For a century of human flight, there has been a hard trade-off between the ability to glide silently and fly under one’s own power.
Whatever gliders offered in stealth came with a larger logistical tail, the reliance on other towing aircraft, and for virtually all military applications outside of a few cases, the freedom gained from a plane-borne engine offset the disadvantage of the screaming engines. Last week, engineers at MIT revealed the successful first flight of a new sort of plane, an uncrewed vehicle without any moving parts that can power itself through the sky, silently, on an ion wind.
All fixed-wing craft work in the same way: an engine provides forward momentum, and then the shape of the wings turns that forward momentum into lift, supporting the plane as it pulls ever forward through the air. While propellers and jets noisily pull air over wings, ionic wind operates in a much subtler, higher-voltage way. A thin wire held before the wing is positively charged, with a thicker negatively charged wire at the back of the wing.
From MIT:
Once the wires are energized, they act to attract and strip away negatively charged electrons from the surrounding air molecules, like a giant magnet attracting iron filings. The air molecules that are left behind are newly ionized, and are in turn attracted to the negatively charged electrodes at the back of the plane.
As the newly formed cloud of ions flows toward the negatively charged wires, each ion collides millions of times with other air molecules, creating a thrust that propels the aircraft forward.
— http://news.mit.edu/2018/first-ionic-wind-plane-no-moving-parts-1121
While ionic winds have been demonstrated before, they usually lifted vehicles that were tethered in some way to the ground, as the power requirements and the weight of batteries are major obstacles for this kind of flight. To that end, the MIT team built a five-pound craft with a 16-foot-long wingspan, powered by lithium-polymer batteries and specifically configured by dedicated power specialists.
For its first flight, the uncrewed ionic wind drone flew almost 200 feet inside a gym, the flight seemingly limited only by the physical constraints of the walls. To make sure that it worked, the team then repeated the first flight 10 times.
This is a new technology, a first flight of a demonstration vehicle, so it’s worth being cautious in what it could possibly mean, no matter how much it may inspire visions of science fictional shuttles or fighters. That said, we will likely see more of its promises for drone designed realized before it scales up to people-containing vehicles, since the delicate architecture and light weights are easier to accommodate without worrying about creature comforts.
Fitting any payload on such a light frame will be again constrained by weight, but sensors and cameras are safe assumptions for what comes first. Scaling the wingspan to the size of quadcopters may pose a problem, though the promise of silent scouts operating in place of the familiar buzzing of hobbyist drones is compelling. Since the first flight took place in a gym, we don’t yet know how the ionic wind works in regular wind, and if weather will prove a major obstacle. Yet the long wingspan and all-electrical power also suggests that this may be the answer to high-altitude drones, recharging with solar power and operating almost effortlessly above the jet stream.
However the future plays out, the possibility of silent flight, especially for uncrewed vehicles, is a compelling development, one worth watching into the future. It may not be the final frontier, but it's certainly a new frontier to boldly go.
Watch a video about it below:
Kelsey Atherton blogs about military technology for C4ISRNET, Fifth Domain, Defense News, and Military Times. He previously wrote for Popular Science, and also created, solicited, and edited content for a group blog on political science fiction and international security.
