The Lilium Jet, the Thirty-Six Ducted Fans That Rejected Every Other eVTOL Playbook, and What the Bankruptcy and Rebirth of Germany's Air Taxi Gamble Tells Us About the Real Cost of Going First

The Lilium Jet defied every standard eVTOL design template - 36 ducted fans embedded in a fixed wing instead of exposed rotors - and the company behind it burned through more than $1 billion before collapsing into insolvency in October 2024. It was then acquired out of bankruptcy and restarted as a new entity. That arc is one of the most instructive stories in aviation right now.

What Makes the Lilium Jet Different from Every Other eVTOL

Most eVTOL designs follow the same basic architecture: large lift rotors for takeoff, a transition to forward flight, then the rotors fold or tilt while the wings take over. Four aerospace students at the Technical University of Munich rejected that approach entirely when they founded Lilium in 2015.

Instead of exposed rotors, the Lilium Jet uses 36 small ducted electric fans - each roughly 8 to 10 inches in diameter - embedded directly into the leading edges of its main wing and a smaller forward canard wing. In hover, the fans point downward and generate vertical thrust. As the aircraft accelerates, they tilt progressively toward horizontal until, at cruise speed, the wings are generating lift and the fans are only overcoming drag.

The engineering term for this architecture is distributed electric propulsion with vectored thrust. The practical logic is straightforward: at cruise speed, a fixed-wing aircraft is dramatically more efficient than any rotor-based system, because the wing carries the weight and the fans only need to push the aircraft forward.

The Performance Case for the Lilium Design

The physics behind this approach are real. At speeds between 150 and 186 mph, a fixed-wing aircraft uses significantly less energy per mile than a helicopter or multirotor design where rotors must simultaneously propel and support the aircraft throughout the flight.

The seven-seat Lilium Jet was targeting a range of approximately 186 miles at a cruise speed of around 186 mph. Those numbers describe a different market than most eVTOL programs have targeted - not metropolitan hops, but city pairs too close for commercial airlines and too far for comfortable driving.

Why the Design Is Also Harder to Build and Certify

The reason most eVTOL engineers default to large rotors is not because they failed to consider smaller embedded fans. It is because the transition from vertical to forward flight is aerodynamically complex, and that complexity compounds when 36 small fans are involved rather than a few large rotors.

During transition, power demand spikes and control authority requirements are substantial. The software required to individually manage 36 fans through that arc - while simultaneously managing airflow over the wing - is genuinely difficult engineering with no direct precedent in existing tiltrotor research.

Battery energy density compounds the problem further. The Lilium Jet requires very high power delivery during hover, a spike during transition, and then moderate power in cruise - all from the same battery cells. Meeting those three requirements simultaneously with today’s battery technology is a hard constraint, and the energy density improvements the original business plan depended on had to arrive on a schedule the market does not guarantee.

From Prototype to Public Markets to Insolvency

Daniel Wiegand and the founding team flew their first unmanned prototype in 2017. It was small, but it flew and demonstrated the core concept convincingly enough to attract institutional capital.

Tencent participated in the Series B round in 2019. LGT, a major European private bank, and Atomico, one of Europe’s leading venture funds, also invested. By 2021, Lilium had raised hundreds of millions of dollars and took the company public on the Nasdaq via a special purpose acquisition company (SPAC) merger - the same vehicle Joby Aviation, Archer Aviation, and several other eVTOL companies used around the same time.

The SPAC era in eVTOL was built on a shared assumption: that certification would arrive on a predictable schedule, infrastructure would develop in parallel, and revenue would start flowing before the mid-2020s. That assumption proved optimistic.

Certification timelines stretched industry-wide. The FAA’s powered-lift regulatory framework - which U.S. operators needed to certify their aircraft domestically - was not finalized until late 2024. Capital markets shifted as interest rates climbed, SPAC valuations came under pressure, and battery density improvements lagged projections.

By October 2024, Lilium had burned through more than $1 billion in total investment. The company filed for insolvency in Germany, and the U.S. subsidiary filed for Chapter 11 bankruptcy shortly after.

Why Investors Chose to Revive the Program After Bankruptcy

The aircraft program did not terminate. The intellectual property, aircraft design, and engineering team were acquired out of insolvency and reconstituted as Lilium GmbH, a new entity. Michael Andretti, through Andretti Global, put capital into the restructured company alongside other investors.

The rationale rested on a specific distinction: Lilium ran out of time and money before reaching the finish line. That is different from the technology being fundamentally broken. The aircraft had accumulated real flight hours on technology demonstrators. Lilium had built regulatory relationships with the European Union Aviation Safety Agency (EASA). The aerodynamics work, and the software coordinating 36 fans through the transition envelope is proven engineering.

The new Lilium GmbH is operating with a leaner structure, targeting EASA certification first before the American market, and has scaled back near-term production ambitions. Attempting simultaneous certification in two jurisdictions while building production capacity and managing public market expectations contributed directly to the original company’s failure.

Why This Matters for the Future of Commercial Aviation

As of late 2024, the first eVTOL aircraft to carry paying passengers are just reaching initial certification. The economics of those early commercial operations are still being tested against real-world infrastructure constraints.

Vertiport infrastructure does not yet exist at commercial scale. This is an industry-wide challenge that is separate from aircraft certification and does not resolve simply because one aircraft program receives approval. Capital and regulatory bandwidth are both finite, and multiple competing programs are drawing on both.

The Lilium story is specifically a case study in what happens when a genuinely novel aircraft encounters a regulatory framework being built from scratch at the same time. The agencies were not slow because they were indifferent - they were constructing certification standards for aircraft that are simultaneously a helicopter, a fixed-wing airplane, and something with no existing category. That process takes time. Companies that priced their survival on it running faster than it actually ran made an expensive assumption.

The broader eVTOL shakeout is not finished. The companies that survive this period will not be determined by which had the best technology on paper or the largest early valuation. They will be the ones that manage capital efficiently, identify a realistic market entry point, and commit only to timelines the certification process can support.

Key Takeaways

• The Lilium Jet uses 36 ducted fans embedded in a fixed wing - a fundamentally different architecture from every other major eVTOL design, with real cruise-efficiency advantages and significantly greater certification complexity.
• Lilium filed for insolvency in October 2024 after burning through more than $1 billion, then was acquired out of bankruptcy and reconstituted as Lilium GmbH, with new investors including Andretti Global.
• The program’s failure was a capital and timeline problem, not a fundamental technology failure - the aircraft flew and the core aerodynamics are sound.
• The FAA powered-lift framework was not finalized until late 2024; the reconstituted Lilium GmbH is now pursuing EASA certification first, a more focused sequencing than the original company’s dual-jurisdiction approach.
• The broader eVTOL industry still faces three unresolved constraints in parallel: certification timelines, battery energy density, and the absence of commercial vertiport infrastructure at scale.