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Drone Startup Claims It Flew Its Ion-Propulsion Drone On 4.5-Minute Test Flight (interestingengineering.com) 65

Posted by BeauHD from the impressive-if-true dept.
An anonymous reader quotes a report from Interesting Engineering: Florida-based tech startup Undefined Technologies announced its unique ionic propulsion drone has passed an outdoor flight test, meaning it's on track for commercial release in 2024, according to a report from New Atlas. The drone, called Silent Ventus, uses proprietary technology to ionize the oxygen and nitrogen molecules in the surrounding air to create an "ionic wind" that propels the machine in the direction it wants to go. According to Undefined, the drone could be used for cargo. Though it's not been used for large-scale drone projects on Earth before, ionic propulsion isn't a new technology. In fact, it's currently one of the best technologies humans currently possess for deep space exploration propulsion and other space applications. According to Undefined, its "Air Tantrum" ionic propulsion technology produces up to 150 percent more thrust than current ion thruster technologies.

Earlier this year, the company released footage of a two-and-a-half-minute indoor flight test, saying the drone emitted 85 decibels of noise. Now, it claims it's flown a prototype for four and a half minutes, though it's only released one minute, 17 seconds of footage. The drone firm also says it achieved a noise level below 75 dB. It's now aiming to secure further investment to build a zero-emissions cargo delivery drone by 2023 that could fly for 15 minutes and make less than 70 dB. Undefined claims its "silent" 70-dB drones will lead to far fewer noise complaints in areas that will be served by urban cargo delivery drones in the future. However, it's worth pointing out that Undefined had yet to test its drone with large payloads, which will require extra thrust and will likely make more noise.
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Drone Startup Claims It Flew Its Ion-Propulsion Drone On 4.5-Minute Test Flight More

Drone Startup Claims It Flew Its Ion-Propulsion Drone On 4.5-Minute Test Flight

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  • Location of investor money? (Score:1)

    by Anonymous Coward
    #Undefined

  • "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; additionally, the engine's minuscule thrust cannot overcome any significant air resistance. Moreover, notwithstanding the presence of an atmosphere (or lack thereof) an ion engine cannot generate sufficient thrust to achieve initial liftoff from any celestial body with significant surface gravity."
    https://en.wikipedia.org/wi [wikipedia.org]

  • Pretty neat thing. I am not sure if they'll outdo traditional propeller based drones, but it's a neat project none-the-less. The force generated is mostly tied to the electric current and space between the anode and the corona wire. The content of the air really only becomes a significant value in higher altitudes (> 10k feet) or (and the really important part) if it's anything BUT a clear sunny day. Moisture makes the air gap a better conductor which sort of isn't what you really want here, not to m

  • This looks (and sounds) much more like they're using a ducted fan inside their secret black box rather than generating much lift from their ion engine. I find it much more plausible that they're only getting 20 or 30% of the lift from ion propulsion, which no one would really call a breakthrough.
    • I’d agree. If you watch the initial video the takeoff thrust gives it a very large upward acceleration against gravity which is dubious for an ion thrust design. Further, if you look closely underneath you can actually see the flaps to direct the thrust. It’s clear the ion thrust engines are only partially helping just the balance and they don’t even look like they have a mechanism in place for the ion thrust engines to control yaw. It’s not clear they have the mechanism to contr

    • Re: (Score:2)

      by SirSlud ( 67381 )

      there's being skeptical, and then there's just being fucking stupid

  • Noise Pollution Thoughts? (Score:2, Interesting)

    by Anonymous Coward

    So, assume a device operates in a neighborhood with background sound-level measures of 40dB. A "silent" ion-propulsion device comes flying in at 70dB (supposedly quiet). That is a 30dB different in sound-levels. Since decibel units represent logarithmic scales, that is about 2^5 relative difference and suggests a relative, human-perceived, sound-level increase of 32 times.

    For comparison, assume that the same neighborhood has a posted speed limit of 35MPH. The analog would be comparable to a vehicle rocketin

  • Flight test engineer's observations (Score:5, Interesting)

    by Goldenhawk ( 242867 ) on Monday September 26, 2022 @10:20AM (#62914561) Homepage

    Just a few quick observations from a flight test engineer.

    There are no "innovative physics" here, unlike what the company website claims. It's pretty rudimentary physics, actually, that's been well-known for a long time. Maybe there are some new tricks at scaling it up, but there's nothing fundamentally different at play here.

    Battery life could be a real problem. The literature is somewhat mixed on efficiency, with some claiming much higher efficiency than jet propulsion.
    https://www.sciencedaily.com/r... [sciencedaily.com]
    But this kind of propulsion requires VERY high voltage source. Getting high voltage out of low voltage power cells requires converting DC voltage to higher levels, which itself has significant inefficiencies. No matter how many low-voltage batteries they use, they'll still need significant conversions up to the 10s or 100s of kilovolts needed to generate ionic flow.

    However, the most significant compromise, in my view, seems to be the low thrust spread across a huge area, which seems to lead to controllability problems. A jet engine or propeller system has fairly small exit areas with high air velocity; this instead requires a fairly large cross section for the lower-velocity thrust exit area. This results in a fairly large platform, but with low thrust spread across its surface. When you get into the physics, or more specifically the mass dynamics, the problem is a large moment of inertia with a low force to control it.

    Imagine, if you will, a rod about five feet long, with a bowling ball at the center (the mass of the system, mainly the batteries and cargo in this case). And there are small thrusters way out at the tips of the rod (like one axis of a quadcopter). You can easily imagine it doesn't take much force on the tips of the rod to make that system rotate. All the mass is at the center. But now imagine the bowling ball mass and the thrust force spread out along the entire length of the rod. If you want to quickly affect the angle of that system, you need a fairly large force differential between the two sides, and it's going to take a while for that force to have an effect. So it is with this system: the mass is spread across a very wide area, and so is the force. Even if the batteries and cargo sit at the middle, you've still got the large structure to hold the thrust components, and the thrust is not concentrated out at the tips where it would have the most effect. At best it can be imagined as effectively only halfway out to the tips.

    I'm also worried about response time. Any system like this inherently uses the thrust to create control forces. Now, the real beauty of a propeller-based drone driven by electric motors is the almost instantaneous thrust response, which is why a typical quad or hex copter can be absolutely rock-steady in the air, even with turbulence. (This is also a reason why you don't see jet-engine-based quadcopters: jet thrust is very slow-responding.) But when your thrust response is spread across square meters at very low local airflow speeds, and depends on voltage changes to induce nearly undetectable airflow changes, response time suffers significantly. When you slow down the response time of your control system, you lower the dynamic stability of the system. And the stability decreases with gain in any system - the harder or faster you try to maneuver, the lower the stability.

    So from my perspective, there are two inherent challenges that will lead to control problems: a hugely distributed thrust area, plus slow response time. The result, as you can easily see in the video, is instability. The thing never ever stops rocking back and forth, and when they get close to touchdown the amplitude of the oscillation increases noticeably. And that was with a basically zero-load condition. Size this thing up to carry cargo, and it will only get worse. You can try to filter it, but that just leads to larger errors and overshoots in desired position or angle. You can't have

    • Really? I took one look at it and noticed the flaps underneath to control what looks (high initial acceleration against gravity in the original video) and sounds like a hidden conventional fan in the magic black box. Also in the original video they had no yaw control and they haven’t made clear how they will despite it being possible with an ion thrust design. You also left off rain or even just high humidity shorting it out and it not working but it’s ok because they aren’t going to b

      • I don't know whether this thing makes sense or not but there's no fan in the box [youtube.com].

        • Did you link the right video? The one you posted is the one I’m talking about. Zoom in and look underneath and you can not only see the control surfaces to direct the central thrus^w cooling fan exhaust, but if you look closely you can see them being actuated to control the gross balance of the craft.
          • If a description helps it’s a + shape and they tilt its axis to direct the thrust^w cooling fan exhaust.

            • I figured you were watching the video where it's got the shroud on it.

              They would be hard pressed to get enough thrust out of those dinky little cones to keep it aloft without a jet engine.

              • My first thought was the 4 cones/landing legs were being used for thrust (and maybe at one time that was the plan) but it’s clear it is in the center and the + shape is on a gimbal to direct it.

        • Re:Flight test engineer's observations (Score:4, Informative)

          by caseih ( 160668 ) on Monday September 26, 2022 @02:35PM (#62915449)

          There's clearly a fan in all the actual test flights they have footage of. the Ionic drive thing only seems to be used to stabilize the drone or control pitch and roll (I don't see any yaw control yet). At most it contributes a tiny amount to the lift. Anyone that's familiar with EDF units in RC aircraft will recognize the sound of the EDF in these videos.

    • They were hoping this almost-obligatory /. post didn't show up until AFTER the meeting with the VC whales....

    • Even more so, is the physics of thrust in general. Since it's air-driven, thrust is based on mass air flow vs weight. In the video you when the vehicle is close to the ground you don't see the grass moving at all (mind that a kick up of debris). All absent as one would expect the grass to be moving wildly from the air mass being "thrusted" onto the ground like any other VTOL that moves air mass to lift the weight. Instead it's antigravity?

    • Replying to myself: one of the replies to my post indicated that someone spotted flaps underneath the thrust-producing grid. That makes sense - you could set up an arrangement that would use actuated flaps (little servo motors would be sufficient) to block or open part of the thrust produced by the grid, providing a fairly fast and effective rolling or pitching or even yawing moment. That would probably be much better than modulating the thrust in real time. It does come with the tradeoffs of weight and com

    • Re: (Score:2)

      by juancn ( 596002 )
      I wonder if a hybrid system would fare better? There maybe is a configuration that's a hybrid between a traditional quad-copter, with the electric motors for stability and the ion plane for load support.

      If it provides some gains in efficiency or noise it may be worthwhile anyway.

  • Ion propulsion engines appear to be all the rage these days. But silent, they are not. The company appears to be playing on the general ignorance of that even in their product's name, Silent Ventus.

    The article claims the current prototype produces 70 dB of noise. And that the prototype can't carry any payload yet. The requirements for additional thrust to carry payload would suggest 70 dB is a lower limit.

    A quick search online provides this very nice page comparing the loudness of typical drones to othe

  • The drone, called Silent Ventus, uses proprietary technology to ionize the oxygen and nitrogen molecules in the surrounding air to create an "ionic wind" that propels the machine ...

    I think I saw this in the Sharper Image catalog -- "What can't those guys ionize?" (Michael, "The Good Place")

  • How the hell do birds fly so silently? I mean, imagine if an eagle made that much noise?

    • I think being able to hover is a big sacrifice in efficiency and noise. A bee for example is audible despite generating only enough lift for its minuscule mass.
  • As far as I know, ion propulsion is very efficient in space, but thrust is a rounding error, unsuitable for the strong gravity over our planet surface. Is this a joke/scam?
  • There is no way ion propulsion can be scaled up to much heavier loads. It is not a scam or fake and to actually achieve untethered flight is quite an accomplishment with even a small payload. I continue to be interested in what happens to these drones when it rains.....

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