Merged DDWFTTW in a “Real” Wind

[spork]

I was way ahead of you...
Again, I am way ahead of you on this...
I do not need to prove...

Just checking to see that you still aren't willing to have a genuine conversation about this - one in which we answer one another's questions.

Please just go ahead and ignore this post to confirm you're afraid of such a discussion.

 

[profpangloss]

You're kidding right?

No really, you're kidding.

You know I'm not. When I see you pretending that vibrational forces that are 30 times greater than the gravitational force acting on the cart, can be wished away because they are "irrelevant" or "inconvenient" to what you want to believe, I think you must be kidding. In any case, your transform is not to be taken seriously; and it never will be!

 

[semper]

You know I'm not. When I see you pretending that vibrational forces that are 30 times greater than the gravitational force acting on the cart, can be wished away because they are "irrelevant" or "inconvenient" to what you want to believe, I think you must be kidding. In any case, your transform is not to be taken seriously; and it never will be!

The thing is, even if we accept that there are mounting forces between the treadmill chassis and the floor of the magnitude you are proposing, there is no explanation of how that will affect acceleration of the belt, nor then how that would affect the cart on the belt,

You've been asked to explain that in light of the evidence that the wheels turn smoothly with no discernible skidding or any behaviour not consistent with the carteers explanation and you have been spectacularly unable to do so.

BTW, what will it have to do with kinematics?

 

[ThinAirDesigns]

Sure. Back away.

Oh, it seems I *can*fine at least a *single* example.

http://community.discovery.com/eve/forums/a/tpc/f/7501919888/m/58619922501/p/9
"The vehicle moving forward on the treadmill in a still air room is not a simulation of DDWFTTW, nor an approximation of DDWFTTW -- it's not even merely equivalent to DDWFTTW ... it is an *instance* of DDWFTTW".

Nope -- still not a single example. That's not what you lie and claim I said, that's what I *actually* said.

Keep looking.

JB

 

[ThinAirDesigns]

Once again our dear Humber posts a link to prove the exact opposite of what he claims!
How the Black Knight manages to shoot himself in the foot so often amazes me.

It's freakin' hilarious how often he does that -- proudly produces a post that shows him to be wrong and then goes on crowing like a retarded rooster.

JB

 

[profpangloss]

The thing is, even if we accept that there are mounting forces between the treadmill chassis and the floor of the magnitude you are proposing, there is no explanation of how that will affect acceleration of the belt, nor then how that would affect the cart on the belt,

You've been asked to explain that in light of the evidence that the wheels turn smoothly with no discernible skidding or any behaviour not consistent with the carteers explanation and you have been spectacularly unable to do so.

BTW, what will it have to do with kinematics?

I think you must accept there are vibration forces on the treadmill frame. Next time you are around a treadmill, just turn it on and touch your finger to the frame and let me know if you detected any vibrations. Now if those vibrations are on the order that was reported in the paper I referenced, ie. 60 N or so, is it so hard to imagine that they will also exist on the belt? I would venture to say you can bet your life that they do exist on the belt! All they need to do is reach a magnitude of one or two N on the belt to have an effect on a 200 gram cart. The effect will be on the traction between the cart's wheels and the belt.
This isn't something you can disregard, simply because it is inconvenient to your theory of how the cart moves up the belt! You and the rest of the carteers are claiming the cart rolls smoothly on the belt. How can that be, when it is being vibrated with periodic forces that may even be greater than the gravitational force that is holding it down? You do know there are conveyors that work on vibration, or do you? If the cart is being vibrated up and down after it has been held so that the propeller has spun up and producing thrust, is it so hard for you to see how that can play a significant part in how the cart advances on the belt? It seems to me now that it is you carteers who are in denial of the evidence. In any event, the presence of these vibration forces in the situation of the cart on the belt, and the absence of those forces in the situation with the cart on the road are more than enough to invalidate any conclusions you can draw about one situation in regards to the other. In simple straight forward words, your transform is invalid.
And what do mean by "no discernable" behaviour not consistent with the carteers explanation? How do you discern vibrations of 1 or 2 N with a period measured in milliseconds? Do you think you are going to see aliasing of the wheels in the videos? I doubt that very much, but you might just discern something if you tried a bit harder to look for it! You might try a strobe light, for example. Or, you could perform experiments with a more massive cart to see if it moves up the belt the same way as the lighter cart. Or you could try placing the treadmill on a vibration dampening mat and see what effect that has on the cart. What you should not do is discount the possibility of vibrations playing a significant part in the cart's motion, until you have at least looked into it with a sincere interest in discovering the truth of the matter.


Kinematics, as in the study of the motion of bodies, has everything to do with this discussion. But I suppose you would like to create another diversion and argue that point?

 

[semper]

I think you must accept there are vibration forces on the treadmill frame. Next time you are around a treadmill, just turn it on and touch your finger to the frame and let me know if you detected any vibrations. Now if those vibrations are on the order that was reported in the paper I referenced, ie. 60 N or so, is it so hard to imagine that they will also exist on the belt? I would venture to say you can bet your life that they do exist on the belt! All they need to do is reach a magnitude of one or two N on the belt to have an effect on a 200 gram cart. The effect will be on the traction between the cart's wheels and the belt.
This isn't something you can disregard, simply because it is inconvenient to your theory of how the cart moves up the belt! You and the rest of the carteers are claiming the cart rolls smoothly on the belt. How can that be, when it is being vibrated with periodic forces that may even be greater than the gravitational force that is holding it down? You do know there are conveyors that work on vibration, or do you? If the cart is being vibrated up and down after it has been held so that the propeller has spun up and producing thrust, is it so hard for you to see how that can play a significant part in how the cart advances on the belt? It seems to me now that it is you carteers who are in denial of the evidence. In any event, the presence of these vibration forces in the situation of the cart on the belt, and the absence of those forces in the situation with the cart on the road are more than enough to invalidate any conclusions you can draw about one situation in regards to the other. In simple straight forward words, your transform is invalid.
And what do mean by "no discernable" behaviour not consistent with the carteers explanation? How do you discern vibrations of 1 or 2 N with a period measured in milliseconds? Do you think you are going to see aliasing of the wheels in the videos? I doubt that very much, but you might just discern something if you tried a bit harder to look for it! You might try a strobe light, for example. Or, you could perform experiments with a more massive cart to see if it moves up the belt the same way as the lighter cart. Or you could try placing the treadmill on a vibration dampening mat and see what effect that has on the cart. What you should not do is discount the possibility of vibrations playing a significant part in the cart's motion, until you have at least looked into it with a sincere interest in discovering the truth of the matter.


Kinematics, as in the study of the motion of bodies, has everything to do with this discussion. But I suppose you would like to create another diversion and argue that point?

It is a bit difficult to have a conversation with you about vibration analysis. You keep saying that the vibration is 60N, well I might say it is 60frog, make sense?

The kinematics of the machine would be welded, molded and milled into place would they not?

 

[humber]

Nope -- still not a single example. That's not what you lie and claim I said, that's what I *actually* said.

Keep looking.

JB

Tragic.

 

[windgrins]

Your claim is that a transform can ignore irrelevant forces and give the example of laying a grandfather clock on its side. Fair enough, but just HOW do you know vibration foces of 60 N on the treadmill frame, for a cart that has a gravitational force of 2 N on the treadmill belt, are irrelevant?

PPG, As stated earlier and I see Semper beat me to it:

PPG,
It is clear from Video #6 with the single speed aliasing effect throughout the video that the cart does not lose traction. Therefore the vibrations are not an issue that seem to be any sort of cause.

If the wheels break traction, the prop would very quickly change their speed due to the load which would be evidenced in this video as alias speed variations which are not present. The reason this video is so good is that it stays very stable at the lowest WS possible for such a long time.

The thing is, even if we accept that there are mounting forces between the treadmill chassis and the floor of the magnitude you are proposing, there is no explanation of how that will affect acceleration of the belt, nor then how that would affect the cart on the belt,

You've been asked to explain that in light of the evidence that the wheels turn smoothly with no discernible skidding or any behaviour not consistent with the carteers explanation and you have been spectacularly unable to do so.

BTW, what will it have to do with kinematics?

You may also have noticed that I agreed with Humber on one of his points about the paper presented, but not all. The one point in my comments that should be noted is the part about not being able to discern from the description how the tests were performed and if the results were valid in the actual magnitudes of the vibrations. As Humber stated, (and I agree on this) if the Hammer used to excite the frame for an impulse test had no sensor for a calibration mechanism for the energy imparted, The measured magnitudes of the resulting force are not meaningless but they can't be used for magnitude values except relatively. In other words, the frequency spectrum of the resonance of the chassis could be ascertained but not the absolute levels. For the authors purpose, they showed that the resonances were all above their area of interest so they could simply LPF (Low-Pass Filter) the transducer signals and eliminate any high frequency resonance introduced by the motor. (This is ascertained from the Integral of power spectrum diagram). They did have one unexplained resonance at about 73 Hz that I'm surprised was not mentioned but it was of the same magnitude of the mentioned 90 Hz resonance. If you read the paper closely, and you have experience in this, you too can glean this.

Now finally, I've taken great care to answer all your questions in a serious and studied way but I see you have ignored most of mine such as:

The one you did answer-How is it that the earth's surface can act as IRF today at noon when the same point on it will be going at 2000 miles/hour (roughly) in the opposite direction at midnight (12 hours later)? That's quite an acceleration! Almost as if the surface of the earth is on one big giant 8000 mile diameter roller! I guess it can't be an IRF either by your argument.

You responded that the minor forces (correctly) could be ignored as they did not have an impact upon our problem. I agreed so I posed the following:

Suppose if we could we built a TM with the belt going entirely around the world and we run it a 10 mph over the earth's surface. (yes, I know we don't have the engineering and money to do this but that's why we call it a thought experiment.)

Question 1. Since the accelerations are all the same on the TM roller as the earth, can this be a valid platform for this discussion. If not, why not?

Question 2. If it is a valid platform, can a small portion of it be simulated by our TM moving at 10 mph? If not, why not?

The other one you seem to ignore is my statement about "force, power, and energy explanations all have to be consistent. Reason correctly in the simplest and derive the remainder from this and you have your explanation. Your'e idea is to find a model where you can ignore the axial force increase that exists on the prop due to the tail wind, make calculations which supposedly prove your point, and remain entrenched in your view. Most of us know this is where your missing power is but you continue to ignore this. You continue to produce power arguments as if the cart is in a no wind situation and ignore the power input from the wind. And one final time, yes I understand that it doesn't look like wind on the prop at WS but there is definitely a difference operating at WS vs no wind which keeps being ignored in your analysis.

On the vibration topic-Asking about vibrations having an effect is reasonable. Ignoring all the evidence which shows that it is inconsistent with results is not.

Overall,

When the questions get tough and they point out the problems in your argument, you duck them. This is indicative of someone who is emotionally tied to their line of thought and not open to learning.

There's not much point in responding to dramatically tortured counter explanations until you are willing to face up to the fundamentals. When (or if) this occurs, I'll be happy to discuss those with you. But again, I said "discuss", not listen to a one way diatribe of someone who is fighting just to stick to a preordained emotional based conclusion-which is of course "the cart can't work because I think it can't"

Fundamentally, I care that the physics is correct and not that I am. You seem to be in the opposite world. Until this changes, we are worlds apart.


Windgrins

 

[spork]

Just checking to see that you still aren't willing to have a genuine conversation about this - one in which we answer one another's questions.

Please just go ahead and ignore this post to confirm you're afraid of such a discussion.

Thanks for confirming for us onse again that you already know you're wrong ppg.

You know I'm not [joking]. When I see you pretending that vibrational forces that are 30 times greater than the gravitational force acting on the cart...

So make a cart that advances on the treadmill without a prop. It should be cake - right? Pretty much any cart on any treadmill should work just fine according to your claim. How about if I take the prop off mine and post the video? Will that convince you? Of course not!

Again - please go ahead and ignore this all together if you've got nothing.

 

[windgrins]

Requested Experiments

Do you think you are going to see aliasing of the wheels in the videos? I doubt that very much, but you might just discern something if you tried a bit harder to look for it! You might try a strobe light, for example. Or, you could perform experiments with a more massive cart to see if it moves up the belt the same way as the lighter cart.

It is very easy to discern the issue of speed changes in the following video by looking at the front wheels. It's not clear why you doubt it if you know anything about frame rates on video cameras and alias effects:

http://www.youtube.com/watch?v=dgHBDESd38M&feature=related

Watch the pinwheels carefully, They never show a break until the cart falls off the back end of the TM which is easily discernible.

and here's your experiments you requested:

Large cart on a TM:

http://www.youtube.com/watch?v=4pgDs50A-Yw

and

Small cart on a TM:

http://www.youtube.com/watch?v=Vjt6G8D4x0k&feature=related

Two dramatically different sized carts going up TM

 

[profpangloss]

You may also have noticed that I agreed with Humber on one of his points about the paper presented, but not all. The one point in my comments that should be noted is the part about not being able to discern from the description how the tests were performed and if the results were valid in the actual magnitudes of the vibrations. As Humber stated, (and I agree on this) if the Hammer used to excite the frame for an impulse test had no sensor for a calibration mechanism for the energy imparted, The measured magnitudes of the resulting force are not meaningless but they can't be used for magnitude values except relatively. In other words, the frequency spectrum of the resonance of the chassis could be ascertained but not the absolute levels. For the authors purpose, they showed that the resonances were all above their area of interest so they could simply LPF (Low-Pass Filter) the transducer signals and eliminate any high frequency resonance introduced by the motor. (This is ascertained from the Integral of power spectrum diagram). They did have one unexplained resonance at about 73 Hz that I'm surprised was not mentioned but it was of the same magnitude of the mentioned 90 Hz resonance. If you read the paper closely, and you have experience in this, you too can glean this.

Lots of words, but very little content. The hammer was used to check for resonance, not to check for vibration levels. Vibration levels were checked with the motor running and no subject on the treadmill. Please do not try to confuse the resonance tests with the vibration analysis with the motor running; they are two completely seperate issues.

By the way, I do have experience in this area and the last thing I would use to perform a vibration analysis on a treadmill is a hammer! That is very old school. What I would do is use a motor that has a tachometer output, and use the tachometer output as an input to a sophistaicated vibration spectrum analyzer. But that really not something we need to get into here.

Now finally, I've taken great care to answer all your questions in a serious and studied way but I see you have ignored most of mine such as:

The one you did answer-How is it that the earth's surface can act as IRF today at noon when the same point on it will be going at 2000 miles/hour (roughly) in the opposite direction at midnight (12 hours later)? That's quite an acceleration! Almost as if the surface of the earth is on one big giant 8000 mile diameter roller! I guess it can't be an IRF either by your argument.

You responded that the minor forces (correctly) could be ignored as they did not have an impact upon our problem. I agreed so I posed the following:

Suppose if we could we built a TM with the belt going entirely around the world and we run it a 10 mph over the earth's surface. (yes, I know we don't have the engineering and money to do this but that's why we call it a thought experiment.)

Question 1. Since the accelerations are all the same on the TM roller as the earth, can this be a valid platform for this discussion. If not, why not?

Question 2. If it is a valid platform, can a small portion of it be simulated by our TM moving at 10 mph? If not, why not?

You want me to reply to this fantasy? A treadmill going around the earth? In the words of one of the other posters, Piffle!

The other one you seem to ignore is my statement about "force, power, and energy explanations all have to be consistent. Reason correctly in the simplest and derive the remainder from this and you have your explanation. Your'e idea is to find a model where you can ignore the axial force increase that exists on the prop due to the tail wind, make calculations which supposedly prove your point, and remain entrenched in your view. Most of us know this is where your missing power is but you continue to ignore this. You continue to produce power arguments as if the cart is in a no wind situation and ignore the power input from the wind. And one final time, yes I understand that it doesn't look like wind on the prop at WS but there is definitely a difference operating at WS vs no wind which keeps being ignored in your analysis.

Nonsense! You want to ignore the fact the cart needs to be dragged up above wind speed and then when it is released, you want to imagine it still has the power given to it by the tow vehicle. When will you wise up?

On the vibration topic-Asking about vibrations having an effect is reasonable. Ignoring all the evidence which shows that it is inconsistent with results is not.

You cannot show that the vibrations are inconsistent with anything because you refuse to even acknowledge they are present.

Overall,

When the questions get tough and they point out the problems in your argument, you duck them. This is indicative of someone who is emotionally tied to their line of thought and not open to learning.

There's not much point in responding to dramatically tortured counter explanations until you are willing to face up to the fundamentals. When (or if) this occurs, I'll be happy to discuss those with you. But again, I said "discuss", not listen to a one way diatribe of someone who is fighting just to stick to a preordained emotional based conclusion-which is of course "the cart can't work because I think it can't"

Fundamentally, I care that the physics is correct and not that I am. You seem to be in the opposite world. Until this changes, we are worlds apart.


Windgrins

Overall, I'd say your comments are off the topic and tend to get far too personal. That should indicate who has the emotional attachment, and who is looking at this objectively.

 

[semper]

It is producing 60 Kermit and generating a Fozziestat reaction in the x-axis, no doubt about it.

 

[humber]

Thanks for confirming for us onse again that you already know you're wrong ppg.



So make a cart that advances on the treadmill without a prop. It should be cake - right? Pretty much any cart on any treadmill should work just fine according to your claim.

Trivial, really. More of a nuisance than a challenge.

How about if I take the prop off mine and post the video? Will that convince you? Of course not!

You have already done that, Spork. Remember? No?

http://www.youtube.com/watch?v=LMgDvC5lqsY&feature=related

Around 1:22

The cart moves back at 0.3 to 0.4m/s. About 10% of the belt's speed.

 

[Subduction Zone]

ppg, your refusal to get involved in a thought problem indicates that you cannot do physics. Thought problems are both an educational tool and a tool used for analysis in physics and other sciences. What is left? Experimentation. Oh wait. You reject that too. In the wise words of spork "You have nothing".

 

[Subduction Zone]

And yes humber, spork already did perform the propless experiment. The results don't match ppg's claims. Why does the cart with the prop advance and the cart without the prop not advance? Or in other words, why does the cart with the prop go faster than the wind and the cart without the prop go slower than the wind?

 

[humber]

And yes humber, spork already did perform the propless experiment. The results don't match ppg's claims. Why does the cart with the prop advance and the cart without the prop not advance? Or in other words, why does the cart with the prop go faster than the wind and the cart without the prop go slower than the wind?

A better question is to ask why it only gets to about 10% of the speed of the belt.

When released, the force accelerating the cart it about .03N.

Once again our dear posts a link to prove the exact opposite of what he claims!
How the Black Knight manages to shoot himself in the foot so often amazes me.

It's freakin' hilarious how often he does that.

 

[Subduction Zone]

A better question is to ask why it only gets to about 10% of the speed of the belt.

When released, the force accelerating the cart it about .03N.

humber, wrong. It doesn't "get to about 10% of the speed of the belt". It starts at belt speed and then it starts to slow down. Once it is slowing down it will eventually fall off of the back of the belt. If the belt was long enough the cart could eventually stop relative to the belt. If the propless cart would stand still in a ten mph wind it would eventually stop on a treadmill moving at ten mph. But we all know that humber cannot do basic physics and that I am wasting my time here.

 

[humber]

humber, wrong. It doesn't "get to about 10% of the speed of the belt". It starts at belt speed and then it starts to slow down. Once it is slowing down it will eventually fall off of the back of the belt. If the belt was long enough the cart could eventually stop relative to the belt. If the propless cart would stand still in a ten mph wind it would eventually stop on a treadmill moving at ten mph. But we all know that humber cannot do basic physics and that I am wasting my time here.

The motion relative to the ground is about 0.3m/s. Belt speed relative to the ground is 4m/s. ( 10mph is the usual speed).

When released a ~ 0.18ms-2

Cart = 0.16kg, Prop .029kg

F =ma = 0.18ms-2*.13kg ~.023N

After that, the speed is around 0.3m/s.

Quite obviously, only .023N ( thrust) is needed to prevent motion down the belt. When the prop is attached, the belt force rises a bit, so becomes about 0.04N.

 

[Subduction Zone]

humber, still failing at Galilean Transformations. You can't even measure relative velocities.

Here is a simple question for you that even you should be able to get right. If you take a propless cart and release it at 10 mph on the road when the wind is blowing at ten mph in the direction of the cart how will the cart react?