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Down wind faster than the wind

The only way to make the friction drive flywheel travel against the motion of the turntable would be to suddenly slow the turntable when the cart was “up to speed“. The reason I want to test with a flywheel is to show how gradual the loss of kinetic energy is when active on the turntable.
 
ynot said:
The only way to make the friction drive flywheel travel against the motion of the turntable would be to suddenly slow the turntable when the cart was “up to speed“.
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Yes. In steady state rotation, the flywheel-cart will just sit it's ass down on the turntable and go along for the ride.

The reason I want to test with a flywheel is to show how gradual the loss of kinetic energy is when active on the turntable.
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You mean you want to determine how long it takes to coast down from some predetermined speed with a flywheel rather than prop? Well, just remember that without the drag of the prop it will coast longer than with the prop.

I'm dyin' to hear the script for this test.

JB
 
humber said:
Please see my post #1427. This is a reprise of many posts on the treadmill. Perhaps you would be so kind as follow the remainder and tell me why the treadmill is not a force balance as I claim. If you think there is a wind, what happens if you should shield it? Surely that is possible, if they are equivalent.
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What does it mean to shield a cart traveling at wind speed from the wind?
 
spork said:
Question to all: can any of you honestly even parse humbers words into sentences anymore? I dip into a post of his now and then just to get my fair share of abuse - but when my brain starts jellifying I have my spotter pull me out. I mean it's like some form of super-concentrated, pseudo-engineering spewage that's produced with liberal use of a random number generator - sort of like the verbal equivalent of white noise at the of 50% distortion level. In fact I think it may be an art form that I simply don't get.
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humber's posts are like those of a religious fanatic. Anything that discredits his faith must itself be discredited. The treadmill video evidence is overwhelmingly damning to his belief that the cart cannot work so therefore it is the treadmill that is in error. Evidence of the wind sock cannot be trusted because that would lead to the "wrong" conclusion.

If the conversation is shifted to be tangential to proof of the cart, humber will settle down and his posts will actually be somewhat lucid. But once he makes the connection of where the conversation is leading he will throw something in from left field like colliding super tankers.
 
Without reading the whole thread, I'm assuming we're not talking about a treadmill that is powered independently and allowing a hypothetical treadmill operator to operate it at any physical speed....but...if that were the case, the operator could select a treadmill velocity such that a plane *would* stay on the ground. Provided the velocity selected was relativistic, the mass of the treadmill increases. This could keep the plane from flying by any number of mechanisms, #1 by increasing gravitational pull it can balance the lift from the plane's wings. #2 This would increase the normal force due to friction preventing the plane's motion. #3 It might exhibit frame dragging on the airplane. #4 Just put the plane in the treadmill's event horizon and *poof* the problem is solved.
 
Michael C said:
Um, zosima: how much of the thread did you read? We're talking about a wind-powered cart that runs down wind faster than the wind. You seem to be talking about something completely different.
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I'm talking about the airplane on a treadmill thought experiment. Related, but admittedly tangential.

EDIT: On topic, that seems a lot of posts on a question that one could answer relatively simply. Just use the wind in combustion. Done.
 
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zosima said:
Without reading the whole thread, I'm assuming we're not talking about a treadmill that is powered independently and allowing a hypothetical treadmill operator to operate it at any physical speed....but...if that were the case, the operator could select a treadmill velocity such that a plane *would* stay on the ground. Provided the velocity selected was relativistic, the mass of the treadmill increases. This could keep the plane from flying by any number of mechanisms, #1 by increasing gravitational pull it can balance the lift from the plane's wings. #2 This would increase the normal force due to friction preventing the plane's motion. #3 It might exhibit frame dragging on the airplane. #4 Just put the plane in the treadmill's event horizon and *poof* the problem is solved.
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We're discussing a treadmill that moves at the speed of a light, steady wind - 10 mph or so.

And anyway, what you said here is totally absurd. Long before you get anywhere near relativistic speeds friction in the plane's wheels would melt the bearings, making it unable to roll and sending it shooting backwards along with the belt.
 
sol invictus said:
We're discussing a treadmill that moves at the speed of a light, steady wind - 10 mph or so.

And anyway, what you said here is totally absurd. Long before you get anywhere near relativistic speeds friction in the plane's wheels would melt the bearings, making it unable to roll and sending it shooting backwards along with the belt.
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Clearly. It was a joke. I don't need to get dragged into 1700 post thread. But there isn't any thought experiment that can't be disabled with physical details, that is why it isn't a real experiment.

I suspect you are joking as well. It is a little difficult to catch tone on an internet forum.

That said, the presence of the wheels in the treadmill thought experiment is actually irrelevant. Without wheels(or with melted wheels) it just means a higher coefficient of static friction.
 
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zosima said:
EDIT: On topic, that seems a lot of posts on a question that one could answer relatively simply. Just use the wind in combustion. Done.
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The question is not "can we burn something to go faster than the wind?". It's "how does the cart that takes only kinetic energy from the wind go faster than the wind that's pushing it?"
 
Michael C said:
The question is not "can we burn something to go faster than the wind?". It's "how does the cart that takes only kinetic energy from the wind go faster than the wind that's pushing it?"
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Truly

Edit:
Answer: It doesn't
 
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zosima said:
That said, the presence of the wheels in the treadmill thought experiment is actually irrelevant. Without wheels(or with melted wheels) it just means a higher coefficient of static friction.
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Nonsense - it is anything but irrelevant. A plane which can take off without wheels is a plane that can take off vertically, in which case the whole treadmill scenario is pointless.

zosima said:
Truly

Edit:
Answer: It doesn't
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Wrong again.
 
Michael C said:
The question is not "can we burn something to go faster than the wind?". It's "how does the cart that takes only kinetic energy from the wind go faster than the wind that's pushing it?"
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zosima said:
Truly

Edit:
Answer: It doesn't
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Good: now we're on topic. I'll put it more precisely: do you believe that the cart presented in this video can keep up a constant speed down wind faster than the wind that is being used to power it?

 
Then you weren't joking? You go from treadmill at the speed of light to wheels melting? It seemed a hilarious juxtaposition to me.


sol invictus said:
Nonsense - it is anything but irrelevant. A plane which can take off without wheels is a plane that can take off vertically, in which case the whole treadmill scenario is pointless.
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Back to Newtonian physics for you. Or maybe just childhood, ever heard of a sled?

Wrong again.
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Please explain.
 
Dan O. said:
humber's posts are like those of a religious fanatic. Anything that discredits his faith must itself be discredited. The treadmill video evidence is overwhelmingly damning to his belief that the cart cannot work so therefore it is the treadmill that is in error. Evidence of the wind sock cannot be trusted because that would lead to the "wrong" conclusion.

If the conversation is shifted to be tangential to proof of the cart, humber will settle down and his posts will actually be somewhat lucid. But once he makes the connection of where the conversation is leading he will throw something in from left field like colliding super tankers.
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Thanks Dan, for putting that so clearly. Humber's faith prevents him from admitting the simplest mistakes. When I took him up on that, he assumed I was starting a puerile contest:
humber said:
You are doing exactly what I and other critics contend. Being seen to be right is more important than being right. You see making mistakes as shameful.
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I certainly don't see making mistakes as shameful (if it turns anyone on to see me admitting a mistake on this thread, just look here). Indeed, people who publicly admit that they were mistaken usually gain respect. It's interesting to see what's been happening on Mark Chu-Carroll's blog: on Dec. 3rd he posted a scathing article explaining how the cart obviously can't work, the people who made it are a bunch of stupid bozos and the whole thing is so obvious that even his third grade daughter can understand it. A couple of days later, he realised he was wrong. He posted a full apology at the top of the original article, leaving the original article intact as a testament to his "own stupidity and hubris in screwing this up". He's gained respect from doing that.
 
zosima said:
Truly

Edit:
Answer: It doesn't
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zosima,

sure you can explain why it doesn't do that, can't you? Look at the cart. Look at the parts of the cart. Now keep in mind that sailboats can indeed travel faster than the wind that is driving them.

So, what is your theory why it can not work? Many people here have given examples why it actually _does_ work. Now you come here, tell us that you didnt read the thread either, but nonetheless you are sure it doesn't work.

Care to tell us why?

Greetings,

Chris
 
zosima said:
Then you weren't joking? You go from treadmill at the speed of light to wheels melting? It seemed a hilarious juxtaposition to me.
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You've got it backwards....

Back to Newtonian physics for you. Or maybe just childhood, ever heard of a sled?
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Go look up some coefficients of static friction for the relevant materials. Metal on metal is often greater than 1, metal on concrete probably is as well. And those tests are conducted for smooth contact surfaces - here there would be jagged, hot or even partially molten pieces protruding down from the plane's landing gear, even assuming it holds up under the pressure and doesn't break apart.

If the plane can take off under those circumstances it doesn't need a runway at all.

Please explain.
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Read the thread. Or just think for yourself.
 
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