The Future of Advanced Air Mobility

Honeywell and Denso Join Forces to Make Electric Motors For Lilium Jet

Honeywell Aerospace and automotive group Denso are to provide the electric motors for Lilium’s seven-passenger eVTOL aircraft. The motors will power the all-electric vehicle's 30 ducted fan engines that are installed in the Lilium Jet’s wing and canard.

Announcing the new partnership at the European Business Aviation Convention & Exhibition on May 23, Lilium reported it has been working on the motor with companies for the past two years. It said the air-cooled design provides more structural simplicity and ease of maintenance versus liquid-cooled.

The piloted Lilium Jet, which will have a range of 155 miles and fly at speeds up to 175 mph, is intended to provide regional services connecting cities, rather than flying within cities. Lilium believes the design could be scaled up for a version that would accommodate between 10 and 15 seats.

Each 100-kW motor, weighing just over 4 kg (8.8 pounds), incorporates a rotor and stator in a centrifugal or "radial" configuration that differs from traditional axial designs. According to Lilium, this approach lowers the component’s weight, manufacturing costs, and susceptibility to foreign object damage.

“Three years ago we started scouting for the best supply partners for these e-motors, which need to be very powerful, very light, and very reliable,” said Lilium COO Yves Yemsi.

Honeywell makes turbofan, turboshaft, and turboprop engines for a variety of business airplanes and helicopters. The U.S. group is already developing the Lilium Jet’s avionics and flight control systems and invested in the company last year.

Denso is expected to provide expertise in high-volume production rates, based on its background in manufacturing engines for cars. Lilium’s other suppliers include aerostructures group Aciturri and battery specialist CustomCells.

Lilium recently resumed flight testing in Spain with a sub-scale technology demonstrator and intends to start building the first production-conforming aircraft for the EASA type certification process in 2023. This will lead to the start of a flight-test campaign expected to run for between 15 and 18 months leading to type certification in 2025.

Lilium has previously indicated that it was working toward a goal of getting approval for the all-electric aircraft and being ready to start commercial operations in 2024. Founder and CEO Daniel Wiegand told reporters on March 31 that the decision to delay is based on “the current status of design activities to develop the safest possible aircraft, our discussions with regulators, and even taking into account the continued supply chain disruption.”

In a letter to shareholders on February 28, Lilium reported that following a preliminary design review in the fourth quarter of 2021, it is reducing the number of electric ducted fans for the Lilium Jet from 36 to 30. The company said this change has been made possible by using a slightly larger and more powerful engine design and will reduce the parts count, weight, and system complexity, as well as improve the aerodynamic balance between the main wing and canards.

The German startup is working to achieve EASA type certification in 2025. Under the European agency’s Special Conditions VTOL rules, eVTOL developers like Lilium will have to prove that there is no single point of failure in the propulsion system. The company has not stated what redundancy there will be in terms of how many of the electric motors can fail without compromising a safe landing.

In February, Lilium reported that it is working to finalize an agreement with U.S.-based private aviation group NetJets to purchase rights for 150 Lilium Jets. The companies are discussing terms under which the fractional ownership and charter group might market the aircraft to private owners and also become an operating partner for Lilium’s planned service network. It already has a provisional operating partnership agreement with Europe-based business aviation group Luxaviation.

“At the heart of Aerospace 2.0 is finding new ways to move cargo and people, and we need new technology in the propulsion space to achieve sustainability that means we’ll be leaving the planet in a better place than how we inherited it,” said Honeywell’s senior business development director Taylor Alberstadt.