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So one of my old teachers from my previous school sent me a contraption to try and figure out what it was and how it worked. Pictures here.

I've played around with it for a while. I tested to see if it did something when spinning really, really quickly by attaching a motor, tried taking it apart numerous ways, and plenty of things in-between.

As far as I've gathered, here's what I think it's doing. The propeller drives a shaft that is attached to something that converts the circular motion into linear motion. At this point the glass is frosted or there's some kind of glue on the inside that makes it very hard to see clearly what's going on. The top is connected to the bottle via two pipes that end in a hole in the side of the bottle. The cap itself has a hole in the top to which the top thing is screwed to, possibly also leaving space for water to go through -- it's unclear. The purple part is sticky on one side, suggesting that the whole thing sticks to the wall or maybe to something that moves like a car.

Or maybe the propeller isn't what does the driving at all. Maybe it's filled with water and stuck to a wall or something facing downwards, and gravity would cause the water to cause the whole thing to leap to life! But, I can't find any way of filling it up -- there's no existing holes as far as I can tell. I may be able to take off the whole red cap but that's made difficult with the yellow pipes.

So I'm stuck. Does anyone have any idea about what this mysterious thing is?


The propellers have arrows on them indicating the direction they should turn. This suggests that the propeller is indeed the driver and not the drivee.

  • $\begingroup$ The pictures should be here in the question, not at the other end of a link. $\endgroup$ Mar 25, 2017 at 15:34
  • 1
    $\begingroup$ @OlinLathrop I don't have the required reputation to post that many images in a question. $\endgroup$
    – Awn
    Mar 25, 2017 at 15:53

1 Answer 1


It looks like it might be a air-powered propeller. You pump up the bottle with air, and the high pressure is used to run a air motor that spins the propeller. This might have been part of a toy airplane, with the wings and tail now gone.

  • $\begingroup$ An air-powered propeller sounds like a decent guess. I can't see where/how it could be pumped up though, surely not by disassembling it each time? I can't see it being an airplane though, the weight distribution and just the way it looks, feels wrong. $\endgroup$
    – Awn
    Mar 25, 2017 at 15:47
  • $\begingroup$ Actually, maybe it isn't an air-powered propeller either: see update to question. $\endgroup$
    – Awn
    Mar 25, 2017 at 16:02
  • $\begingroup$ Can you unscrew the red top without the bottle rotating relative to the "motor" (or whatever it is)? Otherwise, just pull off the yellow pipes, or the clip where they enter the bottle. $\endgroup$
    – alephzero
    Mar 26, 2017 at 2:53
  • $\begingroup$ @alephzero Nope, it's not possible to take off the top. And I tried taking off the pipe but there isn't enough space to be able to pull it out. $\endgroup$
    – Awn
    Mar 27, 2017 at 4:36
  • $\begingroup$ @Olin It seems as though you're right. The hole to fill it up it certainly not standard but it is in fact an air-powered propeller. $\endgroup$
    – Awn
    Mar 27, 2017 at 4:37

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