At the beginning of December 2020, I joined Lilium as Chief Technology Officer. Prior to joining, I was Chief Engineer and Managing Director at Rolls-Royce Germany. In my career I have been responsible for delivering a number of world leading turbofan jet engine programmes including the BR725 for the Gulfstream G650 and the Trent XWB for the Airbus A350. Like many other aerospace engineers who joined Lilium before me, I was curious as to how Lilium’s technology would really perform in practice. At first glance, it certainly appeared tricky for Lilium’s ambitious architecture to achieve the stated mission profile. For example, it appeared to me that the associated fan size and power consumption implications of electric ducted jet engines might make such an architecture impractical, or at least economically non-viable in an eVTOL aircraft given the thrust required for take-off.

I reviewed this technology and architecture in detail as part of my due diligence. I found it to be technically sound and genuinely impressive and now as part of the team, I have seen much of the innovative technology, analysis and, importantly, test data that underwrites the concept. To share some of that insight, this blog lays out the core elements of the Lilium architecture and the principal technical arguments as to why this architecture is powerful when applied to the aircraft mission profile. Where possible, I have also addressed common misconceptions regarding the aircraft architecture.

It is fair to say that the team at Lilium have been keeping their heads down, quietly getting on with things. Going forward, our sincere hope is to be more transparent (sensitive IP notwithstanding) about our technological progress and design thinking. The goal of this blog and updates to come, is to invite a wider audience from the aerospace and high-technology communities into the conversation. Hopefully this is also the beginning of making these exciting technologies more accessible for everyone.

What are we trying to achieve?

To set context, let me quickly explain the ambitions behind the service and its technical requirements.

Lilium envisions directly connecting inner towns and cities across ranges of between 40 and 200km at launch (and up to 500km longer term) at speeds of up to 300km/h, while enabling significant time savings for individual passengers compared to alternatives. We call this Regional Air Mobility (RAM) – not to be confused with Urban Air Mobility (UAM) that typically seeks to connect points within a city over much shorter distances (<20km). In parallel we have aimed for the highest payload of passengers (or freight) in the market since this translates into improved operating economics and, by extension, the flexibility to offer truly competitive ticket prices to customers. The revenue potential of an aircraft can be assessed in terms of passenger-kilometers per day per aircraft, which is ultimately a function of passenger seat-count multiplied by speed.