The Future of Advanced Air Mobility

Lilium Selects Honeywell To Supply Fly-by-wire Flight Controls and Avionics for eVTOL

Honeywell Aerospace will provide its new compact fly-by-wire flight control system and integrated avionics suite for Lilium’s seven-seat eVTOL aircraft. Under an agreement announced today, the U.S. aircraft systems group is also making a direct investment in the German startup and will hold an undisclosed equity stake.

The fly-by-wire system is being developed specifically to control all moveable parts on the all-electric Lilium Jet, including its 36 control surfaces and ducted fans for the lift-and-cruise model. The avionics suite will include flight displays, sensors, radio communications, and transponders.

According to Lilium chief program officer Yves Yemsi, Lilium’s engineering team has been working closely with their counterparts in Honeywell’s Urban Air Mobility (UAM) division for the past 18 months as part of a competitive bidding process for the major program partnership that started two years ago. “Integration of these key systems is always very complex and so getting both the fly-by-wire and avionics from the same company is good because they will absorb this complexity,” he told FutureFlight.

The integrated fly-by-wire and flight control systems will be based on triple redundancy, with each having its own microprocessor to avoid a common cause of failure. “This is a key element of the safety for our aircraft, and we are taking no risks,” Yemsi explained. “We have chosen to take the same approach as for the [Boeing] Dreamliner. It would be expensive for a startup to take this approach [alone] but Honeywell has been thinking about how to take this approach for this market for a long time. Each of the computing platforms will conduct a constant health check of the sensors and if one diverges, the other two will ‘vote’ [on how to manage the flight controls]”

Honeywell’s UAM laboratory in Phoenix has been working on customizing and scaling flight controls and avionics for new eVTOL aircraft for some time. “They have adjusted the size, weight, and power and have designed the systems for our Lilium cockpit and in a way that will limit the workload for our single-pilot operations,” said Yemsi.

Honeywell has already supplied some test versions of the equipment to Lilium’s engineering base near Munich and development work will continue both there and in Phoenix. Lilium has established a systems integration laboratory that will support the development of an iron-bird ground testbed that will pave the way for the first full-scale prototype of an aircraft that is due to enter commercial service in 2024.

Under the agreement, Honeywell also will be involved in devising flight training for the Lilium Jet. The company, which provides avionics, flight controls, and propulsion, for a wide variety of existing aircraft, including light business jets, has extensive experience of single-pilot operations and is pioneering simplified vehicle operating concepts for the advanced air mobility sector.

The Lilium Jet is projected to have a range of more than 155 miles and a cruise speed of 175 mph at 10,000 feet. This performance is slightly lower than the 186 miles/186 mph targets for the five-seat technology demonstrator, reflecting tradeoffs being made to secure the additional payload.

Lilium’s other named program partners include Toray Industries and Aciturri, which will make the fuselage and wings. Lufthansa is leading the pilot training process and business aviation services group Luxaviation has been recruited to handle aircraft operations.

This summer, the Lilium engineering team expects to resume flight testing with the five-seat demonstrator as they prepare for the first fully-conforming prototype to be built in 2022. Five or six of the series production prototypes will be used to support flight testing for the type certification campaign.