Before joining Lilium as head of flight test in 2017, Leandro Bigarella spent almost 16 years in the flight test department at Embraer, working on certification programs including the Phenom 300 business jet and the KC-390 military transport plane. That meant he had been involved with first flights before, but none of them quite as momentous as the one that took place on May 4, 2019, when the full-scale prototype of the Lilium Jet spun up its 36 electric ducted fans and lifted vertically into the air.
“The first flight was a remarkable day,” Bigarella recalled. Unlike a conventional airplane or helicopter — most new models of which are simply variations on well proven designs — the Lilium Jet was something completely new: “new concepts, new flight test approaches, new tests, new technologies,” he said. To see it actually flying was “really intense. . . . Everybody was super excited and very proud, too.”
When that first flight was revealed to the world two weeks later, it marked the re-emergence of the German company, which had been relatively quiet since debuting an early prototype of its eVTOL aircraft in 2017. The urban air mobility industry has grown by leaps and bounds since then, and behind the scenes, Lilium has, too. Buoyed by $100 million in investment, the company now employs more than 300 people at its headquarters near Munich, with another 150 positions currently open. Although Lilium doesn’t expect to continue growing quite as aggressively as it has in the past year — when its team nearly tripled in size — “we still have to grow a lot,” said CEO Daniel Wiegand.
Like many companies in the competitive and secretive eVTOL space, Lilium is still playing most of its cards close to the vest. Access to its aircraft and engineering facilities is tightly controlled, and the company has yet to publicly disclose its latest flight testing progress (suffice to say, the Lilium Jet can do more than a tentative vertical take-off and landing).
In late August, however, Lilium hosted eVTOL.com at its Munich headquarters to discuss its approach to engineering and flight test and its vision for the future of the company. In contrast to many other eVTOL players, Lilium isn’t focused on intra-urban missions, skeptical that the time savings for a short hop across town will justify taking an air taxi. Instead, the company is placing its bets on regional air mobility, looking at using the Lilium Jet to create cost-effective transportation links between cities, or from cities to the countryside.
“Taking the car for a 300-kilometer trip in many cases takes four hours, in some cases five or six hours if there’s a mountain range in between — we can fly this in one hour,” Wiegand said. “And equally taking a commercial aircraft typically also takes three to four hours for the whole trip. So the sweet spot is really below the commercial aircraft, but above the typical inner-city trip.”
The Lilium Jet for the job
Achieving Lilium’s ambitious performance targets for its five-seat, fully electric vehicle — a range of 300 kilometers (186 miles) at a speed of 300 km/h — is a tall order using today’s battery technology. And the Lilium Jet’s design has some vocal critics, notably Uber director of aviation engineering Mark Moore, who earlier this year contended that the aircraft has impractically high disc loading in a hover. Yet Lilium has shrugged off this criticism, previously telling eVTOL.com, “We’re confident that the progress we’re making ‘behind the scenes’ will enable us to deliver our stated goals and we look forward to proving that in due course.”
The Lilium Jet is a fly-by-wire, vectored thrust aircraft that features 36 ducted fans distributed across its main wing and forward canard. (Lilium describes these ducted fans as “jet engines” because they move air much as does a conventional jet engine, albeit using a different power source.) The ducted fans are divided evenly across 12 independently articulating flaps, with flight control achieved through software that varies the position of individual flaps and RPM of individual fans. The current prototype is remotely piloted only, but a future version, which will undergo certification, will have a human pilot on board, and autonomous capabilities are targeted for some point in the future.
For Bigarella, the idea of designing a flight test program for this wholly novel aircraft was what attracted him to Lilium. “I heard about this new VTOL market coming and I said, wow, this is pretty challenging because it’s something that no one has ever tested before from a flight test perspective,” he said. “Lilium came to my attention because of the design, and they were quite advanced in terms of flight testing.”
Bigarella said his biggest challenge “was to find the means of mixing both rotary-wing and fixed-wing disciplines into one single project.” Not surprisingly, his flight test team — encompassing flight test and instrumentation engineers, test pilots, and maintenance technicians — reflects a mix of both fixed- and rotary-wing experience. One particular hurdle was finding test pilots who were proficient not only in airplanes and helicopters, but also with remote-controlled aircraft for the early testing phases. “This was something really different for us — planning flights with this kind of mindset,” he said.
Despite the novelty of the aircraft configuration, Bigarella said that Lilium has followed a fairly traditional, iterative approach to flight testing, starting with extensive flight simulation and systems testing on the ground prior to first flight. Now that the aircraft is flying, the flight test team is expanding the envelope gradually. “So it’s starting to add some maneuvers — some turns on spots, some lateral displacement, some forward and backwards movement — and then start exploring until we are able to fly the whole envelope [out to] 300 kilometers per hour,” he said. While the focus of this testing phase is on aerodynamic and handling qualities, the team is also collecting data on battery discharge rates that will inform optimization activities at future stages of the program.
Bigarella remarked that he has been happily surprised by the stability of the aircraft, which has progressed well beyond its somewhat wobbly first flight.
“It’s amazing how stable the aircraft is,” he said. “[This is] something that caught our attention as flight test, because usually when you see this kind of new development [there are] some instabilities. . . . So the design is really something that is surprising us positively.”
According to Wiegand, Lilium is designing the aircraft systems to transport category levels of reliability: a 10-9 likelihood of catastrophic failure, consistent with the European Union Safety Agency’s recent Special Condition for Small-Category VTOL Aircraft. “It’s pretty clear that if you want thousands, maybe hundreds of thousands of eVTOLs flying around at some point, you need to achieve a similar safety track record like commercial aviation does today,” he said. “So we took the same approach which is standard in commercial aircraft, that you have no single point of failure on the whole plane. Be it on the flight controls and fly-by-wire, on the actuators, on the engines, on the battery, the power circuits — everything [has redundancy].”
Additionally, Lilium has made the decision to install a ballistic parachute on the aircraft, despite the associated weight penalty. At 10-9 levels of reliability, “classic aviation says you don’t need a parachute,” Wiegand said. “But at the same time we can see there are still things against which we can’t design . . . and for these cases, we want to have something on board that gives us a good night’s sleep.”
Another priority for Lilium’s design team is noise, which has been perhaps the greatest obstacle to the wider use of helicopters in urban environments. Through careful attention to ducting and fan speeds, the company is engineering the Lilium Jet to be at or below the noise targets identified by Uber in its Elevate white paper — roughly one-fourth as loud as small helicopters, and significantly less annoying.
“I love the sound of jet engines and helicopters and all these things when I’m excited about the tech, but when I’m on a Sunday afternoon lying in my garden, it’s different, right?” Wiegand said. “This is an area where Lilium is putting a lot of focus — to create something that is low noise enough so we can actually use this in a widespread way in communities, and bring this close to where we live.”
A transportation system for everyone
Wiegand has always been passionate about aviation. He began flying gliders when he was 14, “so long before I was allowed to drive a car,” he recalled. “And I was excited about everything that can fly. I had to have a parrot at home, took lots of slow motion movies from the bird to find out how it was staying in the air, how it was propelling forward, etc.”
Wiegand studied aerospace engineering at the Technical University of Munich (TUM), with an emphasis on flight propulsion. In 2013, he was living in a shared flat in Glasgow, Scotland, when he began sketching the first designs for the aircraft that would eventually become the Lilium Jet. As he recounts it, after seeing what he was up to, his flatmate told him, “If you think this is technically feasible, you should found a company and do this” — and so he did, along with his TUM classmates Sebastian Born, Patrick Nathen, and Matthias Meiner. Today, $100 million in investment later, the advice seems sound, but it was not an obviously wise idea at the time.
Since those early days, the design of the Lilium Jet has undergone remarkably few changes. “There was initially [around] 20 different concepts, but we evaluated [them] and converged quite early on the aircraft,” Wiegand said. However, Lilium’s concept of operations has evolved considerably. The original goal was to create an affordable two-seat vehicle for personal transportation, but the founders quickly realized that the limited market of private pilots wouldn’t sustain the volumes necessary to drive down manufacturing costs. So instead, the company now plans to use the Lilium Jet as the basis for an air taxi service — one it will operate itself.
“I see the Lilium Jet very much in regional mobility, and by regional we are talking about things like inter-city, or city to countryside, or very large metropolitan areas with a diameter of maybe 100 kilometers or so,” Wiegand said. Although the company has yet to announce its launch markets, he said Lilium is seeing interest from local governments around the globe (such as Miami-Dade County, Florida, whose mayor, Carlos Giménez, has disclosed “preliminary talks” with the company).
Wiegand said that Lilium is advocating an open system of VTOL landing pads, similar to public roads or airports today. Under such a framework, any city could build VTOL landing pads for immediate connectivity with all of the other landing pads within range. “They can be served by any service that is compatible [with] these landing pads, so it could be a Lilium service; it could be some other service,” he said. He believes this investment will be attractive to cities because it will connect them with neighboring municipalities “at a speed which is unique in history” — and at a fraction of the cost of ground infrastructure projects like highways and rail.
For similar reasons, Wiegand thinks the Lilium Jet could play a transformative role in emerging markets, too. In places like Africa, for example, there’s “a huge need for infrastructure and transportation in general. And with an eVTOL solution like the Lilium Jet, they can basically leapfrog billions in investment and 20 years of waiting time for a high-speed rail network or for a highway network.”
What will it take to persuade the rest of the world to embrace this vision? For Lilium, “our view on this is we should convince customers with facts,” Wiegand said. “Our idea is we offer a solution to the world that is safe, that is robust, that is reliable, and does what we promise.” He thinks that if the company delivers on those goals, early adopters will flock to the aircraft, followed eventually by more reluctant flyers.
Lilium’s rollout will be correspondingly gradual. The company is aiming to be operational in several locations by 2025, likely launching with scheduled service along limited fixed routes. But Wiegand envisions a not-too-distant future in which “you can pick up your smartphone and say, OK, I need a flight from here to a city 200 kilometers away, and I’m getting that flight within three minutes or five minutes on the landing pad next door.” Who wouldn’t want to live in a world like that?