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Down wind faster than the wind

Fair enough, I'll give it a try.

Okay, the cart is standing still, and the wind causes
(a) an aerodynamic force forward on the entire cart including the propeller. This force together with the friction between the tire and the ground creates a torque that wants to turn the wheels forward.

(b) an aerodynamic torque on the propeller that wants to turn the wheels backward.

Now the question is: Which torque is bigger?
If the prop is small enough and the wheels are big enough the propeller will lose. Therefore the cart will start rolling forward. As soon as this happens, two things follow:

(a) The cart has a forward velocity, which lessens the relative tailwind and therefore the countering torque on the propeller

(b) The prop starts spinning and therefore creating thrust, adding to the forward aerodynamic forces on the cart, and increasing acceleration.

This situation is true for all speeds below wind velocity, so the cart will reach wind velocity (QED).
At speeds higher than wind velocity there must be an equilibrium between thrust on one hand, and friction and drag forces on the other. Since thrust in non-zero at wind speed (as evidenced by the treadmill experiment), the equilibrium speed will be higher than wind speed.

My €0.02

Well, thank you, but I was thinking of evidence of performance. The only evidence I have seen, is a cart being blown in the wind at some indeterminate velocity. The direction of the propeller is also vague and aliasing makes it impossible to be sure.

I'm sorry, I cannot answer that question. I've only read pages 1-4, and the last two.

Also, I don't understand the question.

My turn to say fair enough.

The treadmill and cart are set running at a belt speed of 10mph.
This is put ina van, and driven downwind to wind speed of 10mph.
The behavior of the cart is then said to agree with those conditions, validating the model, and by inference, the equivalence of the 'treadmill wind' to still air.

What then would indicate a failure, and how would you explain it?
 
Sometimes the deception is deliberate, and sometimes it is the designer fooling himself. One of science's attributes, is that it helps control those errors. An 'honest' video would have at least shown the forces involved; a cheap spring force-gauge would have been sufficient, a simple grid behind the cart could show the relative velocities. Evidence need to be more than "look, it works".

I'll remind you that the current offer is a $100K bet at 10 to 1. That's your $10K against my $100K. Take that offer and we'll make sure the evidence meets your demanding standards. Until then "look, it works".
 
Transformation is exactly what Brian M's cart does: it transforms a force of Fc over a distance x into a force of Fc/2 over a distance of 2x. Nothing unusual there.

A transformer cannot give power gain! Only change the ratio of V to F.
You are confusing the apparent acceleration of the vehicle, with power gain.

What do you mean by that? Of course all the power is coming from one source. Indeed, most machines only have one source of energy. That doesn't stop them working.
Can you point out this error and explain it? I don't see it in Brian's calculations.

That is not what I meant. You do have the same, single power source but for the cart to do what you expect, you would need twice as much, or another source to make up the difference.

This is your reasoning, I think.
Follow the force through from the circumference of the top wheel. The ratio between the wheel and gear is 2, so the force is doubled. The bottom wheel has a ratio of 4:1 dividing it by 4, so in total, it is halved. Fc = F/2, but Vc = 2V, so it goes twice as fast for the same input. Yes?

The relative velocity of the vehicles is first derived. The force "gain" is derived. The 'mistake' is to equate the two so directly.

Apply 10N, to a 1kg cart for 1s. Note the final velocity of the vehicle. However, in reality, there are retarding forces. Without this consideration, you have simply provided another example of a vehicle that can be accelerated to any velocity, if you apply a force for long enough!.

Sorry, I failed to point that out earlier F= Fc, when V = Vc. No difference in force, or velocity because of the gears. I did include a drawing in my reply to Brain-M, where parachutes provide the force.

There are the retarding forces of friction and drag. The final velocity is reached when there is no more force available to accelerate the vehicle any further. The incremental acceleration is zero.
What is being done here is to modify the way that the vehicle gets to that terminal velocity. There is only enough power to drive it to the same velocity as an equivalent vehicle without gears. You can trade distance or velocity for force, but power keeps the accounts.

In the case of a very long board (or track) where the board velocity is to V, but force is not limited, you are indeed trading distance to V. If the board is very long, the cart need not reach the puller, but stop when there has been sufficient time for it to reach V.

"What! It would still be going at 2V!" Sorry, but no.

The speed 'gain' becomes divided, as those -Vs and +Vs shift there reference to be symmetrical around V, resulting in V.
Alarm bells should ring!. The speed gain is the differential radial velocity of the two gears. What you are considering are only the initial conditions, where you can arbitrarily ascribe V to be the reference velocity to which you add the gain.

<snip>
The principles of physics, tested and verified over centuries, show that Spork's cart, Brian M's cart and all the other engines presented here can work. Once more: if you really don't think Brian's cart can work, why not make one yourself and test your theory?

A general comment, Michael_C. It does not apply to all followers.
I don't need to test it, nor should you, unless you can find very good reason to doubt those very centuries tell you that it will not work.

If you do believe in the rules of physics, it is not within those rules to manipulate the ratios of V to F, while ignoring the work that must be done.

" It is human nature to be optimistic about systems that beg us to be pessimistic".
Henry Petroski, on the cause of NASA's shuttle disasters.

Perhaps more like that, than deception.
 
If you do believe in the rules of physics, it is not within those rules to manipulate the ratios of V to F, while ignoring the work that must be done.

" It is human nature to be optimistic about systems that beg us to be pessimistic".
Henry Petroski, on the cause of NASA's shuttle disasters.


I'll remind you that the current offer is a $100K bet at 10 to 1. That's your $10K against my $100K. Take that offer and we'll make sure the evidence meets your demanding standards. Until then we can just assume I'm optimistic.
 
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I'll remind you that the current offer is a $100K bet at 10 to 1. That's your $10K against my $100K. Take that offer and we'll make sure the evidence meets your demanding standards. Until then "look, it works".

But that is not a refutation of my claim that you don't have evidence of verifiable wind performance, but evidence that you don't.

Humber would kindly like to remind Spork, that he took a public bet, where the demands were clearly outlined, and gave you a second option for payment. The actual transaction being inter alia

I think that he could argue, that he need only prove that your claim is impossible within the known laws, to invoke a forfeit.
No threat here, he has no intention of carrying it out. Rather a lot of trouble.

You were once claiming that you were not being given the chance to demonstrate, but now you want money.

No comment on the physics, either.
 
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Humber would kindly like to remind Spork, that he took a public bet, where the demands were clearly outlined, and gave you a second option for payment.

What on earth are you talking about? I've offered the bet many times. But no one has accepted as far as I know.
 
Micheal_C,
As I have said, the velocity will be limited by the drag, but in the board case, it perhaps not so clear what I meant by the differential speed.

Put a dot on the big and small gears at 12 o'clock. If you move the cart forward, they will trace 2 sine waves, with a peak to peak value that is equal to the diameter of each gear which, are 2 and 1 respectively.

Please see the attached image.
The white trace is the big gear, and the red, the small gear. But it is going in the opposite direction, so it goes negative or "backwards" at this point.
But note that over one full turn of the white wheel (1s/360deg), the average value of the red trace is zero.
So, the average difference between to two wheels with the gears will be the white trace, which is that of the board. Does that help?

Spork,
Earlier on, with me.
 

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Yes, he does. Bets are 'good faith'.

It was accepted.
Like I said, it is what I could do.

Sine waves too much for you?

humber if you think you accepted a bet with me please give me the post where that happened. I want to get on with failing to collect from you.
 
humber if you think you accepted a bet with me please give me the post where that happened. I want to get on with failing to collect from you.

Dunno. Either case would result in the mentioned failure.
 
I see that humber has progressed from incomprehensible and wrong to totally incoherent.

How incredibly hypocritical - to repeatedly demand that more evidence be added to the mountain already there, refuse to put your money where your mouth is, and then to blatantly lie about posts and refuse to even say where they are (since that would expose the lie even more plainly).
 
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Dunno. Either case would result in the mentioned failure.

Speak for yourself. If someone actually takes this bet up with me, we'll be putting the money in an escrow account and neither side will be able to back out once in place.


There's a guy at our local Arby's that always sits there alone and seems to be having half of an incoherrent discussion about physics. I wonder if humber is in an Arby's somewhere across the country having the other half of that conversation.
 
I see that humber has progressed from incomprehensible and wrong to totally incoherent.

How incredibly hypocritical - to repeatedly demand that more evidence be added to the mountain already there, refuse to put your money where your mouth is, and then to blatantly lie about posts and refuse to even say where they are (since that would expose the lie even more plainly).

You can put a flag on top of the mountain by answering the question about the failure of the treadmill in a van.

That last bit suggests you shouldn't trust me on such matters, well done.
 

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