A group of NASA engineers and private-sector partners working in California is moving forward with creating an X-Plane demonstrator they hope will prove the efficiency of using an array of small electric-powered propellers for general aviation aircraft. “This is a really important demonstrator for us,” NASA’s Mark Moore, the leader of the research team, told AVweb. “There hasn’t been a manned NASA X-plane for about 30 years. This is going to be the first manned aircraft powered by distributed generation, so it’s going to be very meaningful.” Moore said he believes the three-year, $15-million projectwill prove that the distributed-electric propulsion system can achieve up to five times greater efficiency than conventional systems, with 30 percent lower operating costs.
Moore said a lot has been going on since the project began about a year ago, including local ground testing at NASA’s Armstrong Flight Research Center in California, detailed design work for the wing and propellers, and building a custom electric motor. They are just about to buy a Tecnam 2006T, and they willremove the wing and replace it with their own wing and motors and an array of small propellers. “We’re really focusing in on distributed electric propulsion as a key technology,” he said. “Every one of us is just incredibly motivated to make this happen … Seeing these analysis results, you just can’t help but be excited because the changes are so large.” Their research so far is predicting that a series of small motors distributed along the wing can improve aircraft efficiency by 50 percent, compared to using a single electric motor as a direct replacement for a reciprocating engine.
Flight testing with the Tecnam is scheduled for September or October in 2017. Using currently available technology, Moore said he expects the aircraft will be capable of about a 200-nm range. “The batteries are constraining the practicality of this technology,” he said. “But it seems credible that within five to seven years batteries will be about twice as good as what we’re using now.” And even a 200-nm range could make the technology useful for many operators, he said. Commuter airline Cape Air, for example, operates a fleet of Cessna 402s on routes shorter than 220 nm.
Eventually, Moore said, he hopes to expand the project to develop VTOL aircraft, which he says would maximize the technology’s potential for efficiency and usefulness. “That’s where things get really exciting,” he said. Small VTOL aircraft, with two to four seats, using this technology could accomplish the same tasks as a helicopter, with 10 times the efficiency. “They could make helicopters irrelevant and completely obsolete,” he said.
