In a corner of the sun-drenched Paris air show static display, Israeli start-up Eviation co-founder and chief executive Omer Bar Yohay could look to his right and see the French air force’s corral, featuring Dassault Rafale and Mirage fighters. If he looked far enough to his left, he could see all the stars of the modern aviation industry lined up on display, including a Lockheed Martin F-35A fighter, Embraer KC-390 tanker-transport, an Airbus A350-1000 and a Boeing 787-10.
By comparison, Bar Yohay's offering seemed a bit less glamourous, with just a few couches perched under a sun tent that provided little relief from a rare Paris heat wave. Outside the canopy sat the streamlined shape of the Eviation Orca, a tri-motor, all-electric drone designed to function as a proof-of-concept vehicle.
"I’m the one selling a Prius in a Ferrari shop," Bar Yohay jokes, as the whoosh of an Airbus A400M on final approach passes over his sun tent.
Nine-seat Alice will be offered as an all-electric alternative for mainstream GA missions
Eviation Aviation
The comparison works, but is not quite accurate. The Toyota Prius is, after all, a hybrid electric. And the Eviation stand did not exist to promote a small, electric UAV. Eviation made its debut at the Paris air show to publicly unveil a new aircraft concept called Alice, a nine-seat, all-electric alternative to such general and business aviation stalwarts as the Cessna 402, Beechcraft King Air 350 and Pilatus PC-12.
The Israeli business may be a start-up, but it has solid financial support. In addition to Bar Yohay, Eviation was co-founded by Aviv Tzidon, a well-financed Israeli inventor of a potential breakthrough in electric propulsion technology. Eviation has a long-term plan to integrate the air-metal fuel cell invented by Tzidon in the Alice, but intends to go to market within four years with a nine-seat aircraft powered by conventional lithium-ion batteries.
"We aimed at this point because we believe this is probably the most cost-effective entry point to this market that can be certificated under today's regulatory environment," Bar Yohay says.
NEXT STOP OSHKOSH
Eviation’s next stop on the air show circuit is the Experimental Aircraft Association's annual Airventure fly-in in Oshkosh, Wisconsin, later this month. There, the Orca proof-of-concept drone and the promise of the Alice will join not only fields of parked and conventionally powered Cessna 402s, King Airs and PC-12s, but a growing list of proposals and concepts for electric- and hybrid-electric aircraft.
Originally built to mature the Alice configuration, Orca has found a niche in the UAV market
Eviation Aviation
By announcing in Paris a schedule to complete US Federal Aviation Regulations Part 23 airworthiness certification by 2020 and start commercial flights in 2021, Bar Yohay advances the Alice to near the front of the queue. As such, the Alice could become as much a regulatory test case as a leap in propulsion technology. If allowed to proceed, the Alice and the new class of hybrid- and all-electric aircraft must clarify a host of still-murky regulatory issues for airworthiness certification.
Bar Yohay is well aware of the regulatory questions that face any company hoping to introduce electric-powered aircraft in non-experimental categories. Since the company’s foundation in 2015, Eviation has participated in all of the major forums, including the General Aviation Manufacturing Association's electric propulsion and innovation committee, ASTM’s F39 committee developing consensus standards for electric wiring on small aircraft and the F44 committee working on basic standards for all aircraft weighing less than 8,620kg (19,000lb) and carrying fewer than 12 passengers.
That experience has persuaded Bar Yohay that the US and European regulators are open to approving the airworthiness of small electric aircraft. Last December, the US Federal Aviation Administration approved a rewritten Part 23 rule. The new regulation replaces original language prescribing the use of only petrol engines with a standard open to any propulsion technology.
CLARITY REQUIRED
But some details about how the rewritten rule will be interpreted by the FAA’s regulatory officials are not yet clear. Perhaps the biggest question mark surrounds the certification of the propulsion system. In the USA, kerosene- and avgas-fuelled aircraft require an engine that has been independently certificated under FAR Part 33 rules. It is not clear whether or even how a hybrid- or electric-powered aircraft would comply with Part 33 standards. Bar Yohay is optimistic that the FAA will apply the most lenient approach, allowing Eviation to certificate the aircraft and electric propulsion system together under Part 23, avoiding the need to qualify the engine under Part 33.
"Technically, [the Part 23 rewrite] allows us to certifcate the motors as part of the type certification of the aircraft and not specifically [the propulsion system], so in theory we could do it – just certificate the whole thing, and not have the specific certification of the motors," Bar Yohay says.
Bar Yohay’s assumptions are perhaps too optimistic for the regulatory community, though. The FAA has allowed only light-sport aircraft to enter service without engines that were certificated independently under Part 33, but such aircraft face severe weight and operating restrictions, including a prohibition on instrument flight rules flight.
Without such an approval, the Eviation Alice faces an uncertain path to regulatory approval by 2021.
The Alice design features three electric motors powered by a bank of 30,000 Panasonic lithium-ion battery cells. To use the most mature technology, the initial Alice aircraft intends to rely on batteries and motors developed and proven in the automotive industry. Indeed, the Alice propulsion system resembles the electric configuration of a Tesla sedan, but with about 10 times the electric power, Bar Yohay says. Eviation currently plans to use motors developed by UK-based Yasa motors, but is also interested in technology developed by Siemens. Both are primarily automotive suppliers with little experience of the aviation industry’s regulations.
"The companies I’m not sure will go through the process of certifcating their own motors," Bar Yohay says. "So it’s either I take some of the load from them or I just go through with my type certification and have this approved for my specific motor inside. So it will be interesting to see how this plays out."
Indeed, accommodating electric propulsion in small aircraft means aviation regulators will likely encounter a supply chain and a technology dominated by a rapidly growing list of applications in the automotive industry. Compared with gasoline engines, electric motors are far less complex, making them easier to maintain.
"There’s one moving part. It's very simple," Bar Yohay says. "So will the [aviation] industry make us go through the process of certifcating motors separately? I seriously doubt it. I think it would be a mistake for electrics because you're going to have a lot of different motors. It’s not going to be [like the general aviation industry, where] everybody uses a Rotax or whatever."
There may be another path forward to certificating electric motors for the aviation industry, according to Bar Yohay. Instead of relying on automotive technology, the Alice and other electric-powered aircraft could use technology that is already qualified for use in aviation.
The industry's engine suppliers already produce electric motors used to power onboard systems. In the case of the Boeing 787 and Airbus A350, the industry has adopted highly advanced electric power and distribution systems, replacing previously pneumatic and hydraulic power to activate landing gear, de-icing and cabin pressurisation. Leveraging that technology as propulsion systems for smaller aircraft may help regulators as electric motors make the transition.
"One of the approaches that could be looked at is that companies like Honeywell and GE and Rolls Royce can take their existing generators and say this is aviation standard anyway and use them moving forward," he says.
Although the path to certification could still be tricky, the Alice was designed to minimise questions from sceptical regulators. A future version of the aircraft powered by co-founder Tzidon’s metal-air batteries would offer significantly better performance, but Eviation is focused on taking a practical route to certification within five years.
The Orca proof-of-concept drone offers a case in point. The scaled-down copy of the Alice was designed simply to mature the aerodynamic and electric power configuration of the Alice, but Eviation has found a market niche for the speedy little aircraft as a commercial-rated unmanned air vehicle.
"After we built it and started flying it a lot of the drone operators of the world – especially seeing us as an Israeli company – said: 'Hey, can you sell us a drone?' So it got a name. We saw it as a model. The world saw it as a UAV, so why not?" Bar Yohay says.
Equipped with a synthetic aperture radar, the Orca now flies missions for Israeli national water company Mekorot.
Meanwhile, the design of the first full-scale Alice test aircraft is nearing completion of a critical design review. Two suppliers, including Israel-based FBM Composite Materials, are fabricating the aircraft's structure. Eviation is concentrating on integrating the propulsion system. A still-undisclosed risk-sharing partner in Italy is expected to join the certification campaign, which will be conducted in Italy and Israel. First flight of the Alice version with lithium-ion batteries is scheduled in mid to late 2018, followed by certification two years later and entry into service in 2021.
The batteries under consideration are Panasonic 18650s, the standard lithium-ion cells used by the automotive industry, including Tesla.
"We want to get [a battery] that can be built repeatedly with the kind of supply chain management that can go to market within the next two to three years, not the next five to 10," Bar Yohay says. "It’s extremely difficult to do anyway, so we don't want any uncertainties in the battery."
RELIABILITY
The lithium-ion version of the Alice aircraft still boasts solid performance. Flying below 10,000ft, the unpressurised aircraft should be capable of a range of 520nm (963km) plus a standard power reserve. With two wingtip thrusters and an aft-mounted thruster, the streamlined, all-composite aircraft should offer impressive speed.
"We get a lot of speed for the thrust we are using," Bar Yohay says. "240kt [445km/h] we achieve at roughly 250, maybe 260kW. Think about it: Not many 300hp aircraft can do 240kt."
Ultimately, Eviation hopes to move beyond lithium-ion as a fuel source – and it has the inside track on a coveted new breakthrough in battery power. In 2008, Eviation co-founder Tzidon received a patent for a new aluminium-air fuel cell, which offers almost double the same energy density as lithium-ion batteries. Tzidon launched an Israeli-based start-up called Phinergy, which last year closed a $50 million round of financing led by aluminium giant Arconic.
Phinergy’s aluminium-air fuel cell consists of the lightweight metal as the anode, which reacts with an oxidiser cathode to produce energy. Tzidon's patent suggests he has overcome two drawbacks of metal-air fuel cells. Phinergy solves the problem of supplying the oxidiser by harvesting the gas from the ambient air, making the fuel cell inhale oxygen like a fish in water instead of a scuba diver. It is also designed to prevent carbon dioxide from entering the cathode, which has led to metal-air battery failures in the past.
When powered by the Phinergy fuel cell, the Alice-Extended Range (ER) will be pressurised and fly at 270kt at 30,000ft for 850nm, plus a reserve, Bar Yohay says.
"I believe that in the seven to 10-year timeframe we will see it integrated into our airframes after the certification basis becomes more clear," Bar Yohay says. "At the moment it doesn’t make sense to sort of link the two risks until they plan on doing a new battery system. But we are the owners of the [intellectual property] for that and we work very hard to do this integration."
Source: FlightGlobal.com
