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Downwind Faster than the Wind (DWFTTW) Myth Challenge

This is our submission for the Mythbusters video challenge  
 
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This is a video response to Under the ruler faster than the ruler
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Dexistomors (1 week ago) Show Hide
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So the wheels generate the power behind the fan, which then push the cart forward, generating more speed via fan? Or am I misunderstanding this?
mukmuk7 (5 months ago) Show Hide
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One thing you'll notice about machines like this and other things like the windmill driven boat direct against the wind are that they serve to decrease the relative velocities of air to the other medium they happen to be travelling in.
mukmuk7 (5 months ago) Show Hide
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It is not free energy. It is extracting from the pool of energy that is two different media with differing relative velocities.(the air and ground in this case) or air and water in other cases.
Note the equation Energy = Force X distance. The force created by the fan can be greater without violating the conservation of energy law than the force exerted on the wheels, as the distance the wheels travel relative to the road is greater than the distance travelled by the fan relative to the air.
gmrecneps (6 months ago) Show Hide
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I want to buy one. How much will you sell one (that works well outside) for? You should sell them as toys... I think you'd make a fortune if you could make them pretty cheap. Looks cool.
spork33 (6 months ago) Show Hide
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Look at my other videos. I posted a series of three bideos that takes you through the build process in detail. I also give all the part numbers etc., as well as where to get them.
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ancalagon12321 (8 months ago) Show Hide
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I imagine the rotation of the propellor as being like a helicopter's rotor on its side, then can consider the familiar forces of 'drag' and 'lift'. Lift propels the cart forwards whereas drag opposes the rotation of the prop, and hence acts to slow the cart down. However, the connection between the wheels and the prop is such that a small change in prop speed causes a relatively large change in cart speed. Hence, by some 'lever law', the lift 'wins' and the cart is propelled forwards til AOA=0.
Sgrunterundt (9 months ago) Show Hide
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Obviously it would work just as well in a wind tunnle as everywhere else. But it would be hard to study because it would speed of down the tunnel and hit the end quickly.
MultiplePersonas (8 months ago) Show Hide
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I don't buy it. Probably could be done, but the treadmills not a cart in the wind. Goodman video only one I could. find showing one. I didn't see an explanation about how speeds were determined either, wind or cart, or any neutral observers. And what about gusts? They could keep that wind sock showing higher speed than wind speed after a lull, via the kinetic energy. This is all pure woo science at this stage.
subductionzone (8 months ago) Show Hide
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What difference is there between the cart on the treadmill and the cart in the wind? The treadmill test is very analogous to a wind tunnel test for a wing. It allows you to limit distractions. If it works on the treadmill it will work in the wind.

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