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Merged DDWFTTW in a “Real” Wind

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jduffy77 said:
That's easy. There is no proof Humber would except. None. Ever.

ETA: I can almost sympathize with the fact that it is now impossible for Humber to admit he was wrong. Put yourself in his shoes if you can. He has written 7 and 3/4 million words (conservatively) arguing against the possibility that the cart is what it is. It is not very hard to imagine being wrong after that would drive even a quite sane person insane.
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And you say that, when you totally ignore the contradictions provided by the trial evidence, and have no theoretical support, yet hope to rely on the visual, that misled you in the first place.
 
H'ethetheth said:
The thought has occurred to me. And if he is, I can actually appreciate having been a part of it.
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You're a better man than I. If I find out that humber is an art project, I hope to dismantle it one day. That will be my contribution to the performance art.
 
humber said:
You are saying that the experiments confirm that it works. I say it is not a viable idea.


But it is not good enough to say it "could be wrong" and there are no real-world examples that contradict it, let alone any actual mistake.
Why should I change? I can get the same results but not reach the same concluson about the cart or the reel in general.
Take a look at the videos "Prop or Turbine" and "The Harold Bricer Test"

In the former, that fan barely moves the cart, but in the latter, that same fan at a greater distance, blows the cart off the belt. That says a lot about how low the frictions to the belt is. That's how the TM works. It is barely in contact, because of an state induced by holding the cart, so priming it to take up a "latched state". It runs on little energy, so makes little demand of the belt, so very low drag from the belt. Those videos are contradictory. I estimated the force to the belt by observing its motion and timing it by frame stepping the video. The answer is 0.04N. Mender measured that, and came very close to the same value.



Tug on the thread. It may send the reel backwards. That never happens to a car. Small scale needs care.
Click to expand...


So that roughly translates, as an answer to my questions as 'No, there is no experimental result from any experiment that will cause me to admit I am wrong and any experiment that seems to demonstrate that will be handwaved away with 'expermental error' or similar'

Please let me know if I've got this wrong.
 
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I Ratant said:
.
I don't like CGI.
Too easy to not include all the problems the real world stuff throws at you.
The problems with this downwind stuff appear to be how does the gearing between the wheels and the prop affect the motion, which CGI can help explain, but the acrimony about the actual course of the vehicle in the wind needs more illustrative devices to show the wind direction at the cart.. like foam popcorn pellets floating along, and tell-tale streamers not connected to the cart.
With the cart overtaking the pellets, that shows the relative motion, but it has to be real world, not CGI.
And steering through a field of tell-tale streamers also.
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The video is only meant to help people understand that the airfoils of the prop are not ddw.

You have not accused NALSA of fraud so I am assuming that you believe them to be incompetent.

Would you elaborate on your position re NALSA. They are recognized as the worlds leading authority on land sailing. The two deniers, Harold and Humber, could not sing their praise high enough before the Blackbird's record. If I had not already satisfied myself that the cart not only could work (but would violate the laws of physics if it did not) before the record run, I would have accepted that it did work on their say so alone.

They went far beyond pellets and streamers with their safeguards. They did not ratify a world record on a whim or from reviewing videos.
 
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humber said:
And you say that, when you totally ignore the contradictions provided by the trial evidence, and have no theoretical support, yet hope to rely on the visual, that misled you in the first place.
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There were no contradictions provided by the trial evidence. You do not understand the data.

The theoretical support is solid and trivial. You do not understand the physics.
 
I Ratant said:
.
I've seen the PMM chutes before, but, there are two separate shafts involved.
The wheel I use has two separate diameter reels, but they are not independent. The angular motion is identical on each with rotation, although the distance traveled varies depending on the pull location.
The downwind carts with the props use two separate shafts, geared together.
That's the easy part.
Explaining why the propellor assists in driving the drive wheels, that's the stinky part. :)
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The stinky part is getting past stuck false assumptions.

The chute carts I illustrated are not PMMs. They are wind powered.

The propeller does not assist in driving (applying torque to) the wheels. In fact in the Blackbird, a ratchet prevents that from happening (so that the wheels can be braked while the propeller is still spinning).

The propeller provides thrust and applies it directly to the vehicle frame, just like a propeller on an airplane.

[ETA: changed "drive wheels" to "wheels" because even calling them "drive wheels" is misleading. Two of the wheels are drive wheels only in the sense that they drive the propeller. None of the wheels has any power applied to it to drive the cart forward. In that regard they are completely unlike a car or bicycle's drive wheels, and more like the wheels of a plane's landing gear. All of the vehicle's forward impetus comes from the propeller thrust. Note that when at a stop, with a tailwind, the propeller does not need to spin to provide thrust.]

Respectfully,
Myriad
 
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jduffy77 said:
The video is only meant to help people understand that the airfoils of the prop are not ddw.

You have not accused NALSA of fraud so I am assuming that you believe them to be incompetent.

Would you elaborate on your position re NALSA. They are recognized as the worlds leading authority on land sailing. The two deniers, Harold and Humber, could not sing their praise high enough before the Blackbird's record. If I had not already satisfied myself that the cart not only could work (but would violate the laws of physics if it did not) before the record run, I would have accepted that it did work on their say so alone.

They went far beyond pellets and streamers with their safeguards. They did not ratify a world record on a whim or from reviewing videos.
Click to expand...
.
I don't give a **** about NALSA, whoever they are.
The "record" to me is as pointless as any of the Guinness "records", such as the "world's largest collection of ball-point pens".
The situation is interesting/amusing, but hardly worth the rancor and acrimony it has aroused.
The cart can't "violate the laws of physics".
Nothing can.
Misunderstanding the mechanisms of the motion is all that is occurring.
They do go downwind faster than the wind.
That's not anything of any practical use, as many people like to move upwind also. Without doing any major changes to the craft they might employ for the purpose.
Boeing lost the JSF contract because their vehicle, capable as it may have been, could not perform -all- the tasks the requirements listed, without major configuration changes, while the winner needed nothing extra to fly the envelope.
Special purpose vehicles like these carts are interesting to observe, but they have little more than a momentary diversion to offer.
 
I don't see the cart moving in the wind, until it's pushed. The man-carrying jobber-does, that is.
The push begins to turn the prop, otherwise there isn't enough surface area on the propellor to act like a sail.
The models are much lighter, and easier to move in a wind. Much less mass per propellor area.
I think the cart will accelerate to the speed where the wind coming into the prop begins to cut the thrust, as it would on a windmilling prop on a plane, which can be severe enough to cause problems with forward flight.
On my electric r/c planes, a windmilling prop is turning the motor due to the incoming airflow, with a direct drive. That produces sufficient drag on the plane to alter it's flyability.
If the motor isn't braked electrically to a halt, where the prop provides a minimum amount of drag, the plane will descend faster with the windmilling prop.
A free-wheel device which separates the prop from the motor is a better choice.
The prop still windmills, but it's at a zero-slip, zero thrust and low drag condition, relative to having the coupling to the motor.
The best choice is a folding prop, and even these may not fold if the speed can't be reduced to where the wind forces the prop to fold, instead of windmill.
On the internal combustion motored models, a windmilling prop with the motor off is rare, due to the inability of the incoming airflow to move the prop against the motor compression, although I have one clapped-out 2-stroke that will windmill power off, in a dive.
.
I'd love to see a chute powered cart. :)
 
I Ratant said:
.
I don't give a **** about NALSA, whoever they are.
The "record" to me is as pointless as any of the Guinness "records", such as the "world's largest collection of ball-point pens".
The situation is interesting/amusing, but hardly worth the rancor and acrimony it has aroused.
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Hmmm, most of the rancor and acrimony I have seen the cart engender resides in two individuals out of hundreds and hundreds. Perhaps they had issues before the cart?

I Ratant said:
.
The cart can't "violate the laws of physics".
Nothing can.
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Right, that's what I said. Once the cart worked on the treadmill it would have to work full scale subject to engineering.

I Ratant said:
.
Misunderstanding the mechanisms of the motion is all that is occurring.
They do go downwind faster than the wind.
Click to expand...

Only very few (two?) misunderstand at this point. At least you are not questioning it.

I Ratant said:
.
That's not anything of any practical use, as many people like to move upwind also. Without doing any major changes to the craft they might employ for the purpose.
Boeing lost the JSF contract because their vehicle, capable as it may have been, could not perform -all- the tasks the requirements listed, without major configuration changes, while the winner needed nothing extra to fly the envelope.
Special purpose vehicles like these carts are interesting to observe, but they have little more than a momentary diversion to offer.
Click to expand...

You seem a bit fixated on the purpose of the cart. The most interesting thing about your fixation is that it is the first new reaction to the cart I have seen in a while. I asked before but now you bring it up again; what hobbies do you find worthy of your time? In case your passion is "internet posts against non-lifesaving past times" here is a link to a mountain climbing forum: http://www.summitpost.org/phpBB3/.

Why not post and tell all those morons to stop climbing already! There's nothing up there!
 
I Ratant said:
I don't see the cart moving in the wind, until it's pushed. The man-carrying jobber-does, that is.
The push begins to turn the prop, otherwise there isn't enough surface area on the propellor to act like a sail.
The models are much lighter, and easier to move in a wind. Much less mass per propellor area.
I think the cart will accelerate to the speed where the wind coming into the prop begins to cut the thrust, as it would on a windmilling prop on a plane, which can be severe enough to cause problems with forward flight.
On my electric r/c planes, a windmilling prop is turning the motor due to the incoming airflow, with a direct drive. That produces sufficient drag on the plane to alter it's flyability.
If the motor isn't braked electrically to a halt, where the prop provides a minimum amount of drag, the plane will descend faster with the windmilling prop.
A free-wheel device which separates the prop from the motor is a better choice.
The prop still windmills, but it's at a zero-slip, zero thrust and low drag condition, relative to having the coupling to the motor.
The best choice is a folding prop, and even these may not fold if the speed can't be reduced to where the wind forces the prop to fold, instead of windmill.
On the internal combustion motored models, a windmilling prop with the motor off is rare, due to the inability of the incoming airflow to move the prop against the motor compression, although I have one clapped-out 2-stroke that will windmill power off, in a dive.
.
I'd love to see a chute powered cart. :)
Click to expand...

Ooops, you took a big step backwards. Now you are completely wrong again. Is this Humber?
 
I Ratant said:
I don't see the cart moving in the wind, until it's pushed. The man-carrying jobber-does, that is.
The push begins to turn the prop, otherwise there isn't enough surface area on the propellor to act like a sail.
The models are much lighter, and easier to move in a wind. Much less mass per propellor area.
I think the cart will accelerate to the speed where the wind coming into the prop begins to cut the thrust, as it would on a windmilling prop on a plane, which can be severe enough to cause problems with forward flight.
On my electric r/c planes, a windmilling prop is turning the motor due to the incoming airflow, with a direct drive. That produces sufficient drag on the plane to alter it's flyability.
If the motor isn't braked electrically to a halt, where the prop provides a minimum amount of drag, the plane will descend faster with the windmilling prop.
A free-wheel device which separates the prop from the motor is a better choice.
The prop still windmills, but it's at a zero-slip, zero thrust and low drag condition, relative to having the coupling to the motor.
The best choice is a folding prop, and even these may not fold if the speed can't be reduced to where the wind forces the prop to fold, instead of windmill.
On the internal combustion motored models, a windmilling prop with the motor off is rare, due to the inability of the incoming airflow to move the prop against the motor compression, although I have one clapped-out 2-stroke that will windmill power off, in a dive.
.
I'd love to see a chute powered cart. :)
Click to expand...
With respect, you are letting your knowledge of airplanes (model or otherwise) get in the way of your understanding of how the cart operates. I advise taking a step back and starting over with a fresh perspective.
 
Llyricist said:
Ahem:
http://www.youtube.com/watch?v=5CcgmpBGSCI&feature=player_embedded

&

http://www.youtube.com/watch?v=7SYvg40NHtc

The reason they push it is to save the distance eaten up by the long sluggish acceleration, so they have more room to accelerate to top speed.
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.
Missed those.
.
A speed record really needs to be performed in a manner that eliminates the wind... two directions, not one. :)
Bonneville cars go both ways.
Airplanes too.
Even the America's Cup racers have to do that pesky upwind stuff.
Without that, the carts are just pass-times, and money sinks.
 
I Ratant said:
Hadn't seen these.. Ducted fans.
Not as efficient as the monster props.
http://www.youtube.com/watch?v=KQu4hUKnoVE&NR=1&feature=fvwp
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I believe they are more efficient although it depends on what you mean. Those are turbines and they have nothing to do with the ddw cart. They are of course limited to less than WS. I believe the record is about .6x WS.

I think the Blackbird's builders plan to crush that record with an upwind vehicle sometime this summer.
 
I Ratant said:
.
Missed those.
.
A speed record really needs to be performed in a manner that eliminates the wind... two directions, not one. :)
Bonneville cars go both ways.
Airplanes too.
Even the America's Cup racers have to do that pesky upwind stuff.
Without that, the carts are just pass-times, and money sinks.
Click to expand...

Not all speed records go both ways. Records that are supposed to be independent of the wind run both ways to eliminate the wind factor. A record that is for the fastest speed directly downwind can only run downwind by definition. The Greenbird has the land sailing speed record. This record was accomplished on a downwind reach. Again, not both ways since it is a wind dependent record. There are also speed records with kiteboards that are one direction only. I am sure that other posters can think of more.
 
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