Merged DDWFTTW in a “Real” Wind

[I Ratant]

Good God this thread is more pernicious than colds in winter.



It's almost an internet meme it's so everywhere.

opcorn:

Though it is an entertaining ride.

.
Not always.
The "lively and friendly" aspect of interpersonal raggings which can be enjoyable when conducted without rancor was lost a long time ago.

 

[Llyricist]

No, this one
http://www.youtube.com/watch?v=dOUjGzy04DE&feature=related

[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=21714&stc=1&d=1302190757[/qimg]

Why do you keep showing the picture of the bent sprocket, that happened at Ivanpah because they were running without a ratchet, with the pictures of the broken ratchet that happened on the dynamo?

Oh yeah, I know why.....

 

[EHocking]

so you say. Apparent wind. Apparent wind.

I have a good grasp on the concept as I demonstrated in an earlier post.

The actual answer is of course apparent windspeed of 23.2mph, with an apparent wind direction (relative to the southerly heading) of 27.2^o.

Unless you contend this?

The headwind was a transient when the cart just passed WS, and it is well known that boats can tack up wind. Such a wind would accelerate the prop, so it would turn on the ratchet, and be of no use to the cart.

Again, your response has nothing to do with the subject of the post you are replying to - since the cart is not built to tack upwind, but to travel DDW.

But, the point was about your steering, which would fail catastrophically should that happen.

Proof by assertion and then strawman as we are not discussing an upwind travelling cart.

Also, should the tailwind deviate from ddw and the cart adjust itself, then any increase in speed of that same wind, would change it again. The idea is a total failure.

I agree that argument is a total failure - merely because it does not parse into a cogent thought.

Assumes its conclusion, misguides the cart, mechanically impractical and a hazard to stability.

Again - Proof by Assertion.

You are no Aristotle and flies have 6 legs...

 

[EHocking]

...Your cart will fail...

Exept for the fact that we have documented evidence that it did not.

 

[I Ratant]

...

I Ratant's free-wheeler will beat the geared cart, hands down. This time, we have a logical and methodical tester, who controls conditions and responds to remarks. Your cart will fail.

.

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I'd be surprised if that occurred. There's nothing left to "push" if the freewheeler gets to the windspeed.
There's a relation between the windspeed and the pitch of the prop that will reach a steady-state situation downwind.
The geared cart works up to a speed/pitch solution with the help of the driving wheels...I expect that speed would be similar to the downwind speed, but twice as fast (at least) with the headwind because of the connection with the wheels.
I'd been thinking about the guide line underneath the carts, as I do have a lot of flat surface at the airfield to use, and with the needed winds, the airplane fliers stay home... (Although it is fun to fly in winds that are higher than the takeoff speeds.. the airplanes can do no-wheel-rotation takeoffs and landings.) It would take two setups for the simultaneous runs.
May not be possible to make the guide line long enough and not whippy due to the length for a simultaneous run, with a reasonable amount of tension that doesn't require enormous anchors at both ends of both lines.
60 some years ago our first Jetex models ran along strings, over in Germany.
But first the geared cart has to move at all!

 

[Llyricist]

In fairness, above wind speed the simple wind vane steering actually would not work. If the wind direction shifts to the right relative to the cart, the direction the wind is coming from will shift to the left. Which is fine and good below wind speed, because that shift would turn the wheel right and steer the cart back in line with the wind. But above wind speed, that shift would actually turn the wheel left and steer the cart more and more away from DDW, until it turned the cart around into the wind.

 

[I Ratant]

Why it's prudent to build up to the end test....
http://www.youtube.com/watch?v=WXtzaBeACLU

 

[GrouchoMarxist]

Why it's prudent to build up to the end test....
http://www.youtube.com/watch?v=WXtzaBeACLU

Ha! He blowed up real good.

 

[humber]

I have a good grasp on the concept as I demonstrated in an earlier post.

The dea fails because wind vanes respond to force, so an increased windspeed from the same direction, will turn the vane, and so the cart.
To calculate the true wind, you need to know the velocities of the cart and wind, and the vane does not know them. Simple automatic boat steering uses a number of means of overcoming that, but not always. I am sure you will find tales on the boating forums where that system failed.
Electronically-controlled steering is an improvement on that, and measures water and wind speed and direction.

Unless you contend this?Again, your response has nothing to do with the subject of the post you are replying to - since the cart is not built to tack upwind, but to travel DDW.

The topic was the steering.

Proof by assertion and then strawman as we are not discussing an upwind travelling cart.I agree that argument is a total failure - merely because it does not parse into a cogent thought.Again - Proof by Assertion.
You are no Aristotle and flies have 6 legs...

Faux argumentative rhetoric, "assertion", "strawman" "Occam's razor" etc, don't make steering system work, when it won't.

 

[I Ratant]

Strict dieting....

 

[EHocking]

The dea fails because wind vanes respond to force, so an increased windspeed from the same direction, will turn the vane,

Why would an increase in windspeed without a change in direction turn the vane?

To calculate the true wind, you need to know the velocities of the cart and wind,

If you know the velocity of the wind, there is no need to calculate it.

and the vane does not know them. Simple automatic boat steering uses a number of means of overcoming that, but not always. I am sure you will find tales on the boating forums where that system failed.

And, yet again, you change the subject. The discussion is not and was never about boat steering systems - non sequitur.

Electronically-controlled steering is an improvement on that, and measures water and wind speed and direction.

A steering sytem does not need to know water and wind velocities - only direction.

The topic was the steering.

Yet another non sequitur. This last statement was in response to two totally different statements in my post. The first was about apparent windspeed calculations and the second was me pointing out that we were not discussing boats tacking upwind.

Faux argumentative rhetoric, "assertion", "strawman" "Occam's razor" etc, don't make steering system work, when it won't.

Yet it is the only method of argument you use on this forum.

 

[EHocking]

Faux argumentative rhetoric, "assertion", "strawman" "Occam's razor" etc, don't make steering system work, when it won't.

Our chief weapon is surprise...surprise and fear...fear and surprise....

Our two weapons are fear and surprise...and ruthless efficiency....

Our three weapons are fear, surprise and ruthless efficiency... and faux argument, rhetoric, assertion, strawman, Ockham's razor...

Our eight weapons are fear, surprise ...

Amongst our weaponry...are such elements as fear, surprise....


.... I'll come in again.

 

[Llyricist]

I, for one, sure as hell was not expecting the Spanish Inquisition.

 

[CORed]

I've been lurking at JREF for quite a few years, and I finally uncloaked just to sincerely thank Spork, ThinAirDesigns, CORed, Llyricist, Jack by the Hedge, jduffy77, EHocking, Michael C, and the many other posters for the wonderful insights and education I've received from this thread.

I am a sailor and a scientist, so I began reading this thread with some understanding of downwind tacking and velocity-made-good DW. Nonetheless, the concepts behind a DDWFTTW vehicle remained vague to me, and I had only an imperfect understanding of the relationship between the foils on the prop, the wheels, apparent wind direction, etc. Through the analogies, math, and wonderful animation presented here, I now have an intuitive as well as a theoretical understanding of the physics behind the cart.

The engineering of the cart was elegant, and the patience of all in tirelessly explaining it to others is deeply appreciated! The cart quite clearly works in terms of the physics, and it quite clearly works in real life. And I thank even the doubters on this thread for providing me with a renewed appreciation of Monty Python's "Argument Clinic" and "Black Knight" sketches.

I'm glad you appreciate my contribution. Sometimes in this discussion, I feel like second or third dumbest person here (with first clearly going to humber), but I do understand the basics of how the ddfttw cart works, even if I have no clue about the finer points of propeller design.

You realize of course, that in humber's mind, you have outed yourself as a "carteer" and joined the conspiracy.

What all of us carteers stand to gain from the ddwfttw conspiracly, I have no idea. I'm still waiting for my check from spork and jb.

 

[CORed]

Another first-time poster makes a public service announcement when the cart is in trouble. Happens like clockwork.

The cart is in trouble? Only in your head.

See, I told Giordano that humber would think he's part of the conspiracy. Your tinfoil hat is showing, humber.

 

[Giordano]

Another first-time poster makes a public service announcement when the cart is in trouble. Happens like clockwork.

If the implication is that I am a sock puppet, I can only assure you that I am not. Nonetheless, my joining of this discussion was indeed provoked by your rabid denial of DDWFTTW (not to mention spool and wine bottle physics). I do not hope to convince you; either you are simply inherently unwilling to accept the facts of physics, no matter how carefully explained or demonstrated to you, or you are perpetrating the longest running satire I’ve ever seen on a discussion board. Depending on your motivation, arguing with you might be considered either useless or cruel. But the willingness of the other posters to argue with you helped me to see the light, so I dropped by to thank them and as proof something positive came out of the discussion.

CORed- I’ve also followed the various conspiracy, history, and religion threads, and it is ironic that the first conspiracy I am accused of at JREF is “carteer.” I got the check from Spork (maybe yours is stuck in the mail), but it doesn’t pay nearly as well as the Reptilian Overlord gig I’ve got going on Tuesday nights...

 

[humber]

.
I'd be surprised if that occurred. There's nothing left to "push" if the freewheeler gets to the windspeed.
There's a relation between the windspeed and the pitch of the prop that will reach a steady-state situation downwind.
The geared cart works up to a speed/pitch solution with the help of the driving wheels...I expect that speed would be similar to the downwind speed, but twice as fast (at least) with the headwind because of the connection with the wheels.

No, don't agree. There is not energy above WS ddw. It is very difficult to ensure ddw outdoors.
Neither will go faster than the wind, but the sail cart will beat the geared cart. If the wind is reasonably steady, and the wheels stay on contact with the ground, the geared cart will reach a low terminal speed and go no further.

.
I'd been thinking about the guide line underneath the carts, as I do have a lot of flat surface at the airfield to use, and with the needed winds, the airplane fliers stay home... (Although it is fun to fly in winds that are higher than the takeoff speeds.. the airplanes can do no-wheel-rotation takeoffs and landings.) It would take two setups for the simultaneous runs.
May not be possible to make the guide line long enough and not whippy due to the length for a simultaneous run, with a reasonable amount of tension that doesn't require enormous anchors at both ends of both lines.
60 some years ago our first Jetex models ran along strings, over in Germany.
But first the geared cart has to move at all!

Yes, whipping would be a problem I think. No need to add springs to the mix.

If the wind is so strong that the cart needs to be restrained by the guide, then that will be a repeat of the former videos, where wind gusts are responsible for the apparent success.
On the other hand, a guide won't help if the wind changes direction, and the cart remains on a fixed course. If the geared cart retains traction to the ground, then it will be clear enough.

The carts are light, and a rough surface can easily make them bounce, and so have intermittent contact with the ground. Then, the geared cart, behaves much like the sail cart. It would be perhaps interesting to compare a simple sail to both.

 

[humber]

If the implication is that I am a sock puppet, I can only assure you that I am not. Nonetheless, my joining of this discussion was indeed provoked by your rabid denial of DDWFTTW (not to mention spool and wine bottle physics). I do not hope to convince you; either you are simply inherently unwilling to accept the facts of physics, no matter how carefully explained or demonstrated to you, or you are perpetrating the longest running satire I’ve ever seen on a discussion board. Depending on your motivation, arguing with you might be considered either useless or cruel. But the willingness of the other posters to argue with you helped me to see the light, so I dropped by to thank them and as proof something positive came out of the discussion.

If you were a sock-puppet at TAD's calling, then you would have thanked only JB and Spork; they would have not though of the others.
But, your tone suggests that you are strong supporter, seeing the team in peril. When that happens, posts appear from nowhere.
If you are at all a scientist, your remarks about the spool, says it's not physics, nor engineering. Am I right?

It's all "counter-intuitive" is it? What sort of things are like that, behave in ways you don't expect?
Cotton reels, yo-yo's, gyroscopes, whips that crack because the tip breaks the sound barrier, water going uphill when it shouldn't.
All about the conservation of momentum. Guess how the TM really works?

CORed- I’ve also followed the various conspiracy, history, and religion threads, and it is ironic that the first conspiracy I am accused of at JREF is “carteer.” I got the check from Spork (maybe yours is stuck in the mail), but it doesn’t pay nearly as well as the Reptilian Overlord gig I’ve got going on Tuesday nights...

That's a common trait amongst ddwfftw supporters. I never bother to look at those sites, but it's a hot topic for them.

 

[Llyricist]

humber's glasses went opaque black, and just like the bugblatter beast, he assumed WE were in peril.

 

[Llyricist]

btw. you are welcome Giordano, glad to help.