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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."
Agreed. 5m wing span at 2.5kg is extremely light with a massive lifting surface. 60m glide from a head height launch would be easy.
But did it take off from standstill. Article is unclear. If it self launched that is far more interesting.
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).
This looks a lot like the Ionic lifters that were popular in the "anti gravity" circles about 15 years ago. I built a few and they were fun to build, but there isn't any anti-gravity going on here just ion wind. The high voltage was entertaining and the corona was beautiful when the lights were turned off.
The folks at MIT are doing great things. I love it!
https://en.wikipedia.org/wiki/Biefeld–Brown_effect
Same thing was said about the Wright Brothers little effort.
The Wright Brothers' plane carried the weight of a man (Orville), and accelerated from zero under its own power.
To be fair, it also had a strong headwind, while this solid state plane flew in zero wind.
But the Wright Brother's Flyer had a clear path to improvement with lighter and more powerful engines.
Where can this SS tech go? Batteries will get lighter, but no where near enough to give this plane a practical payload or range.
Which is also why this plane won't be pollution free at all. It will generate both ozone and nitric oxide.
Covering the negative electrode with catalytic material might help to break it down, no idea how much would be generated or scrubbed though.
I do believe this is a solution begging for a problem, but I would not say there are hard limits on this application due to batteries in the distant future. We have to extrapolate from current technology that the future will offer wireless power transmission systems. Consider a matrix of ground-based microwave transmitters drawing from solar power that can beam energy to an aircraft such as this in bursts that can charge a meager capacitor. The aircraft is catapult launched, so it only needs to maintain enough energy on board for travelling between energy nodes within the matrix. Actual propulsion would be more efficiently accomplished via traditional means (propeller) for such an aircraft, but my intention here is to highlight that battery scalability should not suppress our freedom to dream of electric aircraft.
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Electric planes are coming, prototypes already exist. Your belief that batteries will stay insufficient for practical payload and range is not widely shared.
The problem is precisely that the "engines" are not powerful enough yet, measured by thrust per area. It is unclear whether that is fixable, but there is certainly hope.
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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!
I wonder how that huge lifting surface would respond to moderate gusts of wind...
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Where can this SS tech go? Batteries will get lighter, but no where near enough to give this plane a practical payload or range.
What if we attach this engine to a big Zeppelin?
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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.
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Electric planes are already here, but they're extremely limited by battery tech.
Since planes are weight-limited, their range is proportional to the specific energy (energy per unit mass) of the battery. That value would need to double before electric planes can be practically used for training. To fly a typical short-haul route, the batteries would need 3-4 times the specific energy. To fly long-haul, they would need 10-12 times. Now that's just considering whether they're able to do it, not whether it would be economical.
I grant you that there are a number of battery chemistries that would be able to accomplish this in theory, but it might be extremely difficult to implement in practice. I mean fusion has been theoretically possible for almost a century and it's still 15 years away according to its proponents.
it's not even just a question of batteries; it's a question of efficiency. From what I can tell this is far less efficient than a propeller. Even if batteries get orders of magnitude better it would make far more sense to just transition to electrically driven propellers and/or fans.
tl;dr there are multiple technologies which need to improve before this could be a viable propulsion method, let alone provide any actual advantage.