NASA plans to fly its X-57 electric plane this year

NASA plans to fly its X-57 electric plane this year

Sometime later this year, maybe this summer, maybe this fall, a NASA electric plane, the X-57, will take flight over California. It’s what NASA describes as its “first all-electric experimental aircraft,” and when it lifts off the ground, it won’t look the way NASA has been depicting the plane on its website.

Instead of a whopping 14 electric motors and propellers, the plane will have just two. But those two engines, powered by more than 5,000 cylindrical battery cells in the plane’s fuselage, should be enough to get it airborne before the end of 2023, which is when the X-57 program is also set to shut down.

Here’s what you need to know about how the plane will perform, the challenges the program has faced, and how lessons from spaceflight helped inform the details of its battery system.

Modification 2

If the plane does take off this year as planned, it will do so in a form called Modification 2, which involves an electric motor and a propeller on each wing that give the plane the thrust it needs to take off.

While the aeronautics and space agency had hoped to fly the plane, which is based on a Tecnam P2006T, in additional configurations, known as Modifications 3 and 4, that will not happen. Why? Because making an airplane that flies safely on electricity alone is hard, and the program is only funded through 2023. (IEEE Spectrum has more on the program’s original plans.)

“We have been learning a lot over the years, and we thought we would learn through flight testing; It turned out that we had a lot of lessons to learn during the design qualification and integration and airworthiness steps, and so we ended up spending more time and resources on that,” says Sean Clark, principal investigator for the X-57 program at NASA.

“And that has been enormously valuable,” he adds. “But it means that we are not going to end up having resources for those Mod 4 [or 3] flights.”

It will still fly like an all-electric aircraft, but in Mod 2, with two motors.

explosive transistors

One technical issue the team had to fix before the aircraft could safely take off involves components that electricity from the batteries has to pass through before reaching the engines. The problem was with the transistor modules inside the inverters, which change electricity from DC to AC.

“We were using these modules that are multiple transistors in one package; they were specified to be able to tolerate the kinds of environments we were hoping to put them in,” says Clark. “But every time we tried them, they failed. We would have transistors exploding in our environmental test chamber.”

[Related: This ‘airliner of the future’ has a radical new wing design]

Component failure, like an equipment explosion, is the kind of problem that aircraft manufacturers prefer to solve on the ground. Clark says they figured it out. “We did a lot of dissection of them; after they explode, it’s hard to know what went wrong,” he notes, cheerfully, in a way that suggests an engineer faced with a complicated problem. The solution was newer hardware and “basically redesigning the inverter system from scratch,” he says.

Now they are “working very well,” he adds. “We’ve put a full set through qualifying, and they’ve all passed.”

NASA aims to fly its experimental electric plane this year
An older rendering of the X-57 shows it with a thin wing and 14 engines; it will not fly with this configuration. Graphic by NASA/NASA Langley/Advanced Concepts Lab, AMA, Inc.

lessons from space

Traditional airplanes burn fossil fuels, an obviously flammable and explosive substance, to power their engines. Those who work on electric, battery-powered aircraft must ensure that the battery cells do not cause fires either. Last year in Kansas, for example, an FAA-sponsored test featured an aviation battery pack that was dropped 50 feet to ensure it could withstand impact. They did it.

In the X-57, the batteries are a model known as 18650 cells, made by Samsung. The aircraft uses 5,120 of them, divided into 16 modules of 320 cells each. A single module, including battery cells and packaging, weighs about 51 pounds, Clark says. The trick is to make sure all of these components are packaged the right way to prevent a fire, even if one battery fails. In other words, failing was an option, but they plan to handle any failure so it doesn’t start a fire. “We found that there was no industry standard for how to package these cells in a high-power, high-voltage package that would also protect them against cell failure,” says Clark.

[Related: The Air Force wants to modernize air refueling, but it’s been a bumpy ride]

Help came from above. “We ended up redesigning the battery pack based on a lot of input from the space station design team here at NASA,” he adds. He points out that the lithium batteries on the International Space Station, as well as in the EVA suits worn by astronauts and a device called a pistol grip tool, were relevant examples in the process. Key points involved spacing between battery cells, as well as how to manage heat if a cell is not working properly, for example experiencing thermal runaway. “What Johnson [Space Center] The team found that one of the most effective strategies is to let the heat from that cell into the aluminum structure, but also have the other cells around it absorb a little bit of heat each,” he explains.

NASA is not alone in exploring the frontier of electric aviation, which represents one way the aviation industry could go greener for short flights. Others working in space include Beta Technologies, Joby Aviation, Archer Aviation, Wisk Aero, and Eviation with an aircraft named Alice. One prominent company, Kitty Hawk, went out of business last year.

Sometime this year, the X-57 should fly for the first time, probably making multiple sorties. “I’m still very excited about this technology,” says Clark. “I hope that my children will be able to take short flights in electric planes in 10 or 15 years; It will be a big step for aviation.”

Watch a short video about the plane, below:

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