On September 18, an all-electric aircraft driven down a runway in Washington state with its nose wheel lifting off the ground. It didn’t start on purpose, however: the test was a precursor to an actual first flight, which the company says is “imminent”.
The 57-foot-long plane, which its creators call Alice, is only a prototype, albeit a rather refined one. When a production version enters service with an airline like Cape Air one day, the aim will be to carry nine passengers and their luggage for flights of around an hour or two – think distances of around 170 to 230 miles. The front of the commuter aircraft will have seating for two pilots, although it is certified to be flown by just one person.
Other companies working on electric flight, which the industry hopes will make it less carbon-intensive, are developing flying machines that don’t look like conventional planes. A Joby Aviation air taxi, for example, can take off and land vertically and therefore has a different design. But Alice, made by a company called Eviation, looks a lot more like a regular airplane. This is how it works now.
batteries in the stomach
The plane’s motors need battery power to give them the juice they need. Unsurprisingly, the batteries that do this are located in the floor of the plane, where the plane’s perimeter is also slightly wider.
Batteries are heavy and don’t have the same energy density as regular fuel, which is a major limitation for electric flight. The batteries on this prototype weigh 8,000 pounds in total, and these lithium-ion cells are cylindrical, which is the same shape used by some automakers like Tesla and Rivian. For luggage, the cargo hold is located behind the passenger cabin.
Other attributes of the aircraft’s design revolve around enabling it to fulfill its intended mission – relatively short-distance commuting – while utilizing battery power. “Building an electric aircraft is a war on weight and a war on drag,” notes Gregory Davis, the company’s CEO and president. “Our challenges are to achieve the best possible lift-to-drag ratio.”
The plane has long, narrow wings that don’t sweep backwards; Wings that are long and thin are referred to as having a high aspect ratio. “We need the most efficient wing we can,” he says. (For a point of comparison, take a look at the wings of an airplane like an F-16, which is designed for performance and supersonic speed, as opposed to efficiency.)
To keep the weight as low as possible, the plane is made mostly of carbon composite material, Davis says. The plane is also known as fly-by-wire, which Davis says also makes it lighter than it otherwise would have been. A non-fly-by-wire aircraft uses mechanical connections, such as metal cables, to transmit what the pilot is doing at the controls to actual surfaces outside of the aircraft. A fly-by-wire airplane uses computer signals to do the same thing and removes those wires or other physical connectors.
props in the back
At the tail of the aircraft are two electric motors that drive two propellers. These motors are made by a company called magniX; One airline, Harbor Air, has also used a magniX engine to power a converted electric seaplane.
In the case of the Alice plane, the propulsion units in the tail “can generate 650 kilowatts of power per side, so 1.3 megawatts of power for the plane during takeoff, which is great,” says Davis.
Right now there’s an understandable gap between what the company expects the range of its production model aircraft to be and the prototype that will soon make its maiden flight. “The batteries aren’t there yet,” he says. “Battery technology is, perhaps unsurprisingly, the biggest challenge in electric aviation.” The hope is that the industry – electric aircraft, electric ground vehicles – will continue to innovate as the development of the Alice aircraft continues.
He describes this battery situation as a “challenge for the entire industry”. The aircraft prototype is good “to demonstrate that the technology works together”.
Certainly, Eviation and their Alice planes aren’t the only ones working on this new frontier. Companies like Beta Technologies and Joby Aviation fly electric air taxis designed to take off and land like helicopters, although on recent flights with Air Force pilots at the controls or a multi-leg trip to Arkansas, Beta’s demonstrator has taken off and landed conventionally. Others are Archer and Wisk. Eventually, Kittyhawk worked on a one-person airplane called the Heaviside, but only announced on September 21 that they would close the company.
And in related news, a company called Heart Aerospace is working on a hybrid-electric aircraft, the ES-30. Visit the Air Current Aviation website to learn more about why Heart recently switched from an all-electric smaller aircraft to a larger 30-seat aircraft that also has turbogenerators onboard.
For Eviation’s Davis, he compares the current state of development to NASA’s Mercury program, where the first American made a suborbital flight in 1961, eight years before the Apollo 11 moon landing. “What we’re doing here with Alice is like Alan Shepard going into space on a Redstone [rocket]– it shows that we can do it,” he says. “Where we’re going when it comes to making electric aviation a part of our world – something our kids will fly on and we won’t think twice about – that’s the goal here.” We have to show that we can do it.”
Check out the high speed taxi test below.