Merged DDWFTTW in a “Real” Wind

[ThinAirDesigns]

.The wheels connection does something.

Brilliant.

JB

 

[Subduction Zone]

The amazing thing about humber's claim about balloons traveling slower than the speed of the wind, which has a small amount of truth to it since in an idealized case a balloon in a perfectly unvarying wind would approach wind speed asymptotically, is that he has claimed that a balloon towed to a speed faster than the wind will slow down to a speed slower than the wind

 

[humber]

Yes Black Knight - yes.

JB

Your irritation at having to try an try again to even get the cart to start, makes that cliche look dull.
The gearing impedes the cart, so you must wait until the wind is strong enough to break the wheels traction to the ground. That is why the prop turn CW, CCW and stops all together. What do you call failure JB?

That same blinkered denial is seen in all the other videos. The spiteful "Harold Bricer" test, shows a distant fan blow the cart backwards and off the belt, while you wait in anticipation of catching it.

The spleen of the "Failed design" video, purposefully directed at Greg London, backfires by showing that rolling objects are unstable on a moving belt unless exactly aligned with the belt. Yet you cart gets away with that, so showing that it slides.

 

[RossFW]

The amazing thing about humber's claim about balloons traveling slower than the speed of the wind, which has a small amount of truth to it since in an idealized case a balloon in a perfectly unvarying wind would approach wind speed asymptotically, is that he has claimed that a balloon towed to a speed faster than the wind will slow down to a speed slower than the wind

..But is happy to accept that a balloon towed to any speed on a still day will come to a complete stop.

Humber don't do relative motion, nope, not at all...

 

[humber]

Yes Black Knight - yes.

JB

The amazing thing about humber's claim about balloons traveling slower than the speed of the wind, which has a small amount of truth to it since in an idealized case a balloon in a perfectly unvarying wind would approach wind speed asymptotically, is that he has claimed that a balloon towed to a speed faster than the wind will slow down to a speed slower than the wind

The time constant tau = m*A/Cd, says that you are wrong.
The "asymptotic" argument is used by naive electronics students to conclude that a capacitor can never be fully charged, and will continue to charge, for ever and ever and ever.

 

[I Ratant]

Brilliant.

JB

.
So you have no explanation.
Sad.
lemme help a tad.

 

[humber]

And while JB is looking for that explanation, perhaps he can tell all why his prop and turbine combo, won't work against each other, or why his indeterminate claim for the prop, contradicts Bauer.

 

[A.T.]

It's funny how I Ratant demands that people define their terms, but at the same time throws around with some self-invented terms like "sail effect", "prop drag effect". Has he ever defined those terms formally, using physical quantities like forces, torques, velocities etc.?

.
Gotme!
Ouuuooo!
The "sail effect"... the propellor on the driven cart has the function of a sail.
It is the sole source of energy available to move the cart at all, presuming no push truck.
It continues this contribution as the cart begins to move, and the wheels then through the drive connection start to rotate the propellor.
We all know (I hope) the propellor would rotate in the opposite direction were it free to rotate, but the drive connection to the wheels prevents that rotation, but that drive connection to the wheels has to fight the natural rotation of the prop.
Up to the point where the cart achieves wind speed, the propellor is functioning as a sail. Hence, "sail effect".
"prop drag effect". On an airplane, when the motor is turned off, the propellor has no thrust. It ---drags- on the airframe.
Many unfortunate incidences in the history of aviation have led to the requirement that propellors do the least worst effect to the airplane in terms of drag, which is a bad thing most of the time.
With airplanes with a wide speed margin, and variable pitch propellors, the unpowered propellor can be rotated on a axis along the blade(s) to where the blade(s) provide the least amount of drag to the airplane.
This is termed "feathering". (just being thorough)
When the prop isn't being powered and isn't feathered, the airspeed and propellor pitch can be such that the propellor rotates. On a single engine airplane, this adds drag. Which will require a change in the flight path.
On a multi-engine airplane, the drag will be off the center line of the plane, which will require some control surface adjustments to realign the flight path.
The lower the pitch (blade angle of the propellor relative to the airstream) the more drag the propellor adds to the airframe at any speed. Therefore the least drag condition is with the propellor feathered, as noted above.
One might, and can say, this is the "prop drag effect".
Or run off into torques and other things, which say the same, but less clearly.
I even gots a pichur...

So you define "sail effect" as "functioning as a sail" and "prop drag effect" as "dragging on the frame". Isn't a sail also dragging on the frame? What is the difference between those effects?

I asked you to define the terms precisely using physical quantities (forces, torques, velocities etc.) because I'm pretty sure, that if you would do so, you would realize that the distinction betweens those "effects" that you have made up, is physically non existent.

 

[A.T.]

.
Why, once the cart passes windspeed, is the pushing sail effect still there?

Instead of making up those nonsense terms, just work with actual physics: velocities and forces. Draw some vectors, or try to understand the ones posted by others.

 

[humber]

Instead of making up those nonsense terms, just work with actual physics: velocities and forces. Draw some vectors, or try to understand the ones posted by others.

[qimg]http://img811.imageshack.us/img811/4922/propellervectors.png[/qimg]

All wrong. If you were even remotely correct, a plane could fly, turn off the engine, and the free-wheeling prop would provide thrust.
That does not happen because the prop is then drag. The free-wheeling propeller does not take energy from the wind, but accelerates the wind, and that is the apparent wind.

Above windspeed, there is no tailwind, but only the drag of the prop accelerating the slower air that must be before it. The cart is faster than the wind, so the air ahead is slower than the cart, and the energy transferred from the cart to the wind, slows the cart.

That is so, if the wheels are geared or not, unless you hope to convince the American Journal of Physics, that wheels are a source of power.

 

[Jack by the hedge]

Not once. Find the quote that supports what you say.

Well, since you seem to have conveniently blocked it out of your mind, here's a refresher:

You can try and make it work up an incline if you like, or can't the cart go up hill?
Do let me know how you get on.

You will need CGI to make that reel move up the incline.
How embarrassing for you! A simple trick, performed by a powdered monkey, had you believing in magic reels.

Oh yeah. On a smooth surface, with the thread underneath. Up an incline. BS

Cotton reels don't roll down hill in Carteerland. The next project is a rocket made from Christmas-tree lights and tinsel. You just need to "get it"

And, perhaps most explicitly, from a post which sadly got shuffled off to AAH: http://www.internationalskeptics.com/forums/showthread.php?postid=7010816#post7010816

No little ones, it won't work on an incline. It's a show-stopper in neon, that will be hard to deny... It is not possible for the reel to simply "wind itself up" the thread that is pulling it.

So, humber, do you still deny that you said it won't work on an incline?

 

[I Ratant]

So you define "sail effect" as "functioning as a sail" and "prop drag effect" as "dragging on the frame". Isn't a sail also dragging on the frame? What is the difference between those effects?

I asked you to define the terms precisely using physical quantities (forces, torques, velocities etc.) because I'm pretty sure, that if you would do so, you would realize that the distinction betweens those "effects" that you have made up, is physically non existent.

.
So what?
It's all ballpark out-of-our-respective asses "data" anyway.
The concepts don't need no steenken' numbers!

 

[humber]

You can try and make it work up an incline if you like, or can't the cart go up hill? Do let me know how you get on.

Different mode of operation uphill as claimed for the cotton reel's part in the cart.

You will need CGI to make that reel move up the incline.

Pull that thread through the incline.

How embarrassing for you! A simple trick, performed by a powdered monkey, had you believing in magic reels.

And?

Oh yeah. On a smooth surface, with the thread underneath. Up an incline. BS

Friction. Dragging the reel up, as it rolls over the point of contact. Not the same as when level.

Cotton reels don't roll down hill in Carteerland. The next project is a rocket made from Christmas-tree lights and tinsel. You just need to "get it"

No, they don't.

No little ones, it won't work on an incline. It's a show-stopper in neon, that will be hard to deny... It is not possible for the reel to simply "wind itself up" the thread that is pulling it.

It doesn't.

 

[Jack by the hedge]

It doesn't.

Wow!

Really, just wow!

Anyone, what's the SI unit of denial?

Wait: let's just pause a moment - humber, are you now saying that when you denied claiming it was impossible to draw an underwound reel up a slope, what you actually meant was that you actually did claim that, and in fact you still do claim that? Is that your position?

 

[humber]

Wow!

Really, just wow!

Anyone, what's the SI unit of denial?

Good answer. Wow!
There is a difference, can you see it yet, viewers?
The cart was a no-brainer to sell.

 

[Llyricist]

All wrong. If you were even remotely correct, a plane could fly, turn off the engine, and the free-wheeling prop would provide thrust.

If it wasn't correct then a sail craft could not get downwind VMG's greater than wind speed while in a broad reach.

 

[Subduction Zone]

The time constant tau = m*A/Cd, says that you are wrong.
The "asymptotic" argument is used by naive electronics students to conclude that a capacitor can never be fully charged, and will continue to charge, for ever and ever and ever.

How so? Quoting a formula does nothing to support your position.

 

[Llyricist]

.
So what?
It's all ballpark out-of-our-respective asses "data" anyway.
The concepts don't need no steenken' numbers!

What is your hangup about the blade direction? You do realize that there are two blades on the propeller, and that the blade on the opposite side of the axle is in fact doing the mirror image of the blade on the side you seem to prefer?

 

[humber]

How so? Quoting a formula does nothing to support your position.

That math...only for geeks, eh?

Time constant, tau.

[latex] V(t) \ = \ V_o e^{-t / \tau} \, [/latex]

All sorts of natural phenomenon are related to 'e'

In the case of the balloon, friction limits the exponential rise to below WS.

 

[I Ratant]

What is your hangup about the blade direction? You do realize that there are two blades on the propeller, and that the blade on the opposite side of the axle is in fact doing the mirror image of the blade on the side you seem to prefer?

.
In discussing an existing machine, why not use the configuration of -that- machine for illustrations?
Most of these carts use what is termed a right-hand twist propellor.
The propellors in most of the illustrations show the propellor blade cross-section from the other side of the machine.
Who would do that?
Other than having that blade going up, why not use the blade on this side of the machine?
That it's going down machs nichts.
It's just being consistent, and simple.
Most of the lethargic explanations (when any at all is offered) of the principles here are equally obtuse, and are not presented in a clear manner, easy for the non-technical persons to untangle.
Educate, don't obfuscate.