Four years ago, Eviation Aircraft CEO Omer Bar-Yohay introduced the all-electric Alice, a nine-seat, all-composite aircraft targeting the short-range regional airline market. Now, the full-scale prototype Alice is at the Paris Air Show and Israel-based Eviation has secured a “double-digit” order for the $4 million airplane from U.S. regional airline Cape Air.
“When we started in 2015,” Bar-Yohay said, “we were written off as delusional at best.” At the time, he promised to bring the full-scale Alice to Paris 2019. “This is the pinnacle of an insanely long effort,” he said.
Alice is equipped with three 260-kW Siemens electric motors fitted with Hartzell variable-pitch propellers, with one on each wingtip and one fitted to the tail. Electric powerplant manufacturer magniX is also offering a motor system for Alice.
The prototype brought to Paris has a completed interior, BendixKing AeroVue avionics suite, and Honeywell’s new lightweight fly-by-wire flight control system. The landing gear, including the tall retractable tailwheel that protects the rear motor/propeller from tail strikes, is made by Italy’s Magnaghi Aeronautica. Carboman is developing the composite-manufacturing processes and built the prototype airframe.
Alice's lithium-ion battery system is enclosed in the nose and underneath the wing-to-fuselage fairings, but also outside the cabin structure (and eventual pressure vessel). The cabin is designed to be pressurized, although the prototype and first production Alices won’t be, and that capability will be added later as a supplement to the type certificate.
Its batteries weigh 8,200 pounds, which is 60 percent of the airplane’s 14,000-pound mtow. Although there are three suppliers for the batteries, which are off-the-shelf automotive-type lithium-ion cells, according to Bar-Yohay, Eviation designed the power and thermal management systems to ensure maximum system safety.
Alice's Honeywell fly-by-wire flight control system will include features unique to an electric airplane, including the ability to manage the propellers’ pitch and rpm to trade power for reduced noise when necessary. Differential thrust from each wingtip-mounted motor will help compensate for crosswinds while landing, so it won’t be necessary to bank into the wind and thus more comfortable for passengers. The thin wings give Alice a high wing loading, which is more comfortable in turbulence, but the fly-by-wire system can also help smooth out the ride, acting as an augmented stability system.
If power is lost in one wingtip-motor, the opposite motor will reduce power to prevent asymmetric thrust from causing a loss of control, while the rear motor can provide enough power to keep the Alice flying. In fact, Alice can continue a takeoff with loss of both tip thrusters at V2, according to Bar-Yohay.
The battery system adds further safety backup in that it can be split into 16 separate “strands” that can each fully power the motors. “It’s taken redundancy to the extreme,” he said.
Performance of the Alice as a regional airliner includes range with 45-minute reserve of 565 nm and 240-knot cruise speed at 10,000 feet (265 knots at 32,000 feet for the pressurized version). The concept, from the beginning, was to develop an airplane that small regional airlines could use for trips that are just too expensive in larger turbine-power airplanes, including serving smaller airports where most airlines can’t cost-effectively operate.
To that end, the Alice’s direct operating costs will be $200 per hour, he said, which is about 20 percent of the cost of operating a similarly performing turboprop or 40 to 50 percent cheaper than a piston-powered airplane like the Cessna 402s that Cape Air currently operates. Even better, he explained, is that as battery technology continues to advance at about 2 to 3 percent per year, operating costs of the Alice will keep dropping.
“Cape Air is the ideal client,” Bar-Yohay said, adding that the airline will work closely with Eviation to develop pilot and technician training programs.
The battery system on the Alice will be fully rechargeable in one hour and 10 minutes, using a half-megawatt charger on a mobile “bowser” truck that itself is charged up by plugging into the local electrical grid. This avoids having to build charging stations at airports, he said. Not all routes will require a full charge—the basic ratio is a half hour of charging time per hour of flight.
After the Paris show the Alice will be disassembled and shipped back to Eviation's facility in Prescott, Arizona, to begin preparation for first flight, which is expected by year-end. The flight-test program should last 24 to 30 months, said Bar-Yohay, followed by FAA Part 23 certification. Flight testing will begin in Prescott but will also take place in Moses Lake, Washington, working with engineering and flight test experts AeroTec.
However, Eviation is facing some steep hurdles in terms of certification, not only because it would be the first all-electric multiengine airplane to be certified by the FAA but also because it would become the first Part 23 fly-by-wire design. Eviation is working closely with the FAA, and by year-end Bar-Yohay expects to have the certification basis and means of compliance completely defined and in hand. Certification is planned in 2021, with entry into service in 2022.
Bar-Yohay is happy to have made it to the Paris show with the Alice prototype on display. “This is an exciting accomplishment,” he said, “especially here on the grounds in Paris, but it's also very clearly just the beginning.”