Travelling without moving

“The future of flight shouldn’t be things with propellers and turbines. It should be more like what you see in Star Trek with a kind of blue glow and something that silently glides through the air.”

That’s what Steven Barret, from the Department of Aeronautics and Astronautics at MIT believes.

And I’m sure many people share that same vision.

The difference is, he and his team have just achieved it. Although on a small scale, for now.

They have created the world’s first “solid state” aircraft. By solid state, they mean it has no moving parts.

Like most technology, until you learn how it works, it seems like magic. And I suppose if you never learn how it works it really is magic.

Thankfully, unlike most magicians, Barret has no qualms about revealing how his invention works.

From ArsTechnica:

In conventional aircraft, air is pushed around by moving parts, either propellers or the turbines within jet engines. But we’ve known for a while that it’s also possible to use electrical fields to push air around.

The challenge is that air is largely made of uncharged molecules that don’t respond to electric fields. But at sufficiently high voltages, it’s possible to ionize the nitrogen and oxygen that make up our atmosphere, just as lightning does all the time. The electrons that are liberated speed away, collide with other molecules, and ionize some of them as well. If this takes place in an electric field, all those ions will start moving to the appropriate electrode. In the process, they’ll collide with neutral molecules and push them along. The resulting bulk movement of atmospheric molecules is called an ionic wind.

Calculations done decades ago, however, suggested that it wasn’t possible to generate a practical amount of thrust using an ionic wind. Given advances in batteries, electronics, and materials, however, a team from MIT decided the time may have come to revisit the issue.

The technology that powers it sounds fittingly futuristic. It’s called an ion drive, because it generates ionic wind, as the excerpt above explains.

Basically this ion drive enables charged wires to generate thrust (ionic wind) without moving, and completely silently.

This idea is not new – but the materials required to bring it into reality are

“The idea dates back until at least the 1920, when an eccentric inventor at the time started experimenting with high-voltage electrodes and thought he had discovered anti-gravity,” says Barret.

The reason it never really got off the ground (sorry) until now is that battery and electrical technology wasn’t up to the task.

So, like many promising ideas, it was shelved until later scientists, with access to new technology, picked it up again.

Wires at the front of the craft’s wings have +20,000 volts of electricity running through them. Wires at the back -20,000 volts. This creates an electric field sending ions from the front to the back of the wing.

Generating that much electricity on a craft that weighs less than 2.5kg is no easy task. Bear in mind that the voltage of your home plug sockets is only 240 volts, and they are connected to the national grid.

Barret’s ion drive plane has flown for 60 metres inside a gymnasium. Which might not sound impressive, until you learn that this was simply the maximum flight they could achieve within said gymnasium.

From ArsTechnica again:

Measurements showed the thrusters collectively generated five newtons for each kilowatt of power, which is actually similar to the output of jet engines.

But because of many inefficiencies in the system, the overall efficiency was only about 2.5 percent—well below that of conventional aircraft.

Still, the researchers have a huge list of potential improvements. The current design was limited by the decision to keep it flying inside the track at MIT. Allowing larger wings and a higher speed could get that efficiency up to five percent without any changes to the underlying technology.

They also plan to explore things like different ways of generating ions, electrode designs that reduce drag and/or are integrated into the wing, and better power conversion electronics, all of which could boost things further.

“Of course we don’t yet know whether it will be practical and widely used”

Barret says that while ion drives may be some way off powering passenger aircraft, they could prove extremely useful for drones.

It will be easier to create smaller vehicles like drones.

I think the near-term advantage is probably in noise. Especially if you think that perhaps in 10 years we might have urban areas that are filled with drones doing things like monitoring traffic, monitoring air pollution, many other services we’re ye to imagine.

Drones today are quite noisy and irritating. We wouldn’t want our urban environments to be polluted by all this noise. So developing a way of developing drones that’s silent, or near silent, would be advantageous in that context.

He has a real point. I don’t know if you’ve had any experience with drones. I have, and I can tell you they are loud. Very loud. Especially for their size.

Given that companies like Amazon believe the future of delivery lies in drones, having silent ones would be a huge advantage for our future sanity.

If you want to find out more about the ion drive, you can read the team’s paper on it in nature. Or, if you’d prefer to watch a video you can see one here.

Until next time,

Harry Hamburg
Editor, Exponential Investor

PS Well done if you got the Jamiroquai reference in the headline.

Category: Robotics

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