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

[swerdna]

If you put the TT and cart back together, with a tachometer on the TT and a tachometer on the wheel, you will have built a very valuable teaching aid for rotational and translational motion. In particular, a very nice demonstration of a mechanical heterodyne which every mechanical engineering department and physics department will be happy to have. That is where you will get the most benefit out of this, not by chasing after some DDWFTTW myth. You have something valuable there if only you recognize it! You find it amazing that I believe the cart slows down to reach the steady state. I find it amazing that you believe in DDWFTTW. One of us is wrong! The best way to determine that is to do the test with the tachometer and I guarantee you will be amazed to see the cart is actually slowing down. There is nothing magical or mystifying about that. Translational motion is replacing rotational motion while energy is being conserved. What I am explaining is according to the laws of physics while DDWFTTW is not! I find it amazing that you choose to believe the stranger of the two claims rather than believe in a heterodyne. I will try to find some more examples of heterodynes in mechanical machinery. They are rare, which is why your TT and cart is a valuable asset. I believe heterodynes also happen on large rollers in paper mills and in some other machinery used in the lumber industry, as well as inside gas turbines. Once you understand the principle, the cart on the TT makes perfect sense. I think you are wasting your time chasing the wind when your TT is far more valuable and certainly worth the cost of at least one digital tachometer and preferably two. But that is entirely up to you. I will try to make some drawings to explain how translation takes the place of rotation, but I am not good at computer animations so it may be a bit crude. Give what I say some consideration as you will benefit if I am right.

Don’t think of the cart as “slowing down”, think of it as “moving less in that direction“.

I can clearly see that the cart is “slowing down” in relation to the turntable if I use myself as the stationary reference. I can also see that it then “speeds up“. But what has the speed of the cart got to do with the speed of the wheel? The tachometer is measuring the speed (revolutions) of the wheel isn’t it? I’m not amazed that you think the cart is slowing down, I’m amazed that you think the speed (revolutions) of the wheel is slowing down. You seem to be talking about the speed of the cart and the speed of the wheel revolving as if they are the same thing (they aren‘t).

When the cart is “hovering (stopped) the speed of the running surface (circumference) of the wheel is the same as the speed of the particular part of the TT surface it runs on. Let's say this is 10kph. If the cart moves against the motion of the TT by 2kph then the speed of the running surface of the wheel is 12kph. It absolutely has to be, there is no other option (assuming it isn‘t slipping).

I have also Googled heterodyne and can’t find any mechanical reference for the term and don’t see how it applies to the TT/cart. Any mechanical examples would be appreciated.

I believe all this is irrelevant anyway as I really don’t see that what happens before the cart reaches terminal speed is of any importance, as long as no effect like stored energy is carried over. Tests I‘ve done on my equipment have conclusively shown me that stored energy at least is not carried over. If there is some other effect called heterodyne then it should be able to be clearly explained and proven by the person that claims the effect exists. If the cart was held against the motion of the TT until the prop thrust could do it, would a heterodyne effect still be applicable? I know enough about basic mechanics to know that the revolutions of the wheel (nothing to do with the speed of the cart) do not slow down as the cart goes throught the process of reaching terminal speed.

Give what I say some consideration as you will benefit if I am right.

ETA - If the turntable and cart are such a valuable asset why don’t you build one of your own? It should be very easy for a professional engineer to do. You could then do your own tests and prove conclusively that you are correct.

 

[ThinAirDesign]

I’ve built an air cart version of the Brennan Torpedo but I’m having a problem with it. The string is being pulled from a spool on the prop shaft and the cart is being held against a backstop until it gets up to thrust speed. It works fine except when the cart leaves the stop it surges slightly which makes the spool overrun and that tangles the string up. It was worst when I tried it with nylon fishing line. That horrible stuff is just designed to tangle. If I put enough friction on the spool to stop it overrunning it puts too much friction on the system and it doesn’t work. Any ideas? I may just concentrate on a water model as I think it would be more constant and stable.

In an attempt to tune out the nasty behavior, I would first simply add weight to the "torpedo". Some combination of weight and different property string should eliminate the feedback, but admittedly the needed weight might sink the project on other grounds.

Water will certainly give more damping, but with careful tuning air would work just fine.

JB

 

[The Dagda]

The problem is that even the notion "relative velocity" is distorted by schroder. Some posts back, when I asked him if he disputed the claim that if a cart was going 2 m/s to the left, and a tread was going 10 m/s to the right, the velocity of the cart wrt the tread was 12 m/s, and for sure he disputed that (see post 755). He claimed that the relative velocity was 8 m/s. (ok, it might have been mph instead of m/s). At that point, I still thought that there might be a misunderstanding about the actual setup - or that he was just trolling.

But it becomes more and more clear that it was not a misunderstanding concerning the setup.

Schroder doesn't understand what it means "relative velocity", or how to obtain it when you have the individual velocities, as he confuses this with mixing frequencies of 2 and 10 (in other words, he gives himself the liberty to alter signs at will in the velocity composition).

I have never met anyone who has such a profound confusion. It is a remarkable phenomenon, and a true challenge to find out how to tackle it, pedagogically. Have you EVER met anybody who disputed such an elementary claim with such vehemence ?
(especially somebody who claims to be an engineer ?)

I've seen this hundreds of times on many forums, he's now locked into the claim by pride, so that even if he did have a glimmer of understanding he's unable to admit he was wrong. When he says things like people consider me a genius, then I can assume he has a high opinion of himself. That doesn't help, the only conclusion is for him to stop posting or to admit he's wrong. Science does not rest on this, only his feelings.

Interestingly I've seen people go on to deny your claims on several threads, even though they are obviously wrong and their arguments have been destroyed. One example is finding WMD's in Iraq, I've seen run long after it was confirmed there were none. It's amazing really.

 

[A.T.]

I am aware that if you know the pressure difference, that's all you need.

That's good then.

 

[rcgldr]

Jeff doesn't ever seem to figure in the low pressure created simply by virtue of the air passing over the front surface of the prop

I've always stated that the prop works the same as any conventional prop. Lower pressure in front, pressure increasing through the prop swept area so higher pressure at the aft edge of the prop "disk".

air which is accelerated, not slowed

Accelerated from the cart's and prop's frame of reference, slowed from the air's (wind) frame of reference. In either frame of reference the net result is some amount of air is accelerated upwind per unit time and this is related to the thrust at the prop. I include the fact that the wind is slowed down by the upwind acceleration from the prop because all wind powered (wind speed different than ground speed) devices extract power by slowing down the wind.

 

[uart]

Wow this has been a pretty amazing thread. Personally I chose not to get involved in this one because I has already grown too tired of trying to convince the doubters in previous threads. I have to admit though that when I saw the first dwfttw video posted here (many long DWFTTW threads ago) that I first thought it was probably a hoax, but only because I thought the fan was operating as a turbine driving the wheels rather than a propeller driven by the wheels. As soon this design aspect was pointed out then it took me about 5 minutes to realize it was easily feasible (physically), and given all the independent verifications, there were just no doubts about the reality of it.

I know the basic maths of this has been posted dozens of times (and probably either ignored or misunderstood by the doubters) but now that this thread has quietened down a bit let's recap why this design is totally feasible and violates no physical laws.

Taking the case of the cart moving at the wind speed "v", show that the wheels can easily provide the power to turn the prop to provide enough trust to both overcome the extra resistance at the wheels (due to the requirement that they drive the prop) and to supply excess thrust to acelerate the cart to faster than "v" (v = wind speed).

Given that the trust of the propeller (rate of change of momentum) is :

F = r u

Where r is the mass per second thrown by the prop and u the velocity (m/s) at which the air is thrown.

And that the power an ideal propeller needs to throw this air (KE per second) is :

P_{\mbox{req}}= \frac{1}{2} r u^2

Then if we use say just half of the available thrust to generate the power required to turn the prop (that is allowing the component of drag at the wheels, due to the requirement that they turn the prop, to be just one half of the available thrust of the prop) then we have power available of :

P_{\mbox{avail}} = \frac{1}{2} F v = \frac{1}{2} r u v

So even with only half the available thrust used for generating power at the wheels we still have :

\frac{P_{avail}}{ P_{req}} = \frac{v}{u}

Clearly this can be made greater than unity when the wind speed “v” is sufficiently large, so more power is available at the wheels than required to turn the prop! Now given that a good http://en.wikipedia.org/wiki/Propeller" is about 80% efficient (P_out over P_in) at moving air then this thing is just a no brainer. I simply cannot believe that anyone with even one year of university level Physics could fail to understand this. It’s just mid boggling to me that some of these silly arguments could have gone on this long in a Physics forum.

 

[rcgldr]

I’ve built an air cart version of the Brennan Torpedo but I’m having a problem with it. The string is being pulled from a spool on the prop shaft and the cart is being held against a backstop until it gets up to thrust speed. It works fine except when the cart leaves the stop it surges slightly which makes the spool overrun and that tangles the string up.

You need something to take up the slack on the string. The simplest method would be mount the string to a pole about 2 or 3 feet tall, and then just under 2 or 3 feet away from the pole on the string, attach a small weight (like ones used for fishing.). Note that this weight setup shouldn't effect the efficiency of the system. Using heavier monofilament fishing line, like 60 lb test fishing line, would be much lighter than string but less likely to tangle.

 

[spork]

I have never met anyone who has such a profound confusion. It is a remarkable phenomenon, and a true challenge to find out how to tackle it, pedagogically. Have you EVER met anybody who disputed such an elementary claim with such vehemence ?

Sure have! humber on the JREF forum, a few physics professors, and an instructor of mechanical engineering at my own alma mater (GA Tech), to name a few.

 

[vanesch]

Sure have! humber on the JREF forum, a few physics professors, and an instructor of mechanical engineering at my own alma mater (GA Tech), to name a few.

I wasn't talking about DDTWFTTW (although it isn't that complicated either), I was talking about the confusion concerning relative motion and non-slipping wheels. I never met anyone who made such claims (that the wheel is spinning when the cart turns in sync with the table, that the wheel will slow down when the cart starts turning "backwards", and that the relative velocity of a thing going 2 m/s to the left wrt another thing going 10 m/s to the right, is not 12 m/s but rather 8 m/s).

What you write about physics professors and mechanical engineering instructors is worrisome, though...
That a business professor or a sailing instructor wouldn't catch on, I can understand. But people who are supposed to teach the tools of which this is an elementary application, that's worrisome.

 

[spork]

I wasn't talking about DDTWFTTW (although it isn't that complicated either), I was talking about the confusion concerning relative motion and non-slipping wheels...

Understood. The folks I listed are stuck on physics principles just that basic. We're up to 80 pages specifically dedicated to humber's extraordinary misunderstanding of the most basic physics principles on the JREF forum. He and the GA Tech instructor share the astonishing quality of being unbelievably wrong (on some VERY basic stuff) while being unbelievably arrogant.

 

[ThinAirDesign]

A couple schroder observations:

A: Clearly the guy has thought the 'sailcart vs. propcart' race over and determined that it's a loser for him. At this point he has got to just be desperately hoping the whole idea will just get dropped. Can't think of any other reason for him to suggest it and then just go silent on the whole idea in spite of repeated requests.

Not going to drop it -- he can get on board and contribute to the setup of the test that he suggested or we'll just aim them DDW and turn them loose. The results aren't going to reflect well on his position no matter what.

B: the funny part about his "heterodyne" obfuscation? -- who cares what the wheels are doing as long as the cart is going DDWFTTW? In swerdna's video, once the cart starts turning CCW, it's going DDWFTTW -- even if schroder is right and the wheels are slowing down (He's not. They're not).

The only possible exception to this would be if the TT itself were slowing down and there were a variable tranmission on the cart -- this would allow momentary use of stored energy to power the cart against the TT. Problem is, the TT isn't slowing down (time the stripe on the TT) and there is no variable transmission between the wheel and the prop.

With a fixed (or increasing) CW TT speed, once the cart turns CCW, schroder can argue anything he wishes regarding the rotation speed of the wheels ... the cart has passed through windspeed and is now beating the wind. If the wheels are slipping and slowing down (they're not), then the cart is dragging a slowing, slipping wheel along for the DDWFTTW ride.

I would still love for schroder, with his "academy" credentials, to make himself available to be the "expert" on a MythBuster's episode -- but by his silence on that suggestion, he's no more interested in being put in that losing position than the sailcart vs propcart race.

JB

 

[swerdna]

Let’s not turn this into a “beat up Schroder” thread. The truth will eventually “beat up” anyone who continues to deny it.

Schroder has said (post #847”) . . .

“I will try to find some more examples of heterodynes in mechanical machinery.”

and - “I will try to make some drawings to explain how translation takes the place of rotation, but I am not good at computer animations so it may be a bit crude.”

Let’s see how hard he tries and what he comes up with. If he expects me to disassemble one cart to remake another, and also go to the time and expense of purchasing and fitting tachometers, then it’s not unreasonable for me to expect him to provide some credible evidence of his claims that are to be tested first.

As far as I can understand them his claims are . .

(1) That the revolutions of wheel of the cart are slowing down as the cart moves against the motion of the TT. He has asked me to fit a tachometer to the wheel to prove this. I don’t know why he keeps saying “the cart is slowing down” when he wants me to measure the revolutions of the wheel. At the very least he should clarify whether he is talking about the revolutions of the wheel or the relative movement of the cart and TT and stop talking about the two things as if they are the same.

(2) That there is a “mechanical heterodyne” effect that is somehow making the cart demonstrate that it’s traveling DDWFTTW when it isn’t. I have no knowledge of any such mechanical heterodyne effect and would like him to provide credible evidence that such a thing even exists. I don’t see how it’s possible for a cart to very clearly demonstrate that it’s traveling DDWFTTW and not atually be doing so.

The ball’s in your court Schroder.

 

[schroder]

Let’s not turn this into a “beat up Schroder” thread. The truth will eventually “beat up” anyone who continues to deny it.

Schroder has said (post #847”) . . .

“I will try to find some more examples of heterodynes in mechanical machinery.”

and - “I will try to make some drawings to explain how translation takes the place of rotation, but I am not good at computer animations so it may be a bit crude.”

Let’s see how hard he tries and what he comes up with. If he expects me to disassemble one cart to remake another, and also go to the time and expense of purchasing and fitting tachometers, then it’s not unreasonable for me to expect him to provide some credible evidence of his claims that are to be tested first.

As far as I can understand them his claims are . .

(1) That the revolutions of wheel of the cart are slowing down as the cart moves against the motion of the TT. He has asked me to fit a tachometer to the wheel to prove this. I don’t know why he keeps saying “the cart is slowing down” when he wants me to measure the revolutions of the wheel. At the very least he should clarify whether he is talking about the revolutions of the wheel or the relative movement of the cart and TT and stop talking about the two things as if they are the same.

(2) That there is a “mechanical heterodyne” effect that is somehow making the cart demonstrate that it’s traveling DDWFTTW when it isn’t. I have no knowledge of any such mechanical heterodyne effect and would like him to provide credible evidence that such a thing even exists. I don’t see how it’s possible for a cart to very clearly demonstrate that it’s traveling DDWFTTW and not atually be doing so.

The ball’s in your court Schroder.

Swerdna, thank you for this post. You are one of the more reasonable people here and I am convinced you are interested in the truth of this matter. It is for that reason that I will continue to reply to you.
I am working on the a better presentation of my analysis of the cart on the Turntable but I cannot devote very much time to this at the moment. I admit that some of my earlier statements were confusing and even wrong. But I am more convinced than ever that the cart is in a heterodyne with the TT. If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT. It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.
It is the revolutions of the cart on the TT that has slowed, not the wheel rpm. Sorry for the confusion on that. What is important to note here is this: The TT is the more massive and directly powered by the motor, so in any heterodyne contest the cart will lose and it will be forced to drop out in a Bessel null. That is exactly what is happening right in front of our eyes in the video. When the cart is on the road, being pushed by the wind, the planet Earth is the more massive (by far!) and the little cart cannot ever force a heterodyne with the earth. Consequently, no heterodyne occurs and the cart just continues along, being pushed by the wind at sub-wind speed with nothing remarkable happening as on the TT.
The TT is clearly a rotating reference frame while the Earth is an inertial frame. Previously, I did not think this was important to the question but I now realize it is all important. What is happening on the TT is due to the heterodyne of two things that are rotating and beating against one another. The wheels of the cart do go faster than the tread. However, as I pointed out, this cannot happen with the earth.
I repeat, what you have, the TT, is far more interesting than chasing the wind. I am now considering building one myself and also looking for any practical applications but going faster than the wind is not one of them!

 

[spork]

I am more convinced than ever that the cart is in a heterodyne with the TT. If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT.

How can this be? The cart gradually accelerates. At what point do you choose to make this relative speed calculation?

It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.

Even if it did just happen to be moving at a speed ratio of 2.4 it would be wildly innaccurate to say "That confirms the heterodyne beyond any reasonable doubt". The first thing you'd have to do to prove the heterodyne is to give us even a hint as to what this physical system has to do with a heterodyne. Are you talking about two physical frequencies combining? Is the cart hopping or vibrating? If so, what does that have to do with anything? If so wouldn't this simply be the mechanism causing it to go DDWFTTW? Afterall, we can SEE that it is going DDWFTTW.

...in any heterodyne contest the cart will lose and it will be forced to drop out in a Bessel null. That is exactly what is happening right in front of our eyes in the video.

It most definitely is not what's happening before our eyes. I am forced to declare a moratorium on the terms heterodyne and bessel null until you're prepared to offer even a vague idea of how they apply to this physical system.

The wheels of the cart do go faster than the tread. However, as I pointed out, this cannot happen with the earth.

And yet despite your considered analysis... it does.

I am now considering building one myself and also looking for any practical applications

I generally recommend not telling a joke you don't get.

 

[vanesch]

I am working on the a better presentation of my analysis of the cart on the Turntable but I cannot devote very much time to this at the moment. I admit that some of my earlier statements were confusing and even wrong. But I am more convinced than ever that the cart is in a heterodyne with the TT. If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT. It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.

Ok, this goes beyond the level of tolerance we can accept here at PF. As you know, the rules here specify that for any unusual claim, you need a peer-reviewed source. I will be more relax, and ask you to show us a "generally accepted" (say, popular textbook, or university website or similar) source where your "heterodyne" thing is put in relationship with a wheel on a table or similar, where a clear definition of the term is given and where examples of its application are shown that make it clear that it is a concept that is "known and useful" in this particular problem. Several times now, posters (including, but not only, me) have indicated that the only known definition of the term heterodyne was in radio receiver technology, and have indicated not to know anything about any relationship with a simple mechanical problem, and its relationship with the zeros of Bessel functions (no, pointing to FM will not be sufficient). This makes your claim (to say the least), "unusual", and hence needs backing up.

This must be in the next post, or sanctions will follow for disinformation and lack of sources.

It is the revolutions of the cart on the TT that has slowed, not the wheel rpm. Sorry for the confusion on that.

Your behaviour concerning that "confusion" was unacceptable. Insulting people trying to point out your "confusion" was not the correct way of handling this. Next time, think before you write.

 

[schroder]

Ok, this goes beyond the level of tolerance we can accept here at PF. As you know, the rules here specify that for any unusual claim, you need a peer-reviewed source. I will be more relax, and ask you to show us a "generally accepted" (say, popular textbook, or university website or similar) source where your "heterodyne" thing is put in relationship with a wheel on a table or similar, where a clear definition of the term is given and where examples of its application are shown that make it clear that it is a concept that is "known and useful" in this particular problem. Several times now, posters (including, but not only, me) have indicated that the only known definition of the term heterodyne was in radio receiver technology, and have indicated not to know anything about any relationship with a simple mechanical problem, and its relationship with the zeros of Bessel functions (no, pointing to FM will not be sufficient). This makes your claim (to say the least), "unusual", and hence needs backing up.

This must be in the next post, or sanctions will follow for disinformation and lack of sources.



Your behaviour concerning that "confusion" was unacceptable. Insulting people trying to point out your "confusion" was not the correct way of handling this. Next time, think before you write.

If anyone should be "sanctioned" for wild unsubstantiated claims, it is YOU, for your wild unsubstantiated claim of directly downwind faster than the wind, which has NO basis in fact and NO peer review.

A heterodyne is most clearly understood when considering radio or audio frequencies but it most definitely is applicable to any mechanical frequencies as well. Simply because YOU do not understand it is no basis for denouncing it. I suggest you study up on it!


YOUR behaviour regarding slinging of insults is the worst I have ever seen on any forum, anywhere and your being a "PF mentor" is unacceptable. You should just slink away in shame!

 

[spork]

A heterodyne is most clearly understood when considering radio or audio frequencies but it most definitely is applicable to any mechanical frequencies as well.

And yet you can't offer a single example of a mechanical heterodyne. hmmmm...

Simply because YOU do not understand it is no basis for denouncing it. I suggest you study up on it!

Ah yes, the ever classic "I don't have to defend my ludicrous claims - you should study up on my ludicrous claims yourself".

 

[A.T.]

 

[vanesch]

 

[vanesch]

If anyone should be "sanctioned" for wild unsubstantiated claims, it is YOU, for your wild unsubstantiated claim of directly downwind faster than the wind, which has NO basis in fact and NO peer review.

I would like to point out that I did not do so. I only pointed out, that, as an elementary exercise in classical mechanics, a sufficiently ideal device modeled according to the descriptions in the videos, is perfectly capable of functioning as the videos show, without claiming that the videos themselves are valid: whether they are true videos or even fake videos, they show a phenomenon which is capable of being explained perfectly well with an elementary mechanical model. The model shows that one has a certain margin for non-idealities and dissipative losses that do not affect the main behaviour. In doing so, I used very standard concepts which are normally known to any first-year mechanics student.

I also pointed out the Galilean equivalence (and its limitation) between the experiments shown in the video (whether these are true videos, or fake ones doesn't matter) and a "true" DWFTTW setup.

None of these "claims" is unusual, but if you need any reference for a particular step, I can provide them easily. Do you need a source for the claim that:
- work is force x distance ?
- power is work per unit of time ?
- kinetic energy of a mass of air is 1/2 m v^2 ?
- momentum of a mass of air is m x v ?

Concerning the kinematics of a non-slipping wheel on a surface, I *did* provide some sources in the end.

I asked you to provide me a source for your extravagant claim that the relative motion between a cart going to the left at 2 m/s and a tread going to the right at 10 m/s is not 12, but rather 8 m/s, based upon an incomprehensible reasoning with a "heterodyne", and especially what the ratio of the rotation rate of the cart versus the rotation rate of the table has necessarily to do with a zero of a Bessel function.
Contrary to generally accepted concepts such as kinetic energy, power, momentum etc.. in a mechanical problem, your claims seem to be totally unfounded. Hence the valid request for a source.

As I said, your NEXT post will have to contain so (or a retraction of all your claims with a "heterodyne").

 

[gabbagabbahey]

But I am more convinced than ever that the cart is in a heterodyne with the TT. If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT. It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.

If your definition of reasonable is indicated by your above statement, kindly provide those with an interest in self-preservation a list of bridges or other structures you may have designed in your engineering career.

All of us "unreasonable" people might like to avoid them.

 

[ThinAirDesign]

But I am more convinced than ever that the cart is in a heterodyne with the TT.

Uhhh... OK.

If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT.

Aaaaand with just a bit of elementary school math (1 / 2.4) we see that this means the cart is exceeding the windspeed by 1.41x. Yes, that's DDWFTTW at a speed 40% greater than windspeed.

It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.

A: Uhhh... OK
B: More importantly (to the OP) it proved DDWFTTW beyond any reasonable doubt.

The TT is clearly a rotating reference frame while the Earth is an inertial frame. Previously, I did not think this was important to the question but I now realize it is all important.

(note to swerdna: remember us saying that the TT's circular nature would confuse some folks? -- we've got our guy. LOL)

What is happening on the TT is due to the heterodyne of two things that are rotating and beating against one another. The wheels of the cart do go faster than the tread. However, as I pointed out, this cannot happen with the earth.

You've gone down a path from which there is no extraction -- the cart goes DDWFTTW no matter the testing apparatus.

• Turntable = independently confirmed DDWFTTW.
• Treadmill = independently confirmed DDWFTTW
• Street = independently confirmed DDWFTTW
• Math = independently confirmed DDWFTTW (theoretically possible)

JB

 

[ThinAirDesign]

When the cart is on the road, being pushed by the wind, the planet Earth is the more massive (by far!) and the little cart cannot ever force a heterodyne with the earth. Consequently, no heterodyne occurs and the cart just continues along, being pushed by the wind at sub-wind speed with nothing remarkable happening as on the TT.

Once again, I would like to encourage you to bring your "Academy" credentials and tryout for the position of "scientific expert" for a MythBusters DDWFTTW episode.

You would be absolutely PERFECT mumbling stuff about your remarkable "mechanical hetrodyne" discovery and how "right in front of our eyes" the cart didn't actually beat the wind -- in spite of the fact that the cart is across the finish line and the balloon is yet to arrive.

JB

 

[rcgldr]

Can we avoid the personal attacks, and terms like galilean and heterodyne? I assume that most people here aren't concerned with the general relativity aspects, or any correlation to heterodyne effects by a DDWFTTW cart.

cart ... will cover one revolution CCW for every 2.4 revolution CW of the TT.

I got 2.33 examining a captured video frame by frame, instead of 2.4 but close enough.

When the cart is on the road, being pushed by the wind, the planet Earth is the more massive and the little cart cannot ever force

The Earth's mass is finite, the cart, wind, and Earth are a closed system, and momentum is consevered (linear and angular). The Earth's momentum is changed just as easily as any component of this closed system, but because of it's huge mass, the change in the Earth's speed (linear and angular) is tiny.

math (1 / 2.4) we see that this means the cart is exceeding the windspeed by 1.41x.

Make that ((1 + 2.4) / 2.4). The cart advances 3.4 revolutions relative to the TT, each time the TT recedes 2.4 revolutions, 1.4167 times wind speed.

|cart_speed_at_cart_radius - tt_speed_at_cart_radius| = 1.4167 |wind_speed_at_cart_radius - tt_speed_at_cart_radius|.

 

[swerdna]

Swerdna, thank you for this post. You are one of the more reasonable people here and I am convinced you are interested in the truth of this matter. It is for that reason that I will continue to reply to you.
I am working on the a better presentation of my analysis of the cart on the Turntable but I cannot devote very much time to this at the moment. I admit that some of my earlier statements were confusing and even wrong. But I am more convinced than ever that the cart is in a heterodyne with the TT. If you examine your video carefully, you will see that after the cart reverses direction, it will cover one revolution CCW for every 2.4 revolution CW of the TT. It just so happens that 2.4 is the modulus for a first Bessel null. That confirms the heterodyne beyond any reasonable doubt.
It is the revolutions of the cart on the TT that has slowed, not the wheel rpm. Sorry for the confusion on that. What is important to note here is this: The TT is the more massive and directly powered by the motor, so in any heterodyne contest the cart will lose and it will be forced to drop out in a Bessel null. That is exactly what is happening right in front of our eyes in the video. When the cart is on the road, being pushed by the wind, the planet Earth is the more massive (by far!) and the little cart cannot ever force a heterodyne with the earth. Consequently, no heterodyne occurs and the cart just continues along, being pushed by the wind at sub-wind speed with nothing remarkable happening as on the TT.
The TT is clearly a rotating reference frame while the Earth is an inertial frame. Previously, I did not think this was important to the question but I now realize it is all important. What is happening on the TT is due to the heterodyne of two things that are rotating and beating against one another. The wheels of the cart do go faster than the tread. However, as I pointed out, this cannot happen with the earth.
I repeat, what you have, the TT, is far more interesting than chasing the wind. I am now considering building one myself and also looking for any practical applications but going faster than the wind is not one of them!

So no need to fit a tachometer to the wheel then (phew!). The cart “slows down” compared to the motion of the TT because it travels in the opposite direction to the TT. In other words to “slow down” it’s actually “speeding up” in the other direction and the speed difference between the TT and cart increases. It continuously and increasingly does this from the moment the TT starts up and the relative speed between the TT and cart increases until the cart reaches terminal speed. Same thing happens to the RPM of the wheel at the same time. I hope you now fully understand and agree that the maximum RPM of the wheel and the maximum speed difference between the TT and cart is when the cart has reached terminal speed (no tachometer required).

Even if some “mechanical heterodyne” does exist and is part of what causes the cart to travel DDWFTTW so what? If a “mechanical heterodyne” is a part of the natural scheme of things then it’s as valid a part of achieving DDWFTTW as using bearings on the wheel is.

 

[ThinAirDesign]

Aaaaand with just a bit of elementary school math (1 / 2.4) we see that this means the cart is exceeding the windspeed by 1.41x.

Make that ((1 + 2.4) / 2.4).

Your way works as well, but doesn't invalidate mine, that's for sure.

Either way the end result is the same -- ~40% greater speed than the wind DDW.

JB

 

[rcgldr]

(1 / 2.4) exceeding the windspeed by 1.41x.

((1 + 2.4) / 2.4).

Either way the end result is the same

Sorry for getting picky. I was just trying to cover any potential comments from the doubters.

 

[cesiumfrog]

I got 2.33 examining a captured video frame by frame, instead of 2.4 but close enough.[...] 1.4167 times wind speed.

Could you elaborate on the uncertainty of your measurement ("close enough" on what grounds?). How many of those five significant figures do you think are completely incorrect?

Sorry for getting picky.

I don't think schroder is disagreeing with your statement that the cart, relative to the turntable, goes DDWFTTW. He just thinks it is occurring by a mechanism unrelated to how a cart on the ground behaves in uniform wind. (And thinks each independent item of evidence is also flawed, in just such a way that they all present the same false-conclusion.)

A heterodyne is most clearly understood when considering radio or audio frequencies but it most definitely is applicable to any mechanical frequencies as well. [..] I suggest you study up on it!

Schroder, could you give a reference for the concepts "heterodyne" and "Bessel null" being applied to a mechanical system, so that I may study up on it?

 

[rcgldr]

rotation of TT versus cart. I got 2.33 examining a captured video frame by frame, instead of 2.4 but close enough. ... 1.4167

Could you elaborate on the uncertainty of your measurement ("close enough" on what grounds?). How many of those five significant figures do you think are completely incorrect?

Three. The video only gives me 1/30 of a second revolution, and I got about 2 1/3 TT revolutions per cart revolution. The cart is accelerating a small amount until the last 2 or so revolutions, so I couldn't pick spots over a longer time period. The 1.4167 was just (3.4 / 2.4), but realistically 1.4 would be a more valid ratio.

So to be valid, I'll restate this as the last 2 revolutions of the cart are about 1 / 2.3 that of the TT, and the last 5 or so average out to be about 1 / 2.4. In either case, the cart speed would be about 1.4 times wind speed.

DDWFTTW. He just thinks it is occurring by a mechanism unrelated to how a cart on the ground behaves in uniform wind.

It seems that if the cart were placed at a latitude very close to the pole of the earth, then the Earth's movement (eastward) relative to the pole would be very close to that of the TT. Add in a wind that moves westward relative to the pole as the same speed that the Earth's surface moves eastward relative to the pole, so that the wind isn't moving with respect to the pole, and the situation is very close to the TT situation.

 

[schroder]

I don't think schroder is disagreeing with your statement that the cart, relative to the turntable, goes DDWFTTW. He just thinks it is occurring by a mechanism unrelated to how a cart on the ground behaves in uniform wind. (And thinks each independent item of evidence is also flawed, in just such a way that they all present the same false-conclusion.)


Schroder, could you give a reference for the concepts "heterodyne" and "Bessel null" being applied to a mechanical system, so that I may study up on it?

It appears you are the first person here to at least try and understand what I am talking about.
If you Google “mechanical resonance in rotating machinery” you will find many interesting sources of information. Unfortunately, most of these sources deal with vibrations, rather than with heterodynes. The difference is that vibrations seldom achieve a true Bessel dropout and a change in operating mode. Vibrations are generally unwanted in rotating machinery and the main courses of study are aimed at ways to reduce them. I have considerable experience with vibration analysis, having worked personally with Ralph Buscarello of Update International in the past. It is because of this experience that I am able to recognize this heterodyne. BTW he has an excellent on-line textbook you may find helpful at this link:
http://www.update-intl.com/VibrationBook.htm
What is intriguing about the cart and turntable is that it may well be the only machine that is actually making use of resonance and in particular a Bessel dropout in order to change its operating mode. This is why there is no information available anywhere on a Bessel null in rotating machinery. What I am being asked to do is essentially write a white paper just to appease this forum! If I am going to go to all that trouble I assure you it will be published somewhere other than here! I can see no point in continuing this discussion as this forum does nothing but heap abuse on anyone who offers up a reasonable explanation that happens to be in conflict with DDWFTTW, which is itself unproven!
As far as “faster than the turntable” is concerned; yes I believe that is happening after the mode change which comes about by the Bessel function. This happens only because of the resonance between the rotating parts on the cart and the rotating TT or treadmill. This cannot and will not happen when the cart is running on the ground. That should be self evident; you do not see the cart first going upwind, entering into resonance and then reversing direction! There is no equivalence between frames when you consider the rotating parts of the system. Yes, the Earth is rotating on its axis and yes theoretically the cart does push on the Earth some calculable but immeasurable amount, but it would be insane to think the cart can cause a mutual resonance with the earth! With this understanding of how the cart behaves on the TT and on the treadmill, it should be self-evident that NO similar behavior is achievable on the ground. This should be the END of all claims for DDWFTTW! On the bright side, this opens up an entirely new field of study in machinery mode changes due to resonance and Bessel dropout! There may very well be practical applications for this, although I have not yet thought of any.

 

[cesiumfrog]

What is intriguing about the cart and turntable is that it may well be the only machine that is actually making use of resonance and in particular a Bessel dropout in order to change its operating mode. This is why there is no information available anywhere on a Bessel null in rotating machinery.

I agree that in principle those concepts may be applicable to mechanical systems.

Schroder, you described the 2.4 value as proof beyond reasonable doubt. Hypothetically, what would it take to disprove your hypothesis? For example, by running the demonstration longer so that the 2.4 value could be measured to much higher precision, would this be a test of the heterodyne model? If we are able to make the turntable cart still go "DDWFTTW" but at a slower rate (by tying on a friction block) as well as at an even faster rate (by optimising the fan blades), so as to disagree with any Bessel null, would that falsify your explanation?

If the outdoor (cart on road in wind) videos turned out not to be hoaxes (and to be independently repeatable under controlled conditions) would that falsify your claim (that DDWFTTW is impossible) or would you say that it proves DDWFTTW actually is possible thanks to heterodyne propulsion?

 

[ThinAirDesign]

I can see no point in continuing this discussion as this forum does nothing but heap abuse on anyone who offers up a reasonable explanation that happens to be in conflict with DDWFTTW, which is itself unproven!

There are two problems with your above *assertions* (bolded):

A: an explanation is only "reasonable" if it fits the actual behaviors -- yours doesn't as described below.
B: DDWFTTW has been proven in all venues, repeatedly and independently.

As far as “faster than the turntable” is concerned; yes I believe that is happening after the mode change which comes about by the Bessel function. This happens only because of the resonance between the rotating parts on the cart and the rotating TT or treadmill.

This assertion, in spite of the fact that no matter the resonance of the various devices and environments, the results are *always the same* -- DDWFTTW. If this "mechanical heterodyne" were so darn special as to be unexplored, it would take more than random interaction to be 100% successful.

This cannot and will not happen when the cart is running on the ground.

Well, of course since the cart *actually does* go DDWFTTW when running on the ground as independently verified by multiple parties, this sort of puts a bit of a damper on your assertions.

That should be self evident; you do not see the cart first going upwind, entering into resonance and then reversing direction!

It is self evident -- you don't see that behavior from the cart on *any* of the venues where it's been tested ... not the turntable, not the treadmill, not the street. Every single test, every single time, every single venue, every single test device -- DDW without "first going upwind, entering into resonance and then reversing direction!" This *alone* blows your theory to smithereens.

Yes, the Earth is rotating on its axis and yes theoretically the cart does push on the Earth some calculable but immeasurable amount, but it would be insane to think the cart can cause a mutual resonance with the earth!

Yes it would insane -- just as it would be insane to think that every single DDWFTTW device, with their various weights and resonances would cause this "mutual resonance" with every single turntable and treadmill given their also various weights and resonances.

With this understanding of how the cart behaves on the TT and on the treadmill, it should be self-evident that NO similar behavior is achievable on the ground.

Yes, of course ... except your "understanding" isn't.

This should be the END of all claims for DDWFTTW!

And it just might be if not for that little niggling, leftover, unexplained (by you) issue of device after device going DDWFTTW upon demand.

I predict you're going to be a very hard man to find once some better documented cases of DDWFTTW on the street pop up -- MythBusters, etc.

JB

 

[swerdna]

If we are able to make the turntable cart still go "DDWFTTW" but at a slower rate (by tying on a friction block) as well as at an even faster rate (by optimising the fan blades), so as to disagree with any Bessel null, would that falsify your explanation?

You mean like this? - http://www.youtube.com/watch?v=VgaXpHOxtQg&feature=related

 

[ThinAirDesign]

You mean like this? - http://www.youtube.com/watch?v=VgaXpHOxtQg&feature=related

A video which shows a DDWFTTW device moving at ~1.03x the wind speed steady state.

JB

 

[ThinAirDesign]

Or this one:

... where the cart goes for ~2 minutes within ~1% of windspeed.

JB

 

[Subductionzon]

You mean like this? - http://www.youtube.com/watch?v=VgaXpHOxtQg&feature=related

A mouse in a block invokes a 3rd degree Besel nut that is resolved at 1.05 further proof that it is an unharmonius reaction to the turntable playing Mozart instead of Black Sabbath.

 

[Subductionzon]

Or this one:

... where the cart goes for ~2 minutes within ~1% of windspeed.

JB

Shame on you JB you know that the cart is hovering (ala humber) to the heterodyned tunes of Surf City Here We Come by the Beach Boys, and Wipeout by I forgot who. Obvious proof of diheterodynamicism.

 

[ThinAirDesign]

Do you think the cart will speed up if we play "Wipeout"?

JB

 

[Subductionzon]

Your best bet is to play either l"Little Deuce Coupe" or "Fun, Fun, Fun".

 

[rcgldr]

Before this thread goes downhill, note that swerdna is planning to make either an air or water based outdoor device, and I'd like to see that posted in this thread.

 

[vanesch]

This is why there is no information available anywhere on a Bessel null in rotating machinery. What I am being asked to do is essentially write a white paper just to appease this forum! If I am going to go to all that trouble I assure you it will be published somewhere other than here!

But you are most welcome to do so! We encourage publication in peer-reviewed literature.
The point is that if there are no sources out there and if it would take you a paper to write up this NEW material, then it is evident that this is not an "obvious and well-known" material, and it might just not stand up to scrutiny.

In fact, we are not talking about any "vibrations", or "resonance modes" or all that - concepts which are well-known to most people having studied some mechanics. Bessel functions do appear in several of these problems. They appear for instance often when a Poisson equation is solved in something with a cylindrical symmetry. They also appear in frequency modulation. Yes, Bessel functions do appear in mechanical problems and in radio-engineering. But it is not because they do appear in some specific problems, that there is an evident (or even hidden) relationship between them and the simple problem of relative motion and a non-slipping wheel.

Because you are trying to wiggle out of the mess you talked yourself in:

- you claimed (post 755):

As seen from the observer on the ground, the cart is going 2 mph to the left, the treadmill is going 10 mph to the right. Do you dispute that the velocity of the cart wrt the treadmill is 12 mph ?
Do you dispute that the air is doing 10 mph wrt the treadmill ?

and you answered:

I DO dispute that "the velocity of the cart wrt the treadmill is 12 mph". I dispute that loud and clear! You are making a linear addition when this is clearly a heterodyne problem. Can you not recognize a heterodyne when you see it? The heterodyne which is the 2 mph is the Difference between the velocity of the tread and the velocity of the cart. The velocity of the cart is 8 mph much less than the tread and much less than the wind. Do you dispute that this is a heterodyne?

This was in reaction to your post 752, which was a similar gem:

I AM saying that the cart with respect to the tread, is going SLOWER than the tread with respect to the air! Is that clear enough for you to understand?

Or even better, your post 760, concerning the condition of a non-slipping wheel:

Here, it is obvious that you do not understand a simple heterodyne problem. The velocity at the point of contact with the wheel is NOT “of course exactly the same as the velocity of the tread”. If it were always exactly the same as the velocity of the tread, the wheel could neither advance or retard. The velocity must change! The tread velocity is constant, so only the velocity of the rim of the wheel changes; the rpm of the wheel changes! For a translation of the axle in the direction opposite to the direction of the tread, the rpm of the wheel must slow down! The rpm slows, the linear velocity at the wheel rim slows, and more tread passes the point under the axle than circumference of wheel does. That results in a translation to the left, in the opposite direction to the tread. This is basic mechanics, Vanesch and you cannot deny it any more!

Followed by what you wrote in post 778 (concerning the trivial relationship between the rotation velocity of a non-slipping wheel on a moving surface).

THESE are the aberrant claims that you should explain, with all the Bessel functions in the world. Not by spouting a few words.

 

[mheslep]

891 posts in three weeks! Marathons posts of 20 hours straight? Has there ever been anything like this on PF? I wonder if there is a way to display the stats.

 

[spork]

It's amazing, but this seems to be the natural cycle of things. It seems pretty common now - many people come to understand and accept DDWFTTW, some quietly go away, and one person remains to be the poster boy for wrongness for 100's or even 1000's of posts.

 

[vanesch]

891 posts in three weeks! Marathons posts of 20 hours straight? Has there ever been anything like this on PF? I wonder if there is a way to display the stats.

We try to keep it going, but I have to admit that there are great actors in the play!

 

[schroder]

I agree that in principle those concepts may be applicable to mechanical systems.

Schroder, you described the 2.4 value as proof beyond reasonable doubt. Hypothetically, what would it take to disprove your hypothesis? For example, by running the demonstration longer so that the 2.4 value could be measured to much higher precision, would this be a test of the heterodyne model? If we are able to make the turntable cart still go "DDWFTTW" but at a slower rate (by tying on a friction block) as well as at an even faster rate (by optimising the fan blades), so as to disagree with any Bessel null, would that falsify your explanation?

If the outdoor (cart on road in wind) videos turned out not to be hoaxes (and to be independently repeatable under controlled conditions) would that falsify your claim (that DDWFTTW is impossible) or would you say that it proves DDWFTTW actually is possible thanks to heterodyne propulsion?

The reason why I find the turntable so interesting is that it would allow for experiments to test the type of things you have mentioned. I don’t think tying on a friction block would detune the resonance but it would flatten out the response resulting in a slower CCW rotation. I am now very seriously considering building my own TT but it will have all the bells and whistles required to do detailed experiments. I will have at least three tachometers, one on the TT, one on the rotating crossarm, and one on the wheel. It will also have at least one accelerometer and a LeCroy oscilloscope to display both rotational speed and resonance as time functions as well as displaying a fast Fourier transform of the resonance signal. I think the blade passage frequency of the propeller must also be monitored. I find this far more interesting than the pedantic claim of DDWFTTW.
I know of NO outdoor test which shows the cart going directly downwind faster than the wind. Obviously, it can go downwind, but so can any wind-blown debris, and in fact, in at least one video, the debris is going faster than the cart!
As much as I appreciate your interest in this, as anyone can see, this thread has degenerated into personal attacks so as to distract from the contradictions to the DDW claim and it really serves no purpose for me to continue here. Maybe I will start a new thread devoted to mechanical resonance but that remains to be seen. Besides the attacks you see here in the thread, I have received particularly virulent attacks via pms, from no less than another “pf mentor”. There is only so much that I am prepared to put up with.

 

[spork]

I don’t think tying on a friction block would detune the resonance but it would flatten out the response resulting in a slower CCW rotation.

I assume you realize everyone knows this is absolute nonsense - right?

I am now very seriously considering building my own TT but it will have all the bells and whistles required to do detailed experiments. I will have at least three tachometers, one on the TT, one on the rotating crossarm, and one on the wheel. It will also have at least one accelerometer and a LeCroy oscilloscope to display both rotational speed and resonance as time functions as well as displaying a fast Fourier transform of the resonance signal. I think the blade passage frequency of the propeller must also be monitored.

You'll do none of that.

I know of NO outdoor test which shows the cart going directly downwind faster than the wind.

So you're saying you know all this really nifty physics stuff and you can't understand this simple toy that goes downwind faster than the wind!?

in at least one video, the debris is going faster than the cart!

Yup. I made that video. I'd be happy to explain it, but I find there are two kinds of people in the world... those that need no explanation, and those for whom no explanation will do.

as anyone can see, this thread has degenerated into personal attacks so as to distract from the contradictions to the DDW claim

There is no "contradiction" to the DDW claim. It's been proven experimentally and analytically.

and it really serves no purpose for me to continue here.

On the contrary. This thread exists expressly for you and because of you. Without you it would simply be a bunch of people that understand the physics behind this thing, and have nothing left to talk or debate about.

Maybe I will start a new thread devoted to mechanical resonance

No you won't.

Besides the attacks you see here in the thread, I have received particularly virulent attacks via pms, from no less than another “pf mentor”.

No you haven't.

There is only so much that I am prepared to put up with.

No there's not.

 

[vanesch]

I am now very seriously considering building my own TT but it will have all the bells and whistles required to do detailed experiments. I will have at least three tachometers, one on the TT, one on the rotating crossarm, and one on the wheel.

Brilliant. I make a strong prediction. If T1 is the tachymeter (giving the number of rotations per second of the table) of the TT, T2 is the tachymeter on the arm (giving the number of rotations per second) and T3 is the tachymeter on the wheel of the cart (giving the number of rotations per second), then, if the radius of the track on which the wheel is running on the table is R, and the radius of the wheel is r, and the wheel doesn't slip, then I predict:

T3 = R/r * (T1 - T2)

The above formula is valid for all motions if T1 and T2 are *signed* tachymeters, that is if they give you a positive number if their object turns CCW, and a negative number if their object turns CW. (or vice versa)

If the tachymeters just give absolute values and no sign indication of the sense of rotation, then we have to use the above formula if both TT and arm turn in the same direction (CW or CCW), and we have to use:

T3 = R/r * (T1 + T2) if the table is going CW and the arm CCW, or vice versa.

The sign of T3 depends on which side the tachymeter is mounted on it and if it is a signed tachymeter.

I make the above prediction without any comprehension of the zeros of Bessel functions in the Superheterodyne Class A Reboosted Overdriven Dolby Surround theory of rotating tables, but just based upon the defining property of non-slipping wheels, that the point of contact has the same velocity on both sides of the contact, and the earlier given formula which you disputed.

Let experiment decide

EDIT:

Just to be more explicit, in post 762, I wrote amongst other things:

Second application:
Now, if the wheel is not on a road, but on a treadmill that GOES TO THE RIGHT with a velocity v_tread (positive number: the velocity vector of a point on the treadmill is (v_tread,0) and this is a vector oriented to the positive X-axis, so to the right), then, if the wheel is making a NON SLIPPING CONTACT, we see that the point at the bottom of the wheel is having the same velocity as the tread (as it isn't slipping there and in contact), so we have equality of the two velocity vectors:

( + w R + vx, vy) = (v_tread,0)

from which:
w R + vx = v_tread and vy = 0

In other words: w = (v_tread - vx) / R.
and no vertical motion.

here w was the angular velocity of the wheel, vx was the velocity of translation of the cart, and v_tread was the velocity of the surface, both velocities in the same direction of course. R was the radius of the wheel, which is now to be called "r".

So, we take this expression to be w = (v_table - v_cart) / r

Now, if we take this direction to be "right to left" on the turntable(*), when the cart is nearby the observer, then we have:

v_table is (2 Pi R T1) (circumference of the track, times the number of times this table turns per second)

v_cart is (2 Pi R T2) (circumference of the track, times the number of times the arm (and hence the cart) turns per second)

w is 2 Pi T3 because 1 turn per second (unit of T3) comes down to 2 Pi radians per second.

So we fill in: 2 Pi T3 = ( (2 Pi R T1) - (2 Pi R T2)) / r

We can bring out 2 Pi R of the numerator of the fraction on the left side:

2 Pi T3 = 2 Pi R (T1 - T2) / r

We can divide by 2 Pi (2 Pi is not zero) on both sides of the equality:

T3 = R (T1 - T2) / r

We can change the order of the factors in a product (commutativity of x in R,+,x) :

T3 = R / r (T1 - T2)Tada Tadaaaa !



(*) Just to be completely clear: I just flipped the positive orientation of the X-axis, which was "left-to-right" in post 762, and which I now take "right-to-left" in this post, to be in agreement with the videos and all the conventions others have used up to now. The formula remains of course just as valid, except that w will now be positive in the CCW direction (we look upon the picture now from the other side).

 

[spork]

Brilliant. I make a strong prediction.
...
Let experiment decide

You are one seriously optimistic dude! First of all, he won't be making any turntables, or running any tests. Secondly, if someone else ran exactly the tests described, and got exactly the results you predict, he could easily explain how you're still wrong, and how you don't see the obvious reason for the observed outcome.

 

[vanesch]

You are one seriously optimistic dude!

That's me

First of all, he won't be making any turntables, or running any tests.

I hope he will. Maybe the motivation to show us wrong will be strong enough. After all, I would be seriously embarrassed, not to say, stand out as an arrogant, ignorant moron if his experiment turns out not to be in my favor ! I'm playing my reputation here. I'm putting my head out. Bait ! Bait !

Actually, the experiment would be in any case useful, as some of us will hopefully finally learn something (a bit the hard way).

Secondly, if someone else ran exactly the tests described, and got exactly the results you predict, he could easily explain how you're still wrong, and how you don't see the obvious reason for the observed outcome.

Mmm. Maybe. You mean, like: http://theflatEarth'society.org/ (?)

(the above link is not to be taken very seriously - for the humour-impaired...)

 

[ThinAirDesign]

I don’t think tying on a friction block would detune the resonance but it would flatten out the response resulting in a slower CCW rotation.

Meaning the device goes DDWFTTW slower than it would were it not dragging the block.

I am now very seriously considering building my own TT but it will have all the bells and whistles required to do detailed experiments.

Excellent -- the results of which are not hard to predict for those of us who understand the basic laws of physics and principle involved. For the record, I'm on board with vanesch's predictions above but I'll add one: Things will also vibrate -- and all the changes in the world to the components to change their resonance will not alter the outputs of the tachometers as long as you keep the wheel as firmly in contact with the ground as we do.

I find this far more interesting than the pedantic claim of DDWFTTW.

Everyone has to focus on the things they can understand ... I get it.

I know of NO outdoor test which shows the cart going directly downwind faster than the wind.

Considering your "heterodyne" position and your absolute inability to accept centuries old principles of physics, I certainly understand your skepticism regarding the documentation quality of the outdoor videos. Unfortunately for you and your blustering statements, these carts DO go DDWFTTW outdoors and eventually the money will be spent to produce said documention. It's very easy to see this happen in person but it's also very difficult to produce a YouTube video that answers even reasonable critics concerns outdoors.

As previously stated, you're going to be a very hard man to find when this documentation is released as the results just leave you standing unshielded from your own ignorance and arrogance.

... and in fact, in at least one video, the debris is going faster than the cart!

LOL ... Yeah, that's what happens in the first few seconds before the cart gets up to wind speed.

Most folks just sort of intuitively understand that a device doesn't accelerate from a total stop to windspeed *instantly*, and during that initial acceleration period the wind is going faster than the device. You on the other hand seem to revel in your inability to grasp such.

There is only so much that I am prepared to put up with.

Yeah Cristoph -- that's why you went over and started your routine on the JREF forum. LOL

JB