Merged DDWFTTW in a “Real” Wind

[Jack by the hedge]

I am saying that the entire claim is BS.

Yeah, though you seem to be having a little trouble bringing the world with you in that conviction.

The reason the BB does not go upwind from rest, is that the prop is geared up. The large sprocket is on the prop, and the small one on the axle. If is that even made 1:1, cart goes backwards. Done it. 20mm diameter pulley on the prop, and 30 on the axle. Always goes towards the fan.

Uh, huh. So, if they'd designed it wrongly, it would have moved off in the opposite direction. But they didn't and it didn't.

It is blown downwind as a tacking sail cart. The headwind does not drive the cart via the prop in any way.

It's driven downwind by the wind acting on its prop. You have never offered anything beyond handwaving to suggest any way the cart itself might be gaining thrust from tacking. You are, however, correct that the headwind does not drive the cart in any way. As has been patiently explained to you, over and over, for several years.

Nothing to do with it. Confabulated nonsense.

The propeller advances through the air as it turns. Unlike the fixed bodywork of the cart therefore, it has to travel forwards faster than the wind before it experiences positive pressure from an apparent headwind. How much faster depends on the speed and pitch. Is that any clearer?

 

[humber]

Yeah, though you seem to be having a little trouble bringing the world with you in that conviction.

They videos not my evidence. We will see what transpires.

Uh, huh. So, if they'd designed it wrongly, it would have moved off in the opposite direction. But they didn't and it didn't.

The sprocket set allows the ratio to be selected. Perhaps the range is not wide enough to allow for the ratio that sends it backwards. I said that a cluster would be fitted.
If the ratio is selected so the cart goes towards the fan, that can be remedied by adding cardboard as a sail. Eventually, that sail force wins, and the cart creeps forwards. The BB does exactly that, until the wind changes and it can tack.

It's driven downwind by the wind acting on its prop.

As a sail. That is why it goes backwards when turned the other way.

You have never offered anything beyond handwaving to suggest any way the cart itself might be gaining thrust from tacking.

The wind measurements are a joke. Even the (average) 4 degrees during the record period becomes 11.03 RMS. The deviation prior to that is up to 17.5 degree average. You can expect that to increase when RMS.

You are, however, correct that the headwind does not drive the cart in any way.
As has been patiently explained to you, over and over, for several years.The propeller advances through the air as it turns.

That is to say the wheel drives the prop. The cart advances itself through the air, because is does? If the wind does not drive the prop, you have no energy source.

Unlike the fixed bodywork of the cart therefore, it has to travel forwards faster than the wind before it experiences positive pressure from an apparent headwind. How much faster depends on the speed and pitch. Is that any clearer?

The prop must travel faster than the chassis, to create less drag?
Not to good. But there is still nothing to power the cart. Wheels do not spontaneously generate power.
The claim is nonsense. There is abundant evidence that the conditions are there during the trial for a sail cart. The street video shows how the game is played. Try, wait, try again. Eventually there will be a favorable wind pattern.

 

[ThinAirDesigns]

Okay, looking at that video agin, I think the rotation is slow enough that the video is representing the rotation correctly. What it appears is happening, is that the wheels slip a bit, and the prop is turned by the wind, then the wheels catch and it starts spinning it the other way. Nothing too surprising.

That is the correct description. Soon after release, a gust hit it from the rear and the desire of the rotor to turbine overcame the frictional abilities of the wheels to keep that from happening. As the cart blew downwind, the relative speed between cart and air soon decreased to the point that the battle swung the other way and the wheels again hooked up.
JB

 

[humber]

Okay, looking at that video agin, I think the rotation is slow enough that the video is representing the rotation correctly. What it appears is happening, is that the wheels slip a bit, and the prop is turned by the wind, then the wheels catch and it starts spinning it the other way. Nothing too surprising.

That is the correct description. Soon after release, a gust hit it from the rear and the desire of the rotor to turbine overcame the frictional abilities of the wheels to keep that from happening.

(1) So they spin backwards as the cart moves forwards. No question.

As the cart blew downwind, the relative speed between cart and air soon decreased to the point that the battle swung the other way and the wheels again hooked up.

The turbine force is opposed by the drag of the sliding wheel. They become equal and the cart slides with the rotor and wheel locked.
It may gain traction if the wind is not directly from the rear, or the lift force changes, or the surface changes. It then travels with the prop CW, and then back to CCW, as the cart's wheels leave the ground, and it's driven as a sail.
The example of (1) shows that actually happening.

There is no reason to think the cart is fttw, nor ddw, if for no other reason than it obviously changes course during the run and there are no measurements whatsoever.

 

[ThinAirDesigns]

There is no reason to think the cart is fttw, nor ddw, if for no other reason than it obviously changes course during the run and there are no measurements whatsoever.

For once you are 100% correct. As you well know (because it's been pointed out to you a couple hundred times), that video was not filmed to be nor every claimed to be a demo of DDWFTTW. It is merely a demonstration that the device can self start in natural wind.

JB

 

[Jack by the hedge]

The wind measurements are a joke. Even the (average) 4 degrees during the record period becomes 11.03 RMS. The deviation prior to that is up to 17.5 degree average. You can expect that to increase when RMS.

That's still evading any attempt to explain how you believe the structure of the BB gains forward thrust by tacking. But I have previously remarked that I don't expect you ever to present such an explanation.

That is to say the wheel drives the prop. The cart advances itself through the air, because is does? If the wind does not drive the prop, you have no energy source.

The wheel turns the prop. The wind pushes on the prop. How many times do you need to read this before you can remember it from one post to the next?

The prop must travel faster than the chassis, to create less drag?
Not to good.

No, not too good. Please try to keep up. We have been over this ground countless times. As the propeller blade turns, its point of contact with the air at any point is moving across the face of the blade. Due to the pitch of the propeller, that point is constantly retreating relative to the body of the cart. The effective speed of those points of contact over the ground is therefore less than the cart, and is less than windspeed. So the wind still pushes on the back of the propeller, even though the cart is moving faster than the wind. As the groundspeed of the points of contact approaches windspeed, the acceleration diminishes toward zero.

The claim is nonsense. There is abundant evidence that the conditions are there during the trial for a sail cart.

Irrelevant, as you've failed to show that BB is a sail cart.

 

[Llyricist]

T
The wind measurements are a joke. Even the (average) 4 degrees during the record period becomes 11.03 RMS.

Only if you make the mistake of taking the RMS of wind direction, instead of the RMS of Deviation from DDW, which is, as anyone can check, 8.8 degrees. And you have never justified the use of RMS in a situation that is so strongly biased to one side. That has clear evidence of vane waggle which is providing the only peaks to the other side, which makes the RMS measure the magnitude of measurement error, rather than wind direction. Why you need RMS and not the arithmetic mean of the absolute values, which is 5.38, and is still measuring the measurement error, rather than wind direction.

The deviation prior to that is up to 17.5 degree average. You can expect that to increase when RMS.

No, the arithmetic mean of absolute values of deviation from when JB stopped pushing to the end of the test period was 9.8 degrees, and the RMS was 11.5 degrees.

 

[mender]

You have not posted a reply to this:
If a simple cart is held by hand on the belt, the force of the rolling resistance is the drag. However, if held at an angle to the belt, such that the wheels are no longer in line with the belt, then the friction becomes more and more the higher static value, and the cart may be eventually taken from the hand.
The obvious extreme being 90 degrees to the belt.
The cart shows no such dependency on the angle, because it is not rolling, but sliding, so the coefficient of friction remains largely independent of angle. So how do you account for that?

Account for your delusions? Or account for your willful ignorance of the actual test results?

Pretty simple either way, really; you are impervious to reason, fact and physical evidence. You've been told so many times in so many ways that the cart does not slide around, yet you persist in saying that it does.

The cart, if not aligned properly when released, will make a prompt exit off the side of the treadmill belt.

Would a video of that happening do anything to convince you of that fact? Or would you brush that off the same as everything else that proves you wrong?

We all know the answer to that one, no need to reply.

 

[humber]

For once you are 100% correct. As you well know (because it's been pointed out to you a couple hundred times), that video was not filmed to be nor every claimed to be a demo of DDWFTTW. It is merely a demonstration that the device can self start in natural wind.

JB

Really? That was not made at all clear at the time, but if so, that means you have never produced a video showing the model cart can travel ddw.
Noted.

As for the self-start you quite obviously had to try quite a few times. It did, self-start, but you stopped it. If showing only that were the aim, what was wrong with that take?

The video may be intended to show what you claim, but perhaps showed more than you intended. The remainder of the video stands as evidence.

 

[ThinAirDesigns]

Really? That was not made at all clear at the time,

Another lie of course.

but if so, that means you have never produced a video showing the model cart can travel ddw. Noted.

And another.

As for the self-start you quite obviously had to try quite a few times.

If by "quite a few times" you mean "it self-started on the very first try", then yes - quite a few times.

JB

 

[humber]

Account for your delusions? Or account for your willful ignorance of the actual test results?

Pretty simple either way, really; you are impervious to reason, fact and physical evidence. You've been told so many times in so many ways that the cart does not slide around, yet you persist in saying that it does.

The cart, if not aligned properly when released, will make a prompt exit off the side of the treadmill belt.

Would a video of that happening do anything to convince you of that fact? Or would you brush that off the same as everything else that proves you wrong?

We all know the answer to that one, no need to reply.

You have never produced a video. But go ahead. It will tell more than you know.
There are countless videos showing the cart to be at all sorts of angle to the
belt. The Harold Bricer test for example. The "fork" test. Video 5, where it moves in elliptical patterns.

You told me that yours drifted to the side of the belt. Not easy to see how a real cart can do that. The cart is quite clearly unstable. It always moves about. As JB says, "no steering", so the probability that it would remain exactly in line with the belt is low. That is, on average, it will spend more time away from alignment, than not. If you were correct, the cart would go down the belt, unless you can tell me how it gains more power away from alignment, than not.

 

[humber]

Another lie of course.



And another.



If by "quite a few times" you mean "it self-started on the very first try", then yes - quite a few times.

JB

How odd that you chose one that DIDN'T.

1) You made the indoor self-start video after the street video. Why was that necessary?
2) The video has often been put forward as proof of ddw.
3) The only other video is the turbine race, where the carts needed restraint, to stop the Beaufort 5 wind, from blowing then away.

 

[I Ratant]

On the wire-frame cart/video, there's a way to clear up what is going on.
First, marks on the treadmill belt to indicate which direction it is going, when it's going. Wouldn't hurt to mark the wheel rims so rotation can be seen.
Second, place the cart without the prop and the shaft to the wheels disconnected. Turn on the fan..... turn on the treadmill.
Third, place the cart with the prop, with the prop fixed, disconnected from wheels still.
Turn on the fan..... turn on the treadmill.
Fourth, free up the prop so it can rotate, but still disconnected from the wheel.
Turn on the fan..... turn on the treadmill.
Fifth. Connect the prop shaft to the wheel axle. Fix the prop so it doesn't rotate. Turn on the fan.... turn on the treadmill.
Sixth. free up the prop so it can rotate, and the wheels can rotate it.
Turn on the fan..... turn on the treadmill.
Take copious notes.

 

[ThinAirDesigns]

1) You made the indoor self-start video after the street video. Why was that necessary?

It wasn't. None of this has been necessary.

2) The video has often been put forward as proof of ddw.

Not by us.

The only other video is the turbine race, ...

Another lie.

JB

 

[mender]

You told me that yours steered itself to the side of the belt. Not easy to see how a real cart can do that.

Sure it is; fixed that for you.

 

[humber]

On the wire-frame cart/video, there's a way to clear up what is going on.
First, marks on the treadmill belt to indicate which direction it is going, when it's going. Wouldn't hurt to mark the wheel rims so rotation can be seen.
Second, place the cart without the prop and the shaft to the wheels disconnected. Turn on the fan..... turn on the treadmill.
Third, place the cart with the prop, with the prop fixed, disconnected from wheels still.
Turn on the fan..... turn on the treadmill.
Fourth, free up the prop so it can rotate, but still disconnected from the wheel.
Turn on the fan..... turn on the treadmill.
Fifth. Connect the prop shaft to the wheel axle. Fix the prop so it doesn't rotate. Turn on the fan.... turn on the treadmill.
Sixth. free up the prop so it can rotate, and the wheels can rotate it.
Turn on the fan..... turn on the treadmill.
Take copious notes.

Could do, but if the gearing is lowered: that is, the sprocket at the prop is smaller than at the wheel, it will go backwards. If the were not possible, then upwind turbines would not exist. Changing the ratio will eventually result in a stalled cart, more still, and it moves forwards..and so on. Cut to the chase, and remove the gears altogether.

 

[mender]

On the wire-frame cart/video, there's a way to clear up what is going on.
First, marks on the treadmill belt to indicate which direction it is going, when it's going. Wouldn't hurt to mark the wheel rims so rotation can be seen.
Second, place the cart without the prop and the shaft to the wheels disconnected. Turn on the fan..... turn on the treadmill.
Third, place the cart with the prop, with the prop fixed, disconnected from wheels still.
Turn on the fan..... turn on the treadmill.
Fourth, free up the prop so it can rotate, but still disconnected from the wheel.
Turn on the fan..... turn on the treadmill.
Fifth. Connect the prop shaft to the wheel axle. Fix the prop so it doesn't rotate. Turn on the fan.... turn on the treadmill.
Sixth. free up the prop so it can rotate, and the wheels can rotate it.
Turn on the fan..... turn on the treadmill.
Take copious notes.

Been there, done most of that, can tell you the outcome of each step.
1) Easy to see in person but not a bad idea for a video.
2) Cart falls off the back.
3) With my fan, the bluff force acting on the cart is 10 grams and diminishes with distance (obviously), and the rolling resistance of the cart at speed is about 4 grams. The cart stays at a distance from the fan that balances the forces.
4) The prop's bluff force is reduced as it freewheels; the cart will stay on the belt but will be much closer to the fan..
5) Cart goes flying off the back of the belt
6) a) with only the fan on, the cart moves forward until the forces balance.
b) once the treadmill is above the break-even speed (6.2 mph on my cart) the cart will stay in place without the fan. More belt speed will have the cart moving forward.


What are you testing with your cart? I skipped quite a few pages so I think I missed your intent.

 

[humber]

Sure it is; fixed that for you.

Not good enough. Your argument fails, because the cart has no steering.
If the force increases when away from alignment as you claim, then without some means of compensation, the cart will go back with the belt. Aligned is an unstable state.

 

[CORed]

You have never produced a video. But go ahead. It will tell more than you know.
There are countless videos showing the cart to be at all sorts of angle to the
belt. The Harold Bricer test for example. The "fork" test. Video 5, where it moves in elliptical patterns.

You told me that yours drifted to the side of the belt. Not easy to see how a real cart can do that.

Only for humber is it not so easy to see how it does that. The front wheel is a little misaligned with the back wheels and steers the cart to one side. I guess how the steering wheel of a car works is still a mystery to humber.

The cart is quite clearly unstable. It always moves about. As JB says, "no steering", so the probability that it would remain exactly in line with the belt is low. That is, on average, it will spend more time away from alignment, than not. If you were correct, the cart would go down the belt, unless you can tell me how it gains more power away from alignment, than not.

Uh, what?

 

[humber]

It wasn't. None of this has been necessary.

You made two indoor self-start videos, after you say you already proved it.
Either the wind video is not good enough, or the indoor videos are not good enough. The cart in the wind stalls, and then the prop goes this way and that, and there are several attempts within the apparently "successful" video. One wonders what you call failure.

Not by us.

Hah.

Another lie.

The small cart has appeared in the wind but twice, as you well know.