This article provides a brief insight into the new and emerging technologies that will enable the Airbus A320 successor to be 30% more fuel efficient by the mid-2030s.
Image Source: Airbus
Last Tuesday, 9th June 2020, the French government announced a staggering €15Bn aid package for the French aerospace industry. Part of these funds will be used to lay down the groundwork and strategy to develop a successor to the Airbus A320, a workhorse for many airlines flying regional routes.
The A320 successor is to be “30% more fuel efficient” – the A320neo is assumed as the baseline.
The A320neo (a legacy design) is around 15-20% more efficient than the older A320s, and B787 (a clean sheet design) is somewhere around 20-25% more efficient than the B767 it replaced.
One can appreciate how massive a 30% improvement in fuel efficiency will be.
This A320 successor is most likely the new single aisle that Airbus CEO Guillaume Faury mentioned at the Dubai airshow in 2019. Faury mentioned the key enablers as cutting-edge production, design, and propulsion technologies.
Propulsion Technologies
The propulsion system – the power plant – is always usually the top of the list when it comes to improving fuel efficiency improvements, greenhouse gas reductions, or noise reductions. After all, this is where the fuel is burned.
The biggest improvements will likely come from 3 major pieces of technologies.
Ultra-high by-pass ratios (UHBR)
Turbofan engines used in the likes of an A320 have a big fan that you see when you board the plane from the front door. Majority of the air coming into the engine is accelerated and is never used for combustion – this is where most of the thrust is produced. Some of it that goes in is used for combustion and is used to mainly keep the big fan running.
Image below illustrates this.
The interesting challenge with UHBR engine integration would be where to place these. Most aircraft engines are typically placed underneath the wings, but the limitation becomes required ground clearance.
High Temperature Materials
Increasing thermal efficiency of the engine will reduce fuel consumption. Thermal efficiency depends on the ratio of temperature change during compression inside the engine core. The hotter the air is when it goes in for combustion, the better.
Materials need to be able to sustain these high temperatures without melting, and operate for years in this harsh, high stress environment. Heat management is another challenge when running at higher temperatures than previous engines.
Hybrid-Electric Propulsion
Hybrid-electric propulsion for aircraft works in principle the same way as for hybrid-electric cars. Depending on the architecture, they could be used at cruise where energy requirements are less than during take-off and climb, or they could be used during climb to save fuel.
A lot of development related challenges will be for megawatt motors, necessary electronics and the high voltage systems required to supply power to these, and how it operates in the low air density, cold cruise environment at 35,000 – 40,000 feet.
What about Hydrogen?
The French government’s announcement also mentioned the possibility of the new aircraft being hydrogen powered. It makes sense since hydrogen is about three times more energy dense than jet fuel. This has been done before too. More recent examples include Boeing Phantom Eye UAV, and DLR’s HY4, while it was originally tested by NASA and the Soviet Union too.
Hydrogen powered vehicles are certainly less polluting, more quite, and offer excellent efficiency compared to fossil fuels. I have written about hydrogen-powered aircraft here, which gives a great insight into this technology and its limitations.
Cutting-Edge Design
Aircraft design and engineering has come a very long way since the A320 was originally designed. With today’s massive high powered computing resources and digital tools available, a clean sheet design will leverage these for design throughout the supply chain.
Majority of improvements can directly be attributed to the following three.
Digital Twins
You may have heard this thrown around at digital and tech conferences. Really, a digital twin of an aircraft is a digital model representative of the aircraft to help simulate and test a part of the aircraft’s structure or system – for example, structural digital twin that simulates the stresses, or an avionics digital twin to simulate and test the aircraft behavior and response.
This will allow is rapid iterations of design, reaching design maturity faster. Boeing, as an example, has been able to improve first-time quality of parts by up to 40% using digital twins. Their use is quickly becoming widespread.
Topology Optimisation
Fancy word, but in simple terms, for a given set of constraints and loads for parts design, this is a computational method which outputs possible answers for which shapes work, and more importantly, WHERE material is required.
The reason this is so great is that it will be no heavier than it needs to. Until recently, this couldn’t be used to its full potential, because of manufacturing limitations. Which brings me to the next big technology.
Robust Additive Layer Manufacturing (ALM)
Also known is 3D printing, ALM methods have seen a lot of development and are maturing quickly! There have been small parts and brackets that are currently used on A350 and other aircraft. However, these have only been small parts.
With ALM methods becoming more mature and robust, they will be combined with structural topology optimization and digital twin tools to truly provide a very optimized design that had not been possible before. Here’s an example of an automotive part designed using topology optimization, which will be produced using ALM (Image source).
Cutting-Edge Production
The production rate of an A320 before disruptions due to coronavirus was 60 per month – it is now 40. Developing a product that will need to be ramped up to meet similar rates (or more) will require a fantastic level of effort to meet production schedules.
Aircraft parts factories and assembly lines have already started automating. Advancements in collaborative robotics and automation resulting from better more precise sensors, increasing level of compute, and connectivity brought on by ‘Industry 4.0’ will have a massive shift in ways of working throughout supply chains, increasing productivity.
The A320 has been a wildly successful workhorse for Airbus and the European aviation industry. All the new technologies, cutting-edge design tools and new engines would not make much difference in meeting aviation industry’s targets for fuel efficiency improvements and carbon emissions if they cannot be manufactured fast enough.
To summarise...
The A320 successor's 30% more fuel efficiency (compared to the A320neo) will be due to these technologies
Propulsion enabled by new ultra-high by-pass ratio engines that use more thermally advanced materials, run in a hybrid-electric configuration, and utilise biofuels.
Cutting-edge aircraft design enabled by use of digital twins, topology optimization for parts and assembly designs, and designing for ALM / 3D printed parts allowing for a much more optimized design than possible today. Truly cutting-edge.
Cutting-edge production enabled by use of collaborative robotics and automation, availability of digital data for manufacturing and production, making meeting high rate production possible.
Hydrogen will likely become a bigger part of this picture too.
Each one of these technologies warrants its own in-depth series of articles to explain fully.
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