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DDWFTTW Turntable Test

  1. Jan 10, 2009 #1
    I have built a turntable and “cart” to test the claim of being able to travel directly downwind faster than the wind using only the immediate force of the wind. Here is a video of the test. The turntable is level but looks like it’s on an angle because of the camera angle. The cart ran against the motion of the turntable for over 5 minutes without loosing any speed. Is this conclusive proof of DDWFTTW?

    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Jan 10, 2009 #2
    I'm new here, so I'm not crazy enough to get involved in this debate, but I would like to say that's a pretty cool turntable. Nice job!
  4. Jan 10, 2009 #3
    First of all, interesting design.

    I do not see how the fact that the cart ran against the motion of the turntable is a definite proof that DDWFTTW (Downwind Faster than the Wind) exists. Rather, if you can prove that the cart speeds up with respect to the motion of the turntable, then maybe you have a case. Of course, there might be something that I am missing.

    In addition, you have not taken into consideration of the possible lift within the device. IF the cart is speeding up, it is completely possible to be an effect of lift rather than some "additional speed".

    Personally, I do not think DDWFTW is true, because it contradicts the conservation principles and suggest a perceptual motion machine. But then again, I am only a high school student. My personal belief is that the effect of DDWFTW comes from lift, after all, the birds had been doing it for centuries.
    Last edited by a moderator: Sep 25, 2014
  5. Jan 10, 2009 #4
    Thanks. It was fun to build.
  6. Jan 10, 2009 #5
    Unlike all other moving surface DDWFTTW tests I’ve seen this cart is not held against the moving surface to gain propeller thrust. This cart moves freely on the surface and only gets it’s propeller thrust from the wind created when it moves through the still air with the turntable.

    Not sure what you mean by “lift”. Can you explain in more detail?

    Seems to do the “impossible” to me as well. But as anyone can plainly see, it does it! I like your typo (or humour) “perceptual motion”. It seems to be being continuously positively geared from the speed of the wind and doesn’t have to represent perpetual motion or free energy.
  7. Jan 10, 2009 #6
    Hahaha, I was wondering if I should have put LOL next to it. But I guess people got it.

    Anyways, here is more about lift
    http://en.wikipedia.org/wiki/Lift_(force [Broken])
    ^my personal belief, I don't know if there are any research on its effect on these motion (prob.)

    Just wondering, have you seen this setup?
    Last edited by a moderator: May 3, 2017
  8. Jan 10, 2009 #7
    To assimilate actual outside wind conditions as much as possible I have done a test where the cart is held to the turntable with a removable block so the cart initially has to move at the same speed as the turntable. The block is then removed (after about 3 - 4 seconds in video) and the wind then powers the thrust of the propeller to make the cart travel against the motion of the turntable.

    Here’s the video -
    Last edited by a moderator: Sep 25, 2014
  9. Jan 11, 2009 #8
    Well the cart doesn’t have a wing. Even if it gets some form of lift from the propeller so what? It still appears to effectively travel downwind faster than the wind. And it does it sustainable, I have now tested the cart speed is constant against the turntable for over 10 minutes.

    Yes I’ve seen all the Spork & Co videos on another forum and they are what got me interested in this to begin with.
    Last edited by a moderator: May 3, 2017
  10. Jan 11, 2009 #9
    I'm not sure what I'm looking at. The table is turned by a motor. What is turning the propeller on the end of the rotating arm?
    Last edited by a moderator: Sep 25, 2014
  11. Jan 11, 2009 #10
    The wind created by the propeller moving through still air.

    ETA - And the wheel rolling against the motion of the turntable surface.
    Last edited: Jan 11, 2009
  12. Jan 11, 2009 #11
    I watched it three more times. I don't know what this does to your downwind thingy concept, but it's clear that airflow is coming off the spinning table, which is, in effect, a one blade Tesla turbine, dontcha know? I think this airflow is probably turning the propeller. Run the table without the rotating arm and feel anywhere near the periphery of the turntable: you'll feel airflow coming off it. I'm thinking whichever side of the propeller is nearest bottom dead center is getting turned by this air flow while the other one is pulling the propeller forward in the usual way.
    Last edited: Jan 11, 2009
  13. Jan 11, 2009 #12


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    Are you sure it's not the frictional force at the pivot point next to the vice grips causing the motor car to move slower than the turn-table, generating a relative speed which at some point causes the propeller to have enough thrust to propel the little car in the direction opposite that of the table.

    I do love these FTTW machines. I always scratch my head for a bit when I see them.
    I actually like yours the best. You should build a small model and sell it as a novelty.
    You might make a million dollars!

    Have you seen the motor car that goes faster than the ruler video? It seems to be somehow related to these FTTW devices.

  14. Jan 11, 2009 #13
    I think if he reconfigured it a bit he could use it for good rather than evil: to prove than an airplane can take off while sitting on a backwards moving conveyor belt.
  15. Jan 11, 2009 #14
    I’m not “sure” of anything. I built this turntable and cart thinking that it would more than likely disprove the DDWFTTW claim made by others. It seems to me however that it serves to prove the claims rather than disprove.

    I don’t see that friction at the centre pivot is any different than the overall friction of rolling resistance of the cart. Can you explain how slight friction at the pivot point would have any effect that is different than the overall friction of the rolling resistance? In my mind the thrust of the propeller shouldn’t exceed the overall rolling resistance of the cart. But apparently it does!

    I like mine best as well (but I might have a slight bias). A million dollars you say! . . . Hmmmm

    Think I have seen all (if not most) FTTW videos.

    ETA - I can also make the cart "hover" with no (or very little) movement against the centre pivot.
    Last edited: Jan 11, 2009
  16. Jan 11, 2009 #15


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    With a fast enough belt, we could launch a shuttle all the way to the moon! No more of those toxic solid rockets and explosive hydrogen tanks. Perhaps we could run one up the side of Mt. Everest to give it just the right angle.
  17. Jan 11, 2009 #16
    It’s a gimmick so there’s gotta be a buck in it. Maybe I should have a talk with my Irish friend Pat Pending. Hmmmmm . . . world domination . . . evil it is!
  18. Jan 11, 2009 #17


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    I'm not even sure what they are trying to prove.
    Why did the cart move slower than the turntable when you started it then?
    That one was faster than a ruler though. And the maker has a British accent. And he has prequels and sequels. I've watched them all.
  19. Jan 11, 2009 #18
    That it is possible to sustain ably travel directly downwind faster than the wind only using the immediate speed of the wind.
    Not just because of friction at the centre pivot but also because of all the friction of the cart and resistance of the still air. Un-tethered three wheel carts can do the same thing.

    But the demonstration was that ruler = wind.
  20. Jan 11, 2009 #19


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    I've yet to see that.
    Your next model should be on stationary ground with a wind tunnel.
    And the puppets were incredible.
  21. Jan 11, 2009 #20
    Just because there isn't wings doesn't mean lift doesn't occur. Helicopters, for example, doesn't have wings but they rely on the concept of lift to fly. After all, the cart does have a propeller.

    And once again, I don't see how a cart moving against the turntable definitely proof that a sail can go faster than the wind that propels it.
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