Down wind faster than the wind

[humber]

I’ve been ciritcal of the treadmill demonstrations provided as the treadmill is too short to perform adequate testing. Myself and others have suspected that the cart was using stored kinetic energy and that this was being lost too gradually to be shown on a treadmill. The turntable design I suggested provides an endless “treadmill” and I have been disappointed that nobody has built one despite most saying it was a good idea. <snip>

What I wanted to test was whether the thrust of the fan could continuously exceed the the rolling resistance of the wheel (mine only has one drive wheel). The construction is crude and there is still lots of fine tuning to do but early tests have been conclusive enough for me to say the answer to this question is 99.99999999% YES!

When you enter the world of humber:

A: There is no test which validates our model -- even if the results are exactly as our model predicts.

B: There is no test *which could * invalidate humber's model.

JB

You seem to be unaware of what Ynot hopes to demonstrate. It is explained above. That is his primary interest, and why he wants to try a flywheel.

I remarked that this test will fail because of reaction to the tether. Only Brian_M responded. (ETA: Though Ynot said he understood why I wanted to a test without a propeller)
But now that you recognise that my prediction will be seen to be true, you have proffered a number post hoc caveats, that were formerly ignored, though they only serve to show that the treadmill is also likely to rely upon the same balance of forces. There is a difference;

Quote Dan_O

If you replace the prop with an equal mass and moment flywheel, you would be able to measure the total friction drag force directly. This would make it easier to see the effects of tweaking your design. Reversing the prop gearing would allow you to determine the thrust and drag components of the prop.

The force from the wheels will be divided between the propeller and the tether. They may not result in the desired balance, so that may need to be manually tweaked, as suggested above.
The treadmill does not provide an additional path of the tether, so the forces must in balance as I claim

In both cases the cart will stay in place anyway, by the balance of frictional forces. For that you do not need a propeller. The treadmill model is false.

 

[humber]

Very well.

A Galilean boost acts on the cart, the air, and ground, and everything else by shifting its location from x to x-vt, where x is position (a vector), v is the velocity of the boost (another vector), and t is time (so this is usually written x'=x-vt, where x' is the boosted coordinate). This transformation is the limit of a Lorentz boost when v<<c.

There is of course no integral.

Yes, so there is no power that can be gained. Also, you have not quantified those velocities, or their actual effect upon the cart.
Otherwise your claim, even if correct, may be trivial.

 

[sol invictus]

Yes, so there is no power that can be gained. Also, you have not quantified those velocities, or their actual effect upon the cart.
Otherwise your claim, even if correct, may be trivial.

I have no idea what you're talking about - and obviously neither do you. This is like "conversing" with a salad vegetable.

Enough of this stupidity.

 

[Christian Klippel]

.... test without a propeller ....
The treadmill model is false.

So, you want to test something without a propeller, that originally needs a propeller to work in the first place, just so that you can say later that it doesn't work? You _do_ notice the stupidity of that, do you? This is like wanting to do a real-world lift-off of a jumbo jet, while having its jet-engines unmounted and left in the hangar.

As for the "false treadmill model", you still have not brought a simple explanation why it is invalid. While you try to keep pondering on that false assumption of yours, you fail to explain how you come to that assumption. And keep in mind that when explaining it, you have to consider all the facts and parts and stuff that spork, tad and others have mentioned are important.

Since it is clear that the treadmill is a usable test-environment, you want to do fancy test like using the cart without the prop on either the disc or the treadmill. Just so that you can say "see, it doesn't work" afterwards. But you keep forgetting (i would say, you are avoiding) the fact that such a test would have nothing to do anymore with the original cart, that indeed requires a prop.

So, again, explain why the treadmill isn't equivalent for the purposes of the testing the cart. And stop evading the issues, moving goalposts and shifting topics. Can you do that?

And while you are at it, would you please point out the error's in the descriptions that people gave as to how the cart works? Since you imply that you understand how it works, you must be able to point out the flaws in the descriptions. Why i say that you imply it? Easy. You claim the treadmill isn't an equivalent test to outdoors. You can have such an knowledge only if you know how it works. Otherwise you would have no reference of its functioning that you compare to the functioning on a treadmill.

Greetings,

Chris

Edit: I could also have said that what you want to test is like putting a jumbo-jet in a wind-tunnel to see if it can fly, just that you want to have the test done without the wings attached to it so you can claim "see, it won't fly!"

 

[humber]

I have no idea what you're talking about - and obviously neither do you. This is like "conversing" with a salad vegetable.

Enough of this stupidity.

You are right. You do not know what I am talking about. I have noticed that you only respond if you see a 'mistake' of mine.

It makes no difference how you split or transform the power input from the wind. All forces and velocites distributed within(and without) the cart, will sum to the applied vectors, as dictated by the available power of Force x Velocity.

Power is also Work/Time, and that cannot be changed by transformation.
The cart cannot 'demand' more than is available. It can change the load it presents so as to allow more efficient transfer, but that will not change the level of available power itself.
Trivial.

 

[ynot]

Just to make my position clear - My motivation to test with a flywheel came from my former assumption that the thrust of the propeller couldn’t exceed the rolling resistance of the wheel. Now that I have found that it apparently can (to the degree of testing done), the flywheel test becomes somewhat redundant (but I will still do it).

Rigorously test + rinse and repeat = good science.

 

[Dan O.]

Not like the space station and judge you introduced?

The tanker is often used as part of the description of how a small force can move a large object if applied for adequate period. I used it to show the irrelevance your questions.
(1)You know that.

I know that you introduced grossly irrelevant factors to a simplified model presented to explain the energy balance of the cart.

.
<snip>
In this sample world we have only kilograms of mass, joules of energy...

In the same simple world, I can accelerate an oil tanker as I please.
Two airstreams, 10kmh, relative to each other. Reverse their velocities. Now the relative velocities have increased. What has happened?

Here is the full problem stated again:

Let's try a little physics instruction in a virtual world far away from the everyday surroundings of space, time, gravity and the friction that bogs everything down.

In this sample world we have only kilograms of mass, joules of energy and velocity in meters per second. The basic rule that applies to this world is that if you have two masses of 1 kilogram each, you can expend one joule of energy to accelerate one of the masses by +1 meter per second and the other mass by -1 meter per second.

Your first task in this world is to derive how many joules are required to get the masses moving at +2 and -2 meters per second using only the basic rule provided.

A fifth grader should easily be able to solve this but since it may lead to a violation of your faith, you instead choose to regurgitate garbage over it.

A cart can accelerate and store momentum in the propeller. You know that. If allowed an adequate period of acceleration, it may store enough energy got the purposes of the test. It is if it had a motor. That's right. The stored energy is the equivalent of a motor.
(2) you know that.

Are you claiming that there must be a motor on the cart? You already said that you didn't think there was any cheating. Do you think that Jack's cart can change it's mass at will? If not those then where does the energy get stored?? Any energy stored as momentum will be visible in the velocity of the cart (you do know that momentum is the product of mass time velocity don't you). Do you think that a gust of wind added momentum to the propeller? Remember that the wheels are linked to the propeller so if the propeller has additional momentum that is not reflected in the velocity of the cart, the wheels must be slipping. But which way are the wheels slipping? Try and make your case on the timeline of Goodman's video. Show the cart velocity profile and explain when the gusts occur and their direction and the periods when the wheels are slipping.

You say the my description of the sock is not correct.
(3) You know that it is.

You gave some wishy-washy treatment of the sock and I responded with a clear explanation and asked if you agreed. You did but somehow think that acceleration of the cart will give a false reading. Feel free to take acceleration into account when you put together the scenario to explain the total evidence for Jack Goodman's video.

OK Dan O. Without resort to a magic wind, describe the treadmill's
operation, in a way that does not require it to be a balance I claim it is.
There is huge error, that none of you have noticed, in the "equivalent" model of the treadmill. Do you know what that is?

Yes, the error is in your mind. Did you miss some of my earlier post?

For the purpose of our test, the road is simply a flat surface moving at a constant velocity upon which the cart can roll. The treadmill is a valid simulation of the road since the only function of the motor is to keep the surface of the treadmill moving at a fixed speed.

If it would help, imagine that the motor is replaced with a giant flywheel. After all, the road is atached to a giant flywheel that keeps it moving at over 250 kilometers per hour.

What does it mean to shield a cart traveling at wind speed from the wind?

Lucid enuff for ya?

If you were a psychiatrist, you would have a whole world of delusional patients.

 

[Christian Klippel]

Just to make my position clear - My motivation to test with a flywheel came from my former assumption that the thrust of the propeller couldn’t exceed the rolling resistance of the wheel. Now that I have found that it apparently can (to the degree of testing done), the flywheel test becomes somewhat redundant (but I will still do it).

Rigorously test + rinse and repeat = good science.

I understand.

Keep in mind that, according to humber, "Your conclusion is "it looks like it works to me, so it must be so"...", and that "Taking eye witness as evidence, is one way to stay in the cave,...". So, while you can witness yourself now that it does what it should do, that observation is according to our "scientific skeptic" quite meaningless and would just force us to stay in the cave! Beware of the ghosts and gremlins! Humber said it doesn't work, so it can't work, even if you see yourself that it does work.

Must be some kind of group-hallucination that the people, who test this cart or its working, experience.

Ynot, good work on your side. Thumbs up for that.

Greetings,

Chris

 

[humber]

So, you want to test something without a propeller, that originally needs a propeller to work in the first place, just so that you can say later that it doesn't work? You _do_ notice the stupidity of that, do you? This is like wanting to do a real-world lift-off of a jumbo jet, while having its jet-engines unmounted and left in the hangar.

You do not appear to know much about the scientific method. Have you not heard of a placebo trial? Now join the dots.

As for the "false treadmill model", you still have not brought a simple explanation why it is invalid. While you try to keep pondering on that false assumption of yours, you fail to explain how you come to that assumption. And keep in mind that when explaining it, you have to consider all the facts and parts and stuff that spork, tad and others have mentioned are important.

It is a force balance. It does not need 'wind' from the belt to achieve this. The model fails the equivalence test, so the "explanations" are wrong.

Since it is clear that the treadmill is a usable test-environment, you want to do fancy test like using the cart without the prop on either the disc or the treadmill. Just so that you can say "see, it doesn't work" afterwards. But you keep forgetting (i would say, you are avoiding) the fact that such a test would have nothing to do anymore with the original cart, that indeed requires a prop.

So, again, explain why the treadmill isn't equivalent for the purposes of the testing the cart. And stop evading the issues, moving goalposts and shifting topics. Can you do that?

If you call that a "fancy test" then, yes. The original cart would do the same. Replace the propeller with something that generated drag. A paddle wheel or a disk with slots. It will stay on the belt, and probably travel, but with no propeller.
It won't then look so much like it is travelling at "windspeed", but then it never was. If you know why not, tell me.

The turntable shows that TAD did not consider the effect of the tether, saying that the test was good, but it is not. I posted why, including a drawing. Now that Ynot has actually built the turntable, they can see trouble ahead, and offer excuses.
This leads me to doubt their skill at correctly analysing test platforms in general.

And while you are at it, would you please point out the error's in the descriptions that people gave as to how the cart works? Since you imply that you understand how it works, you must be able to point out the flaws in the descriptions. Why i say that you imply it? Easy. You claim the treadmill isn't an equivalent test to outdoors. You can have such an knowledge only if you know how it works. Otherwise you would have no reference of its functioning that you compare to the functioning on a treadmill.

I have never commented on those descriptions, for the reasons I gave you. They are based upon the false model of the treadmill, so they are moot. I have perhaps commented on the general nature of carts in wind and sailing boats, but not specifically those descriptions.

Edit: I could also have said that what you want to test is like putting a jumbo-jet in a wind-tunnel to see if it can fly, just that you want to have the test done without the wings attached to it so you can claim "see, it won't fly!"

Is a car, a propellor driven vehicle, but without a propellor?

Is the cart on the treadmill driven by friction or the thrust from the propeller?
How can I tell. Let's see. Keep the friction, but remove the thrust. Fit a disk.
Mmm.....,Professor, it seems that the behavior is independent of thrust, but quite reliant upon friction. What is your conclusion?

ETA:
See post #1741, where I posted Ynot's quote regards his intention. You will not find one line where I have said of Ynot "look it works". I read and understand his posts, so I know that he is aware of the scientific method. You are do neither, ans are ignorant of the last.

 

[Christian Klippel]

Is the cart on the treadmill driven by friction or the thrust from the propeller?

By the thrust of the propeller, whereas the prop gets the energy to spin (and thus produce thrust) through the wheels. So, if you take out the prop, it wont work as claimed. What is so hard to understand?

What is your conclusion?

that you are deliberately twisting things around just to try to make your faulty viewpoint the right one. But it doesn't work that way, as you should know.

My explanation as to how i think the cart works in post #1667 doesn't involve a treadmill, so why do you evade the question "how do you think it works"?

Again, the prop's surface is moving slower in relation the cart. So even when the cart is at windspeed, the speed at the prop surface is below windspeed, so the wind still has something to push against. As long as the props's surface is slower as the wind, the cart can accelerate. Once that speed matches the windspeed, the maximum speed of the cart is reached which is above windspeed.

You agree that a 5 km/h tail wind on the stationary prop is the same as the prop moving backwards 5 km/h in still air, do you? So, as for the treadmill, it doesn't matter if the wind pushes the prop as it would outside, or if the prop pushes the air as on the treadmill. Notice that with "push" i mean a simple linear force along the axis of travel of the cart. I do _not_ mean to have the wind making the prop rotate. Actually, the energy captured from the wind by the prop is splitted up, part goes into said linear motion, the other part tries to spin the prop.

You agree that a kite with an area of 1 m² produces less "pull" on the string holding it than a kite with 2 m² area, right? More energy would be available with the 2 m² area, compared to the 1 m² area, right? So, you have a prop with wind pushing on its surface. That brings the energy into the system. That energy has just to be big enough to push the cart itself, to make the prop spin and to accommodate for mechanical friction losses in the cart. Once the prop spins, you have a surface that moves slower through a line in space along the direction of travel of the cart than a surface on the cart's frame.

It doesn't matter if the energy for the linear motion comes through the wind pushing on the prop which moves the cart which makes the wheels turn, or if it comes from the treadmill directly driving the wheels. If the cart stands motionless on the running treadmill, the energy input to the cart is the same as if the wind would push on the moving surface of the prop to bring the cart to windspeed.

So, again, what is wrong with that, what don't you understand?

And now, for the last time, explain it and don't evade. If you fail to state what is wrong with the treadmill vs. outside, and can not state how the cart would work outside and on the treadmill and show the difference, and also if you fail to explain why the cart is supposed to stay below windspeed, then well, then you simply failed. And the only impression that one can get from this is that you already seen your error, but refuse to admit it, probably to "keep your face", while in reality you simply ridicule yourself more and more.

Greetings,

Chris

Edit: Moved on sentence re: kite area to the proper place, changed "across" to "along" re: prop surface.

 

[Christian Klippel]

You will not find one line where I have said of Ynot "look it works".

And you will not find a single line where i said that you said of ynot "look it works".

What makes you come to the conclusion that i did? Or is that just more twisting of facts to distract from the real issues? You know, smokes and mirrors and all that.

So, show me where i said that, and if you can't find it, at least admit that you got it wrong and just made it up.

Greetings,

Chris

 

[Christian Klippel]

Ah, and just in case that someone missed it:

http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attempts_to_aton.php

Saw it just now. That's the new article from MarkCC on the cart and why he was wrong.

Greetings,

Chris

 

[Christian Klippel]

Ah, and just in case that someone missed it:

http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attempts_to_aton.php

Saw it just now. That's the new article from MarkCC on the cart and why he was wrong.

Greetings,

Chris

 

[humber]

I know that you introduced grossly irrelevant factors to a simplified model presented to explain the energy balance of the cart.

​

Here is the full problem stated again:

​

A fifth grader should easily be able to solve this but since it may lead to a violation of your faith, you instead choose to regurgitate garbage over it.

That's you simplification right there. The treadmill is simple. You can use the idealised forces and masses that you post, and conclude that my description is correct.
The remainder, the actual levels of friction for example, are details that cannot deny the basic argument.

Are you claiming that there must be a motor on the cart? You already said that you didn't think there was any cheating. Do you think that Jack's cart can change it's mass at will? If not those then where does the energy get stored?? Any energy stored as momentum will be visible in the velocity of the cart (you do know that momentum is the product of mass time velocity don't you). Do you think that a gust of wind added momentum to the propeller? Remember that the wheels are linked to the propeller so if the propeller has additional momentum that is not reflected in the velocity of the cart, the wheels must be slipping. But which way are the wheels slipping? Try and make your case on the timeline of Goodman's video. Show the cart velocity profile and explain when the gusts occur and their direction and the periods when the wheels are slipping.

Do you think "as if having a motor" is actually having a motor"?
You know that is not so, because I already flatly denied cheating several times. Do the logic.
So you cannot conceive of the idea that a cart can gather momentum, during some former period, for later use?

1. When driven in the wind, Cart A will reach a velocity of 10kph
2. Cart B, has a massive prop, and stores a lot of energy by the time it also reaches 10kph.
3. Would not the driver of Cart B then be able to change gears, as in a car, and accelerate on that stored energy and exceed the velocity of Cart A? The answer is a resounding yes.

4. Automate that procedure, with a simple mechanism involving the wheels, and over time you, get the same effect. I only need to film the cart by method and circumstance, to have it accepted by you, as "evidence".

You gave some wishy-washy treatment of the sock and I responded with a clear explanation and asked if you agreed. You did but somehow think that acceleration of the cart will give a false reading. Feel free to take acceleration into account when you put together the scenario to explain the total evidence for Jack Goodman's video.

Not wishy washy. They are in addition to the primary flaw of only indicating the cart's velocity w.r.t the local air, and nothing about speed relative to the ground.
The sock moves to the left when the cart is traveling greater than windspeed, you say. Also when simply accelerating, I think. If not, then is must not be in the breeze.

Yes, the error is in your mind. Did you miss some of my earlier post?

Missed nothing. You are assuming the model is equivalent, and arging from there. I say that the model has a gaping hole in it that flat out denies that "equivalancy". It is nothing subtle, Dan O. I have posted why, but you still hang on to the error.

If you were a psychiatrist, you would have a whole world of delusional patients.

We do. Sometimes your arguments rely upon the acceptance of the contrary. That's how at least sometimes, I know you know.

 

[Thabiguy]

Saw it just now. That's the new article from MarkCC on the cart and why he was wrong.

Hmm... unfortunately, he still hasn't got it quite right in the article.

 

[ThinAirDesigns]

I want to emphasize how much I respect the path that ynot has chosen.

Here is a guy who has struggled with this device, it's principles and our explanations. He has taken the time to create an environment that allows him to convince himself of the behavior of the device.

The world of science would be a better place with more of you ynot. Seriously.

JB

 

[humber]

Hmm... unfortunately, he still hasn't got it quite right in the article.

Yes. It seems that he has quite a few things wrong. Some of the comments point them out. As I wrote, I did not agree with his first critical post, and now not with this one.
Fear of having those previous mistakes exposed, and the language used, forced him to make a hasty apologia.

 

[Christian Klippel]

Hmm... unfortunately, he still hasn't got it quite right in the article.

Right, but he is on the right track at least, and is willing to spend some time thinking about it. I'm pretty sure that he will correct the remaining mistakes as well.

Greetings,

Chris

 

[mender]

1. When driven in the wind, Cart A will reach a velocity of 10kph
2. Cart B, has a massive prop, and stores a lot of energy by the time it also reaches 10kph.
3. Would not the driver of Cart B then be able to change gears, as in a car, and accelerate on that stored energy and exceed the velocity of Cart A? The answer is a resounding yes.

4. Automate that procedure, with a simple mechanism involving the wheels, and over time you, get the same effect. I only need to film the cart by method and circumstance, to have it accepted by you, as "evidence".

Well, Humber actually has a point. A vehicle that spins up a mass can use that momentum to momentarily increase the speed of the vehicle. And to do so requires a transmission or gear changing mechanism. The only way to do this smoothly and for more than a quick burst (after which the vehicle again succumbs to drag and slows) is through a CVT.


Humber, please point out where I can find the automated mechanism for changing gears in these plans:

http://www.rtfa.net/2008/12/04/downwind-faster-than-the-wind-dwfttw-plans

Oh wait, just had a close look, not there, no room to hide one. Oops, no way for your momentum idea to work. Thought so, but just wanted to check.

 

[humber]

Well, Humber actually has a point. A vehicle that spins up a mass can use that momentum to momentarily increase the speed of the vehicle. And to do so requires a transmission or gear changing mechanism. The only way to do this smoothly and for more than a quick burst (after which the vehicle again succumbs to drag and slows) is through a CVT.

So you admit the possibility. What if that transient is longer than you think, and there is a mechanism that you have not considered?

The gearbox of the car is analogous. I wrote "Automate that procedure, with a simple mechanism involving the wheels, and over time you, get the same effect."
Changing the pitch of the propeller is another option.A variable gearbox is not required.

The propellor has effectively two 'choices'. It can store energy or use it to drive the cart. At anytime the available energy is more than the cart can demand by its effective load , that load can be increased, and the excess stored. (This is more like changing the propellor's pitch.)
The controlling mechanism, is the friction between the ground and wheels. The effective load can be modulated; propellor only, propellor + drive to wheels. The excess goes into storage. It can't not happen. When the prop changes speed, momentum goes in or out.

If wind slows, the cart is still driven by the wind, but also by the momentum from the propellor, resulting in a higher velocity than it would otherwise have. It can exceed the velocity of a cart that cannot store energy, when working at a constant velocity against a load.
I do not have the details of this cart, and wind changes will play their part, but the means are there. Small wheels on a rough road? He does not seem to care about efficiency.

Humber, please point out where I can find the automated mechanism for changing gears in these plans:

http://www.rtfa.net/2008/12/04/downwind-faster-than-the-wind-dwfttw-plans

Oh wait, just had a close look, not there, no room to hide one. Oops, no way for your momentum idea to work. Thought so, but just wanted to check.

There is the momentum of the propellor, but like Goodman's cart, there is no literal gearbox. They share the same wheel mechanism, but there is another form of storage. Can you see it?

If I wanted to deceive you, do you think that I would do it in such a way? DOH, no gearboxes!
ETA: I forgot. I must be literal. I am NOT trying to deceive you.