A Safe, Ducted Drone With No Visible Blades

We love a good drone build here at Hackaday, but no matter how much care is taken, exposed propellers are always a risk: you don’t have to look far on the web to see videos to prove it. Conventional prop-guards like those seen on consumer drones often only protect the side of the propeller, not the top, and the same problem goes for EDFs. [Stefano Rivellini]’s solution was to take some EDFs and place them in the middle of large carbon fibre thrust tubes, making it impossible to get anywhere near the moving parts. The creation is described as a bladeless drone, but it’s not: they’re just well hidden inside the carbon fibre.

We’re impressed by the fact that custom moulds were made for every part of the body, allowing [Stefano] to manually create the required shapes out of carbon fibre cloth and epoxy. He even went to the trouble of running CFD on the design before manufacture, to ensure that there would be adequate thrust. Some DJI electronics provide the brains, and there’s also a parachute deployment tube on the back.

Whilst there’s no doubt that the finished drone succeeds at being safe, the design does come at the cost of efficiency. The power electronics needed are far more serious than we’d usually see on a drone of this size, to compensate for the extra mass of the thrust ducts and the impediment to the air-flow caused by the two 90° bends.

One of our favorite EDF drone innovations that we saw recently was this thrust-vectored single rotor device, a really unique idea that took some interesting control methods to implement.

[Thanks, Itay]

47 thoughts on “A Safe, Ducted Drone With No Visible Blades

        1. Regulus, you should stick to opining on things you’re familiar with…

          The US is first-to-file (since 2013), AND:

          [a] person shall be entitled to a patent unless—

          (1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention;

    1. Video says “patent pending” at the end, so perhaps that process is in motion. The amount of power the design requires will be a bit of a stumbling block. 10,000 watts is just around thirteen horsepower, so it’s not beyond the realm of a good small ICE, but that will also add more complication and weight. And kill the whole green aspect of the system.

      Wonder why the ducts need to be so long / have two 90-degree bends? Couldn’t it just have four vertical tubes to keep stuff away from the ducted fans but otherwise function as a normal drone? It sure looks cool with its curvy Giger-esque black tubes, though. Most cyberpunk-looking drone, A+ from me.

    1. Yeah agreed. Suprerlatives are the most dangerous words in the universe.

      Really we should be teaching the seriousness of using them better in school. Along with effective debate skills and critical thinking.
      There can only be exclusively ONE “first” of anything, which is hard to prove. And “only” is a temporal adjective. Only (potentially) true for the moment.

    2. HaD writers are very prone to this too or they are unexperienced and have a small ”world”. Adding ”ever” after that kid of statement is illogical. Unless the world is destroyed, something smallER or better would be made.

      1. Unless there are silencers within the ductwork, there will be almost no attenuation between the fan and the duct outlet. And I doubt there are silencers, because that would mean reducing the airflow of an already too-restrictive duct. It really depends on how loud the fans are, and their load.

  1. Wouldn’t it be fine if you just added wire mesh/grid all around standard propellers?
    Fans do that for ages and the ducts feel like additional unnecessary (really cool) steps.
    I really like the idea and drone as a fun toy though.

  2. This is really interesting idea. I am only suspicious how much do the tubes decrease the ducted fans power. I am also curious whether such concept would also work with one central ducted fan in the centre of the drone – maybe gasoline one which has better weight/flight endurance ratio – and the output of particular nozzles could be controlled by some sort of electrically operated flaps in the tubes. But I am aware that this is not easy thing.

    1. Well one central fan would cause it to spin pretty badly and remove the ability to vary the thrust per duct, but with the ability to rotate or otherwise aim the tubes that might be manageable.

        1. I was thinking something along those lines but I prefer to have multiple engines feeding into a central thrust chamber and then having each tube throttled with flaps or deverters, that way if one engine fails you still have enough power to get the drone to the ground.

          1. Yeah, it might work with two combustion engines placed above each other with fans like coaxial rotors … One big advantage of gasoline engines would be decreasing weight during flight. But it would still require some additional battery for the engine flap controls, radio etc.

  3. Nice proof of concept, and the video is also vey well made.
    It shows lots of details of building things, such as the molds for the carbon fibre and the cardboard jigs to orient things properly before a more final assembly.
    The video is a bit too fast paced for my brain though. I do not have enough brain capacity to let sink in all the very short shots.

    Needing 10kW to get this thing into the air is another big issue.
    First: impressive that you can pump 10kW into those motors, but there must be some horrible inefficiencies.
    The added weight of all the pipes does not help and the bends in the pipes make it worse.
    Why not simply use simple ducted fan’s with around 10cm of straight pipe?
    (10 cm is just a guess, should be long enough to keep your fingers safe).

    1. I also thought a few straight pipes would be better. I mean he still ends up having to put a grille over the intake; why not just put a grille on either side of an EDF?

      10,000 watts is around 13 hp but it’s a hell of a lot for some 22-volt electric motors.

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