CIVIL | LILIUM JET
36 engines, no tail, no rudder, no oil circuits, no gearboxes, and no variable pitch fan blades is what defines and differentiates the Lilium Jet
There’s no denying that technology has consistently ignited human curiosity and has never failed to leave us amused by its innovations. It cannot be argued either that the forthcoming future that will soon have air taxis flying across the city skies to end the traffic woes of people, will be one of the most awestriking creation. Not just that, these taxis are being claimed to be unmanned which might be a bit challenging but is way more exciting. Many of the established names of the aerospace and aviation industry as well as the newcomers are all competing to be the most innovative with their air taxis and also to be the first ones to set this transition flying.
One of the most awaited unmanned air passenger taxis is that being built by the Munich-based startup, Lilium. Being called as the Lilium Jet, this upcoming flying taxi is set to compete with regular taxis and the company vouches that nothing like the Lilium Jet has ever existed before. With no tail or ailerons but 36 engines, Lilium Jet is already being hailed for its extremely unique design. It is a five-seater, electric, vertical take-off and landing (eVTOL) tilt jet.
Some of the most prominent features of the Jet have been listed as its two wings, one main wing measuring 11m across at the rear of the aircraft and a ‘canard’ wing at the front of the jet which resembles to a duck.
The canard wings each have two flaps and the main wings have four. Three of the company’s pioneering all-electric jet engines are mounted on each flap (each flap can move independently), which allows them to pivot and change the direction of the thrust they create.
THE UNIQUE DESIGN
The company states on its website that when they designed the Lilium Jet, they looked at more than 20 existing aircraft concepts but soon realized that none of them would deliver what they wanted. They were looking for levels of efficiency that were close to the limits of physics, delivered in the simplest way. So instead of tweaking an existing design, they chose to design something from scratch.
The result is the Lilium Jet which has no tail, no rudder, no oil circuits, no gearboxes, no variable pitch fan blades and only one moving part in the engines. The engine nacelles, the technical name for the engine casing, perform the function of aerodynamic control surfaces and act like the ailerons and elevator of a normal aircraft which is how the plane is balanced even without any tail or ailerons.
The aircraft is not created with just one main wing because it would have to sit in the center of the aircraft which would make accessing the Jet difficult for passengers. Additionally, it would make the aircraft longer as a conventional aircraft tail would be required then to maintain stability, which isn’t great from a weight or ground-maneuverability perspective.
Capable of traveling up to 300km in a mere 60 minute, the all-electric Lilium Jet is a pioneering tilt jet aircraft with 36 engines mounted on its flaps and is claimed to be the only jet-powered transition aircraft in the market
To make the aircraft more robust, safer, and easier to maintain and to lower the cost to certify, manufacture and operate the aircraft, Lilium follows its philosophy of simplicity being the key. The simplicity of the aircraft design not only contributes to the safety and affordability of the aircraft, but it has also allowed the design team to focus their efforts on creating a magical customer experience in the cabin, from panoramic windows to gull-wing doors.
To move the aircraft both vertically as well as horizontally, a concept called thrust vectoring is used. The concept is more commonly known to be associated with space rockets and fighter jets since in space you can’t rely on flaps and ailerons to direct the aircraft as you’re in a vacuum; there the direction is changed by adapting the angle of the thrust you generate. The Lilium Jet makes use of a similar premise. As the engines move together with their nacelles, they perform the function of aerodynamic control surfaces, allowing us to direct and move the thrust. This contributes in delivering a very smooth transition from vertical to horizontal flight. It also allows to change the rpm (revolutions per minute) and angle of each set of three engines allowing a very smooth and very precise trajectory. A shorter, canard wing generates more lift and controls the aircraft more effectively.
Capable of traveling up to 300km in a mere 60 minute, the all-electric Lilium Jet is a pioneering tilt jet aircraft with 36 engines mounted on its flaps and is claimed to be the only jetpowered transition aircraft in the market. With a top speed of 300 km/h and a range of 300km, the Lilium Jet claims to be capable of completing much longer journeys than the majority of its competitors. The 36 engines make the Lilium Jet more efficient, safer and more maneuverable, as they are well covered in the very unlikely case that an engine fails, the company ensures. Having more engines also allows distributing the power along the wing, generating further efficiency. Additionally, the maneuverability of an aircraft also increases if smaller engines are used. The time taken to increase or decrease power in a small engine is much less than that in a typical aircraft engine, meaning the Lilium Jet is able to respond much more rapidly to a control input. The ducted design of the engine captures and dissipates noise before it leaves the engine. The low vibrations of the engine ensure a smooth and quiet ride for passengers. With zero operational emissions and record-breaking power-toweight and thrust-to-noise ratios, they are the first-ever electric jet engines in commercial certification.
THE STORY BEHIND THE DESIGN
When designer Mathis Cosson sat down to sketch the Lilium Jet for the first time, his inspiration came not from the skies, but the oceans. He was inspired by one of nature’s most majestic creatures - the manta ray. “The way it glides almost magically through the water was something we wanted to emulate with the Lilium Jet, delivering a sense of calm elegance and minimalist design. From the initial design direction I received from an external agency to my earliest hand sketches and the casting of the final parts for the aircraft, we kept our focus on delivering something that looked as if it had been sculpted by nature rather than by the human hand,” said Cosson.
As a result, the manta ray-inspired Lilium Jet has been selected as a ‘Best of the Best’ award winner by the Red Dot Design Award organization in its 2019 ‘Design Concept’ competition - one of the most prestigious design awards in the world. It has also been selected as a ‘Best of the Best’ in their Concept category and nominated for Red Dot’s highest accolade - the Luminary Award, given to only one of more than 4,200 entries annually.
THE FIRST LOOK
Lilium revealed its new five-seater air taxi prototype for the first time in May 2019. The unveiling of the new Lilium Jet came as the all-electric aircraft completed its maiden flight in the skies over Germany earlier that month. The full-scale, the full-weight prototype was powered by 36 all-electric jet engines that allowed it to take-off and land vertically while achieving remarkably efficient horizontal, or cruise, flight.
Celebrating the landmark, Daniel Wiegand, co-founder, and CEO had said: “Today we are taking another huge step towards making urban air mobility a reality. In less than two years we have been able to design, build and successfully fly an aircraft that will serve as our template for mass production. Moving from two to five seats was always our ambition as it enables us to open up the skies to many more travelers. Whether its friends or families flying together or business travelers ride-sharing into the city, having five seats delivers an economy of scale. The Lilium Jet itself is beautiful and we were thrilled to see it take to the skies for the first time. With the perfect balance of range and speed, our aircraft has the potential to positively impact the way people choose to live and travel, all over the world.”
The prototype aircraft, which was controlled remotely from the ground, had since begun a rigorous flight test campaign to prove its capability and lay the foundations for certification of the aircraft.
THE FIRST FLIGHT
A complete test flight was successfully performed by the Lilium Jet on October 1, 2019, as part of the first phase of testing with the Lilium Jet, a milestone it has reached in less than six months since starting its flight test campaign. The flight, which lasted approximately three minutes formed part of the controllability tests and looked specifically at how the aircraft performs during banked turns in transition flight. Lilium’s on-demand air-taxi is aimed to be a reality by 2025.
The flight demonstrated the aircraft completing a vertical take-off and landing, climbing and descending at a rate of 300 ft/minute and cruising at 35 knots. The aircraft performed as expected during the test.
The aircraft completed a rough figure of eight during the flight, with the left turn being the specific test point for this flight. During this left turn, the aircraft banks first at 20° AoB (Angle of Bank) for approximately 90° heading change, before increasing the AoB to 30° for the remainder of the turn. The right turn was just for repositioning before landing and did not target a specific AoB. The entire test flight video can be seen on Lilium’s official website.
Since this test, the Lilium Jet has been successfully flown at higher speeds, recently reaching the 100 km/h milestone, and has completed the first phase of testing. The focus of the company in the second phase of testing, which is already underway, is on completing a full transition to wing-borne flight, which will mean moving the flaps through to 0°. This is a particular challenge as it means passing through a zone where the airflow will detach and reattach to the control surfaces.
Post its maiden flight the aircraft has been undertaking increasingly complex maneuvers and longer flights and has successfully completed more than 100 different ground and flight tests.
The first manufacturing facility, a 3,000 square meter space located at the company’s headquarters, will soon be complemented by a second, much larger, facility which is already under construction at the same site. Combined, they will support Lilium’s aim of producing hundreds of aircraft a year by the time commercial services begin in 2025.
Lilium had also announced earlier that it had selected London to be the base for a world-class software team that it plans to develop.
AIR TAXI THROUGH AN APP
What’s further interesting is that Lilium plans to let the passengers order this flying jet through an app. The Lilium Jet is part of an app-based flying taxi service that the company expects will be “fully-operational in various cities around the world by 2025.” Capable of traveling 300 kilometers (186 miles) in 60 minutes on a single charge, the battery-powered jet will connect cities through a network of landing pads. While the cost for the air-taxi’s service was not revealed, Lilium claims that it will be “comparable in price” with regular taxis.
Holding the promise to deliver the best range, speed, noise, and cost, allowing the customers to travel in style anywhere, anytime, without worrying about the impact on their pocket, or the environment, the Lilium Jet is certainly the most awaited air taxi.