Your Quadcopter Has Three Propellers Too Many

While studying failure modes for quadcopters, and how to get them safely to the ground with less than a full quad of propellers, a group of researchers at the Institute for Dynamic Systems and Control at ETH Zurich came up with a great idea: a mode of flight that’s like the controlled spinning descent of a maple seed.

The Monospinner runs on the absolute minimum number of moving parts. Namely, one. Even a normal helicopter has a swash plate for adjustable blade pitch, and a tail rotor to keep it from spinning. Give up the idea that you want to keep it from spinning, and you can achieve controlled flight with a lot less. Well, one motor and a whole lot of math and simulation.

The Monospinner is carefully weighted so that it’s as stable as possible while spinning, but so far it’s unable to spin itself up from a standstill. In initial tests, they attached it to a pivot to help. The best part of the video (below) is when the researcher throws it, spinning, into the air and it eventually stabilizes. Very cool.

There’s an academic paper on the general idea, so you can get started with the number crunching. Our guess is that getting this thing to fly is non-trivial in the extreme. So kudos to the ETH folks for getting it (to stay) off the ground.

Thanks [lluki] for the tip!

50 thoughts on “Your Quadcopter Has Three Propellers Too Many

    1. There’s a little cheap plastic toy my mate got a few years ago, was like that. A tiny little UFO shape, with a copter blade on top. The body also had some wings on it. So both parts spun, in opposite directions, and gave some sort of lift. It had infra-red remote control, can’t remember what control you actually had though, whether it was just up / down.

      1. I had one of those I think:

        From what I recall, it could move forward, back, left, and right. It knew which way was forward by sensing which direction the IR signal was coming from and timing the throttles of the two motors at the wing tips so it would fly away from the IR beam. Same principle for all of the other directions.

        It was a cool toy, but it (or I) was quite feeble at flying and had to be retired due to crash damage.

        1. Ah, no, one I’m thinking of is much cheaper and nastier. Yours looks cool though! Must weigh almost nothing, those little rice-grain motors powering it. Very impressive it could do direction, must be some fast reactions.

  1. So, could you use this in airdrops? Agriculture? Combat? I’m trying to see a use for this – despite the fact that it’s hella cool. Also – zero moving parts? How on earth can you get ‘solidstate’ flight?

    1. With an ion engine. Over 10 years ago so called “lifters” were a hit on the internet. Everything you need to build one can be bought at the supermarket. Except for the ~30KV power supply…

    2. To learn how to have at least some control in case you damage a traditional x-copter thing…Would definitely make combat x-copter drones a lot harder to “kill”.

      1. It also works with one motor, and the creator of that particular (ingenious) innovation has also done research on passively stabilizing single motor copters using inertia and the form factor of the frame itself. It also appears far more responsive to control input than this thing.

  2. it’s absolutely brilliant! the only thing left to do is to engineer a drive system that accepts a constant input but is geared for the specific delays it needs to avoid flopping over.

  3. NASA at one point proposed the “Samara Camera” – think of a spinning maple seed with a camera taking 360° images as it rotated downward through the atmosphere. There was a central camera hub and a single lateral sail to slow it down and cause it to rotate/scan.

    I can’t find any reference to it now, and I realize that it wouldn’t be self-sustaining, but…you wanted simple.

  4. That last comment has me scratching my head…how on earth do you design a controllable flying machine with no moving parts at all? Some kind of Ionocraft based control?

  5. A quadcopter could well be flown within 3Km(2 miles) of an airfield if they are above 17 years of age(but there are arguments who is above 17 years of age in possession of a quadcopter – perhaps why police are so slack at taking them away…hmmm)

    Drone Quad-copter flight control demo – Legislation (What they didn’t tell you) !

    Australian news article…”regulation needed as drones threaten planes”…

    In basic terms, there are actions that can improve quality of life with equipment such as these smaller drones e.g. Tarantula X6 with FPV but the only problem is its all the same to a legislator(e.g. bees and stingless bee species)..

    original cartoonist (US gun debate)

    modified cartoon -( Australia – Britains Commonwealths)
    Note: To attempt to obtain or possess a bullet proof vest in these countries is a serious offence

  6. Holy hell, that is one of the crazier things I’ve seen… it moves through the air with all the grace of a flying hammer. lol!! I never would’ve imagined that something making such a crazy eccentric motion could sustain flight for any length of time, let alone HOVER!

  7. Two moving parts. The big rotor (the main structure which looks like it spin s off center with an angle of attack that provides some lift) and the propeller or small rotor running counter to the big rotor. If you change the frame of reference to on-board you get bigger moving parts – the small rotor and the Earth spinning about 100 RPM.

  8. Not to be that guy, but samara wings are not a new idea. They have been used in smart munitions, for example, for years to steer bomblets toward detected targets. For that matter, it’s the failure mode of a helicopter, and why they don’t plummet to earth after engine failure.

    1. Technically no, when a helicopter looses engine power but still has all the controls, it just has to adjust the counter-torque…it will descend no matter what the pilot does, but it can do in a controlled manner and if it has the space, can usually land intact.
      Loosing the counter-torque ability however, is quite a different story…

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