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First Ever Plane With No Moving Parts Takes Flight (theguardian.com)
An anonymous reader quotes a report from The Guardian: The first ever "solid state" plane, with no moving parts in its propulsion system, has successfully flown for a distance of 60 meters, proving that heavier-than-air flight is possible without jets or propellers. The flight represents a breakthrough in "ionic wind" technology, which uses a powerful electric field to generate charged nitrogen ions, which are then expelled from the back of the aircraft, generating thrust. Steven Barrett, an aeronautics professor at MIT and the lead author of the study published in the journal Nature, said the inspiration for the project came straight from the science fiction of his childhood.
In the prototype plane, wires at the leading edge of the wing have 600 watts of electrical power pumped through them at 40,000 volts. This is enough to induce "electron cascades", ultimately charging air molecules near the wire. Those charged molecules then flow along the electrical field towards a second wire at the back of the wing, bumping into neutral air molecules on the way, and imparting energy to them. Those neutral air molecules then stream out of the back of the plane, providing thrust. The end result is a propulsion system that is entirely electrically powered, almost silent, and with a thrust-to-power ratio comparable to that achieved by conventional systems such as jet engines. "I was a big fan of Star Trek, and at that point I thought that the future looked like it should be planes that fly silently, with no moving parts -- and maybe have a blue glow," said Barrett. "But certainly no propellers or turbines or anything like that. So I started looking into what physics might make flight with no moving parts possible, and came across a concept known as the ionic wind, which was first investigated in the 1920s."
"This didn't make much progress in that time. It was looked at again in the 1950s, and researchers concluded that it couldn't work for aeroplanes. But I started looking into this and went through a period of about five years, working with a series of graduate students to improve fundamental understanding of how you could reduce ionic winds efficiently, and how that could be optimized."
In the prototype plane, wires at the leading edge of the wing have 600 watts of electrical power pumped through them at 40,000 volts. This is enough to induce "electron cascades", ultimately charging air molecules near the wire. Those charged molecules then flow along the electrical field towards a second wire at the back of the wing, bumping into neutral air molecules on the way, and imparting energy to them. Those neutral air molecules then stream out of the back of the plane, providing thrust. The end result is a propulsion system that is entirely electrically powered, almost silent, and with a thrust-to-power ratio comparable to that achieved by conventional systems such as jet engines. "I was a big fan of Star Trek, and at that point I thought that the future looked like it should be planes that fly silently, with no moving parts -- and maybe have a blue glow," said Barrett. "But certainly no propellers or turbines or anything like that. So I started looking into what physics might make flight with no moving parts possible, and came across a concept known as the ionic wind, which was first investigated in the 1920s."
"This didn't make much progress in that time. It was looked at again in the 1950s, and researchers concluded that it couldn't work for aeroplanes. But I started looking into this and went through a period of about five years, working with a series of graduate students to improve fundamental understanding of how you could reduce ionic winds efficiently, and how that could be optimized."
This plane's wingspan is already five meters, for just 2.5kg of weight, most of it going to the battery pack. To make it carry more weight, one will have to make it much bigger, which will require much stronger wings, which will make it heavier. And to make things worse, batteries do not get lighter as they discharge.
It's a great toy, but it will be a while before it is useful.