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Comment by superkuh | Hacker News Reader

This is absurd and scientific american sure has taken a fall from grace in order to believe it. Electrostatic "lifters" have been around for half a century. They are toys. They do not scale up. They cannot even lift themselves as their power supply or energy storage has to be on the ground with tiny wires going up to the lifter. There is absolutely no chance this can be called a 'plane'. It always has to be tethered with wire to deliver the power.

They were really popular with the UFO/Free energy crackpot crowds back in the late 90s and early 2000s.

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It's not entirely clear from the article, and I can't find the Nature publication yet... but I think you're wrong.

It does carry it's own power supply and battery: "Finally Barrett used a computer model to get the most out of every design element in the aircraft, from the thruster and electrical system designs to the wires that ran through the plane. “The power converter, the battery, the caps and fuselage—everything was optimized,” Barrett says. “The simulations failed all the time. We had to make hundreds of changes.” In the end, they had the triumphant Version 2."

Here's the researchers earlier publication (2015) on the physics behind it: http://rspa.royalsocietypublishing.org/content/471/2175/2014...

Edit: found some more material. No video of the actual plane yet. But the professor has a website here.

http://electricaircraft.mit.edu/research/

This is such a typical Hacker News dismissal. The paper isn't even on Nature's website; please give it at least a week or a read before dumping on the author.

Well this particular plane runs off a battery...

And from TFA (sadly, the paper in Nature is referred to, but not properly cited) a main innovation is the development of a system that provides the required 40,000 volts from a battery in a form-factor amenable to small aircraft (think drone) usage.

Will make being a baggage handler pretty exciting.

Does it? As far as I can tell it doesn't exist outside of the person's mind. Having played around with lifters myself using balsa, al foil, and a rectified neon sign transformer I just don't think the physics can work out. And there's no physical plane photos or videos to support otherwise. Until then I'm sticking with this being absurd.

That said, ionization does have it's place in aircraft in terms of controlling attachment or detachment of turbulent airflow over wings. It can significantly improve fuel consumption by reducing drag.

But it is not a viable propulsion source. At least not on Earth for things larger than a meter or so.

Here is a time lapse of the flight: http://electricaircraft.mit.edu/wp-content/uploads/2018/11/a...

Larger: http://electricaircraft.mit.edu/wp-content/uploads/2018/11/a...

https://youtu.be/boB6qu5dcCw?t=128

>But it is not a viable propulsion source. At least not on Earth for things larger than a meter or so.

It's 5m wide

Thanks for providing that. It does prove my point though. That plane is not flying at all. It is falling with style. The initial forward momentum is from the launch rail, not from the electrostatic propulsion.

https://sci-hub.tw/https://www.nature.com/articles/s41586-01...

see the top of page 534, figure b. You are correct that the initial forward momentum is from the launch rail, but the graph clearly shows that the ion engine provides thrust.

Is the title of the HN submission misleading? Yes.

Did the plane achieve flight with the ion engine alone? No.

Was the plane able to maintain and gain altitude because of the ion engine? Yes.

A step forward in the right direction but not as much of a breakthrough as the submission title would have you think.

>As far as I can tell it doesn't exist outside of the person's mind.

Based brah. I'm being serious when I say that I think HN needs more of this type of comment. They seem to love rigidity in comments, but not any bluntness or banter thrown in there.

Nice work finding the paper.

Thanks for finding the paper.

Sucking almost 3A out of the battery, it's not going to fly very long, but that's also a fairly inefficient power converter design. There is lots of room for improvement.

"As far as I can tell it doesn't exist outside of the person's mind."

Why would you say something like this? You sound arrogant and stupid.

You are talking about an article which says "he built the thing and flew it". And you deny that based on your balsa wood experiments?

Someone else has done you the favor of posting a video of it flying. Perhaps you'll believe that?

https://www.youtube.com/watch?v=boB6qu5dcCw

At 2:11 you can see it moving in a straight line.

Not shown: all the momentum imparted by the launch itself.

For the Nature paper they compared unpowered vs powered flight. Unpowered got about 10m, powered got to 60m, the length of their test facility.

In that clip it is not slowing down, showing that the ion drive is generating sufficient thrust to sustain flight. It's irrelevant that it used assistance to initially reach that speed.

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