Ion thrusters allow a plane with no moving parts

Wednesday, November 21st, 2018

Electrohydrodynamic thrust, or ion thrust, could power aircraft — silently:

Ionic thrusters are simple in design: They feature one thin copper electrode, known as an emitter, and one thicker tube of a metal-like aluminum called a collector. A lightweight frame supports the wires, which connect to an electrical power source, and keeps them apart—the gap between them is vital to creating ionic wind.

When voltage is applied to the wires, the resulting field gradient pulls electrons away from surrounding air molecules, ionizing them. The ionized air molecules are strongly repelled by the emitter and strongly attracted to the collector. As they move toward the collector, they push the other air molecules around them, creating thrust.


Steven Barrett, assistant professor of aeronautics and astronautics at MIT, has now shown that ionic thrusters may, in fact, be perfect for aerospace applications—especially, he says, for surveillance vehicles.

“I first had the idea as an undergrad,” Barrett says, “because it was interesting to me that hobbyists were making small lifters, which showed this worked on some level. And I found out that these hobbyists were all wondering if it could be efficient enough to power a larger craft.” He picked up the project again when he became a faculty member and had more creative freedom.

Why pursue ionic thrusters? For one thing, Barrett says, they have the potential to outperform current jet engines. In a series of experiments in which Barrett fed electricity to a simple ionocraft attached to a digital scale, which allowed him to measure the exact thrust produced each time the craft left the ground, the model produced 110 newtons of thrust per kilowatt, versus a jet engine’s 2 newtons. Ionic thrusters are silent and, because they give off no heat, completely invisible to infrared sensors.

The system was most efficient at a low velocity, but Barrett explains that this is actually a positive. “You want to produce the most thrust you can at the lowest velocity,” he says.

He recently demonstrated the idea:

But unlike its predecessors, which had tumbled to the ground, Version 2 sailed nearly 200 feet through the air at roughly 11 miles per hour (17 kilometers per hour). With no visible exhaust and no roaring jet or whirling propeller—no moving parts at all, in fact—the aircraft seemed silently animated by an ethereal source. “It was very exciting,” Barrett says. “Then it crashed into the wall, which wasn’t ideal.”

(Hat tip to Jonathan Jeckell.)


  1. Russ says:

    You know who’d really be interested in an absolutely silent drone? The military. This professor can expect a billion dollar grant shortly.

  2. Isegoria says:

    On Twitter, Nyrath voiced some concerns:

    And if it rains does the glider short circuit like the 4th of July? Or if somebody touches it does the shock stop their heart?

    Naturally, I replied:

    A silent drone that kills on contact? What use could that possibly be?

  3. Bruce says:

    ‘perfect for surveillance purposes’? Not with the radio noise that thing’s got to be giving off. James Blish mentioned this idea in passing in A Case of Conscience.

Leave a Reply