After navigating challenges—from exploding transistors to a full redesign of its battery packs—NASA’s all-electric airplane will take its first test flight this year.
Instead of using jet fuel, the plane, known as the X-57 Maxwell, will sail among the clouds powered by 800 pounds of rechargeable lithium-ion batteries. Its flight will mark a major milestone for the program and for the field of aviation as it seeks to become more sustainable.
“This industry of building electric airplanes is very competitive,” Starr Ginn, NASA’s Advanced Air Mobility lead strategist said in a statement last month. “Having a NASA-sponsored project, where we get to share all our lessons learned with the public, allows the industry to grow. The X-57 project has been a wealth of knowledge so people don’t have to reinvent the wheel.
However, the X-57 program is on track to shut down before it accomplishes everything it set out to do. The program began in 2016 with a twofold goal: to demonstrate that a plane can be powered fully by electricity and to increase efficiency and performance through a new wing design with several small electric motors. But due to pandemic disruptions and obstacles during the creation of the plane, the program doesn’t have enough time to complete its later stages before its funding ceases at the end of this year.
The X-57 Maxwell is one of the latest projects of NASA’s X-plane program, which builds experimental aircraft to test new technology. In its history, the program has produced many revolutionary crafts, starting with the Bell X-1, which was the first aircraft to break the sound barrier in level flight. Later projects, such as the X-15, which set unofficial world speed and altitude records, have continued to test new designs and technology. The X-57 is the program’s first crewed X-plane in two decades.
When the X-57 takes wing, it will be in a form that NASA calls “Modification 2.” This version of the plane, based on a Tecnam P2006T, has two electric motors and more than 5,000 battery cells in its fuselage. That’s a marked difference from the planned final iteration, “Modification 4,” which was meant to have twelve small motors distributed across the two wings, as well as one larger motor on each wing tip. This design, called a blown wing, could allow for a shorter runway and smaller wings on the airplane itself.
X-57 will not reach this final design, though, since the project team no longer has the resources to accomplish it.
“We tried to do a very ambitious thing,” explains Nick Borer, the deputy principal investigator for the project at NASA’s Langley Research Center, to IEEE Spectrum’s Edd Gent. “Trying to do a new type of airframe and a new motor project is not very typical, because those are both very, very challenging endeavors. The agency funds a lot of different things and they’ve been very generous with what they’ve provided to us. But there are priorities at the top and eventually, you’ve got to finish up.”
Still, what the team has accomplished to arrive at an airworthy Modification 2 is no small feat. In 2017, they had to completely redesign the plane’s battery packs with the help of NASA’s design team for the International Space Station. They needed to ensure that if one cell in the pack failed, it wouldn’t result in a fire.
Another problem emerged when it came to the transistors in the aircraft. The original transistors the team used were built to withstand high levels of power, but they were unable to cope with the temperatures and vibrations produced during flight tests.
“They were specced to be able to tolerate the types of environments we were expecting to put it in,” says Sean Clarke, the principal investigator for the program, to Rob Verger at Popular Science. “But every time we would test them, they would fail. We would have transistors just blowing up in our environmental test chamber.”
After careful investigation—made extra difficult by the explosive manner of the transistor failures—the team used transistors with newer hardware and redesigned their system. A full set of these improved transistors has now successfully made it through qualification for flight.
While the X-57 will likely taxi back to its hangar for the final time this year, the plane’s team and others in the industry say the project has made important strides for the potential of electric aircraft, and they’re optimistic that others will continue to build on their achievements. The team has been publishing their data throughout the project in hopes that it will help others building electric planes. A few of NASA’s contractors for the program have gone on to commercialize the X-57’s battery pack and develop other flying vehicles with electric motors.
“The whole idea of an X-plane is to do something that has never been done before, and so I think it is just normal to expect that there is a learning curve,” says Sergio Cecutta, founder and partner at the electric aviation-focused SMG Consulting, to IEEE Spectrum. “In the end, you want to lay the groundwork for the industry to become successful, and I think on that metric, the X-57 has been a successful project.”
Clarke agrees. “I’m still really excited about this technology,” he tells Popular Science. “I’m looking forward to my kids being able to take short flights in electric airplanes in 10, 15 years—it’s going to be a really great step for aviation.”