GENEVA—German electric vertical-takeoff-and-landing (eVTOL) aircraft manufacturer Lilium has signed a formal partnership with its avionics provider Honeywell and Japanese automotive specialist DENSO to co-develop and manufacture electric motors for the Lilium Jet. 

The deal, publicized during a press conference held by the three companies at EBACE, confirms a direction of travel implied by earlier announcements. Honeywell and DENSO signed a long-term agreement to develop propulsion units for the urban air mobility (UAM) sector in 2021. Shortly after, Honeywell was selected by Lilium to supply the Lilium Jet's avionics and flight-control systems. Honeywell also announced an undisclosed investment in Lilium. 

The Lilium Jet design involves 30 ducted fan motors mounted on wings and canards. The motor being developed for and with Lilium is bespoke to the Lilium Jet, despite Honeywell and DENSO's partnership being aimed at the eVTOL sector as a whole. 

"Three years ago I started the scouting for the best supply partner for this unique piece of technology," Lilium chief operating officer Yves Yemsi told the EBACE press conference May 23. "They have to be very powerful, they have to be very light, and they have to be extremely reliable—of the highest quality. We were made aware of this alliance between what I think are the two best suppliers in their field: so we think, if there is an alliance like that—two powerhouses getting together just to support the eVTOL sector—then we have to jump on that. So that's what we did."

Yemsi, who stresses that Lilium prefers to describe its vehicle as a regional air mobility solution as opposed to a purely intra-urban vehicle, said that the design collaboration between the three firms has been ongoing for more than two years. 

"Because our jet has a unique architecture we wanted to make sure that we could get to the best technological solution," he said. "We spent hours, days, with DENSO engineers to optimize, get prototypes, and optimize again—until the point where we were all satisfied. And then we asked Honeywell to help us together to pass qualification, because we rely on Honeywell already with their experience to qualify and supply."

The details of Honeywell's pact with DENSO allow both partners flexibility in how to approach different projects. 

"We are delivering all the solutions from the alliance as the alliance," says Taylor Alberstadt, senior director of business development in Honeywell's hybrid-electric propulsion division. "We're equal partners. The details behind manufacturing may vary between different applications, but for solutions ultimately delivered to the customer, it's an equal Honeywell-DENSO relationship. In this instance Honeywell is the prime to Lilium, but Honeywell and DENSO work together in everything we do to provide our solutions to Lilium." 

"We will provide the stator and the rotor of the propulsion unit," said Florian Walter, DENSO's European sales lead for UAM. "We'll have in advance of 100 kW, and will be approximately below 4 kg (9 lb.).”