Next-gen all-electric drone featuring ion-propulsion technology with a very low acoustic profile – is it really that silent?

If there’s anything not-so-pleasing about a drone, it’s the sound pollution caused by the propellors rendering the otherwise extremely useful aircraft, noisy.

I am concerned that drones are taking to the air without a lot of thought for the ears of people on the ground. Will there be a weight limit on delivery-drone payloads? Who will monitor the sound levels, and how? Should there be a curfew on hours of operation? There must be a reason companies don’t include the sound of the drone in advertising materials – and it’s probably not because they sound so nice. In this ad, the drone seems silent

Garth Paine-Associate Professor of Digital Sound and Interactive Media, Arizona State University

An electric drone with absolutely zero noise levels and emissions might seem to exist in a utopian world, not in ours? Or, can they?

If reports are anything to go by, “Undefined Technologies”- a Florida-based tech startup,  unveiled a new aesthetic design of its silent eVTOL drone last month, dubbed “Silent Ventus”. It is unlike any other drone you’ve seen before and is reportedly powered by ion propulsion- touted to produce a very minimum noise signature.

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Silent Ventus is a vivid example of our intent of creating a sustainable, progressive, and less-noisy urban environment. The design brings us closer to our final product and enables us to showcase the dual-use of our technology

 said Tomas Pribanic, Founder and CEO of Undefined Technologies
Tomas Pribanic | Commercial UAV News

Now for the main question- what is ion propulsion and is it practically possible?

Ion Propulsion

What is ion propulsion?

Theoretically, an ion thruster ionizes propellant by adding or removing electrons to produce ions. Most thrusters ionize propellant by electron bombardment-a high-energy electron (negative charge) collides with a propellant atom (neutral charge), releasing electrons from the propellant atom and resulting in a positively charged ion. In simple words, Ion thrusters eject ions instead of combustion gases to create thrust.

Illustrative | Online Star Register

Ideally, Ion thrust engines are practical only in the vacuum of space and cannot take vehicles through the atmosphere because ion engines do not work in the presence of ions outside the engine. Furthermore, the engine’s minuscule thrust cannot overcome any significant air resistance.

Illustrative | NASA

Coming back to “Silent Ventus”- this concept vehicle reportedly uses proprietary technology to fully activate the ion cloud surrounding the craft, which is believed to generate high levels of ion thrust in atmospheric air, thereby pushing the flight to a near-silence environment.

According to the stats displayed on the website, commercial delivery drones generate between 85 and 96 dB of noise, while U.S. regulations allow for noise levels of 50 to 70 dB in residential, industrial, and commercial zones.

With the commercialization of this aircraft, the company hopes of achieving noise levels below 70 dB and has already shared footage of its prototypes completing test flight missions of up to two and a half minutes at below 85 dB.

The company’s ultimate goal is to slash the noise levels even further while at the same time, increasing the overall flight time, thereby making it feasible for a variety of applications, from last-mile delivery to civil, military operations and more.

Although, though much is not known about the “proprietary ion propulsion technology” at the moment, what we do know is that it uses “innovative physics, making it viable to use ion propulsion in atmospheric conditions with the superior performance of up to 160% compared to current ion thruster technologies.

Scientifically, atmospheric ion propulsion usually generates minuscule thrust hence if there’s an appreciable amount of thrust generated, this truly would be revolutionary in the world of drone propulsion.


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