Where we’re going, we don’t need roads
This eVTOL from Lilium has zero operating emissions thanks to its innovative jets based on ducted electric vectored thrust.
Land mobility infrastructure is expensive to build and to maintain. Road congestion isn’t just bad for the environment, it’s bad for commerce and our general well-being. But air travel over short distances is expensive. The new wave of electrically powered vertical take-off and land (eVTOL) vehicles is the answer.
The European Union Aviation Safety Agency (EASA) defines a VTOL as having redundant propulsion systems and the capability of landing or taking off vertically. This loose description covers a growing number of design concepts, some of which are expected to be in service within two years.
With Europe’s first fully integrated vertiport being built in France, Volocopter, one of the many start-ups in this area, plans to operate an air taxi at the 2024 Olympics.
Heavy investment in eVTOL startups
The first opportunity widely recognized for eVTOLs is urban mobility. This describes short journeys within the boundaries of a city or urban area. For that reason, the term “air taxi” is already being used widely. There are now tens of startups vying for this emerging market. Urban air mobility, or UAM, is expected to be worth billions and see a compound annual growth rate in the range of 20% throughout this decade.
The aircraft in development vary. Not all will need pilots. Not all will have rotating propellers. Not all will have short range, or relatively low payloads. Initially, however, most will. It is the nature of electric flight that – after safety – weight and range will be the two biggest factors for early examples.
These necessary limitations will put pressure on the startups behind eVTOLs and, perhaps more importantly, demand more from the established aerospace companies that will be supplying them.
Diehl Aviation is an international first-tier supplier of avionics and cabin integration. Diehl signed a contract in 2020 with Volocopter to develop the primary and backup control computers for the company’s eVTOL aircraft, VoloCity. The contract for the development and production of Volocopter’s Flight Control Computers (FCC) marked Diehl’s entry into the UAM market, which it sees as a perfect addition to its portfolio.
More recently, Volocopter asked Diehl to develop the optical avionics communications that will operate with the flight control system. VoloCity features 18 rotors. Instead of a conventional fly-by-wire approach, it uses a fly-by-light control system. The optical splitter developed by Diehl is integral to the system. Using optical fibers instead of wires makes it immune to electromagnetic interference from sources commonly found in cityscapes, such as cell towers.
Diehl is also working on the battery management system. VoloCity has nine battery packs that are removed for recharging after each flight. The pilot can monitor the state of the batteries throughout the flight.
Volocopter has conducted successful crewed test flights in France.
New demand for vertiports
Although known for their ability to operate vertically, eVTOLs will still require somewhere for takeoff and landing. These areas, which we will all soon be referring to casually as vertiports, will be a hybrid between a service station and an airport.
According to EASA, vertiports will require careful planning, with space for not-quite vertical maneuvers. The approach and depart trajectory will be curved rather than vertical, as this is a more energy-efficient flight pattern. The higher the vertiport, the easier it will be to achieve this trajectory without obstacles. For this reason, vertiports are likely to be found on top of buildings, making use of existing helipads.
But there will be just as many, perhaps more, vertiports at ground level. These will require larger sites, with keep-clear areas around them. This could have a significant impact on town planning and urban development in the future.
New opportunities for established aeronautic companies
Not all companies developing eVTOLs are fresh-faced startups. Both Boeing and Airbus have announced eVTOL projects.
The CityAirbus NextGen from Airbus is an example. Airbus is developing it for city missions. It will have a range of 80 km and a top speed of 120 km/h. Airbus expects to have the aircraft certified by 2025.
Diehl is also working with Airbus and Thales on the control computers for the CityAirbus. Specifically, Thales is developing the primary computing system, while Diehl will be developing the secondary flight control computer. The secondary computer will work independently and monitor the primary computer. If needed, the secondary unit can assume flight control.
“In the future, eVTOLs will be a key part of mobility,” said Josef Köcher, CEO at Diehl Aviation.
The CityAirbus NextGen from Airbus represents one of many eVTOLs planned for launch in the coming years.
Not all eVTOLs will use propellers.
Instead of electrically driven propellers, Lilium has developed an all-electric ducted air jet engine to power its eVTOLs. This innovative approach gives its aircraft greater speed and range.
Diehl has also been selected to collaborate on the design and development of Lilium’s jet cabin. Diehl will integrate and manufacture interior components. This is part of the move toward sustainable mobility, which will demand lightweight design for eVTOL interiors.
“We are extremely happy about the extensive cooperation with Lilium in the innovative growth market of Regional Air Mobility,” said Harald Mehring, Chief Customer Officer at Diehl Aviation.
An artist’s impression of Lilium’s eVTOL interior
Where urban meets advanced air mobility
Urban air mobility is a subset of what NASA refers to as advanced air mobility (AAM). This will also include regional air mobility (RAM), which references more traditional air travel between regional airports using light aircraft.
Ultimately, AAM will also encompass unmanned aerial vehicles, or UAVs. Today this usually refers to military surveillance drones, but it is evolving to cover commercial delivery drones. These may be completely autonomous or remotely piloted.
Within a decade we can expect UAM to perpetuate large cities and extend into other urban areas. The eVTOL is beginning a long evolutionary journey. As the price point drops, they could become more important than electric cars and perhaps even more prominent.
Safety will, of course, be the overriding requirement and this is certainly one of the hurdles early pioneers still need to address. But with growing support from governments and licensing organizations, it feels certain that we will soon see eVTOLs in our skies.
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About Author
Philip Ling
Philip Ling is a senior technology writer with Avnet. He holds a post-graduate diploma in Advanced M...
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