DDWFTTW Turntable Test: 5 Min Video - Is It Conclusive?

[rcgldr]

Have you taken into account, that the propeller is further away from the turntable axis than the wheel?

I ignored that factor. Guestimating that prop is 8 inches further out than wheel:

Turntable speed at wheel = 13.1 mph
Turntable speed under prop = 17.5 mph
Prop advance speed = 7.5 mph

 

[Subductionzon]

Schroder, your last argument had one huge logical fallacy to it, no one is claiming that the cart is an over unity device except for you. It runs off of the difference between the speed of the wind and the speed of the surface. Outdoors that would be the speed that the wind goes over the ground. Indoors on the treadmill it would be the speed of the treadmill. The cart cannot tell the difference between the two cases.

Here is a "real life" device that can go faster than the wind, an ice boat. It also extracts energy from the difference between the speed of the wind and the speed of the ground. They have been observed going four to five times the speed of the wind on a broad reach, that is sailing at an angle 45 degrees to the wind. So if the wind was blowing straight North the ice boater would tack back and forth with the wind going northeast and northwest. Let's say he is an accomplished sailor with a good boat and the wind is 10 mph. He would be able to maintain a 50mph speed on those tacks with a resultant straight north speed of 35 mph. Now if he sailed due north the most he could go is that, 10 mph, but by tacking he can outrace the wind by 25 mph. That is what the props on the propeller are doing, they are acting as a sail and driving the boat.

 

[rcgldr]

The velocity of the wind working against the sail is not used as a reference to measure the velocity of the boat because the boat is not working against the wind, it is working against the water.

The boat is working against both the wind and the water. Both the air and the water are accelerated by the boat, even when the boat itself is not accelerating. The cart also interacts with air and ground, but the effect on the ground is tiny because the mass of the ground versus cart is huge.

It is a closed system, and momentum is being conserved. If the wind speed decreases, then the cart and/or ground speed increase in order to conserve momentum. In this case, most of the increase in speed occurs with the cart (as oppose to with the ground), because of the difference in mass of ground versus cart, and because the cart has wheels that allow it to advance with respect to the ground.

 

[rcgldr]

8). Since the cart is not an over unity machine, but it is advancing on the tread in the opposite direction to the tread and it is being powered by the tread it cannot possibly be working against the tread. Because if it were working against the tread , due to being being worked on by the tread , it would be doing more work on the tread than the tread is doing on it which means it is an over unity machine and they do not exist!

Applying Newton's 3rd law, any force exerted by the tread onto the cart is opposed by an equal and opposite force by the cart onto the tread. The work done by the tread onto the cart and the work done by cart onto the tread are equal and opposite. Energy isn't being created here, just exchanged. The same logic applies to the prop + air interface.

 

[Subductionzon]

I also like to use the phrase "difference between the speed of the wind and the speed of the surface" because it helps get you from thinking of the wind blowing directly on the cart, or with a sailboat on the sail. If you think of the wind blowing on the sail it would seem impossible for the boat to go faster than wind speed when sailing on a beam reach, I mean its outrunning its power source isn't it? But no it isn't and this has been observed countless times, it is still "within" the wind. It is running off of the difference in speed between the wind and the ice. If you are really nuts you could put the treadmill on the back of a flatbed truck on a day with a known windspeed. For example say it was another 10mph wind day and the truck was going with the wind at 10mph. Net result no wind, now we start up the treadmill like we did before and run it at 10 mph. Just like the indoors test the cart will advance up the treadmill. But how do you measure its speed now schroder? With respect to the treadmill and the ground it is going 10 mph plus whatever its advance speed up the treadmill is. With respect to the flatbed truck and the wind it is just going up the treadmill at its advance speed up the treadmill. In either case it is going faster than the wind.

 

[vanesch]

Now right here you are doing something that is unscientific. You may consider it to be “fun” and I agree there is an element of that, but there is also a serious side of this. This ridiculous claim needs to be rebuked by the physics community. You are dismissing what I wrote as illogical without showing where the logic fails. That is like saying “You are wrong because my name is Vanesch, and I say so.” I would expect better from you.

I never used any argument of authority as far as I remember. I do make "authoritative statements" concerning certain properties of Newtonian mechanics, because I think that I know the theory well enough to make them. Like I could make the authoritative statement that Newton's equation is F = m.a without arguing it, because I think that the "physics community" won't dispute it.
If I tell you (or if I say in general) some statements like "you can do the calculations in any frame you like", then this is not on my authority, but simply because I know it is an entirely accepted fact, and that I don't think that there is any physics professor out there who will dispute it.

However, I have taught university level courses, and I can tell you that any student of mine who would display such ignorance of basic material together with such a refusal to reconsider, would have been in serious trouble. I consider this discussion on my side as an exercise in the Art of Zen

And of course it matters what is working against what! The velocity of the wind working against the sail is not used as a reference to measure the velocity of the boat because the boat is not working against the wind, it is working against the water.

You see, that phrase, by itself, doesn't have any meaning when you use standard terminology. The only meaning one could give to it is that no physically meaningful quantity can ever be calculated using the velocity of the wind. That's of course glaring nonsense. After all, the totally valid question "what is the velocity of the boat wrt to the wind" would need to use the velocity of the wind AND the velocity of the boat, in *any randomly chosen frame*, to be able to calculate the answer to the question.

So if you want to know where your logic fails, it is already right here.

How can you honestly say it does not matter what is working against what when you measure velocities?

Because it is true. The kinematical description of a situation (that is, the positions and velocities and so on) are independent of the dynamical description of the situation (the interactions, the forces...). That is what is explained in about the first chapter of every book on classical mechanics.
For instance, in my engineering education, I started out with 45 hours of kinematics, without even mentioning the word "force". It was only in the next course, 90 hours of "dynamics" that force was introduced. I'm not saying that this is the only or best way to teach mechanics, but at least it demonstrates that the kinematical description has nothing to do with what thing is exercising what force on what other thing.

So I am going to walk you through the logic one more time, and this time You need to show me where the logic fails.

Well, it failed already, but let us continue (in my practice of the Art of Zen...: I want at least black belt 6th dan in it...)

If you cannot do so, you must accept the conclusion that the logic leads you to. I am going to be very fair to you and give you advance notice that I am now placing you in checkmate.

Whoo...

You cannot simply knock over the chess board and say this is nonsense. You need to show how and why you are not in checkmate and then show me that you can get out of it.
Just follow the logic:
1) A machine that can do more work than the work that is done on it is by definition an over unity machine.

Yes. At least in steady state. Granted. However, be very careful what is "doing work on" and "work done on it". These are frame-dependent quantities. You can of course have a machine that "does work" on something in one frame, "on which work is done" in another frame, and nevertheless find out that it does more work as per the first quantity than it receives as per the second quantity, without it being an over-unity machine. So, granted on the condition that both amounts of work are calculated in the same frame.

2) There are no over unity machines.

Granted.

3) A machine that can do more work on a tread than the tread does on it, is an over unity machine.

No, not necessarily. You have to find out if there are other contributions. Otherwise, the motor driving the treadmill is an over unity device. But the electric grid does work on the motor, so this is not a problem in this case.

4) There are no over unity machines.

Granted (second time).

5) From 1 - 4 : a machine that has work done on it by a tread cannot do more than that amount of work on the tread.

I don't know exactly what you mean by this. If you mean: *in a specific reference frame, the force exerted by the treadmill on the system, multiplied by the displacement of the treadmill in that frame, is the power provided by the treadmill*, yes, that's the power provided by the treadmill in that reference frame. And this power should not be larger than any work the device is doing on anything else, such as the air, *in that same reference frame*.

6) From 1 - 5 : A machine that has work done on it by a tread, but is clearly seen to be advancing on that tread in the opposite direction to the tread cannot possibly be an over unity machine because there are no over unity machines.

Well, you can simply say: the machine cannot be an over unity device because there aren't any. And the first part of your sentence is not related to this, nor to 1-5.

7) From 1 - 6 : The cart is being powered by the tread. It is also advancing on the tread in the opposite direction to the tread. The cart is not an over unity machine.

Well, whether the cart is powered by the tread or not is dependent on from which frame you look upon it. In the frame of the tread, it isn't, of course. Because "powered by" means: has a positive value of "the product of force exerted by and displacement by". But as in the frame of the tread, the tread is not moving, the displacement is 0, and hence it is not doing any work. In the frame of the ground, this might be the case, if the force exerted by the treadmill on the cart is in the same direction as the movement of the treadmill.

8). From 1 – 7 : Since the cart is not an over unity machine, but it is advancing on the tread in the opposite direction to the tread and it is being powered by the tread it cannot possibly be working against the tread.

Not at all. This is wrong. The treadmill can exert a force on the cart in the same direction as it moves, and that is then the power given by the treadmill to the cart *in this frame*. And this number depends on what frame one uses.

The state of motion (position and velocity) of the cart wrt the treadmill is independent, a priori, of the direction and magnitude of the force that one can exert on the other. Moreover, the statement "moves in the opposite direction as the treadmill" is also a frame dependent quantity. In the airplane that flies by, both move in the same direction.

Because if it were working against the tread , due to being being worked on by the tread , it would be doing more work on the tread than the tread is doing on it which means it is an over unity machine and they do not exist!

No, that's wrong, for several reasons, but the main reason is this: the exchange of power is not only with the treadmill, and, as I said before what exchanges power with what is frame dependent. You can do the balance in any frame, and as long as you stick to it, things will come out all right. But when you switch frames during the calculation, you will make errors.

In the frame of the tread, the tread is NOT doing any work on the cart, and the air is doing all the work. That means: you calculate the total force exerted on a certain mass of air, and the displacement that goes with it, you multiply and that gives you the amount of energy (in the given time lapse) that the air has given to the system. As the treadmill didn't move in this frame, it can't give any energy.

In the frame of the air (= frame of outside ground), the air is not moving and not doing any work, and the treadmill is doing all the work. Now, in this frame, the treadmill is exerting a certain force on the cart, and undergoes a certain displacement in doing so, hence delivers an amount of work to the system. That's the power that is available. It doesn't matter at what velocity the cart is moving, the power that is extracted from the treadmill is the velocity of the treadmill here (in the ground/air frame) times the force it exerts on the system. It is this amount of power that the motor of the treadmill will have to deliver.

In the frame of the cart, the treadmill is moving (faster than in the previous frame btw). So in this frame, the cart receives energy from the treadmill (a larger number than the number calculated in the previous case), but has to spend also energy with the propeller on the air.

Now, the erroneous objection might be that in *this frame* (the cart frame) the cart receives more energy from the treadmill than the treadmill delivered *in the ground frame*. So did there go *more energy* in the cart than the treadmill actually delivered ?
No, the error here is that we are using energies calculated in two different frames, and we shouldn't use them in the same balance. It is an error that is easy to make. It is the one I pointed out already several times.
It is even more confusing. Let us place ourselves in the ground/air frame. Now, there's something weird. The treadmill is going at velocity v1 and is undergoing a force - F by the wheel (v1 and F positive numbers). So it is "receiving" power from the cart v1 x (-F), or in other words, the treadmill is DELIVERING the power v1 x F.
The air is still and is exerting a force F on the cart (as the cart is in steady state, there's no net force on it). However, the air being steady, there is no power delivered by the air to the cart.
The cart is going at a velocity v2 in the opposite direction as the mill (v2 positive number).

So the cart is delivering a power F x (v2) to the treadmill and is receiving power F x v2 from the air.

Now, note that it is extremely confusing that what the treadmill is giving to the cart, is not what the cart is receiving from the treadmill, and that what the air is giving to the treadmill (nothing) is not what the cart is receiving from the air.

That is because we used an abuse of language. It is not because we have a force, and its reaction, that the displacements along them are equal, in a random reference frame. So a force F and its reaction -F do not correspond to individual power balances because the v1 of the point where F acts, and the v2 of the point on which -F acts, doesn't have to move at equal velocities ; hence F x v1 will in general not be equal and opposite to - F x v2.

So the abuse of language has been to take couples of "action / reaction" and to call the associated powers "the power given to ... " and the "power received from".

Newtonian mechanics doesn't require a detailed power balance for every interaction individually, but it does require a power balance overall.

And that's ok here: power balance of the treadmill: lost v1 x F.
power balance of air: 0
power balance of cart: delivered F x (v2), received v2 x F.

The power balance of the cart is actually trivial in the steady state, as the total force on it is 0, so it is normal that the total amount of mechanical power received by it is 0. If the system were not steady yet, there would be an effect: the acceleration of the cart would make for a positive power balance which is going into the kinetic energy of the cart.

So we have that the overall mechanical power received by the system is - v1 x F + 0 + v2 x F - F x (v2) = -v1 x F < 0 as it should be. Energy balance is ok: in the steady state, the entire energy delivered by the treadmill (the only external source of power) is dissipated.

If the total balance would have been > 0, we would have had an over-unity device.
So far from being an over-unity device, this thing is just dissipating the power of the treadmill, which is obvious, because once steady state is reached, no energy is stored anymore in the system, no power is done by the system on anything, and the treadmill is delivering power to the system (in the frame of the ground). So whatever is pumped into it, is dissipated.

Now, this amount of dissipated energy IS a frame-independent quantity. However, the *source* of it is dependent on the frame. Let's redo the exercise in the frame of the treadmill.

Here, the cart is moving at (v1 + v2), and the air is moving at v1, both in the opposite directions as the treadmill was moving in the ground frame. Let us call "forward direction" this direction of the motion of the air and the cart. (in this frame, they move in the same direction, v1 and v2 are positive numbers).

Now, in *this* frame, the air is exerting a force F on the cart in the positive direction, the air is hence undergoing a force -F, and the work done on the air is v1 x (-F) ; in other words the air is DELIVERING power to the system here, and that amount of power is v1 x F.

The cart undergoes a force +F by the air, and is undergoing a force -F by the treadmill. Hence the cart receives a power (v1 + v2) x F from the air and delivers a power (v1 + v2) x F to the treadmill (but we know again that this "to this" or "to that" is just indicating where the force is coming from, and isn't a power balance). Again, we could also have said that because the total force on the cart is 0 (steady state) that the cart doesn't receive or do any work overall.

The treadmill undergoes a force +F by the cart. As it is not moving in this frame, however, it is not delivering any work.

Overall balance: power received by all components: - v1 x F + (v1+v2) x F - (v1 + v2 ) x F + 0 = - v1 x F.

Total balance negative, this is what is dissipated. It is again equal to v1 x F.

Third way of calculating: the frame of the cart.

Here, the air is moving at velocity v2 and the treadmill is moving at velocity (v1 + v2), both in the sense of the motion of the treadmill in the frame of the ground. Let us call this direction positive.

The air is undergoing a force F in the positive direction. It is hence RECEIVING the power v2 x F.
The cart will again give a 0 balance, this time for two reasons: total force = 0, and on top of that, velocity is 0.
The treadmill is undergoing a force F in the negative direction. So it is DELIVERING the power
(v1 + v2) x F.

Total balance of received power: v2 x F - (v1 + v2) x F = - v1 x F.

Again, this indicates that the total power dissipated is v1 x F.

You see that no matter what frame one uses, we come out all the same. However, we see that the individual contributions of treadmill and air are different according to the frame in which we do the calculation.This comes about because in steady state, if there were no dissipation, the force F would actually be 0 when steady state would be reached. This would be (in the frame of the cart) when the propeller is not delivering any work anymore to the air (that is, when v_out would be equal to the apparent headwind velocity), and if dissipation-less, would hence not require any power from the wheel, which would then be rolling totally freely over the surface.

First definitive conclusion: From 1 – 8 : The cart is being powered by the tread. It is advancing on the tread in the opposite direction to the tread. The cart is not an over unity machine. The cart is not working against the tread.

I think I explained you why it is not correct.

If you accept (and you have no choice) that the cart is not working against the tread, then you need to justify why you insist on measuring the velocity with respect to the tread.

First of all, it is not right that the cart is not "working against the tread" in any frame. But second, I can measure a velocity wrt to anything I like. So your statement hasn't head or tails (let alone follows from any logical deduction).

If you can justify that, you would also be saying that the velocity of a sailboat can be measured with respect to the wind which is pushing it.

Of course it can. That's actually what is most easily done with an anemometer on the boat.

You would get some very low numbers because the boat is moving in the same direction as the wind.

yes.

And the reason you are getting high numbers for the cart velocity is because the tread and the cart are moving in opposite directions and you are measuring the velocity of the cart with respect to the tread.

yes.

In both cases, sailboat and cart, the only CORRECT approach is to measure the velocity of the vehicle with respect to the interface it is moving against.

This is a nonsensical statement.

Since you have displayed a disturbing tendency, when cornered, to simply dismiss even the most logical presentation as mere gibberish, I now openly challenge you to go through the above presentation and show where you feel it is wrong. You like chess?

I do.

 

[vanesch]

I also like to use the phrase "difference between the speed of the wind and the speed of the surface" because it helps get you from thinking of the wind blowing directly on the cart, or with a sailboat on the sail. If you think of the wind blowing on the sail it would seem impossible for the boat to go faster than wind speed when sailing on a beam reach, I mean its outrunning its power source isn't it? But no it isn't and this has been observed countless times, it is still "within" the wind. It is running off of the difference in speed between the wind and the ice. If you are really nuts you could put the treadmill on the back of a flatbed truck on a day with a known windspeed. For example say it was another 10mph wind day and the truck was going with the wind at 10mph. Net result no wind, now we start up the treadmill like we did before and run it at 10 mph. Just like the indoors test the cart will advance up the treadmill. But how do you measure its speed now schroder? With respect to the treadmill and the ground it is going 10 mph plus whatever its advance speed up the treadmill is. With respect to the flatbed truck and the wind it is just going up the treadmill at its advance speed up the treadmill. In either case it is going faster than the wind.

Ha, we're back to my train experiment

 

[schroder]

I never used any argument of authority as far as I remember.




Not at all. This is wrong.





This is a nonsensical statement.

I have laid it all out in front of you in black and white. I have given you and Physics Forum the opportunity to redeem your prestige.

False pride is all that stands in your way. You are very skillful at dancing around the issue.

But, you know, at some point that old tumbleweed will go past that ridiculous little cart as if it was standing still. ( Relative Velocity and all that)

What will all your dancing numbers mean then?

What will your professional credibility and the credibilty of this forum mean then?

I am done playing this silly game.

I will wait and see how this plays out.

Meanwhile, the people who are running this scam are guilty of fraud. Selling these carts through the mail while making fraudulent claims. That is mail fraud, A Federal offense. This is no game.

I can take this to the Academy but they already consider it to be nonsense.

I tried to do you a favor.

It is now too late.

Oh, and you need not bother with the ban, or the infractions That does not affect me.

 

[vanesch]

False pride is all that stands in your way. You are very skillful at dancing around the issue.

It is amazing how applicable your advice is to your own viewpoint.

I am done playing this silly game.

That must be the 10th time you say you will quit.

The bare bones fact is that you haven't gotten a clue of the most basic concepts of mechanics, and that you've smeared this out along this thread.

You take offense at anyone pointing out the myriads of errors in what you call your reasoning, which is nothing else but a succession of demonstrations that you never opened a book on theoretical mechanics or had a decent course in it - or if you had, that you never understood anything there, or have forgotten all of it.
There's no problem in being wrong. But there's a problem in keeping to one's opinion despite careful explanation, while not once trying to understand what people try to explain to you. That comes because you have convinced yourself of the end result of the reasoning, and as such, that you think you don't even have to consider the other person's reasoning, given that he arrives at the conclusion you think is impossible, he must hence be wrong.

There's nothing difficult in the presented mechanics. It is elementary, first year mechanics in any physics or engineering curriculum. True, it is at first somewhat counter intuitive. If you would have asked me 2 weeks ago whether such a cart would work, from my bones I would probably have said, no.
Then there was this video demonstration, and then one had to sit down a few minutes to "understand the trick", by working it out in a bit more detail. And that's all there is to it.

But given your total lack of the most basic understanding of mechanics, you can't do that, and hence you keep with your intuition.

One single statement of yours illustrates this: the fact that you are requiring "proper" frames which are related to what you call "the medium the thing works against". That is such an obvious glaring nonsensical statement that it doesn't need any further comments.

Meanwhile, the people who are running this scam are guilty of fraud. Selling these carts through the mail while making fraudulent claims. That is mail fraud, A Federal offense. This is no game.

Unless, of course, you haven't gotten a single clue in the whole discussion.

I can take this to the Academy but they already consider it to be nonsense.

I tried to do you a favor.

It is now too late.

Oh dear. Well, I tried to do you a favor, by going all out of my way to teach a very elementary course in mechanics. You are visibly not interested in learning anything here.

BTW, telling you that you are wrong is not a statement of authority. I *explain* to you why you are wrong. If I write: 3 + 4 = 12, and someone tells me that this is wrong because 3 + 4 = 7, is he making an authoritative statement ?

EDIT: one more thing. You are visibly convinced that a DWFTTW cart is an over-unity device, right ?

If I give you one, how would you go about in making unlimited amounts of electricity from it (which is what an over unity device can do) ?

 

[uart]

I have laid it all out in front of you in black and white. I have given you and Physics Forum the opportunity to redeem your prestige.

False pride is all that stands in your way. You are very skillful at dancing around the issue.

But, you know, at some point that old tumbleweed will go past that ridiculous little cart as if it was standing still. ( Relative Velocity and all that)

What will all your dancing numbers mean then?

What will your professional credibility and the credibilty of this forum mean then?

I am done playing this silly game.

I will wait and see how this plays out.

Meanwhile, the people who are running this scam are guilty of fraud. Selling these carts through the mail while making fraudulent claims. That is mail fraud, A Federal offense. This is no game.

I can take this to the Academy but they already consider it to be nonsense.

I tried to do you a favor.

It is now too late.

Oh, and you need not bother with the ban, or the infractions That does not affect me.

This is just mind boggling. I can't believe the patience that vanesch and Jeff (along with others) have displayed in trying to explain to you the operation of this device. I gave up trying to explain anything to you in the last DWFTTW thread and absolutely won't waste anymore time on it. Your attitude is completely un-scientific in the way you have simply assumed that this device violates some physical law (which it doesn't) and on the basis of that assumption you’ve basically refused to even try to understand anything anyone tells you. That's sure how it looks to me anyway.

 

[zoobyshoe]

The first term rho_air x S x K x v_cart x ((K-1) x v_cart + v_wind)

represents the thrust by the propeller. It is obtained by making the momentum balance between the mass of air that is accelerated from "incoming velocity" to "outgoing velocity" by the propeller (of course, in the frame of the propeller).

If it is positive, it means a *forward* force, which *accelerates* the cart.

In all of this, we didn't need any "stored kinetic energy of the cart".

In order to understand the non-stored forces at work on the cart at wind=0 we have to imagine a "virgin" situation where the propeller is not in motion at all. Not rotating.

Wind speed = 0

Ground speed = say, 10mph but contrary to the direction we want the cart to accelerate into

Prop rotation speed = 0

Is there a total force on the cart here in the right direction that will cause acceleration in the right direction?

 

[zoobyshoe]

Yes if the prop speed is zero then it can't work, but how did you get this far into the discussion without working out the the prop is driven by (directly coupled) to the wheels, so it won't (can't) be at zero speed when the cart is moving at wind speed. I'm not sure if you really didn't understand this or if you just wanted to change things so it couldn't work? (Like Schroder, he wanted Swerder to connect the prop to run in the wrong direction and re-test it for whatever that would prove).

I understood this from the start. The counterargument, though, was that there is still relative velocity between air and ground, therefore available power. I have been waiting for someone to show me a way for the cart to take advantage of that.

 

[OmCheeto]

... Selling these carts through the mail ...

Has swerdna taken my advice and put them on the market? That would be awesome. I want one to amaze my friends with. And to do my own testing on of course. I suppose I could build one myself. I've most of the parts on the back porch. I'm only missing an efficient wheel to prop interface device.

I was actually thinking about this problem the other day and came up with a 4th DDWFTTW device. Only this time, the power comes from an on-board motor. Exact same setup though, with the wheels and prop linked up. I was curious at which point the wheels stopped being the primary source of power and the propeller took over.

Sorry if this has already been mentioned. I've not read the middle 30 or so pages in the thread.

And btw:

Zoob, could you maybe consider my post #378 and answer the y/n questions ?

https://www.physicsforums.com/showpost.php?p=2036877&postcount=378
...

Did anyone ever answer the questions to post #378? I thought I might have missed it amongst all the shopping carts, windmill boats, sail boats, ice sail vehicles, trains, fences, fence posts, torpedo's, cart #1, cart #2, cart #3, etc. etc.

 

[uart]

I understood this from the start. The counterargument, though, was that there is still relative velocity between air and ground, therefore available power. I have been waiting for someone to show me a way for the cart to take advantage of that.

Ok I think I misunderstood what you were trying to get at here. You want the wind at zero and the cart is moving in the negative direction correct. Well you might have to modify the design but you could make it take power from the wheels to help it more rapidly reach the wind speed (that is to stop). It's already been established that this thing can't go faster than the wind if the wind speed is too low. No it can't sustain faster than wind speed in zero wind, nobody ever claimed it could.

 

[rcgldr]

Wind speed = 0, Ground speed = say, 10mph but contrary to the direction we want the cart to accelerate into, Prop rotation speed = 0. Is there a total force on the cart here in the right direction that will cause acceleration in the right direction?

This is virtually the same as the treadmill test, except the prop has been disconnected from the wheels and is fixed in place. From start up, the prop and cart still act as a bluff body, so the cart accelerates in the "right" direction, but at terminal speed, the cart retreats instead of advacing on the treadmill, because it's speed with a non-spinning prop will be slower than the wind.

 

[vanesch]

In order to understand the non-stored forces at work on the cart at wind=0 we have to imagine a "virgin" situation where the propeller is not in motion at all. Not rotating.

Wind speed = 0

Ground speed = say, 10mph but contrary to the direction we want the cart to accelerate into

Prop rotation speed = 0

Is there a total force on the cart here in the right direction that will cause acceleration in the right direction?

I think in the crude model I pointed to before (the 3 forces: prop force, air drag and wheel resistance), you can put K = 0 (gearing ratio 0) and then what remains is simply the drag term.

F_tot = rho_air x S x K x v_cart x ((K-1) x v_cart + v_wind) + W x (v_wind - v_cart)^3 - ...

... rho_air x S x K x ( (K^2-1) x v_cart^2 + 2 x v_cart x v_wind - v_wind^2)


So fill in K = 0 (gearing ratio 0, the propeller doesn't turn, no matter the wheel turning):

F_tot = W x (v_wind - v_cart)^3

Don't forget that the velocities here were originally expressed in the "floor" frame. However, as this is a difference of velocities, it is simply the air speed wrt the cart, and it doesn't matter where you calculate it.

 

[ThinAirDesign]

Wow -- watching this thread has been an absolute blast.

While giving swerdna props for his turntable, as expected it didn't convince anyone of DDWFTTW who already understands basic physics. Vanesch did a great job of explaining how a simple tilt of the treadmill proves the 'steady state' claim without all the rotational complications.

swerdna says that every test he has done confirms our DDWFTTW conclusions -- I'm glad he convinced himself. We didn't necessarily predict what his position would be in the end, but we certainly perfectly predicted the outcome of his tests before he performed them.

What I did find entertaining was how swerdna resisted performing Schroder's tests until he could understand what Schroder was testing for and what different results would mean. swerdna of course understands why I find that entertaining -- it's the same routine I went through with him before he built his own test rig. Being on the other end of that treatment is always educational.

Schroder was the same as ever -- starting with an 'over-unity' assumption and then ignoring everything not compliant with that position ... and in the end, against overwhelming evidence and reason, claiming fraud and and an "Academy" that claims DDWFTTW is nonsense. No evidence or course ... just claims.

Vanesch and JeffR -- amazing patience. Kudos.

JB

 

[A.T.]

In order to understand the non-stored forces at work on the cart at wind=0 we have to imagine a "virgin" situation where the propeller is not in motion at all. Not rotating.

Forces cannot be stored. You are confusing stuff again (forces and energy I guess). And by stored energy you mean the rotational kinetic energy of that ultralight plastic propeller? Well, since the wheels are still turning, they also have rotational kinetic energy stored in the "virgin situation" you describe.

But can you have your "virgin situation" in the Brennan torpedo. Initially the propeller is not moving and the torpedo has the same speed as the water(=~air). Then when the wires(=~ground) start to move relative to the water(=~air), the propeller spins up and accelerates the torpedo to 30mph beyond water speed(~=wind speed) in the wire's(=~ground's) frame. And then it goes for 2000 yards underwater, certainly not on energy stored in the propellers.

 

[swerdna]

What I did find entertaining was how swerdna resisted performing Schroder's tests until he could understand what Schroder was testing for and what different results would mean. swerdna of course understands why I find that entertaining -- it's the same routine I went through with him before he built his own test rig. Being on the other end of that treatment is always educational.

JB

Big difference being however that I actually conducted the test Schroder requested and quickly gave him the results. Also offered to conduct any other test Schroder or anyone else wants done on my turntable.

 

[zoobyshoe]

Ok I think I misunderstood what you were trying to get at here. You want the wind at zero and the cart is moving in the negative direction correct. Well you might have to modify the design but you could make it take power from the wheels to help it more rapidly reach the wind speed (that is to stop). It's already been established that this thing can't go faster than the wind if the wind speed is too low. No it can't sustain faster than wind speed in zero wind, nobody ever claimed it could.

I think I need to poll the adherents of the cart and make sure I understand what amount of stored energy the criteria allow. You can't accelerate the cart without giving it some momentum including the momentum of the prop, gearbox, and wheels. It is therefore possible to "optimize" the power storage to the point where whether or not you're violating the "powered only by the wind" part is a value judgment. Why can't we charge up a battery from a wind turbine and use that to power an electric motor to send the cart zipping downwind faster than the wind? That's powered "only by the wind".

 

[ThinAirDesign]

Big difference being however that I actually conducted the test Schroder requested and quickly gave him the results.

That certainly is one big difference between you and I -- you will do tests that make sense to the requester and not to you.

Also offered to conduct any other test Schroder or anyone else wants done on my turntable.

We have made the same offer and have followed through repeatedly -- we of course require the the user be able to justify the results of the test as something of additive value to our library of videos. As you concluded with your 'why are you attempting to use non-equivelancy in an attempt to prove equivelancy" comment back to Schroder, his test was useless, poorly conceived and did nothing to lead him towards the truth.

If you ever become 100% convinced of the validity of your testing and the DDWFTTW testing I suspect you will grow tired after about the 100th request for some cockimamy usless test. I understand that you have your doubts ... we understand the device and thus don't have doubts. That delta simply leaves you vulnerable to testing requests that lead nowhere.

I'm aware that outdoor tests have been done but they seem to be very rare and poorly conducted.

With the time and energy people put into a number of forums to debate this issue they could have built and tested an outdoor cart.

C'mon now swerdna -- that's just a silly question considering both the time you have put into various forums and the time you spend making your turntable rig. The above fingerpointing only leaves you with four fingers pointed back at yourself -- **Why didn't YOU build and test and outdoor cart rather spending time on the forums and rather than building your turntable?**

Check those four fingers and I suspect you'll have the answer to your own question.

JB

 

[ThinAirDesign]

I think I need to poll the adherents of the cart and make sure I understand what amount of stored energy the criteria allow. You can't accelerate the cart without giving it some momentum including the momentum of the prop, gearbox, and wheels. It is therefore possible to "optimize" the power storage to the point where whether or not you're violating the "powered only by the wind" part is a value judgment. Why can't we charge up a battery from a wind turbine and use that to power an electric motor to send the cart zipping downwind faster than the wind? That's powered "only by the wind".

Zoo, here is our claim:

"Directly downwind, faster than the wind, powered only by the wind, steady state."

Your 'turbine, battery and motor' fail the "steady state" portion of the requirement.

No matter how much rotational mass a device has, if it's operating steady state that mass isn't being used to motivate it.

JB

 

[cesiumfrog]

The above fingerpointing only leaves you with four fingers pointed back at yourself

four?

 

[zoobyshoe]

Forces cannot be stored. You are confusing stuff again (forces and energy I guess). And by stored energy you mean the rotational kinetic energy of that ultralight plastic propeller? Well, since the wheels are still turning, they also have rotational kinetic energy stored in the "virgin situation" you describe.

Indeed, I allowed myself once again to slip into a non-rigorous use of terms.

But can you have your "virgin situation" in the Brennan torpedo. Initially the propeller is not moving and the torpedo has the same speed as the water(=~air). Then when the wires(=~ground) start to move relative to the water(=~air), the propeller spins up and accelerates the torpedo to 30mph beyond water speed(~=wind speed) in the wire's(=~ground's) frame. And then it goes for 2000 yards underwater, certainly not on energy stored in the propellers.

I am ignoring the torpedo altogether at this point. Vanesh has already offered a comprehensive test of one's ability to analyze different frames, which I have also put on hold.

As I said earlier:

...the zoobie brain is a slow, rust-encrusted, squealing, steam- emitting, gear-grinding, contraption with lots of loose hoses and shorted wires, and no one remembers the last oil change.

 

[ThinAirDesign]

four?

Would you buy dislocated thumb? LOL

JB

 

[OmCheeto]

...here is our claim:

"Directly downwind, faster than the wind, powered only by the wind, steady state."

Do you have evidence of this?

 

[M Grandin]

Differential on a rail ...

I think you are discussing this issue in a wrong way, as it appears impossible convince "schröder & Co" in this specific example. Instead you could discuss this in more general terms: Is it generally possible drive something faster than (and by help from) a surrounding medium? A propeller in air is somewhat "fuzzy" and invites to fuzzy arguing.

Let us assume a long rail resting on ground and a second moving rail at velocity Vo parallell to this. Is it possible make a wagon that is driven faster than Vo on these rails? Yes it must be: Assume a differential (such that is used in car transmission) and orient it so it acts as difference gearing unit C = A - B , where A is rotation speed of wheel on fixed rail,
B is rotatiton speed of wheel on moving rail and C is resulting speed of shaft out from the differential. (Let us for simplicity call rotation speed of shaft corresponding to velocity Vx
also Vx - to simpify this hasty text).

Now you get C = Vo out from the differential whatever speed V the cart has and at the torque and power the moving rail can deliver. And moreover: Towing this cart on rail doesn't require any force or power whatever the torque at C is. So whatever speed the cart has, rolling on the rails, the power and torque from C-shaft can be used to accelerate the cart further. If Einstein admitted, it could even reach light velocity.

In this example the C-shaft should be suitibly geared and loosely coupled to wheel on rail
to accelerate cart to not lock the system.

If you replace the B-wheel by propeller and moving rail by wind you in essens hould have the DDWFTTW vehicle.

I thought this out myself, but may have read about aquainted earlier.

 

[zoobyshoe]

Zoo, here is our claim:

"Directly downwind, faster than the wind, powered only by the wind, steady state."

Your 'turbine, battery and motor' fail the "steady state" portion of the requirement.

No matter how much rotational mass a device has, if it's operating steady state that mass isn't being used to motivate it.

JB

Thanks!

 

[swerdna]

That certainly is one big difference between you and I -- you will do tests that make sense to the requester and not to you.



We have made the same offer and have followed through repeatedly -- we of course require the the user be able to justify the results of the test as something of additive value to our library of videos. As you concluded with your 'why are you attempting to use non-equivelancy in an attempt to prove equivelancy" comment back to Schroder, his test was useless, poorly conceived and did nothing to lead him towards the truth.

If you ever become 100% convinced of the validity of your testing and the DDWFTTW testing I suspect you will grow tired after about the 100th request for some cockimamy usless test. I understand that you have your doubts ... we understand the device and thus don't have doubts. That delta simply leaves you vulnerable to testing requests that lead nowhere.



C'mon now swerdna -- that's just a silly question considering both the time you have put into various forums and the time you spend making your turntable rig. The above fingerpointing only leaves you with four fingers pointed back at yourself -- **Why didn't YOU build and test and outdoor cart rather spending time on the forums and rather than building your turntable?**

Check those four fingers and I suspect you'll have the answer to your own question.

JB

Unlike yourself and Spork I certainly don’t think I know it all and will happily listen to others and carry out their tests in an attempt to understand their case.

I only belong to two forums (hardly various) and have only been involved with this debate since November 2008. Since then (even with a 3 week overseas holiday) I have constructed and tested several carts and the turntable. How many years (3? - 6? - more?) and how many forums (6? - 10? - more?) have Spork & Co been involved with this debate and what have they achieved? They didn’t come up with the principle as it has been known of for years (Brennan, Bauer, Robinson). The “Spork” cart is a direct copy of someone elses design and this person also used a treadmill for testing.

I have built and tested on a turntable to answer the main question I had that the cart on the treadmill might be storing energy that it was losing too slowly to be shown on a treadmill. That question has been answered well enough for myself and I now believe DDWFTTW is possible. I don’t neeed to build and conduct “real wind” tests but am planning to do so as further confoirmation for myself and to hopefully help others. I will video and publish all tests I conduct (watch this and the other space).

I really have no idea why you have bought your childish, unsubstantiated attacks against myself to this forum or why you even continue them on the other. Hardly the actions of a person of science. In future I will not reply to any of your posts as well as Sporks. You can continue your unsubstantiated personal attacks against myself to your heart’s desire.

To suggest a use for the fifth digit would be too easy.

 

[atyy]

Your 'turbine, battery and motor' fail the "steady state" portion of the requirement.

Why does it fail the "steady state" portion? I would think it passes that, but fails a requirement that not only the centre of mass, but also the boundary of the vehicle move faster than the wind relative to the ground? Actually, I liked the example, because it shows that energy is not the issue.

 

[rcgldr]

Is it generally possible drive something faster than (and by help from) a surrounding medium?

Already covered along with a link to a video in this post:

Have you seen the motor car that goes faster than the ruler video? It seems to be somehow related to these FTTW devices.
http://www.youtube.com/watch?v=9Yt4zxYuPzI&feature=channel

 

[rcgldr]

claim: "Directly downwind, faster than the wind, powered only by the wind, steady state."

Powered by the difference between wind speed and ground speed, not just the wind. Also to eliminate frame of reference issues, I've restated this as:

|v_cart-v_ground| > |v_wind-v_ground|

(where |...| means magnitude of the expression inside).

Do you have evidence of this?

That's what the videos demonstrate. A simplified description is that you have a forward force between prop + air, and an opposing force relative to the torque of the prop between wheels + ground. Because of the tailwind situation, using the cart's frame of reference, the relative speed of the air is less than the speed of the ground, so this allows the prop parameters (pitch and diameter) plus any effective gearing to be configured to generate more thrust than opposing force from the wheels, but at a lower than ground speed. The force at the prop is higher than the opposign force at the ground, but the power output at the prop is less because of the reduced speed of that thrust.

 

[rcgldr]

I think I need to poll the adherents of the cart and make sure I understand what amount of stored energy the criteria allow.

There isn't any restriction regarding stored energy with theoretical devices used to explain the possibility. For the actual carts made, a "steady state" only occurs at terminal velocity and requires that the wind to ground speed remains constant. In an outdoor situation, the varying wind versus ground speed would result in the cart oscillating between coast (momentum) mode and powered mode. If the wind is reasonably steady, then the average |v_cart-v_ground| > |v_wind - v_ground|.

You can't accelerate the cart without giving it some momentum.

The momentum exchange is the result of slowing the wind. The momentum of the downwind air is reduced in order to increase the momentum of the cart. The ground also gets an increase in momentum, but since it mass is huge compared to the cart the cart ends up with most of the change in speed. The math for this involves noting that total energy and total momentum of the air + cart + ground system remain constant.

 

[zoobyshoe]

Zoo, here is our claim:

"Directly downwind, faster than the wind, powered only by the wind, steady state."

Your 'turbine, battery and motor' fail the "steady state" portion of the requirement.

No matter how much rotational mass a device has, if it's operating steady state that mass isn't being used to motivate it.

JB

There isn't any restriction regarding stored energy with theoretical devices used to explain the possibility. For the actual carts made, a "steady state" only occurs at terminal velocity and requires that the wind to ground speed remains constant. In an outdoor situation, the varying wind versus ground speed would result in the cart oscillating between coast (momentum) mode and powered mode. If the wind is reasonably steady, then the average |v_cart-v_ground| > |v_wind - v_ground|.

OK. I was afraid of this.

 

[OmCheeto]

That's what the videos demonstrate.

Which video's? Like swerdna, I've seen lots of them. I've yet to see any evidence that the air alone can push a cart faster than itself.

A simplified description is that you have a forward force between prop + air, and an opposing force relative to the torque of the prop between wheels + ground. Because of the tailwind situation, using the cart's frame of reference, the relative speed of the air is less than the speed of the ground, so this allows the prop parameters (pitch and diameter) plus any effective gearing to be configured to generate more thrust than opposing force from the wheels, but at a lower than ground speed. The force at the prop is higher than the opposign force at the ground, but the power output at the prop is less because of the reduced speed of that thrust.

That doesn't sound very simplified to me.