German aerospace company Lilium unveiled its electric vertical take-off and landing (eVTOL) Lilium Jet in March 2021. The development of the seven-seat aircraft will facilitate next-generation sustainable, high-speed regional transportation.
The quiet vertical take-off and landing capabilities will allow the aircraft to access more landing sites, providing an opportunity for the company to build a higher density network without expensive ground infrastructure. The seven-seater Lilium Jet together with the regional shuttle service business model can deliver economical urban air mobility (UAM) for passengers and enterprises.
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In 2018, the company applied for concurrent type certification for a high-capacity aircraft with the European Aviation Safety Agency (EASA) and Federal Aviation Administration (FAA). The company subsequently started the development of the seven-seat Lilium Jet in stealth mode.
The Lilium Jet secured CRI-A01 certification basis from EASA in 2020 and is expected to be launched for commercial operations in 2024.
The company intends to list on Nasdaq through a merger with Qell Acquisition and is planning a launch network for the aircraft with up to 14 vertiport development sites in Florida.
Design and features of Lilium Jet
Lilium’s 8.5m-long eVTOL aircraft will have a wingspan of 13.9m (45.6ft) and capacity for six passengers, along with a pilot. The airframe of the Lilium Jet will be made of high-performance carbon fibre composite materials.
The aircraft will feature a separate cockpit with a single pilot seat, while luggage space will be located at the jet’s rear end. The cabin is designed for a comfortable passenger experience, with spacious window seats and a central aisle for legroom, without compromising the performance of the aircraft.
The electric jet engines of the aircraft will depend on an electric motor-driven single-stage rotor or stator system.
Designed for ease of manufacturability and scalability, the aircraft will have 30 times fewer components than a commercial airliner. The company will utilise automotive-style methods for manufacturing and is working towards a fully automated high-quality production of the engines, actuators and batteries.
Flight control and avionics of Lilium Jet
Lilium Jet will be controlled by Honeywell’s next-generation integrated UAM avionics system and state-of-the-art fly-by-wire flight control system.
The avionics system is designed to ease operations for a single pilot, free up greater passenger capacity and reduce training time. The flight control system features a customised advanced flight deck as the central interface for the pilot, along with a vehicle management computer and high integrity flight controls computing platform. The system will control the aircraft’s movable parts, including the 36 control surfaces and ducted fans.
Propulsion system
The aircraft will be driven by Lilium’s proprietary technology, Ducted Electric Vectored Thrust (DEVT) propulsion system. The propulsion system will contain 36 individually controllable wing flaps. Each wing flap will have a ducted electric fan. The 36 ducted electric fans will be incorporated in a 1:2 ratio on the canard to the main wing. Acoustic liners will be installed into the duct walls for noise absorption.
The ducted fan propeller system will improve the loading capacity of the aircraft compared to similar-sized open propeller system-based aircraft. An active electronic differential thrust control will provide directional stability and ensure the manoeuvrability of the aircraft during all phases of flight.
The propulsion system will offer payload advantages and aerodynamic efficiency with a lower noise profile and ground footprint.
Performance
The fixed-wing aircraft with embedded distributed propulsion and no tail will offer superior aerodynamic efficiency and the ability to cruise.
The eVTOL aircraft will have a maximum range of 155 miles (250km), including service range and reserves. It can reach a cruise altitude of 10,000ft (3048m) at a cruise speed of 175mph (280km/h).
Contractors involved
Lilium entered a long-term partnership with Aciturri, an aerostructures manufacturer, to build the airframe of the Lilium Jet in February 2021. Aciturri will produce Lilium Jet’s primary composite structures, utilising materials supplied by Toray Industries.
Honeywell, a manufacturer of electronics and mechanical systems for aircraft, was contracted to develop flight control systems and avionics for the Lilium Jet in June 2021.
Other contractors include Lufthansa Aviation Training, Tavistock Development Company and Ferrovial.
