Steady steps to sustainability

Cranfield Aerospace Solutions, a subsidiary of Cranfield University, has received backing from the UK Government for a project to develop electric aviation. Professor Iain Gray, Cranfield University Director of Aerospace, talks Project Fresson and the development of electric aviation.

With an increasing focus on climate change and sustainability across the world, the aviation sector has been held to account in terms of its contribution to making a change. However, as Professor Iain Gray explains, sustainability is not a new concept for the aviation industry and Cranfield University has been a leading aircraft integrator in green commercial aviation for many years. “I think the aviation industry was arguably ahead of the curve in terms of its studies into electrification. You’ll find some consideration of electric flight has always been made since the beginning of aviation, but in terms of this current generation of electric aircraft ideas, Cranfield University began to be much more serious about it around seven years ago when it began to create its own product ideas, as well as doing studies with the likes of NASA.

“In the last two to three years, we’ve really seen industry come in alongside and wanting to capitalise on some of these early research ideas. Therefore, although it can be said there has been a much more accelerated vision of how we move the zero-carbon agenda forward since last year’s Paris Airshow, the impetus for Project Fresson far predates the last 12 months.”

Turning ideas into reality

With a £9m grant from the ATI Programme – a partnership to maintain and grow the UK’s competitive position in civil aerospace design and manufacture – Project Fresson will design, manufacture and integrate a hybrid–electric propulsion system into a nine-seat Britten-Norman (B-N) Islander aircraft, typically used on short flights such as island-hopping routes.

“When it comes to electric aircraft, there are two different approaches: electrifying an existing aircraft and manufacturing one from scratch. There’s an adage in aviation industry that you don’t change the airframe and engine at the same time, as there are many examples of people having tried and failed, but if you can keep one of the concepts, the risks are more manageable. That’s why in my view, electrifying an existing aircraft is the sensible approach, and this is what we are doing at Cranfield University with Project Fresson. We are taking an airframe and adapting it; taking a structure that’s well known and understood but developing an electric aircraft architecture.”

Following the demonstrator project, Cranfield Aerospace Solutions (CAeS) will go on to certify the modification through EASA to obtain a Supplemental Type Certificate. This will then be immediately available in the global market, allowing the 400+ current operators of B-N Islanders to convert their aircraft, reducing operating costs and their carbon footprint. “For emerging start-up companies creating an entirely new aircraft, I think they will find the technology looks good at a paper-based level and will develop benefits, but they will hit a ‘regulatory wall’ which they will find hard to progress through.”

In follow-on phases of CAeS’ green aircraft strategy, the intention is to design and implement a similar modification, this time to a larger existing 19-seat subregional aircraft type, then continuing with partners to design and build a new 19-seat aircraft. The design of the new aircraft will be optimised for emission-free propulsion, making use of the certified propulsion systems architecture from the earlier phases.

Safety considerations

In an industry where safety cannot be compromised there are always safety considerations, and electric flight is no different, but the considerations themselves are different from conventional aircraft. “The main difference is that if you have a conventional kerosene or Avgas-fuelled aircraft, then by definition, as that aircraft flies it’s burning fuel off and is getting lighter. Therefore, by the time it lands, the maximum landing weight consideration might be quite different from the take-off weight considerations, and the whole concept of that as a regulatory rule and what you do by way of diversions, or what you do if there’s a problem, such as dumping fuels, are all governed around a maximum landing weight consideration.

“With an electric aircraft, by definition, you’re not losing weight as the aircraft flies. The maximum take off therefore is pretty much the same as the maximum landing weight and that introduces some safety considerations, particularly when you’re looking at fuel reserves or the operational aspect of what to do if something goes wrong. You definitely have to take into account what happens in the event of a fire, or thermal management issues; all of these are recognised as needing to be addressed in the design process and of course no one would allow an aircraft to be certified where we cannot meet regulatory requirements.”

Supported by infrastructure

With a background working for Innovate UK – part of the UK Research and Innovation agency – Professor Gray has been a part of electric transport’s evolution. “I saw the development of electric cars and the way it evolved from pure research to prototype vehicles, on to demonstrative vehicles where big companies started to get involved, to today where literally every car manufacturer in the world is producing some sort of electric car. So, from an aerospace point of view, we are now starting to look at those early prototypes, to understand the technologies and the market itself. It really is still early days, though there are some parts of it that are moving quite fast and we have to be prepared for this.

“I think one of the biggest mistakes that the automotive sector made was that it didn’t quite look at the infrastructure requirements and vehicle requirements together in the way it should have and the way the aircraft industry is structured, it is so much more important to get this right. The consideration of the aircraft design itself, alongside the infrastructure and the regulatory framework that can deliver it, can’t be isolated. So, at a very high level, you need to look at it from an overall systems point of view right from the beginning, whether it be airport infrastructure, recharging capabilities, turnaround times, or ATM; and these need to be managed in both conventional terms and emergency procedures. It’s that emphasis of having to look at the overall system that I think is very important.”

Making a change

Professor Gray concludes: “If we are going to address the zero-carbon issue – which I believe we are – then electric is not going to be the answer by any stretch of the imagination. A statistic that sticks quite clearly in my mind is that one per cent of aircraft flights that take place today are for 8,000 nautical miles or greater and yet that one per cent contributes 20 per cent to the carbon footprint, and there’s just no way large transport aircraft travelling these distances can be electric, at least not in the near future. Therefore, electric aircraft only opens new market opportunities at the regional level. It’s really important to acknowledge that electric aircraft are only one part of the solution and climate change needs investment and support across the whole system.”