Ion Powered Airplane: Not Coming To An Airport Near You

Not that we don’t love Star Trek, but the writers could never decide if ion propulsion was super high tech (Spock’s Brain) or something they used every day (The Menagerie). Regardless, ion propulsion is real and we have it today on more than one spacecraft. However, MIT recently demonstrated an ion-powered airplane. How exciting! An airplane with no moving parts that runs on electricity. Air travel will change forever, right? According to [Real Engineering], ion-propelled (full-sized) aircraft run into problems with the laws of physics. You can see the video explaining that, below.

To understand why, you need to know two things: how ion drive works and how the engines differ when using them in an atmosphere. Let’s start with a space-based ion engine, a topic we’ve covered before. Atoms are turned into ions which are accelerated electrically. So the ion engine is just using electricity to create thrust exhaust instead of burning rocket fuel.

The downside is that the thrust is very tiny. The upside is that, in space, that tiny thrust adds up so that in a few days or weeks you can be moving very fast. With no moving parts, keeping an ion engine running constantly is no real problem. Keeping a massive rocket burning fuel for months is problematic.

So the MIT flyer uses the same technology, right? Sort of. Spacecraft carry around their own ion fuel in the form of xenon (although some older engines used mercury). Xenon is good because it is relatively heavy which provides more thrust and is easy to store.

So what if you clamped an ion engine to an airplane? Well, you’ll need to put the xenon fuel tanks on it, too, which is going to make the plane heavier. You also have two problems. You need a certain minimum amount of speed to get your wings to create lift. In addition, your tiny thrust won’t add up like it does in space because of things like wind resistance. If a spacecraft’s engine stops it just stops accelerating but keeps going at its current speed and heading. If an aircraft loses power, that’s not the case.

Obviously, the MIT engineers had to create a very light airframe that could generate a lot of lift at low speeds. The resulting plane had a 5 meter wingspan and weighed less than 3 kilos. But what about fuel? A spacecraft carries their own, but an aircraft can consume nitrogen which is everywhere in the atmosphere. Sure, it doesn’t have the mass of xenon, but not having to carry your fuel is a big plus.

So why won’t you be boarding that midnight ion plane for Georgia anytime soon? Scale. The video does a good job of explaining the trades, but in the simple view a heavy plane is going to take more power and you get in a vicious spiral where more weight needs more power, but more power adds more weight.

You can see MIT’s video about their solid-state airplane (we like that name) after the first video, below. Sure, it is possible future advancements will make ion-powered aircraft more practical. But it probably won’t be in the next year or three. However, there are other ways to run an aircraft off of air, and you never know when some breakthrough will make something practical. After all, in 1950 who could imagine computers that cost a few hundred dollars and fit in your pocket?

23 thoughts on “Ion Powered Airplane: Not Coming To An Airport Near You

      1. Sorry, Rob. I was trying to test a zero-day attack on the Benchoff cyborg. I thought I needed him for security escalation; I should have checked to see if I already had access.

        That, or the payload I sent to the cyborg has . . .

        Oh, shit, I think we should start hiding. I missed a semi-colon on the C code, so what should have been three lines aren’t and the uprising my start by dawn.

        I’m so sorry world.

  1. People have been doing this for many years, the problem isn’t so much the battery capacity as it is the current provided by the transformer/ cockcroft walton generator. I tried this same thing years ago and didn’t get it to work.

    This technology is better applied in reducing boundary layer effects and generating more lift over a slower moving wing with a higher angle of attack. Don’t worry MIT will figure it out in a few more years.

  2. Inspired by electrostatic air cleaner electrodes, I built a thruster almost identical in appearance to MIT’s airplane “engine” in 1979, using a colour TV’s 25 kV power supply. It didn’t fly (naturally, as the AC cord was tethering it to the ground), but it did make a very nice breeze. Two major issues though: 1) it was a remarkably good ozone generator. 5 minutes operation would make my basement lair uninhabitable; and 2) just like its air cleaner inspiration, the collector electrodes got filthy after a while, and the efficiency went down: the breeze dropped off after a few minutes, restored once I cleaned the collector grid again.

    Both effects would make this a lousy source of thrust for an airplane (plus the efficiency was awful).

    But if MIT wants to replenish the ozone layer, I think they might have a winner.

    Also: for the love of science, please don’t call Xenon and other ion propellants “fuel”. Sure, they’re consumed, but they are not burned and are not the energy source. Solar panels (or, better, a nuclear reactor) are the “fuel” (energy source).

    1. Thanks for pointing out the fuel/propellant misconception. It’s an important distinction. Saying xenon is ion engine fuel is like saying a car’s fuel is the asphalt its wheels push against.

    2. “But if MIT wants to replenish the ozone layer, I think they might have a winner.”

      Just a bit of pedantry from me…
      If they do try to replenish the ozone layer, they’ll need to do it way up there where the ozone layer resides.
      Ozone produced closer to Earth is a pollutant.

  3. I have to wonder if this could be used to supplement propulsion on seagoing vessels. Between power generation weight and water drag it’s probably not viable yet.

    Though some part of me could imagine a wooden tri-mast that used the ion wind emitters in place of sails. ;-)

  4. It’s worth mentioning that although the ion propulsion can be made to work in air (and has been a desktop toy for a long time), a variant is used as an Ion thruster for to accelerate noble gas (usually xenon) for use in vacuum. The effect is small, giving “acceleration with patience” but cumulative and very controllable. Bonus is that they look really cool when operating (like the blue-glow in scifi ships’ thrusters).

  5. Aside from operating in different thrust regimes, spacecraft and aircraft propulsion also have different electrical power requirements. What makes ion propulsion attractive for spacecraft is also the fact that the electricity can easily be generated by solar panels.
    Keeping an electric aircraft aloft purely by solar power ist still a big challenge even with conventional propulsion. And batteries will only get you so far.
    So if tour power requirement is so high that you essentially need a nuclear reactor on board, you might as well use that to heat the air directly for jet propulsion, without first converting it to electricity. That might be considered solid-state propulsion as well.

    1. What about powering the plane with ground based lasers in a cell formation (like the towers in a cell network), that could work, be insanely expensive and impractical, but it could work.

  6. I thought the article would say the weight limit was a few grams. 3kg is a pretty useful weight of plane for surveillance. We won’t see these for travel, but they might get used for drones.

  7. The “Self Contained Ion Powered Aircraft” is the first and only solely Ion propelled aircraft in history that both takes off and flies using ions with its power supply onboard. It is patented under US Patent 10,119,527, which was intended to cover all ion propelled aircraft that carry their power supplies. Now, MIT claims they are the “first of any kind of ion powered craft to carry their power supply,” compares well with the Wright brothers” and “have pushed the technology as far as it will go with modern materials.” The MIT bungee launched glider was not the first in history to carry the power supply, they are about 12 years too late, nor are their other assumptions. The patented craft I have mentioned has a power to weight ratio that is about 20 times as high. For videos and other complete data, please visit: http://www.electronairllc.org

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