two planes have a lot in common, which may enable a pilot trained on one aircraft to fly the other, with only minimal extra instruction.

And would it be a simple process to upgrade a pilot from an A 320 to a ZEROe Turbofan?

The Fuselages Of The ZEROe Turboprop And The ZEROe Turbofan

I estimated earlier that the fuselage of the Turboprop was based on the cross-section of the A320.

Looking at the pair of front views, I wouldn’t be surprised to find, that both aircraft are based on an updated A 320 fuselage design.

Passengers and flightcrew would certainly feel at home in the ZEROe Turbofan, if internally, it was the same size, layout and equipment as a standard A 320 or more likely an A 320 neo.

The Market Segment

These are my thoughts of the marketing objectives of the ZEROe Turbofan.

• The cruising speed and the number of passengers are surprisingly close, so has this aircraft been designed as an A 320 or Boeing 737 replacement?
•  I suspect too, that it has been designed to be used at any airport, that could handle an Airbus A 320 or Boeing 737.
• It would be able to fly point-to-point flights between most pairs of European or North American cities.

It would certainly fit the zero-carbon shorter range airliner market!

In fact it would more than fit the market, it would define it!

The ZEROe Blended-Wing Body

This is Airbus’s summary of the design.

The exceptionally wide interior opens up multiple options for hydrogen storage and distribution. Here, the liquid hydrogen storage tanks are stored underneath the wings. Two hybrid hydrogen turbofan engines provide thrust.

This screen capture taken from the video, shows the plane.

This aircraft is proposed to have the same performance and capacity as the ZEROe Turbofan, which includes a 2000 nautical mile plus range.

The only other aircraft with a similar shape is the Northrop Grumman B-2 Spirit or Stealth Bomber. This is not a fast aircraft, but it is able to fly at an altitude of 50,000 ft, which compares to the 60,000 ft of Concorde and the 43,000 ft of an Airbus A 380.

I wonder, if the blended-wing body is designed to fly very high at around the 60,000 ft, which was Concorde territory.

It would only be doing 515 mph and would be well below the speed of sound.

So what is the point on going so high?

The air is very thin and there is a lot less drag.

It is also worth reading Wikipedia on the design of flying wings.

It might be possible to fly much further than 2000 nautical miles. After all Airbus did put in a plus sign!

Is this aircraft the long-distance aircraft of the three?

Extending The Range

I do wonder, if the engines in these aircraft could be capable of running on both hydrogen and aviation biofuel.

As the ZEROe Turboprop and the ZEROe Turbofan planes have empty wings, which in a conventional aircraft would hold fuel, could the space be used to hold aviation biofuel to extend the range?

Certification Of The Planes

The ZEROe Turboprop and ZEROe Turbofan are aircraft, where a lot of the design will already have been proven in previous aircraft, so will probably be much less onerous to approve, than the blended-wing body design.

Conclusion

It looks to me, that Airbus have designed three aircraft to cover the airline market.

I also feel that as the ZEROe Turboprop and ZEROe Turbofan, appear to have conventional airframes, that they could be delivered before 2035.

If I’m right, that the blended-wing body is a high flyer, it will be a ride to experience, travelling at that height all the way to New York.

September 22, 2020 Posted by AnonW | Hydrogen, Transport | A 320 neo, Aerodynamics, Airbus, ATR 72, Flying, Hydrogen-Powered Aircraft, Rolls-Royce, Rolls-Royce 2.5 MW Generator, ZEROe, ZEROe BWB, ZEROe Turbofan, ZEROe Turboprop | 6 Comments