Elysian Aviation Plans on Pushing the Limits

Electric aircraft offer a simple proposition: decarbonization, a goal for airlines and operators large and small worldwide.

Given the energy density limitations of today’s aviation batteries, zero-emission flight is expected to come at the expense of range and capacity. But according to Daniel Rosen Jacobson, cofounder, co-CEO, and chief business officer of Elysian Aviation, it doesn’t have to be that way.

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“Because of the weight of the battery and the low energy density of batteries, what you need to do is actually build a bigger plane,” Jacobson told FLYING at the Paris Air Show in June.

Most electric models are destined for short-hop flights and a handful of passengers. Think electric vertical takeoff and landing (eVTOL) air taxis like Archer Aviation’s Midnight or Joby Aviation’s S4, both intended for a maximum of four travelers and trips under 100 nm. Even hybrid-electric designs, such as Electra’s EL9 or Heart Aerospace’s ES-30, are expected to max out at about 30 passengers despite improvements in range.

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But Elysian’s E9X—its concept for a full-electric, zero-emission regional airliner—is being developed for as many as 90 passengers. Jacobson predicted it will have a range of about 800 kilometers (432 nm) at launch, targeted for early next decade.

“It is essentially a bigger is better concept,” he said. “Because if you can build a plane that is truly zero emission, that can already fly a significant range without any major battery improvements…then having a larger plane has a better business case.”

Jacobson believes the E9X will one day be a staple of large airline fleets. He envisions it flying regional routes under 1,000 km (540 nm) that are occupied by turboprops or even narrowbody models. Per Jacobson, these account for about half of the world’s flights, though some estimates place that share even higher. Already, Elysian is working with Dutch flag carrier KLM and subsidiary Transavia to turn its vision into reality.

“At go to market, it’ll be likely that an airline will incorporate this where they currently fly turboprops or regional jets,” Jacobson said. “But the fact that it will likely be already close to, or even already competitive with, the narrowbodies means that in their network they can be quite flexible.”

Bigger Is Better

Building a large electric aircraft may seem counterintuitive given the inherent limitations of batteries. But Jacobson believes the industry is looking at it from the wrong angle.

“Most academics have said, ‘If we want to electrify aircraft—we take an efficient plane, a turboprop of today, and we try to electrify it—what happens is the weight becomes a huge blocking factor, and your range is too limited because of the weight of the batteries,’” he said. “But you shouldn’t look at aircraft like that. Because [turboprops] are designed to carry the least amount of fuel possible, or at least be very efficient with fuel.”

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Jacobson and Elysian cofounder Rob Wolleswinkel, who spends his weekends flying for a small Dutch airline, instead looked to the past, when aircraft like the Boeing 707 or B-52 carried tens or even hundreds of thousands of gallons of fuel. 

“Their energy weight was much higher in ratio than their other types of weight, their structural and their pedal weight,” Jacobson said. “And that is what is applied here [with the E9X].”

After that “lightbulb moment,” Elysian commissioned a study with Delft University of Technology, a few miles from its headquarters in the Netherlands, to study the feasibility of a larger electric model. Researchers found that with a low enough structural weight, such a design could fly farther than previously thought.

According to Jacobson, Elysian’s clean-sheet design will weigh about 75 tons, in the neighborhood of the 707 and B-52. But much of that weight comes from batteries, which will be stored within an approximately 138-foot wing—wider than the Boeing 737. The batteries are intended to power eight electric engines and propellers, with a gas turbine-based reserve system for emergency power.

Elysian believes the configuration could achieve a range of 500 km with existing battery technology. However, Jacobson said that if battery energy density reaches 300 watt-hours per kilogram—at the high end of lithium-ion batteries for electric cars—the E9X could reach 800 km.

Researchers at Massachusetts Institute of Technology, meanwhile, contend that regional electric planes will need to hit 1,000 watt-hours per kilogram to be viable.

“We are totally dependent on where the battery technology will go,” Jacobson said.

To mitigate that, the plan is for airlines and operators will swap out the batteries when they degrade below about 90 percent in quality.

“That means that at every battery swap, there is an opportunity to swap in slightly better battery cells into the pack,” he said. “And so our idea is, every couple of years, an airline can upgrade the battery cells in their battery pack and increase their range.”

Despite being more of a “moon-shot project,” the E9X could integrate more seamlessly with large airlines—or corporate or aerial tourism operators—than eVTOL and other smaller electric models. A second study Elysian commissioned with consultancy CE Delft found its efficiency on short-haul routes could surpass hydrogen or even sustainable aviation fuel (SAF). Jacobson said those technologies will be “part of the solution, but not the entire solution.”

Decarbonization is an obvious draw.

“But why it’s really a no-brainer is the cost profile,” Jacobson said. “It’s the fact that batteries get cheaper and cheaper and cheaper. Fuel for now is getting more expensive because of SAF cost and supply.”

Elysian projects the E9X will be cost competitive with existing turboprops and narrowbodies, assuming energy costs double due to SAF or European Union emissions trading scheme (ETS) mandates. The company is working with KLM to validate its economic model.

The Runway

It could be years or even a decade before the E9X enters service. However, Elysian is collaborating with a few key partners to hit its early 2030s target. Jacobson said the company has already begun working with the European Union Aviation Safety Agency (EASA) to certify to the regulator’s CS-25 standard for large aircraft, with plans to involve the FAA at a later stage. It is progressing toward EASA design organization approval (DOA), which would allow it to begin building aircraft.

Aiding those efforts is sister company Fokker Services Group, an OEM that also offers a full suite of aftermarket services from parts supply to MRO. Elysian and Fokker engineers share an office and collaborate frequently, Jacobson said.

In addition, both companies were spun out of Panta Holdings, which in 2022 sold AvCorp Industries—a supplier of major structures for Boeing, Lockheed Martin, Bombardier, and others—to France’s Latecoere.

“We’ve been able to benefit from people who have certified aircraft, who have a lot of experience,” Jacobson said.

Jacobson said there is still work to be done on the regulatory side. Elysian and a few other startups, for example, are in discussions with the European Commission to modify weight-based airport charges.

“If you’re going to be charged on the basis of MTOW, that is not a level playing field,” Jacobson said. “That means a kerosene plane will be massively advantageous in terms of cost.”

Still, he said, “we do feel that…there is an increased desire for the aerospace sector and startups within that to be successful, to stay in Europe.”

Post-certification, Jacobson expects Fokker to serve as an MRO partner. He envisions pilots being able to add an E9X type rating to their commercial certificate. And already, Elysian is soliciting their feedback.

“We find it very important that pilots can give feedback on this aircraft early on,” Jacobson said.

The company in July launched a workshop with current and former KLM and Transavia pilots, many of whom have experience on turboprops and narrowbodies. It asked them how the E9X may compare in terms of earning potential and gauged their level of comfort with electric propulsion and certain operational quirks, such as a steeper-than-typical takeoff. Elysian does not yet have a cockpit mockup but is using virtual reality technology to simulate the experience.

“For now, it’s really more of a conceptual exercise,” Jacobson said. “Our plan is to kind of evolve it into getting more and more physical in terms of the hardware that we create.”

Jacobson said Elysian and KLM are planning about eight more workshops in 2025, each with a different focus. An initial workshop in June, for example, centered around passenger experience. Future sessions could involve network planning and aircraft maintenance.

Over the course of the multiyear partnership, the companies will study aircraft specifications, pilot controls, operational profiles, and other aspects to ensure the E9X fits within current and future KLM networks. Pilots will also have a say in the concept’s direction.

“It’s really about making sure that pilots understand and feel comfortable with the operation, so we’re not making big mistakes from the pilot point of view,” Jacobson said. 

This feature first appeared in the September Issue 962 of the FLYING print edition.