The Future of Advanced Air Mobility

Eve Steps Up Ground Tests In Preparation For eVTOL Prototype Assembly

Eve Air Mobility is now selecting “main equipment” suppliers and during the second half of this year will begin assembling the first full-scale prototype of its eVTOL aircraft, according to Eve co-CEO Andre Stein. Speaking to reporters during a briefing held by parent company Embraer in Portugal on May 26, he said that recent ground tests of propulsion systems and wind tunnel testing have also helped move the program forward. 

“Eve Air Mobility is not just about routes, solutions, or infrastructure,” Stein said, “it's about the evolution of mobility as the key to making life more fluid and cities friendlier. This is the first project to graduate from EmbraerX,” he added, referring to the airframe manufacturer’s innovation hub.

Having submitted the basis for type certification to Brazilian aviation safety regulator ANAC in March, Eve plans to build its full-scale prototype in the second half of 2023, to be ready to start a flight test campaign in 2024 that it hopes will lead to certification and entry into service in 2026. ANAC will be the primary certification organization, Stein said, and Eve will seek FAA validation of the design, hopefully simultaneously as Embraer did with its E2 airliner.

Meanwhile, the cabin mockup of the Eve eVTOL is making the rounds of events, with its first showing this year at the SXSW show in Austin, Texas, in March. Eve’s first appearance after becoming a publicly-traded company takes place at the Paris Airshow June 19-25, where the mockup and a virtual reality simulation of an eVTOL flight will be on display at the Eve/Embraer pavilion.

Eve Air Mobility's revised design for its eVTOL aircraft.
Eve Air Mobility unveiled a revised design for its eVTOL aircraft in July 2022. (Image: Eve Air Mobility)

Embraer is the majority stockholder and it is closely involved in the development of the all-electric vehicle. Eve, which now employs around 300 people, can call on support from a 3,500-strong engineering team at its parent company. “We see that as an advantage,” Stein said. “We can flex that up and down. We don’t always need the same expert at the same time.”

Eve is aiming to garner a chunk of what it and its many rivals project to be a huge market for advanced air mobility (AAM) aircraft, estimated at three-quarters of a trillion dollars by 2040. So far Eve has signed letters of intent for 2,770 Eve vehicles from 26 prospective operators that include airlines, technology companies, and lessors, including Brazil's FlyBIS. “This gives us confidence there is an actual market behind it,” Stein said. 

Eve Expands eVTOL Ground Testing

The recent testing involved measuring aerodynamic performance and sound properties of propellers on a test rig, with the aim to maximize efficiency, lower the sound footprint, and reduce operating costs. Eve also began testing vertical-lift rotors on a truck-mounted mobile testbed at Embraer’s facility at Brazil’s Gavião Peixoto Airport, to evaluate rotor performance during the transition phase of flight. 

“This allows us to understand the sound profile,” he said. “It’s not only about decibels, it’s the profile.” He explained that engineers were able to test various propeller shapes on the rig and to gather visual data showing the sound profile during various phases including the transition between hover and cruise. This testing along with computational fluid dynamics calculations will help Eve refine the fidelity of its flight simulator and fly-by-wire flight controls, according to the company. “We have been doing rig tests, and we have been flying the engineering simulator for a while to develop the fly-by-wire controls,” he said. “There are lots of tests and building blocks. We don’t fly things just for the sake of it.”

Unlike some competing eVTOL designs, Eve engineers say they have selected a simpler lift-and-cruise design, where eight vertical-oriented propulsion units enable vertical takeoff and landing, while two rear-mounted units power the vehicle in forward flight, aided by the lift generated by Eve’s wings. The lifting rotors switch off for forward flight. This eliminates the need for a tilting mechanism for the wing or propulsion units, which adds weight and complexity.

“Aircraft have been tube and wing [configurations] for more than century,” Stein said. “With electric designs, we can think about distributed propulsion.”

Eve Air Mobility's eVTOL aircraft.
Initially, Eve Air Mobility's eVTOL aircraft will have a range of around 60 miles. (Image: Eve Air Mobility)

Eve’s initial 60-mile (100-km) range, based on the current limits of battery technology, is designed to fulfill 99 percent of urban air mobility trips, and it will initially carry a pilot and four passengers. Eventually, if fully-autonomous flight without a pilot on board becomes possible through regulatory changes, Eve will accommodate six passengers. 

With its noise footprint up to 90 percent lower and operating cost six times lower than an equivalent helicopter, the Eve eVTOL promises to be “community friendly” and suitable for cross-town, airport-shuttle, and sightseeing flights as well as serving areas where roads are impassable or nonexistent, according to Stein. Eve isn’t directly targeting the defense market, although Embraer could explore that in partnership with BAE Systems. “It’s a very different thing to be successful in that market,” Stein said.

As it refines the design of the eVTOL aircraft and prepares for prototype construction, Eve is selecting suppliers for the aircraft’s components. “We’ve been talking to them for years,” he said.

Likewise, Eve has “been engaged with regulators since the beginning [of the program],” Stein said. “Safety comes first. We’re deeply engaged with [Brazil’s] ANAC, and we have regular conversations with the FAA. Our engagement with ANAC is very positive and we have their undivided attention. We’re not fighting with other aircraft developers in Brazil. We believe we are in a good pace with the regulatory authorities.”

Certification By 2026 Could be a Challenge

Stein admits that it will be a challenge to certify the Eve eVTOL in 2026, particularly considering a typical Embraer aircraft program takes six to seven years from conception. However, he said, “We started with the date we believe is most possible.” He noted that many other eVTOL programs have moved their certification schedules “to the right.” 

Plans for production of the Eve eVTOL aircraft call for manufacturing “first in Brazil,” he said. “A future facility could be elsewhere.” Maximum initial capacity would be 500 aircraft per year, and the aircraft would have to be shipped to their destination in containers, more like long-distance helicopter deliveries than airplanes that can be flown to the buyer location.

As for buyers’ flight operations, Stein said, “We are engaged with our customers in understanding what the limitations are going to be.” There are no plans for fly under instrument flight rules, for example, and in cities where customers plan to operate their aircraft, there are plenty of days where flying under visual flight rules (VFR) is sufficient. Embraer worked with MIT on a tool to model these flying networks, and, he said, “There is enough of a market VFR.” 

Meanwhile, Eve announced that it has completed its urban air traffic management (ATM) prototype, which “focuses on concepts and services essential to supporting the introduction and scaleability of urban air mobility operations.” This means that Eve can now begin “commercial product development of urban ATM solutions to ensure UAM’s airspace integration is successful.”

Eve has tested the urban air traffic management prototype, most recently late last year during its Chicago simulation experience using helicopters as a substitute for eVTOL aircraft. It wasn’t just flights that replicated the eVTOL experience but ground services, infrastructure and equipment requirements, and the passengers’ end-to-end journeys. 

One key difference between helicopters and eVTOLS, Stein explained, is that eVTOLs “bring different benefits, they don’t do everything a helicopter does. Because they’re so disruptive with lower costs, they need to be seen as a different operation. That’s why we’re doing so much with conops [concepts of operation], to work together with [local communities and authorities].” 

Helicopter routes, for example, are “very inefficient,” he said, often routed over less populated areas such as rivers because of their noise footprint. “We are so much quieter.” 

Electric aircraft should also have a different requirement for reserve power than helicopters or airplanes, Stein said. FAA regulations require a 30-minute fuel reserve for airplanes flying VFR (45 minutes at night) and 20 minutes for helicopters. He expects the FAA to issue special conditions in the next few months that will clarify electric aircraft reserve requirements.

Few eVTOL manufacturers will discuss how much their vehicles will cost to buy and operate, other than comparing costs to helicopters, but Stein did say that he expects an eVTOL ride to cost near the $100 or so that a surface taxi charges to go from New York's JFK Airport to downtown Manhattan. “We can get close to that,” he said, adding, “All these networks are modeled considering the value of time.”

The Grownups Are In the Room

With its background stemming from being part of the Embraer family, Stein believes that Eve has a huge head start on the competition to bring an eVTOL to market. “Hell yeah, we do have an advantage,” he said. “We’ve seen big players trying to certify and failing. Having a cohesive group of engineers, access to IT, and tools, it gives us an advantage. Finally, the grownups are in the room. It’s an ambitious timeline,” he admitted, “but we have a much better understanding of the process. Our peers weren’t expecting certification to be so complicated.”

That said, Eve isn’t expecting to hit a switch and suddenly start manufacturing thousands of eVTOLS. “We’re ramping up,” Stein said. “We’re not waiting for a magic battery or magic composite [materials]. We’re doing our math on existing technology.”