NASA begins tests on cruise motors for its all-electric plane
08 February 2018
The cruise motors that will power NASA’s first full-electric X-plane have begun endurance testing in preparation for full integration into the X-plane.
A test stand called Airvolt is testing the motors and motor controllers to help verify that the experimental electric propulsion system is ready for flight. If successful, along with the controllers and propellers, the motors can in integrated into NASA’s all-electric X-plane – the X-57 Maxwell.
“We want to confirm that the motor system is as safe as possible before X-57 begins flight testing. The testing is important at this stage because X-57 is a manned test research project, meaning the aircraft will have a pilot on-board,” Airvolt Lead Systems Engineer Yohan Lin said. “Previous electric propulsion projects have been conducted using unmanned aircraft, and at a smaller scale, but with a pilot on-board, the level of risk is higher.”
NASA Armstrong will receive a total of five JM-X57 cruise motors, designed and built by Joby Aviation in Santa Cruz, California. The team plans to use two of these electric motors in place of the standard Rotax 912 S3 piston engines for the first flight tests of the X-57’s first modification, known as Mod II. While additional motors are currently being tested as spares, the idea would be to use the same two motors from Mod II as the primary propulsion system for the aircraft’s later modifications, according to X-57 Principal Investigator Sean Clarke.
“The two motors that we fly in Mod II, ideally, will be the same two that we take and put on the following Mod III vehicle, which will see the standard Tecnam wing replaced with a thinner, high-aspect ratio wing, and we’ll also see the relocation of those cruise motors to the wing tips,” explained Clarke. “After that, we’ll again evaluate the status of the motors, and go with the best option for the wingtip cruise motors for Mod IV, which will add twelve smaller ‘high-lift’ motors along the new wing’s leading edge.”
The fifth motor will undergo testing on Airvolt at its full operational capability, and will then be taken apart to have its components inspected as part of what’s called a “destructive inspection”. The state of the bearings, rotor and magnets will be observed and analysed to see how healthy they are. This provides more insight about the motor than can be observed by inspecting the exterior, and NASA researchers will be able to learn more about the motor’s performance and safety limits.
For more information visit the NASA website.
Video courtesy of NASA Armstrong Flight Research Centre