Much of the motivation behind electric aviation startups is the belief that lower operating costs, and therefore fares, will unlock pent-up demand for regional connectivity using aircraft that are within reach of today’s battery and fuel cell technology. But first the companies have to convince airlines.
Feedback from those prospective customers has led Dutch startup Maeve Aerospace to redesign its planned hybrid-electric aircraft to match more closely the characteristics of the regional jets (RJ) it is intended to replace, while still promising a 30-40% reduction in fuel burn.
Delft-based Maeve has been assisted in its rebranding by Mitsubishi Heavy Industries RJ Aviation (MHI RJ), which acquired the legacy CRJ program from Bombardier in 2019. Under an agreement announced in November, Maeve is paying MHI RJ to provide engineering and marketing services.
The result of that collaboration is the newly unveiled Maeve Jet Series 500 (MJ500), a CRJ-inspired 76-100seat aircraft with five-abreast seating and hybrid-electric propulsion. Gone are the propellers mounted regionalturboprop-style on a high wing that marked Maeve’s previous concept, the 80-seat M80. The MJ500 has a low-set swept wing and aft-mounted openrotor/stator propulsors.
When configured as a 76-seater to comply with U.S. pilot scope clause limits, the MJ500 is designed to fly 1,200 nm, cruising at Mach 0.75 and 35,000 ft. while burning 30-40% less fuel than the CRJs and Embraer ERJs and E175-Els it is designed to replace. Operating cost is reduced by about 20%.
This is the third redesign for Maeve, which was founded in September 2020 to develop a 44-seat all-electric regional airliner with a range of up to 300 nm. In December 2023, the startup switched to a hybrid-electric 80seater, and Pratt & Whitney Canada joined the program in July 2024 to supply the powertrain.
“Optimization of the aircraft configuration is driven by customer feedback,” Maeve Chief Technology Officer Martin Nusseler says, explaining the latest design changes. “We are not changing the proposition of a high-economic-value regional aircraft, but we received two key pieces of feedback.”
One concerned internal noise and customer perception that passengers do not want to see propellers next to the cabin. The second concerned aircraft productivity and the need to match the cruise speed of today’s RJs. Together they necessitated a change in propulsion architecture.
The engine is unchanged, but the propulsor is new. “We still have this advanced thermal hybrid engine from Pratt, which gives us a unique efficiency at altitude versus normal turbine engines,” Nusseler says. “In combination with a new propulsor, we have a step change in overall engine performance.”
Maeve needed to replace the M80’s propellers with something smaller in diameter to enable rear-fuselage mounting to remove noise from the cabin. “This is not possible with a normal propeller because the diameter is too big,” he says. “The installation challenges are too high.”
Instead, Maeve is planning to develop an unducted propulsor with a rotor swirl recovery system, similar to the open fan that CFM International is developing under the Revolutionary Innovation for Sustainable Engines (RISE) program. “And rear-mounting the engine was driving opportunities to improve the aircraft configuration,” Nusseler says. “We changed from a high-wing to a low-wing configuration, which is a natural effect.
“We have this open-rotor and stator combination, similar to the RISE concept from CFM but with a much better engine behind it,” he continues. “Typically, the rear-engine configuration gives you a weight challenge because you have a longer pylon. We compensate for this with the clean wing.”
The MJ500 has a parallel hybrid configuration, with both the advanced thermal-cycle engine and an electric motor driving into the propulsor gearbox. “It’s a mild hybrid because batteries are not born to fly,” Nusseler says.
The aircraft is optimized for performance at altitude. “This is why we are flying at Flight Level 350 like a jet,” he notes. “We have an engine with the power of four PW150s at altitude, but on the ground, we do not have more power [than Pratt & Whitney’s big turboprop], Takeoff power from the thermal engine is 5,000 shp, and at altitude it’s nearly the same—it’s 4,800 shp.”
The electric motor provides 300 kW (400 hp) to the gearbox, which can be used to boost power for takeoff if required by field performance. “We are optimizing the thermal engine completely for cruise, and the remaining gap for takeoff and initial climb performance we are covering with hybridization by the electric motor,” Nusseler explains.
“We can with full payload start at a 4,900-ft. runway, and the engine does not have the typical thermal stress with a higher power setting,” he notes.
The thermal engine runs at constant output, and power is set with the electric motor. “We don’t have an impact on the ground infrastructure at airports because the batteries will be charged during cruise flight,” he says.
Six battery modules are housed under the floor, behind the avionics bay, in a Are compartment separating them from the cargo. “The batteries are not huge,” Nusseler says. “And we’re targeting a life of 1,800-2,000 cycles for one year of operation. The minimum target is to exchange the batteries during yearly maintenance.”
The level of hybridization is limited to providing takeoff boost and powering the aircraft’s 800-volt more electric systems. “We are not taking bleed,” Nusseler says. “We have an electric environment control system, no auxiliary power unit, and we have electric anti-icing. This combination of hybridization to boost takeoff with a more electric aircraft gives us an overall system benefit and also a weight benefit versus just implementing a more electric system in a traditional aircraft architecture.”
Maeve took the opportunity of the redesign to reconsider the cabin. “There was clear feedback to futureproof the platform for the coming decades,” he says. “This needs a wider, flve-abreast cabin because four-abreast is too squeezed for the passenger.”
Passengers do not like the change when moving between a regional and a narrow body. Neither do the airlines. “Today, everybody is coming into the cabin with a trolley, and only a flve-abreast cabin with the same size bins provides room to reduce the increasing lead times for boarding,” Nusseler says.
A flve-abreast cabin also provides more space for below-floor cargo. “The wetted area is not significantly increased with the five-abreast,” he says. “With four-abreast, you are pushed to a double bubble to give you room for underfloor cargo and the right cabin height.”
With a completely circular five abreast cross-section, the lower weight penalty for pressurization offsets the drag penalty from increased wetted area, Nusseler says. The wider fuselage also results in a shorter aircraft, which is better for weight and balance with rear-mounted engines.
Key to the redesign was producing a single aircraft that can seat 76 in a three-class configuration, 90 in two classes and in a 100 single class. “The aircraft will be able to achieve the weights required by U.S. scope clauses,” says Ross Mitchell, MHIR J senior vice president for strategy and business development. “It will be able to make 76 seats and 86,000 lb. We also believe the aircraft we’re designing will be able to meet 50 seats and 65,000 lb., the weight limit for small regional jets with a CRJ550-type interior.”
Maeve is primarily targeting the replacement market for the U.S. fleet of scope-compliant CRJ550s, -700s and -900s, ERJs and E175-Els. “With the 76-seat configuration, we can fly 1,200 - 1,500 nm,” he says. “For the 100-seater, it’s more like 900 nm. We are not targeting a 2,500-nm range because we think it’s not necessary. What is the benefit of it? Because with longer range, you increase the aircraft weight.
“The design target is around a 1,000-nm range, which gives us a lighter aircraft,” Mitchell continues. “We can go down to 50 seats and still maintain the scope-clause requirements. This gives high flexibility to the MJ500 family and a big opportunity for customers to have one aircraft and reduce the diversity of their fleets.”
Beyond the U.S., Nusseler says the MJ500 will be more economical than flying Airbus A220s and Embraer E2s when their longer range is not required. “Five-abreast gives you this narrowbody feeling, and what we are doing is stretchable to 150 seats,” he says.
Maeve and Montreal-based MHI R J are in the concept design phase, which is planned to be completed by early next year. “We will then start the preliminary design phase,” Nusseler says. “PDR [preliminary design review] will be from the end of 2026 to mid-2027. We will fly at the end of 2029. Entry into service is targeted for the end of 2032, beginning of 2033.”
As a startup, Maeve does not expect to take the M J500 to production on its own, but to assemble a consortium of industry partners. “It is important to demonstrate the customer acceptance and concept robustness, that we have a business case,” he says. “The plan is to take the aircraft to PDR, then someone takes over.” Supported by initial investors, Maeve aims to tap public grants and loans to reach PDR.
“The reason MHI RJ is helping us is to ensure we have a consortium to take over the program,” Nusseler adds. “Such a program cannot be financed by a startup. We only can complete the predesign and make sure the main supply chain is complete. We are starting those discussions now.”
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