Solid State Airplane

[Shpaget]

Guys at MIT claim to have made a solid state airplane, meaning powered flight with no moving parts.

http://news.mit.edu/2018/first-ionic-wind-plane-no-moving-parts-1121

It uses high voltage to ionize air and accelerate it backwards to produce thrust.

We've talked here several times about electric airplanes and how impractical they are, but I see this as futile on a whole other level. All the problems with conventional propellers or ducted fans powered by electric motors and batteries apply, only to be further complicated by abysmal efficiency of this approach.

The only advantage this thing has is lower noise, but that at what cost?

[Bill Phil]

Could be useful in space exploration. I mean, thermocouples aren’t efficient either but they’re used all the time. No moving parts would be a great thing for, say... a plane on Titan. 

[mikegarrison]

Could be useful for military applications. Fly a silent sensor drone over an enemy location before you attack it....

Anyway, these sorts of demos are not intended to be useful in and of themselves. But getting it to fly means you move the technology one TRL higher.

[K^2]

55 minutes ago, mikegarrison said:

Could be useful for military applications. Fly a silent sensor drone over an enemy location before you attack it....

There are demos with flexible wings that are just as silent, but have way better flight characteristics in just about every way. I don't think we'll find any real uses for something like this on Earth. Bill Phill could be right about space exploration. Though, I suspect low density atmospheres, like that of Mars, are a better place for it than Titan.

[cubinator]

I don't mind if this is useful or not, I think it's cool!

[Bill Phil]

44 minutes ago, K^2 said:

There are demos with flexible wings that are just as silent, but have way better flight characteristics in just about every way. I don't think we'll find any real uses for something like this on Earth. Bill Phill could be right about space exploration. Though, I suspect low density atmospheres, like that of Mars, are a better place for it than Titan.

Maybe. I was thinking that the low gravity of Titan could allow the plane to carry more science equipment, and the thicker atmosphere means less velocity is needed for an equal amount of lift. I’m not sure about specifics, but Mars’s atmosphere may not be dense enough. I’m not well versed in ion engine planes though.

[cubinator]

29 minutes ago, Bill Phil said:

I’m not sure about specifics, but Mars’s atmosphere may not be dense enough. I’m not well versed in ion engine planes though.

If my understanding of airplane physics is correct, the issue with Mars is that the stall speed for a given plane is really fast. So no matter whether it's an ion plane, a propeller plane, or a rocket plane, you need giant wings and you can only land and take off at really high speed.

[ThatGuyWithALongUsername]

This brings back KSP memories more than anything tbh... remember ion-powered planes?

[razark]

5 hours ago, Shpaget said:

The only advantage this thing has is lower noise, but that at what cost?

I'd say that one advantage it has is that we now know a little bit more about the world around us and how we can manipulate us.

Whether it can be exploited for anything practical is a completely different question.

[mikegarrison]

3 hours ago, ThatGuyWithALongUsername said:

This brings back KSP memories more than anything tbh... remember ion-powered planes?

Different though. They are ionizing the air itself, not a propellant gas.

[Nuke]

pretty cool. i was wondering how long it would take to get a psu small/light enough to do this. modern power components have gotten really small thanks to smart phones, so it was only a matter of time.

[0111narwhalz]

Interesting toy. I'm interested in how much power this actually takes. Sure, it's high voltage, but what kind of current is involved?

[Green Baron]

Paper: https://www.nature.com/articles/s41586-018-0707-9

https://www.nature.com/articles/d41586-018-07485-9

For now, the plane just flew on a stretched glide slope. The thrust is still far too low to take off and climb. But its been demonstrated that the technology can work.

"Full impulse, Mr Crusher !"

:-)

[NSEP]

Ok cool.

Can we get flying cars now or do we have to wait another 70 years? 

[Cassel]

22 minutes ago, NSEP said:

Ok cool.

Can we get flying cars now or do we have to wait another 70 years? 

Even better

[Shpaget]

6 hours ago, Green Baron said:

But its been demonstrated that the technology can work.

The tech in question is nothing new. In fact it's almost 100 years old.

https://en.wikipedia.org/wiki/Ionocraft

I suppose it was just the matter of combining modern battery tech with principles in use for F1D class of model airplanes (things that can fly for more than half an hour using less energy than those ugly LEDs from OP use in that 12 second glide).

[Nivee~]

17 hours ago, ThatGuyWithALongUsername said:

This brings back KSP memories more than anything tbh... remember ion-powered planes?

Whaaa?? That was a thing? How??

[ThatGuyWithALongUsername]

4 hours ago, Nivee~ said:

Whaaa?? That was a thing? How??

A long, long time ago, before the 1.0 update, Ions had even higher thrust (still low, but higher nonetheless), better performance in atmospheres, and the aerodynamic model was worse. Ion gliders were great for slow but long-range gliders, especially on Duna. With the exception of that one Bradley Whistance video in 1.13, they have been impossible on Kerbin ever since.

[K^2]

22 hours ago, Bill Phil said:

Maybe. I was thinking that the low gravity of Titan could allow the plane to carry more science equipment, and the thicker atmosphere means less velocity is needed for an equal amount of lift. I’m not sure about specifics, but Mars’s atmosphere may not be dense enough. I’m not well versed in ion engine planes though.

Ion drive is advantageous at high speeds you need to sustain glide in thin atmosphere, and disadvantageous at low speeds of a thick atmo world. Even in the frigid cold of Titan, there are simpler and way more efficient propulsion methods. And battery weight is a huge factor. Conventional propulsion methods on Mars, in contrast, would require very large moving parts on delicate, large wingspan glider. Ion drive actually benefits from large wingspan and rarified gas as medium, and does not add a lot of extra weight to the glider, making it viable despite some loss of efficiency. Mars is about as close as it gets to best case for an ionocraft.

[ThatGuyWithALongUsername]

Crazy idea: what about an ice giant? It could survive fine in the upper atmosphere, right? A balloon would probably be better since you probably wouldn't be going anywhere in particular, since, in the case of the friendlier of the two, there's almost no variation on the "surface." But still, maybe it could have its advantages!

[Nuke]

On 11/21/2018 at 11:38 PM, 0111narwhalz said:

Interesting toy. I'm interested in how much power this actually takes. Sure, it's high voltage, but what kind of current is involved?

i thought about sticking in the resistance of air into the ohms law equation but it turns out its not that simple. the resistance of air varies a lot based on its ion content. and air conducting electricity will always produce additional ions, so its resistance will likely fluctuate. this makes estimating the properties of the power supply difficult. maybe its in the paper. 

[Ultimate Steve]

20 hours ago, ThatGuyWithALongUsername said:

 A long, long time ago, before the 1.0 update, Ions had even higher thrust (still low, but higher nonetheless), better performance in atmospheres, and the aerodynamic model was worse. Ion gliders were great for slow but long-range gliders, especially on Duna. With the exception of that one Bradley Whistance video in 1.13, they have been impossible on Kerbin ever since.

I remember the big scramble to make an ion plane work after 1.0. That was fun! It was a collection of designs competing to just demonstrate that temporarily sustained flight was possible. Early on the consensus was probably not, but eventually, utilizing rover wheels to get to takeoff speed, using fuel cells for power, and launching from Kerbin's highest mountain, I was the first person to demonstrate that an ion plane that could gain altitude and velocity at the same time time in the new aero. Not to toot my own horn or anything. Although you can make a case for it not being a "true" ion plane because of the rover wheels.

Excuse the cringe video quality, this was years ago.

After that, there were several more designs. It was mathematically determined that it was just past the edge of possibility to launch one from runway altitude, although people got really close. If you catapulted to a higher altitude, maybe. Eventually, I refined the design and it got to 18 kilometers and posted screenshots. I vaguely remember getting to 22km but I never posted the video, or screenshots. I probably still have it somewhere, but it would be on the old computer.

Link to the thread if interested:

 

 

[Shpaget]

On 11/22/2018 at 9:38 AM, 0111narwhalz said:

Interesting toy. I'm interested in how much power this actually takes. Sure, it's high voltage, but what kind of current is involved?

At eevblog forums there is a thread about a lifter_

http://www.eevblog.com/forum/dodgy-technology/ionic-lifters-has-anyone-else-around-here-build-one/

tldr, 297W to lift 250g

[munlander1]

On 11/22/2018 at 6:55 AM, NSEP said:

Can we get flying cars now or do we have to wait another 70 years? 

People can’t properly control cars in 2 axis. You wanna give them another?

[Nuke]

i found a schematic of the psu in this hackaday article.

 

ok after having the chance to look at the schematic i can get an idea of whats going on.

voltage starts in the 160-225 range. that's like 54 lipoly cells in series. they are going to need to be thin cells. these are available in thicknesses in the 0.5-2 mm range and <= 200mah. these cells are designed for low discharge rates but can handle 10c in short bursts. the plane likely only has a couple minutes of battery life. 

anyway thats converted to ac using an h-bridge so that's 450v peak to peak. the control side just watches the output through the divider and provides appropriate pwm signals to the h-bridge. then it goes to a 1:15 transformer (multiply by 15), and then the voltage multiplier has 6 stages (multiply by 6). this type of multiplier also rectifies so it comes out as vdc. so with a fully charged battery that gets it up to 40.5kv if i did my math right. much of this can be done solid state, though a transformer is required its likely a tiny one.

estimating the ampage of the psu requires guesstimating the stats of the battery. 10 amps in short bursts if they used off the shelf batteries would probably be the best case scenario. general rule of thumb for power supplies is that when you double the voltage you halve the current. since its battery voltage is going up by a factor of 180 (2*15*6) that takes our 10 amps down to about 56ma.

Edited November 28, 2018 by Nuke