The Farnborough International Airshow is quite unlike anywhere else on earth.
Every year, the largest aerospace and defence companies, along with military delegations from around the world, descend on the otherwise unremarkable town in the south of England to show off their latest wares and peruse the latest tech.
This year, however, was different. The show, which ran from 17 July until 22 July, coincided with the two hottest days on record in Britain. Temperatures topped 40 degrees celsius in some areas and there were wildfires across London, Leicestershire, Norfolk, and South Yorkshire.
Nonetheless, the show continued. New jets were taking off from the runaway outside the sweltering conference halls and defence contractors demonstrated their newest wares.
But, amongst it all, was a coterie of sustainable aviation companies including Lilium. Located front-and-centre at the entrance to conference hall one, the company was hard to miss and was turning heads with its stylish multi-purpose eVTOL (electric Vertical Take-Off and Landing) craft. We sat down with Alastair McIntosh, the company’s CTO, to get the low-down on the fast-growing company.
Seeing is Believing
“We’re coming into the market in 2025. I think once people see it’s real, I think you’ll get an accelerator effect,” says McIntosh.
“You see it in so many industries. Moving from propeller to gas turbine in aerospace. Once that got going, it just ran away with it.”
For many people, the idea of eVTOL craft whizzing above our heads still seems like science fiction. But, according to McIntosh, we’re closer than you might think.
“The uptake will be quite quick. But I think the important point for everybody who’s involved is recognising that it’s not kids’ stuff. It’s a serious business, it’s a regulated business, and we’ve got to do it in a safe manner.”
Central to the safety of Lilium’s craft, beyond extensively working with regulators and safety agencies, is its Ducted Electric Vectored Thrust (DEVT) propulsion system.
“DEVT is really at the heart of what we’re trying to do here. It had its genesis in how you create a low noise footprint. And that was kind of where it really started. And then the whole aircraft was kind of designed around capability,” explains McIntosh.
The DEVT system uses 40 small rotors located along the front canard and rear wing that can pivot to push Lilium’s jets off the ground and manage the transition to horizontal flight.
“The duct itself, in the unlikely event of a failure, will contain it [the rotor]. So it’s good for safety,” says McIntosh.
However, McIntosh says that his company’s manifold ducted rotors offer a range of performance improvements compared to Lilium’s open-rotor competitors.
“Having small engines containing a low speed gives actually a good low noise signal by having a duct around it, that helps contain the noise even further. So, you can actually tune as well the signals that you get. In the actual design, you’ve got one set of rotating blades, the fan, and a static structure behind it. You can match all that together and get a really good low-noise profile.
“It’s very simple as well, if you actually take a look properly at the cross-section, it’s just quite simply, one set of rotors, with direct drive and electric motors sitting behind it. How you then lay all that out in the aircraft is the kind of trick but allows us with a small diameter, to play tunes on the configuration.”
Open-rotor designs, by contrast, tend to be “quite noisy” and offer diminishing returns when it comes to expanding payload size — regardless of whether your payload is people or things.
“If you want to grow the aircraft, you’re limited to a 15-metre diameter heliport size,” says McIntosh.
“So, you’ve got that part that you’ve got to work within. Then, if you want to grow your payload, make the aircraft bigger, the most space that you have with open rotors, you’ve got one option to make the diameter of them [the rotors] bigger, and all of a sudden you run out of space, or you keep them the same size, you run them faster, which makes them noisier.”
A Multi-Purpose Plane
From an engineering point of view, it seems clear that Lilium has found a solution that works. Recent flight tests in Spain have shown it can manage the transition from vertical to horizontal flight successfully, for example.
That early promise is bearing fruit, as well as the company is winning clients around the world. In fact, during the five days of the Farnborough Air Show, the company announced four different new clients across the US and Europe.
Much of this might be due to the aircraft’s flexibility.
“The cabin at the moment, you can configure it as a four-seater private business jet. Or you can configure it as a six-seater shuttle. You can also take all the seats out of the cabin for air cargo, so it can do sustainable, eco-friendly activity in any of these sectors,” says McIntosh.
The only limiting factor, according to McIntosh is current battery technology. For many eVTOL sceptics, battery tech has been held up as the predominant reason why electric flight will not, ahem, take off. For McIntosh, this is simply a strawman argument.
“A huge amount of work when in the early days, we were talking to battery suppliers. I think we’ve talked to 50 plus, including the biggest in the world. We’ve landed upon Zen Labs and CUSTOMCELLS,” he says.
“The technology that they bring forward, is a bit of a differentiator. They can combine high energy density and high power density into one cell. Cells are normally optimised for either-or, whereas we need a high power density to get the aircraft off the ground and to land it. And you need the energy density to carry the distance that you want to fly. So that’s the sort of difference
“We’ve not just put all our eggs in one basket, we’re actually looking at other players, other battery cell suppliers as well. So there’s more to come in that. And we, we also see this as a continuum, you know, we’re at a point in time where that technology will keep moving forward, and it’ll help us extend the range and give us other options about extending a family of aircraft.”
The Future of Flight
“We’re not so much just waiting to see, we’re actually driving the technology that we’re interested in. Also, the people that we’re partnering with, Azul, NetJets, and now Bristow as well, are all targeted for a reason. Azul is a great market, Sao Paulo is one of the biggest areas where helicopter operations happen, so a huge network,” McIntosh tells us.
“NetJets, the biggest business jet operator, has great accessibility. Again, it’s how you bring your prime to the aircraft and such as accessibility, they’re a great market to unlock. And then, Bristow, again, a great helicopter operator in their own right. So again, that unlocks another market.”
However, while many are concerned that eVTOL craft will require new forms of infrastructure and investment in order to operate, McIntosh explains that this won’t be a problem when the craft actually begin commercial operations.
“There are things that can be done today. So there’s no reason why we can’t just get on with it. I think in terms of the number of players that we have in the market already, we welcome it. And the more the merrier. I think the first-to-market will have great success. But the second, and the third will also have great success. And once you open that up and actually show it can be done, more people will come.
“The bit that we’re working with as well, we’ve got a number of partners, airports, networks, looking in Germany, for example, looking in Florida, there’s a huge amount of interest in different states in North America, we’re looking at setting up networks. Ferrovial is a good example of one of the companies that we’re working with on actually disrupting vertiports.”
While the world around Lilium at Farnborough was, quite literally, catching fire, it seems as though the Munich-based company might prove a breath of fresh air for the aviation industry.