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Down wind faster than the wind

Myriad said:
Wind acts on propeller to push cart. It can do this even while the cart body is travelling at the same speed as the wind because the propeller blade surfaces are advancing against the wind (toward the rear of the cart) due to the spinning of the prop.

As the cart is pushed forward, the wheels rolling on the ground spin the prop.

If properly constructed, there's no reason for it not to work.

Here's an easier-to-understand example:

[qimg]http://www.internationalskeptics.com/forums/imagehosting/13012493204e1d7668.jpg[/qimg]

The open parachute at the top moves toward the rear of the cart frame as the cart rolls left to right. That is, it moves right to left relative to the cart frame. However, for each rotation of the wheel at bottom center, the parachute moves a shorter distance left to right (a distance equal to the circumference of the inner wheel that the belt carrying the chutes is wrapped around) than the cart frame moves toward the right (a distance equal to the circumference of the outer wheel that's in contact with the ground). Therefore, the parachute moves left to right relative to the ground.

To repeat: the parachute at the top moves right to left relative to the cart frame, and left to right relative to the ground.

Now, imagine the cart is moving downwind, left to right, at the speed of the wind.

1. Because the parachute is moving right to left relative to the cart frame, it's moving slower than the wind, and the wind still pushes it.

2. Because the parachute moves left to right relative to the ground when the cart rolls, the wind pushing on the parachute provides thrust to the cart in the left to right direction.

Accept points 1 and 2, and the device has to work. Some people seem to have a problem with point 2, but many physical models of it have been presented here. The downruler-faster-than-the-ruler model is a very close analogue, with the top surface of the wheel corresponding to the top parachute in the above device.

Respectfully,
Myriad
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The propeller blades have to do some work in order to spin. where do they get this?
 
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Tsig:
>No the treadmill has no wind.

You can keep saying that all you want, but saying it won't make it true. "Wind" is nothing more than relative motion between air and surface. With the treadmill set at 10mph in a still air room, anything -- that's right ANYTHING traveling with the belt of the treamill sees 10mph of wind.

>All the power comes from the treadmill.

That's correct -- every bit of the power to create that 10mph of wind comes from the treadmill. So what!! -- we don't care what powers the wind -- it can be the sun, it can be an electric motor, it can be the FSM ... we don't care and the cart doesn't care, just give us wind.

Again, use an electric fan. Use an electric treadmill. Use the sun. Use the bed of a truck powered by a diesel motor. Use whatever you want -- just give us wind and the cart is set.

>The treadmill leaves out the wind not me.

Don't blame the treadmill. The treadmill is creating 10mph of wind -- it has left nothing out.

JB
 
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ThinAirDesigns said:
Tsig:
>No the treadmill has no wind.

You can keep saying that all you want, but saying it won't make it true. "Wind" is nothing more than relative motion between air and surface. With the treadmill set at 10mph in a still air room, anything -- that's right ANYTHING on the belt of the treamill sees 10mph of wind.
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No. A propeller cannot be forced to supply energy just because of the relative motion of the air. Take a small propeller on a shaft. Hold it in your hand in the wind. The amount of work done depends upon the load, and the propeller's capacity to provide it at those particular angular and wind velocities. A propeller spinning in still air with no load, si doubly damned.

>All the power comes from the treadmill.
Click to expand...

That's correct -- every bit of the power to create that 10mph of wind comes from the treadmill. So what!! -- we don't care what powers the wind -- it can be the sun, it can be an electric motor, it can be the FSM ... we don't care and the cart doesn't care, just give us wind.

Again, use an electric fan. Use an electric treadmill. Use the sun. Use the bed of a truck powered by a diesel motor. Use whatever you want -- just give us wind and the cart is set.
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The treadmill motor is an analogue of the wind's power. Therefore all energy must come from it, and so the wind in the real case.

That above is a tautology of "all power comes from the wind"



>The treadmill leaves out the wind not me.

Don't blame the treadmill. The treadmill is creating 10mph of wind -- it has left nothing out.

JB
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No, it should go back with the belt, then the 'wind' is present. Otherwise, there is no load and no wind, to boot.

ETA:
Kudos to JB, for answering. Where's the master when you need him?
 
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Oh.. how long is the treadmill in question? I want to calcluate how long you can feel 10mph wind for.
 
tsig said:
No the treadmill has no wind. All the power comes from the treadmill.
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tsig said:
The treadmill leaves out the wind not me.
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tsig said:
It is not a matter of belief.
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tsig said:
The propeller blades have to do some work in order to spin. where do they get this?
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tsig said:
There is no wind in the treadmill tests.
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tsig said:
You said that the wheels powered the propeller now you say that the wind powers it.
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Compelling as this "proof by absolute (and repeated) assertion" is - I'm going to have to say TROLL.
 
spork said:
Compelling as this "proof by absolute (and repeated) assertion" is - I'm going to have to say TROLL.
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And you will be wrong.

Don't forget your sunglasses next time you go to the gym, wouldn't want your eyes to dry out... ;)
 
I haven't followed this thread well enough to even ask a question, but let me ask a few.

1.What is the general consensus? It seems like it is that a device that could travel downwind faster than the wind is possible. Is that the consensus with perhaps some doubters?

2. Assuming that a iceboat on a reach can have a downwind component velocity component faster than the wind can the plausibility of this device be established by just imagining a single vehicle that consists of two iceboats reaching and tacking downwind tied together? I think maybe somebody earlier tried to make this point in a more complicated way. Since it was more complicated, though, I didn't understand it.

3. Is the consensus that the treadmill is a valid way to test the device? Has any attempt been made to do so?

Undoubtedly a lot of these issue have been addressed at various points in this thread. My apologies for bringing them up without searching through it for the answers. In my defense this thread did generate a lot of tension that was confusing to the causal observer trying to make sense of it.
 
Smackety said:
3. There is no wind on a treadmill, sorry. At least, not for very long.
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I was hoping to have a better understanding of this before I posted again but a 10 mph treadmill seems to produce a very similar situation to the situation when the wind blows past an observer at 10 mph. If one imagines a very large treadmill one one could imagine a situation where one couldn't tell the difference between being on the treadmill running at 10mph and being on the non-moving treadmill with a wind rushing past oneself at 10mph. Assuming no exterior clues how could one tell if he was on a stationary treadmill with the wind blowing past or on a moving treadmill with no wind?
 
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