Down wind faster than the wind

[John Freestone]

All right. Okay. Let's give it a try.

Forget about the propeller-based device for now. Just forget about it.

Look at this device (illustration by Myriad):

Using the laws of physics, answer these questions:

When you pull on the upper chain towards the right, will it move? Will the wheel move? If the chain moves, and the wheel moves, and the chain's velocity towards the right is v, what is the velocity of the wheel?

Note: when answering these question, please do not refer to the propeller-based device. Refer only to this one.

Ok. Assuming that I understand Myriad's odd way of drawing stuff, if the chain is drawn right and drives the inner wheel without any slip, which is fixed to the larger wheel, and that is located similarly without slipping in teeth on a fixed surface, the wheel ought to progress to the left (oddly, a big arrow suggests otherwise, but I can't see how that could be possible). The notes even describe this as a down-chain crawler moving at v, with that arrow pointing right. That must surely not even conform to your suggestion of just tugging on the chain towards the right. You both seem to be so confused as to what is driving what in any given situation, it's no wonder you can't explain it to me.

If the thing is at rest and the chain is pulled right, that will try to rotate the wheels together over their resting position on the track, if I'm not mistaken. However, if that point of contact to the track is unslippable, the reverse should take place. The chain pulling on the inner wheel (assuming the chain can just move any distance we like to the right) would drive the wheel round its centre, forcing it to the left. It has to be in that sense, but I'm not sure what the speed would be. Somewhere in the region of 2v woud be my guess. The relative circumferences or radii aren't given. It would depend on that.

I'll come to the other mystical creations of myriad later. Please go on.

ETA: Whoops, no that's probably all wrong, now I've thought about it more. Maybe the wheel and chain can both move right as depicted. I think so. the wheel can be rolling right over the chain, which is also moving right wrt the track, but left wrt the wheel. Yeah?

 

[sol invictus]

John, then this discussion is really pointless until you educate yourself on the above point.

Well I guess ThinAirDesigns is right. Denying that sail-powered vehicles can go faster than the wind is like denying that airplanes can fly - it's just delusional, and there's no point in arguing with it.

I'd enjoy watching someone with that belief try to jibe a windsurfer. You're flying along on beam reach (90 degrees to the wind) and you decide to reverse direction by turning away from the wind (i.e. jibing). So you tilt the board and the sail to turn and in a second or so you're headed nearly straight downwind. The first thing you notice is a headwind.... followed by the sail pushing you off the back of the board into the water from the force of that headwind - if you're not expecting it, that is. Or worse, if you don't believe it can be there at all.

 

[sol invictus]

Ok. Assuming that I understand Myriad's odd way of drawing stuff, if the chain is drawn right and drives the inner wheel without any slip, which is fixed to the larger wheel, and that is located similarly without slipping in teeth on a fixed surface, the wheel ought to progress to the left (oddly, a big arrow suggests otherwise, but I can't see how that could be possible).

Think again, John.

It might help to delete the track from the picture for a moment. That might help you realize that the wheel can move at any speed, or rotate at any rate - but the relation of its speed to its rotation rate is fixed by the contact with the chain. The track fixes a different combination, which means there's a unique speed and rotation rate at which it can move (for a given v). Your task is to determine whether that speed is faster or slower than v.

 

[spork]

Oh, this is priceless. If the vanes are positioned to catch the wind when below the axle and flop over to avoid it when above the axel, any wind would tend to push the bottom of the wheel, and tend to rotate it backwards against the wind.

You're right - this IS priceless. Go grab a spoke on your bike below the hub. Now apply a horizontal force toward the front of the bike. Which way does it go? How fast does the bike go? I'll answer since you're not going to try it. The bike will go forward and it will go FASTER than the point you're pushing on.

The speed of the vane at bottom being slower than the centre of the axel doesn't make any difference to the force applied to it by the wind, but in order to understand that, you'd probably have had to get the first bit right.

You have an interesting style - wrong and condescending.

"Land yachts attain a downwind velocity component greater than the wind as an everyday affair. This is not even in contention"

Oh yes it very much is.

Sorry - ignorance is not an argument. This is well documented everyday stuff. Get back to me when you want an intelligent discussion.

This suggests that if you take the wind's direct force and reduce it by going at some angle to it, you are at an advantage, which reduces as you point directly downwind again. This is utter nonsense. I don't know about land yachting, but if we are discounting energy added to the system by a person rocking or swinging a vane, etc., the most efficient use of the wind power would be to have a perpendicular sail catching it full on and pointing downwind.

Did you ever notice how planes tend to go forward when they fly? Did you ever notice the blades of a helicopter spin when the heli is in autorotation? If the most efficient thing was to have the wind hit the airfoil broadside the heli would stop its blades when the engine died - and then the pilot would.

I am allowing you to explain any way you like. The only problem is that your explanations so far are contrary to the laws of physics.

Again, not an insult - just your opinion - eh? I guess your opinion just happens to be insulting.

However, nothing will really convince me except making my own, and I ain't gonna do that, now am I?

Of course not. Why would you? Particularly when you could do it for $40 and less than 1 hour invested, and it would clearly be the greatest physics lesson you ever had. But I guess it's still more work and less fun that insulting people from your keyboard.

Let's take another think about this from the physics again....I think we can all see where that's going.

Yes, it's going exactly where it always goes when someone that doesn't understand the most basic laws of physics decides to "think about this from the physics" - nowhere.

You have disproved Newtonian physics.

You have disproved your claim that you're not intending to be insulting. You've also disproved the notion that you have an open mind or understand the first thing about physics. But I'll tell you what smart guy - since you KNOW this is a scam I'm going to make you an offer no smart guy could refuse... I'll bet it's real. In fact I'll give you 10 to 1 odds. My $100K against your $10K. And I'll provide physical proof.

But are you actually going to take me up on the bet and take my $100K? Of course not. You'll just ridicule me further for even making that offer.

 

[spork]

the chain is drawn right and drives the inner wheel without any slip, which is fixed to the larger wheel, and that is located similarly without slipping in teeth on a fixed surface, the wheel ought to progress to the left...
You both seem to be so confused as to what is driving what in any given situation, it's no wonder you can't explain it to me.

Taking a page out of your book of logic - EAT ME.

And yes, you're right - it is no wonder we can't explain it to you.

Take my bet and take my money smart guy.

ETA: Whoops, no that's probably all wrong, now I've thought about it more. Maybe the wheel and chain can both move right as depicted. I think so. the wheel can be rolling right over the chain, which is also moving right wrt the track, but left wrt the wheel. Yeah?

WAIT - what was that - an acual thought? Did it scare you? What to do now?

 

[Modified]

Ok. Assuming that I understand Myriad's odd way of drawing stuff, if the chain is drawn right and drives the inner wheel without any slip, which is fixed to the larger wheel, and that is located similarly without slipping in teeth on a fixed surface, the wheel ought to progress to the left (oddly, a big arrow suggests otherwise, but I can't see how that could be possible).

Do you own a yo-yo? How about a spool and a piece of string? You can do your own experiment and quickly change your mind.

ETA: Missed that - he already did.

 

[John Freestone]

I posted a link a while back to some GPS data recorded by an iceboat during a race, which shows the boat exceeding the speed of the wind by factors of 5 and more. Was that a fake as well?

You've obviously never windsurfed or been on a fast sailboat - it's very easy to exceed the speed of the wind across a broad range of reaches.



Why don't you tell us precisely which laws of physics you think are being violated? Be specific, please - "Newton's laws" doesn't cut it.

It can't be conservation of energy, unless you think wind turbines violate that too.

It can't be conservation of momentum, unless you keep track of the momentum of the earth and the air as well as the cart.

It can't be conservation of force, because there is no such thing.

It can't be F=ma, because people have posted force-balance analyses which show clearly that the cart can accelerate down wind starting from wind speed (the only thing that can possibly prevent it is friction, which can be minimized).

So..... what law of physics is it, John?

Look, I don't know. Ok. I'm not a physicist or an engineer, and apparently even they are all wrong too. I can see that if my intuition is wrong about this, it would be irritating to be criticised by someone who doesn't really understand the physics of it.

 

[John Freestone]

Well I guess ThinAirDesigns is right. Denying that sail-powered vehicles can go faster than the wind is like denying that airplanes can fly - it's just delusional, and there's no point in arguing with it.

I'd enjoy watching someone with that belief try to jibe a windsurfer. You're flying along on beam reach (90 degrees to the wind) and you decide to reverse direction by turning away from the wind (i.e. jibing). So you tilt the board and the sail to turn and in a second or so you're headed nearly straight downwind. The first thing you notice is a headwind.... followed by the sail pushing you off the back of the board into the water from the force of that headwind - if you're not expecting it, that is. Or worse, if you don't believe it can be there at all.

I think this point is only possibly relevant. It depends on how analogous it is. Few state that you can sail directly downwind at windspeed or faster (all else being equal), and in an overview that seems to be the relevant analogue of the system. A sail can't make a vehicle travel directly downwind, can it, at windspeed? If the answer is no, then I need to understand what is fundamentally different between that and the vehicle described/shown. The latter is not tacking. It's clear that if you move faster and faster at 90 degrees to the wind direction, you ain't losing any windspeed, but if you're moving directly down wind faster and faster, you are. I still have not read anything that overcomes the apparent lack of windpower on a machine travelling at 0 relative wind velocity, from which it is supposed to accelerate even more. Sorry if that's not technical enough for you.

 

[sol invictus]

Look, I don't know. Ok. I'm not a physicist or an engineer, and apparently even they are all wrong too. I can see that if my intuition is wrong about this, it would be irritating to be criticised by someone who doesn't really understand the physics of it.

Fair enough. Many of the people posting in this thread are professional physicists and/or engineers. And all of those posters - with the exception of humber (an incoherent and ignorant troll) and a few flipfloppers, have come to the conclusion that this device can work in principle, and (given the video evidence) almost certainly does.

You're catching part of the backlash against humber (who has non-negligible trolling skillz and caused a lot of annoyance).

 

[sol invictus]

I think this point is only possibly relevant.

You're correct that standard sailed vehicles cannot sail directly downwind faster than the wind. If they could, this thread (and this device) would be rather uninteresting. They can, however, sail downwind on a steady reach such that the downwind component of their speed is faster than the wind (i.e. they proceed in the downwind direction faster than the wind, as well as moving in some other direction at the same time).

In any case, the fact that boats can sail faster than the wind in any direction makes it clear that there cannot be any violation of the laws of physics here. An iceboat could pick up speed and then lower its sails and turn directly downwind, or it could jibe back and forth, or one can imagine a Rube Goldberg device consisting of two iceboats connected somehow, each of which jibes back and forth so that the whole contraption sails straight downwind faster than the wind.

What these guys have done is build an elegant version of that jibing contraption, making use of an advanced and obscure technology known as a "propeller".

 

[John Freestone]

WAIT - what was that - an acual thought? Did it scare you? What to do now?

Look, we're both getting a bit insulting, aren't we. How about we stick to discussing the issue (although I've got to nip off for a while anyway soon). Can you tell me what the error is in one of my discussions - for instance, the one where I suggest that if the machine on the treadmill happens for whatever reason to slow down a little (I gave as example that it is travelling faster than what I assume it has, a speed where it is in equilibrium), then its wheels' speed relative to the driving treadmill is less, which should cause it to drive itself up-tread slower, etc.? This seems to predict a machine slowing to fall off the down-end of the belt, as per intuition. If it slows down, how does it gain energy again to speed up?

 

[spork]

A sail can't make a vehicle travel directly downwind, can it, at windspeed?

No.

If the answer is no, then I need to understand what is fundamentally different between that and the vehicle described/shown.

No you don't. You've made it clear that you KNOW it's not possible. All that's left is to take my money.

I still have not read anything that overcomes the apparent lack of windpower on a machine travelling at 0 relative wind velocity

Indeed you have. You've even repeated it, misquoted it, and ridiculed it. You've done more than a day's work.

Sorry if that's not technical enough for you.

Oh - it's plenty technical. Just 100% wrong. Now please don't take any of what I say as insulting. Afterall, it's just my opinion.

 

[Modified]

Look, we're both getting a bit insulting, aren't we. How about we stick to discussing the issue (although I've got to nip off for a while anyway soon). Can you tell me what the error is in one of my discussions - for instance, the one where I suggest that if the machine on the treadmill happens for whatever reason to slow down a little (I gave as example that it is travelling faster than what I assume it has, a speed where it is in equilibrium), then its wheels' speed relative to the driving treadmill is less, which should cause it to drive itself up-tread slower, etc.? This seems to predict a machine slowing to fall off the down-end of the belt, as per intuition. If it slows down, how does it gain energy again to speed up?

It it slows down, it experiences a faster wind.

 

[John Freestone]

Fair enough. Many of the people posting in this thread are professional physicists and/or engineers. And all of those posters - with the exception of humber (an incoherent and ignorant troll) and a few flipfloppers, have come to the conclusion that this device can work in principle, and (given the video evidence) almost certainly does.

You're catching part of the backlash against humber (who has non-negligible trolling skillz and caused a lot of annoyance).

You're correct that standard sailed vehicles cannot sail directly downwind faster than the wind. If they could, this thread (and this device) would be rather uninteresting.

However the fact that they can sail faster than the wind in some directions makes it clear that there cannot be any violation of the laws of physics here. An iceboat could pick up speed and then lower its sails and turn directly downwind, or it could jibe back and forth, or one can imagine a Rube Goldberg device consisting of two iceboats connected somehow, each of which jibes back and forth so that the whole contraption sails straight downwind faster than the wind.

What these guys have done is build an elegant version of that jibing contraption, making use of an advanced and obscure technology known as a "propeller".

Ok. Thanks, that was helpful. However, the sailboat or land-yacht or whatever that is jibing is achieving its faster than windspeed because of that lack of loss of relative windspeed past it. How could it be that if you connect these things together so that they are now a mechanical system, that system, as you say, moving downwind with the wind, that it won't outrun the wind and have no further power?

I keep getting to this point where it's like the answer to get more power at windspeed is something to do with power already grabbed from somewhere else (which is going to dissipate), like jibing then heading downwind gives you a temporary advantage, but if you cant sail directly downwind faster than the wind then you can't do that, so you slow down again, or someone appeals that it comes from the current movement of something (which again, can only have been put in motion by the forces it is now being suggested it's motion will overcome).

Oh well, must stop now for a bit.

 

[Modified]

How could it be that if you connect these things together so that they are now a mechanical system, that system, as you say, moving downwind with the wind, that it won't outrun the wind and have no further power?

As long as parts of the system are slower than the wind at some times, those parts can drive the whole vehicle. Even that isn't strictly necessary though.

 

[Modified]

I keep getting to this point where it's like the answer to get more power at windspeed is something to do with power already grabbed from somewhere else (which is going to dissipate), like jibing then heading downwind gives you a temporary advantage, but if you cant sail directly downwind faster than the wind then you can't do that, so you slow down again

If a group of boats do that and each average faster than the wind, then the speed of the group is faster than the wind. Now if you're picky, you just need to connect them and arrange them so that they take turns going slow.

 

[spork]

I keep getting to this point where it's like the answer to get more power at windspeed is something to do with power already grabbed from somewhere else...

I'd explain it with simpler analogies like pulling the string of a yo-yo or pushing on the spoke of your bike. But you're way ahead of me. You've already ridiculed experiments that would require THAT much effort on your part.

 

[humber]

You sure do spout one helluva lot of pseudo science B.S. when you could just build one of these things yourself for $40. But I guess the real world doesn't count unless it's faithful to your bizarre notions of the laws of physics.

If you mean that if a build yours or a similar device, it will make progress up the belt, then I already know that. On the other hand, I don't see why I should spend $40 to demonstrate it.

In the case of windspeed travel, you do not have the evidence, otherwise you would have responded to my repeated requests for it.

There are simple tests that you could undertake in a garage, to demonstrate or quantify much of what is missing. If you are right, then this information can only lend support to the claim of windspeed travel.

That you think that is unnecessary is one of your bizarre notions.
Please point to one 'bizarre' notion that I have expressed, that is not a response to your metaphysical view of "equivalence"

 

[humber]

You're correct that standard sailed vehicles cannot sail directly downwind faster than the wind. If they could, this thread (and this device) would be rather uninteresting. They can, however, sail downwind on a steady reach such that the downwind component of their speed is faster than the wind (i.e. they proceed in the downwind direction faster than the wind, as well as moving in some other direction at the same time).

In any case, the fact that boats can sail faster than the wind in any direction makes it clear that there cannot be any violation of the laws of physics here. An iceboat could pick up speed and then lower its sails and turn directly downwind, or it could jibe back and forth, or one can imagine a Rube Goldberg device consisting of two iceboats connected somehow, each of which jibes back and forth so that the whole contraption sails straight downwind faster than the wind.

A sailed vehicle cannot travel faster than a steady wind, but a vehicle in variable wind may travel faster than the wind if it can gather enough energy from those bursts, and then deploy it as needed.

If the vehicle's velocity is measured by a timed trial, then this will lead to an error, because the 'average' windspeed may vary over that period.

If the windspeed is measured in a manner that accounts for that variation, but pilot is allowed to change the vehicle, or even worse, look ahead at the water's surface to take the most advantageous course, then this will again screw up the result.
If information is obtained over the course of the trial, it may invalidate the result.
[/QUOTE]

What these guys have done is build an elegant version of that jibing contraption, making use of an advanced and obscure technology known as a "propeller".

I don't agree. There are no more lines of force, or energy sources that do not impinge directly upon the propeller.
As for the general comparison with sailing boats, I can turn a cat into a rat if I only look for the similarities.

ETA:
Re: your other personal remarks. I accept them in preference to believing that a cart on a treadmill is really going at windspeed, and best of all, driving it around in a car proves it.

 

[Michael C]

Ok. Assuming that I understand Myriad's odd way of drawing stuff, if the chain is drawn right and drives the inner wheel without any slip, which is fixed to the larger wheel, and that is located similarly without slipping in teeth on a fixed surface, the wheel ought to progress to the left (oddly, a big arrow suggests otherwise, but I can't see how that could be possible). The notes even describe this as a down-chain crawler moving at v, with that arrow pointing right. That must surely not even conform to your suggestion of just tugging on the chain towards the right. You both seem to be so confused as to what is driving what in any given situation, it's no wonder you can't explain it to me.

[...]

ETA: Whoops, no that's probably all wrong, now I've thought about it more. Maybe the wheel and chain can both move right as depicted. I think so. the wheel can be rolling right over the chain, which is also moving right wrt the track, but left wrt the wheel. Yeah?

You're getting there. I made a little demonstration that illustrates the principle of Myriad's cart, and by analogy also the principle of the DDWFTTW vehicle:



The essential thing is that the strip of paper is always pushing at a point directly below the centre of the wheel. When a wheel rolls forward along a flat surface, any point on the wheel directly below the centre is moving forward slower than the centre, while any point directly above the centre is moving faster. The lowest point of all, being in contact with the ground, is stationary.

By pushing with a constant velocity at a point below the centre, you can make the centre of the wheel (and therefore the whole vehicle) move faster than this velocity.