Another Dutch start-up is vying to enter the commercial aircraft market with a disruptive, sustainable aircraft design. After Maeve and Fokker Next Gen, this week saw the launch of Elysian Aircraft's battery-electric 90-seater in Orlando at the American Institute of Aeronautics and Astronautics (AIAA) Sci-Tech conference. Elysian is the brainchild of three Dutchmen: Daniel Rosen Jacobsen as CEO and Chief Business Officer. He is the son of Jaap Rosen Jacobsen, who through Panta Holding tried for years – in vain – to resurrect Fokker and launch a revised 130-seater called Rekkof, which is Fokker spelled the other way around. Jaap Rosen Jacobsen passed away last August. Acting as Chief Technical Officer is Rob Wolleswinkel, who has worked at Fokker Aircraft and the Royal Dutch Air Force. Reynard de Vries is Director of Design and Engineering. Together with French company Caravelle and Panta Holding, the Rosen Jacobsen family is investing a start-up capital of $10 million in Elysian Aircraft. Later this year or in 2025, Elysian has planned a first capital raise as part of the estimated $5 to $8 billion required to develop the airliner and have it available in 2033. Low wings with eight motors Elysian unveiled the E9X concept of an all-electric 90-seater with a range of 800 kilometers. The aircraft, which is almost the same size as an Airbus A320neo, has a low wing, four electromotors with small propellers fitted on each wing, and a T-shaped tailplane. It should weigh around 76 tonnes. However, the approach of Elysian is rather different from the two other Dutch start-ups. Initially, Maeve Aerospace intended to design an all-battery 44-seater, but it radically changed this to a hybrid-electric 80-seater in December after CTO Martin Nüsseler concluded that an all-battery aircraft was not going to work. It is too heavy and slow and battery technology is not advancing quickly enough. Earlier, Airbus and easyJet already concluded that batteries are not the solution for decarbonizing medium-haul aircraft. Fokker Next Gen is all about hydrogen, although it can offer a new 130-seater based on SAF and kerosene too. Elysian, on the other hand, is fully behind the battery concept. It backs this up with two studies it commissioned for Delft University in The Netherlands, which re-examined the pros and cons of batteries, looked at misconceptions, and included revised calculations based on new design principles. The first study says: “We conclude that a battery-electric aircraft for up to 120 passengers with a battery-electric maximum cruise range beyond 1.000 km, plus 300+ km reserve range, provided by a SAF-fueled gas turbine, is feasible, assuming a usable battery energy density of 300 Wh/kg. The discrepancy between the cruise range estimates presented in this paper and the range of electric aircraft as concluded in previous studies is caused by four misconceptions.” Batteries integrated in the wings The second study specifically looks at an aircraft the size of the Elysian E9X. With an energy density of 360 Watthours per kilogram, a 90-seater should be able to fly 800 kilometers or even 1.000 kilometers when new batteries become available. This range covers 50 percent of all scheduled flights. Joris Melkert, senior lecturer of aerospace engineering at Delft University, adds that the E9X has a gas-turbine turbogenerator in the tailplane solely to cover energy reserves. It is a reserve energy system and not a range extender. One of the innovations that should offer Elysian an advantage is that the batteries are not integrated within the fuselage, but in the wings with a modest aspect ratio and folding wingtips. This way, unused space within the wings is used and the weight is there where lift is generated. This allows for a lighter fuselage construction. “Placing the batteries in the wing is crucial to minimize the structural weight of the aircraft, since it reduces the root bending moment compared to having batteries in the fuselage, and thereby reduces the wing structural weight. (…) This design choice comes with its own challenge regarding access to batteries for replacement and ensuring safety in case of cell or module failure (e.g. thermal runaway). This requires an integrated design of the battery-wing system where several compromises have to be made. However, the substantial weight reduction enabled by placing batteries in the wing gives ample room for new integration solutions.” Hot potatoes The second study identifies in total ten “hot potatoes” or design challenges. The first is wing/battery-pack integrated design, followed by wing structural sizing for aeroelastic and landing loads with batteries in the wing. Design and certification of the reserve energy system, high-voltage component and system design, and thermal management system sizing for powertrain components and batteries are other challenges. Others are the sizing of tail surfaces and control surfaces with distributed propulsion, the propeller/wing aerodynamic performance in cruise and high-lift conditions, and low-noise propeller design for distributed-propulsion aircraft. Yet, the study concludes that “we believe that battery-powered aircraft for commercial air transport deserve at least the same amount of attention as hydrogen, hybrid-electric, and SAF-based propulsion systems. The opportunity that electric aircraft offer to substantially reduce the negative impact of aviation on global warming warrants substantial investments into the maturation of the technological building blocks that enable electric aviation.” Joris Melkert welcomes the way Elysian has approached the project. "They have taken a scientific approach to the battery concept and presented it at the AIAA Sci-Tech conference in all openness, willing to accept criticism from scientists. They want to demonstrate that in their view, there is a place for a battery-powered airliner between the smaller electric aircraft and bigger ones," Melkert tells AirInsight. Elysian will have to convince investors that its concept offers the best solution and return on investments. With various projects vying to do the same, it remains to be seen if this project will get beyond the concept phase. "I have left my crystal ball at home today, but it remains to be seen if the industry is open to other players or will wait and see what Airbus, Boeing, and Embraer will do," says Melkert.