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Down wind faster than the wind

mender said:
His response (#2323) to my post (#2310) seems to indicate that generally I have his theory correct. He couldn't just agree however, and tried to nitpick a few items. I felt that his rebuttal lacked his usual conviction and was being presented more out of habit than actual disagreement.

I was going to mention the offset as well but felt that the wheels would slip well before the cart flipped!
Click to expand...

Oh, these must be the posts where you explained my ideas to Spork?
The nitpicking are you put it, are quite significant differences between what I said, and what you said, I said.
If you do understand then you will appreciate the value of this test.

Put a weight over the cart's drive wheel, so that is in good contact with the belt, to see the cart go backwards down that belt.
 
humber said:
Put a weight over the cart's drive wheel, so that it is in good contact with the belt, so that we can all see it go backwards down the belt.
There you go, for the nth time.
Got that? Do that one.
Click to expand...

Oh, this is just excellent. Something concrete that can be tested.

Humber, the device weights 5.7oz total. ~50/50 split front to rear. With currently just over 2.5oz on the front axle how much weight would you like us to add over the front axle to make it go backwards on a level belt rather than forwards?

Thanks

Also, if you will confirm your position that I refer to in post #2333, we will be able to perform a second test for you.

Two tests, one video. All we need is A: specific weight to add from above, and B: a confirmation from #2333.

JB
 
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Obviously there is some mass in the drive wheels and gears attached there. For completeness, just specify the mass you consider sufficient to make the cart go backwards on the treadmill. Perhaps also just confirm that you mean it will go backwards with that added mass, when it has been making progress forwards without the added mass. I hope you'll see my reasoning. If spork puts a couple of ounces on and you say it's not enough...where will we stop? I think spork would agree that if you get seriously silly masses sitting on the drive wheel(s), there will be enough friction, and even frame warping problems, to have the kind of effect you predict. Let us be clear, you mean enough mass to overthrow the possibility that it is staying centred or moving forward due to slipping of the wheels/tread surface. I think you need to agree what kind of range you're happy with. It's a light little thing and if you bend the axel it's going to have a lot more losses.

While we're on about it, I guess it might be useful to clarify something else, spork - does your cart have a drive wheel, or drive wheels? I imagine they are coupled together on a single axel, with a central gear to the propshaft.

For fun, I'll also make a prediction - up to the kinds of masses such a small light machine can handle, it will progress pretty much as before. It should accelerate slower, but still accelerate forward.

System Q? Nope, no idea.
 
John Freestone said:
While we're on about it, I guess it might be useful to clarify something else, spork - does your cart have a drive wheel, or drive wheels? I imagine they are coupled together on a single axel, with a central gear to the propshaft.
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Hello John,

according to the published build plans, it is a single axle with a central gear. Otherwise one side would have more friction losses than the other, i.e. needs more energy input than the other wheel, making the cart go round in circles because of that.

Greetings,

Chris

Edit: Unless a single driving wheel would be placed dead center of the cart's axle, of course. But that in turn would conflict with having a gear at that center.

Edit2: And i make the very same prediction as you.
 
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humber said:
Put a weight over the cart's drive wheel, so that it is in good contact with the belt, so that we can all see it go backwards down the belt.
There you go, for the nth time.
Got that? Do that one.
Click to expand...

If the camera is fast enough, some marking dots on the belt and wheels would verify that the wheels are not slipping without changing the performance of the cart. 3mph = 52 in/s = 1.7 in/frame at 30 fps, so it should be doable.
 
humber said:
Put a weight over the cart's drive wheel, so that is in good contact with the belt, to see the cart go backwards down that belt.
Click to expand...

You don't even need to bother making a video fo that one. The combined weight of the wheels on this cart (youtube video MfZt19F-OA4) are nearly 3/4 of a pound all of which is directly over the point of contact. Furthermore, their urathane composition gives them ULTRA HIGH traction against the moving belt.

Enough traction to split the carbon drive shaft and shove carbon fiber splinters into your fingertips if you manage to snag the propeller in your shirt sleve as you are playing with it on the teadmill. Ask me how I know.

Mark C.
 
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humber said:
Have you tested the cart with a weight over the wheels so that we can all see it go backwards down the belt?
Why haven't you done that?
Click to expand...

Tell me what to do and what to expect and you'll see a video tomorrow.

Can't be lack of time, because you had lots for Greg London's device.
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Definitely not a lack of time. When it comes to making a fool of you I've got all the time in the world (although it seems you've got me covered in case I don't get around to it).

The reason we did Greg London's cart is that he described what his cart was and what he expected it to do. Tell us your test and what you expect.
 
Christian Klippel said:
Hello John,

according to the published build plans, it is a single axle with a central gear. Otherwise one side would have more friction losses than the other, i.e. needs more energy input than the other wheel, making the cart go round in circles because of that.

Greetings,

Chris

Edit: Unless a single driving wheel would be placed dead center of the cart's axle, of course. But that in turn would conflict with having a gear at that center.

Edit2: And i make the very same prediction as you.
Click to expand...

ThinAirDesigns said:
Straight axle, no differential.

JB
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Thanks guys. I haven't come across the build plans yet, but that's ok. I just wanted to confirm after humber said to put a weight over the drive wheel (just a typo probably).

I see you beat me to it, JB, about the value of mass to add.
 
spork said:
Tell me what to do and what to expect and you'll see a video tomorrow.




Definitely not a lack of time. When it comes to making a fool of you I've got all the time in the world (although it seems you've got me covered in case I don't get around to it).

The reason we did Greg London's cart is that he described what his cart was and what he expected it to do. Tell us your test and what you expect.
Click to expand...
Then those values are too low.
The test is to add sufficient weight to the cart so that the drive wheel is in good contact with the belt. If you do not know how much that is, then you must either measure it or calculate it. It is your cart, not mine.
If you feel that you cannot perform that demonstration without my assistance, that will only serve to confirm that you do not know how your cart works, and that you are unwilling to take the risk of having that exposed.
The other is not relevant because the above test will invalidate the concept, so that detail is unimportant.
 
humber said:
Well. I don't see that it is so important. Another video made by an incompetent engineer, is unlikely to persuade me. A preponderance of mistakes only make things worse, really.
The flywheel on wheels is Goodman's cart. If you want to confuse it with something else because the difference is to subtle for you, then continue to bray. If you understood what I meant by system Q, then you would able make the distinction, but you don't.
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I'm sorry if you said what you meant by system Q, but I missed it. I'm willing to learn. I assume you mean the Q of a system, but what the Q is, I don't know.

I tried to find out about it myself, but it's not an easy thing to google, especially as 'Q' gets caught by all sorts of Questions about anything and everything. I tried 'mechanical measures q', 'physics quantity q' and suchlike, but I can't see the sort of thing you might be refering to.

I got some hits about geology, a few on quantum mechanics. Q is the quality factor of resonators in laser physics. 'Q-measurement theory' is something about the problem of representing real values, which are transcendental numbers, or continuous variables, on digital instruments (I think).

I found a synopsis, "Entropy measures going beyond Boltsmann-Shannon entropy are important in physics. This paper demonstrates the q- and k-entropies fit into a general theory based on measures of complexity. This depends on game theoretical considerations." but I'd have to log in to find out more (I flatter myself).

Q, also spelled kyu, is apparently equal to about 0.71 typographical points, or exactly 0.25 mm., which is nice. Q is also a unit of heat energy equal to one quintillion (1018) Btu, 1000 quads, or about 1.055 zettajoules (ZJ). Warmish, unlike my search.

I give up. Would you tell me what Q is, please, or refer me to an earlier post or other web page?
 
Humber:
The test is to add sufficient weight to the cart so that the drive wheel is in good contact with the belt.
Click to expand...

That test has already been completed and posted. The cart drives forward on the belt, not backward as you predict.

If you feel that you cannot perform that demonstration without my assistance, that will only serve to confirm that you do not know how your cart works, and that you are unwilling to take the risk of having that exposed.
Click to expand...

As stated above, been there -- done that test.

So, the results of our test show your theory to be incorrrect.

If you would like us to modify our test to suit any special requirements you might have, feel free to define the amount of weight that would the prove you right and us wrong.

JB
 
Me:
Are you saying that it advances *faster* on an incline?
Click to expand...

Humber:

Yes.
Click to expand...

I wish to confirm that I am not misrepresenting your position above.

It appears that you hold the position that for a given speed, the cart advances faster when the treadmill is placed in an inclined position.

Correct?

JB
 
Modified said:
If the camera is fast enough, some marking dots on the belt and wheels would verify that the wheels are not slipping without changing the performance of the cart. 3mph = 52 in/s = 1.7 in/frame at 30 fps, so it should be doable.
Click to expand...

It is not a question of the wheels slipping, Modified. That will occur if the propeller load is greater than the friction to the belt can sustain. I say that the cart acts to minimise the torques in the opposing shafts. This means that the friction need only support a small force, so slipping wheels is not the problem.
If the contact to the belt is firm, then the friction should rise, but the propeller's opposing "thrust" will not rise proportionally, so the cart will go back down the belt. The cart can only remain in place if the net forces are low.
As I have said earlier, failure to do this does not actually harm my general argument, because the cart is placed there by hand and has zero KE. To actually comply with claimed equivalence, the cart would need to accelerate from traveling back with the belt, to at least reach the point where there was no motion relative to that belt. In this case, the KE falls, as the cart decelerates to the point. The cart would then need to show that it can gain KE to reach that of the real cart at windspeed. Not easy standing still..
To claim validity, the treadmill must address those matters too, but my expectation is that the above test will fail.
 
ThinAirDesigns said:
Humber:


That test has already been completed and posted. The cart drives forward on the belt, not backward as you predict.



As stated above, been there -- done that test.

So, the results of our test show your theory to be incorrrect.

If you would like us to modify our test to suit any special requirements you might have, feel free to define the amount of weight that would the prove you right and us wrong.

JB
Click to expand...

Nope. While the cart shows that it can be pushed around readily on the belt, it does not have sufficient friction to that belt. Tell me when you have can demonstrate that, and I will take a look at whatever it is that you think you have succeded in doing.
Also, if you read any of what is written, I have said that this test does not confirm your claim. If it passes this one, there are others.
I do not have the cart at my disposal, and only your poor demonstrations as evidence, so too bad if that means you must do some more work as a result.
Also, I can show the following;
(1) I can tell your treadmill frame of reference/porch, and that even if the porch is a frame of reference, the treadmill is not.
(2) I can tell real wind from treadmill wind.
(3) The wind is a direct function of friction to the belt, but not of the road.
(4) The cart is only travelling at the speed observed by the treadmill side observer.
(5) Your claim that my treadmill test (the one with the motorised treadmill in wind) is invalid id wrong, and if conducted, exposes a mathematical error in you reasoning
(6)...there are more.
 
ThinAirDesigns said:
Me:


Humber:



I wish to confirm that I am not misrepresenting your position above.

It appears that you hold the position that for a given speed, the cart advances faster when the treadmill is placed in an inclined position.

Correct?

JB
Click to expand...

Not a relevant test. Given that climbing the belt only demonstrates the cart's capacity to work against a random gravitational load, you would then have to show how that can be related to the cart's performance at windspeed. Go ahead, but I will then show that whatever happens, faster or slower, is a result of the failed performance of the system.
 
Wow, just wow. Talk about incoherent statements.

humber said:
Put a weight over the cart's drive wheel, so that is in good contact with the belt, to see the cart go backwards down that belt.
Click to expand...

humber said:
It is not a question of the wheels slipping....
Click to expand...

humber said:
...it does not have sufficient friction to that belt.
Click to expand...

From three posts in chronological order, all to be found on this single page (page 62).

Is it just me, or does this dude contradict himself each time he says something?

This is just so ridiculous, it aint no fun anymore.
 
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