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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."
I cannot see this as immediately useful for plane construction but I can imagine some uses for it. Most notably, one could power this from a real fuel-powered motor rather than a battery and use it as a secondary propulsion mechanism. So for example, this could maybe eliminate the second rotor on choppers (which is a source of major mechanical complexity and does not do much lifting, just torque balancing).
"Lifters." First thought that came to my head!
It was really instructive for me, to watch the process unfold:
1. People started proclaiming that they had UFO and anti-grav technology.
2. The scientific community said, "No, you don't."
3. People started posting videos of their "lifters."
4. People were scratching their heads. Many people said, "These must be photoshopped."
5. After a time, scientific community started researching what these things are.
6. Scientific community responds with, "OK, we've looked at this, and: It's ionic breeze."
I saw this as an interesting interaction between the public (eager to have anti-grav tech, or something from UFOs, or whatever,) and the scientific community (eager to fight against the forces of ignorance and superstition.)
Lessons I took from it are:
* The scientific community gets it right, eventually, and provides what it knows after some study. (It's trustworthy.)
* Sometimes the public has something interesting, even if the scientific community initially says "no." (It's sometimes worth paying attention to the public, but not at face value if the public is on some crazy interpretation.)
EHD propulsion is well modeled, and it's just not possible to achieve a high thrust density per unit of propulsive surface area at reasonable efficiency. It's a more interesting concept for propulsion of lighter-than-air aircraft, where you have an extremely large surface are and can have your electrodes double as surface reinforcement. But the electrode longevity problems remain. So does ozone generation.
On the upside, EHD propulsion is surprisingly efficient when surface area is not a limiting factor. You're moving a large mass of air at low velocity rather than a small mass of air at high velocity, which leads to higher propulsive efficiency.
You people make me envy the deaf and the blind!
Imagine a plane with a rectangular fuselage 10x1x1. Its volume would be ten units, and the weight proportional. "Doubling the size" would be 20x2x2.
Doubling the size would be 20x1x1. That you allow you to carry twice as much cargo... Probably a lot more than 2x as much since the 10x1x1 aircraft would have fixed size equipment and mechanical stuff that doesn't scale proportionally.
What you suggest is multiplying the size by 8. In practice very large aircraft are economical and not as impractical as your numbers would suggest. Per unit of cargo (e.g. per person) an A380 compares well to a small business jet.
const int one = 65536; (Silvermoon, Texture.cs)
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