ISF Logo   IS Forum
Forum Index Register Members List Events Mark Forums Read Help

Go Back   International Skeptics Forum » General Topics » Science, Mathematics, Medicine, and Technology
 


Welcome to the International Skeptics Forum, where we discuss skepticism, critical thinking, the paranormal and science in a friendly but lively way. You are currently viewing the forum as a guest, which means you are missing out on discussing matters that are of interest to you. Please consider registering so you can gain full use of the forum features and interact with other Members. Registration is simple, fast and free! Click here to register today.
Reply
Old 12th November 2008, 11:33 PM   #281
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Well, Spork you should contact this guy:
http://www.reference.com/browse/SMOT&

A few years ago, he was running an alternative energy business. I haven't met him, so I have no evidence, but I feel quite sure that he will take your $100K.

If only I had known how easy it wouldhavebeen.

Last edited by humber; 12th November 2008 at 11:34 PM.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 12th November 2008, 11:38 PM   #282
ThinAirDesigns
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,058
humbert:
Quote:
Brian-M, Mhaze. At least 3 of us understand.
Originally Posted by Brian-M View Post
So, I guess I was wrong after all.
To Brian -- congrats. No shame -- it's truly a frustrating brainteaser.

To humbert -- I guess there's only two guys who "understand" it now.

JB
ThinAirDesigns is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 12th November 2008, 11:38 PM   #283
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by Brian-M View Post
So, converting this back to a fixed ground reference, the maximum speed of an idealized version of device (including 100% power transfer at the propeller, no wind resistance, no friction, etc) would be up to twice wind speed.
You're definitely getting closer, but in fact ice boats regularly achieve downwind velocity components of more than 3X the wind speed. Given sufficient efficiency a cart such as ours could do the same.

But I'm glad to see you're willing to look at things critically and consider a new perspective. This thing is not intuitive to most folks. Of course that's what makes it interesting.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 12th November 2008, 11:42 PM   #284
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by humber View Post
I feel quite sure that he will take your $100K.

If only I had known how easy it wouldhavebeen.

Forget about how easy it "would have been". It's still available. You know how this thing operates and I don't - so it seems like a sure thing for you. Just step up with your own cash and claim mine.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 12th November 2008, 11:42 PM   #285
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Yes, but you've already lost one convert. More to come, I expect.

OK, I'll take it. What do I have to do?

Last edited by humber; 12th November 2008 at 11:44 PM.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 12th November 2008, 11:53 PM   #286
Modified
Philosopher
 
Modified's Avatar
 
Join Date: Sep 2006
Posts: 6,401
Originally Posted by Brian-M View Post
Of course traveling downwind faster than the wind is possible. I do this all the time in my car, using stored energy from fossil fuels. I could do the same thing in an electric car using stored energy generated from the wind. Your iceboat example uses stored energy to do this too (in this case, it's stored as kinetic energy perpendicular to the direction of the wind). With zero friction, any idealized hypothetical vehicle can maintain this high speed indefinitely.
Even with a small non-zero friction, you can average faster than the wind by re-accelerating occasionally. By connecting several boats through sliding connections, you can build a vehicle that as a whole maintains a steady downwind speed that is faster than the wind. All this happens even if you don't believe that the downwind component of the speed can exceed the wind speed while tacking.

So, by the construction presented, given that it is possible for an iceboat to exceed the speed of the wind in some arbitrary direction, then there exist some non-zero values of iceboat friction and drag such that it is possible to construct a vehicle that can exceed the speed of the wind while traveling straight downwind.

In other words, the fact that the speed of an iceboat can exceed the wind speed (even at some angle to the wind, which is something we can all agree on) implies that a wind-powered vehicle that can travel straight downwind faster than the wind at a steady rate of speed is possible in theory. If you see something wrong with this, what is it?
Modified is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:23 AM   #287
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by humber View Post
Yes, but you've already lost one convert. More to come, I expect.
We did?

Quote:
OK, I'll take it. What do I have to do?
It's a bet. You have to do the bet thing. You and I each put our $100K into a joint escrow acct. We'll draw up the agreement on the statement of the wager and exactly how it will be decided. Escrow pays all proceeds to the winner.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:27 AM   #288
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by Modified View Post
In other words, the fact that the speed of an iceboat can exceed the wind speed (even at some angle to the wind, which is something we can all agree on) implies that a wind-powered vehicle that can travel straight downwind faster than the wind at a steady rate of speed is possible in theory. If you see something wrong with this, what is it?
The fact that an ice boat can exceed the wind speed in certain directions doesn't necessarily imply that it can exceed the wind speed in all directions (steady state), or that it's downwind velocity component can exceed the wind speed steady state - only that it can exceed it in bursts.

But we do know from basic aero theory and simple vector analysis that the ice-boat can in fact maintain a downwind velocity component 3X or more the wind speed.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:28 AM   #289
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
JWideman has seen the light.

OK. But, what do I have to show, prove or do in order to take the money?
I mean what is the actual task ?
Also, who will be the judge?

Last edited by humber; 13th November 2008 at 12:30 AM.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:44 AM   #290
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by humber View Post
JWideman has seen the light.
So that's the "convert" we lost!? I'm reasonably certain none of us that understand what's going on ever counted him among the enlightened.

Quote:
OK. But, what do I have to show, prove or do in order to take the money?
You don't have to prove a thing. I have to prove that the cart we built is capable of going directly downwind, faster than the wind, steady state - whether on the open road or a treadmill. For the heck of it I'll also prove that your bizarre theories have no merit. It will be an expensive lesson for you, but I'll try and see you get your money's worth.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:54 AM   #291
casebro
Penultimate Amazing
 
casebro's Avatar
 
Join Date: Jun 2005
Posts: 14,356
The propeller vanes are acting like the ice boat sails. The prop shaft axis is down wind, the vanes are tacking across the wind. Easily understood, correct?

So, the prop can have a peripheral speed greater than the wind speed. Actually, propeller airplane prop tips go the speed of sound, but the aircraft ( analogous to windspeed) is much slower. That's why some prop airplanes are so noisy- the prop tips break the sound barrier, causing "sonic booms", shock waves. It's not all exhaust noise.)

So, each blade is tacking at a speed much greater than the wind. Now it is just a question of how much power the prop has, versus the drag of the whole vehicle. Hmmm, it could certainly go up-wind pretty well . And the faster it goes upwind, the faster the apparent wind, to drive the prop even faster - perpetual motion machine here?

But just how fast can even an ice boat go, down wind? Oh, they go several times wind speed across the wind, but what is their speed made good down wind? Anybody here have a polar chart of wind speed vs hull speed of an ice boat? I only have one of a sail boat. I suspect that ice boats are very low friction, like we would hope in our fan-powered cart. So the efficiency of the ice boat might give a hint of the possibilities of a fan powered cart. And it's diminishing returns as the hull approaches wind speed.

See, even in a cross wind, as an iceboats speed picks up, the apparent wind swings closer to astern, diminishing the gains of going cross wind. So the ice boat has to turn up-wind to maintain the same cross-wind speed. This limits the speed made good in a down wind direction.

Anyway, lets build a cart, prop hooked to wheels. Put the cart on a treadmill. Tether the cart, so it can't roll. Turn on the treadmill motor. The spinning wheels will turn the propeller with some force, which will thrust the cart against it's tethers. Now lets remove the tethers, and use an incline instead. The incline being such that it's slope will equal the drag of the mechanisms. The cart will remain stationary against the rotation of the treadmill. Balancing the treadmill's speed vs the incline, and you just might get motion in the direction opposite the treadmills direction. No wind speed needed. Nor does this prove that the cart can even function in wind at all. Only that a treadmill is a viable way to input power to a fan-propelled cart.

No, still air vs a moving treadmill is NOT the same as moving air vs still pavement. You forgot that the drag of the slope will be exactly equal to the power being input from the treadmill's belt. That power input is what moves the cart 'relative' to the belt.

I think I'll need to see some air speed indicators, hull speedometer, and independent verification before I'll lose my skepticism here.
__________________
Great minds discuss ideas.
Medium minds discuss events.
Small minds spend all their time on U-Tube and Facebook.
casebro is online now   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 12:59 AM   #292
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
When someone familiar with your stuff says:
"The treadmill is merely a misdirection"
That's a win

I still need to know who the judge will be.

As a preliminary step, you can write a Matlab script. You can turn it into an executable, so I can't see the source code. Just the simulation will do.
Simulink is relatively quick. So as to be fair, you can post it on You Tube.
Then there will be no question of plagiarism

Please, define 'steady state'.

ETA:
I just had a thought. I am so sure that the treadmill experiment has no validity, that I will accept proof of concept on that. You have already revealed all there is to know, I understand.
Post the calculations, and a simulation at the Physics Forum, and perhaps we can ask the moderators to take a look at it. If they say that it has potential as the basis of faster than wind travel, then we can go directly to the device.

Last edited by humber; 13th November 2008 at 01:36 AM.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 01:10 AM   #293
CaveDave
Semicentenarian Troglodyte
 
CaveDave's Avatar
 
Join Date: Mar 2005
Location: Buddy Holly's home, Surrounded by tumbleweeds, duststorms, and tornados.
Posts: 1,743
Originally Posted by my_wan View Post
Here is a very simple diagram of the craft.
http://www.internationalskeptics.com...aaeb9be526.gif
Direction of travel is to the left <----.
Thanks for the drawing, it helps clarify things for me. I assume, even though I can't "see" it from above, that prop. axis, wind direction, and cart travel direction are parallel, despite the many references to "vector diagrams", sail boats and tacking?
(I am more than 90 posts behind, but I am trying to read all, so I may be awhile.)

----------------------

Originally Posted by humber View Post
Yes, if only people read Einstein's papers, those that he won the Nobel prize for, perhaps the would learn something about momentum.

The Photoelectric Effect -- the one that started Quantum Mechanics?

Do you mean as in Photon momentum? I don't understand how that relates.

His papers on Relativity, Gravitation, and others did not win Nobel Prizes.

Dave
__________________
I, for one, welcome our new Authoritarian Socialist Overlords! . . . All Hail, Comrade Obama!
WHO IS JOHN GALT? . . . Read "Atlas Shrugged" by Ayn Rand.
"Some say that I'm a wise man, some think that I'm a fool. It doesn't matter either way: I'll be a wise man's fool."
Procol Harum "In Held 'Twas In I"

Last edited by CaveDave; 13th November 2008 at 01:13 AM.
CaveDave is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 01:14 AM   #294
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Yes, but it's not connected with this matter. It was sarcasm.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 03:30 AM   #295
my_wan
Graduate Poster
 
my_wan's Avatar
 
Join Date: Feb 2007
Posts: 1,074
I despair of debating with you because you are not debating. You don't even make an attempt. You state your opinion with no supporting argument and then think repeating yourself is debating.

Originally Posted by Thabiguy View Post
It's not a question of describing the equivalent thing differently. We are saying different things. You are saying that the device can, in theory, accelerate indefinitely (for a given construction). I'm saying that it can't, even in theory.
No, I never made that claim. I've described the limits in velocity of this craft many times. I have said the force of a house fly can accelerate an elephant indefinitely in empty space. This device cannot even in principle operate in such an environment.

Originally Posted by Thabiguy View Post
Originally Posted by my_wan View Post
This was in response to me saying:
"When the craft first takes off the prop is moving air in the opposite direction of the wind."
When the craft first takes off wrt the ground and wrt the device is the same thing. Remember this, the speed of the craft is almost but not quiet zero here. Look at the diagram:
<-- Craft moves to the left
You say:
1) The air pushed back is moving in the opposite direction of the air wrt device.
2) The air pushed back is the same direction as the air wrt ground.
Number 2 is dead wrong. It will be right once the craft exceeds the ground air speed but the single sentence you quoted and responded to specifically labeled it, "when the craft first takes off".
Number 2 is right, all the time. Particularly when the craft first takes off. I know what I'm saying.

No. The statement that I want you to realize is actually true. The problem is that you think it is false, and it is not.
So the wind is by definition going right to left wrt the craft while to prop blows the air left to right wrt the craft and this is the same direction wrt the craft? Only you didn't even bother to make an argument of any sort. You simply responded with, "I know what I'm saying". I don't despair of debating you for your claims I despair of you actually making a case for anything.

Originally Posted by Thabiguy View Post
*sigh*
You wanted me to answer your question concerning magical notions of zero friction/drag with a (one way?) force that requires drag. I ask you if two real empirical devices are equivalence and ask you about real empirical differences and this is the answer I get.

Originally Posted by Thabiguy View Post
What I was asking was to ignore practical losses, practical inefficiency. To take it as an ideal model.

I have absolutely no idea what you're talking about here. What I asked you was a perfectly valid question. There is no "bait". It's all about understanding the physics of the model.

Again, I have absolutely no idea what you're talking about. I can only conclude that you must have misunderstood what I was asking you. I asked you to consider it as an ideal model.
What you described was not an ideal model of anything. It required assuming the effects required for the devices operation doesn't exist but that they do exist in some (uni?)directional sense when you want them. What about the wheels? If they are frictionless/dragless, even if the prop turned them do they have any effect on the craft motion or just spin freely on the ground? An ideal model in physics depends on taking the limit on a well defined physical aspect, not removing physical effects except when you want them. That's what pseudoscience does.

It bears no resemblance at all to the empirical fact that a tiny persistent force can accelerate a massive object to arbitrarily high speeds in space. Do you deny that the persistant force of a fly can do this to an elephant in empty space?

Originally Posted by Thabiguy View Post
This has no relevance to what I was saying.
Nothing in this whole Universe has any relevance to what you were saying. That was the point. You can claim the fly force accelerating an elephant does but your fairy tale properties removes by definition the very effects the device depends on except when you want them to exist.

Originally Posted by Thabiguy View Post
I apologize for assuming that you were here to discuss.
When asked to clarify what you mean you simply repeat yourself. When admitted assumptions are made about what you were trying to say you say "wrong". When you do say something that is wrong by definition, not physics, you respond with, "I know what I'm saying". Well maybe I don't but that response gives me no clue. *sigh* is not a clue. When asked to explain why other devices work as they empirically do you respond that it has nothing to do with it. The you invent grossly different devices with no empirical precedence and assume magical fairy properties and claim it has everything to do with it. It is you that is not actually discussing anything.
__________________
Peace to all people of the world. The evidence indicates that this is best accomplished through a skeptical approach.
my_wan is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 04:02 AM   #296
my_wan
Graduate Poster
 
my_wan's Avatar
 
Join Date: Feb 2007
Posts: 1,074
Originally Posted by CaveDave View Post
Thanks for the drawing, it helps clarify things for me. I assume, even though I can't "see" it from above, that prop. axis, wind direction, and cart travel direction are parallel, despite the many references to "vector diagrams", sail boats and tacking?
(I am more than 90 posts behind, but I am trying to read all, so I may be awhile.)
Yes, they are parallel. The "tacking" used by sailors is used as an example model of how ground wind speed vs apparent wind speed relative to a craft can produce craft velocities greater than the wind speed relative to the ground. By itself it doesn't prove this craft works but it does prove that the principles behind the effect is physically sound.

I'm very sure this device works and even more sure that it can be made to work as advertised. I do have some differences with some pro people here concerning the equivalency of a bidirectional analysis of force vectors, but only wrt efficiency. However, the craft has a well defined direction of torque on the individual craft components and the way these vectors compliment in my analysis is showing the craft should come out on the extreme high end of efficiency.
__________________
Peace to all people of the world. The evidence indicates that this is best accomplished through a skeptical approach.
my_wan is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 04:22 AM   #297
my_wan
Graduate Poster
 
my_wan's Avatar
 
Join Date: Feb 2007
Posts: 1,074
Originally Posted by Thabiguy View Post
my_wan says that the maximum speed of the device is only limited by practical considerations (such as drag on the device as it moves at higher than wind speed), and that no matter how fast the device is going, it would always be (in theory) able to utilize the power of the wind for further acceleration, if it weren't for the drag etc. (I hope I have not misrepresented what he says. If I have, I apologize, and invite him to offer his own summary.)
Close but with qualifications. It is always possible to add a tiny amount of speed but it is a exponentially diminishing return. By doubling the cross-section of wind for more max velocity you fall way short of doubling the max velocity. This is because the resistance of an object to motion through a fluid increases as the cube of the velocity. So even though it is always possible for any given design to be improved to add some amount of top end speed, larger prop cross-section, etc., there remains an approximate practical limit.
__________________
Peace to all people of the world. The evidence indicates that this is best accomplished through a skeptical approach.
my_wan is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 04:26 AM   #298
Thabiguy
Muse
 
Join Date: Feb 2007
Posts: 784
Originally Posted by my_wan View Post
So the wind is by definition going right to left wrt the craft while to prop blows the air left to right wrt the craft and this is the same direction wrt the craft? Only you didn't even bother to make an argument of any sort.
In fact, I explained with great detail why that is. You just didn't understand my explanation. Perhaps I didn't explain it clearly enough.

Let me try again. The craft is travelling right to left, wrt ground, at 4 mph. The wind is going right to left, wrt ground, at 8 mph (and also right to left, wrt craft, at 4 mph). The prop blows the air left to right wrt the craft, at 2 mph.

What direction is the air blown by the propeller travelling, wrt ground? In the same direction as the air, or the opposite direction of the air?

Does this make statement number 2 true, or false?

Originally Posted by my_wan View Post
When asked to clarify what you mean you simply repeat yourself.
Does this clarify what I mean? If not, what is still unclear to you?

ETA: I'm sorry, I mistyped one of the directions when I was typing this post. The error is now corrected. If you have read it before, please read the post again.

Last edited by Thabiguy; 13th November 2008 at 04:40 AM. Reason: ETA
Thabiguy is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 04:33 AM   #299
my_wan
Graduate Poster
 
my_wan's Avatar
 
Join Date: Feb 2007
Posts: 1,074
Originally Posted by .13. View Post
I see. I just got confused again. I thought he disagreed with the direction the wheels would spin. That they wouldn't spin backwards if the wind were spinning the prop freely.

Anyway this bolded part makes a lot more sense now (post #153):


Initially this seemed wrong because I didn't realise the direction of the torque. But if I have understood this thus far: The force from the wind pushing against the frame is greater than friction + torque from the prop (which acts against forward motion). And as the cart picks up speed the torque resisting the forward motion decreases.
This is at the root of my differences with the other pro people here but it seems you have nailed it quiet well here. I got the torque direction wrong myself before I started analyzing it.
__________________
Peace to all people of the world. The evidence indicates that this is best accomplished through a skeptical approach.
my_wan is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 04:43 AM   #300
my_wan
Graduate Poster
 
my_wan's Avatar
 
Join Date: Feb 2007
Posts: 1,074
Originally Posted by Brian-M View Post
Wait... I originally thought this device was supposed to be powered by the wind turning the propeller, like a windmill.

But from what's been written since, it's the propeller pushing the air backwards which supplies the forward momentum which turns the wheels which powers the propeller which pushes the air backwards...

Am I understanding this correctly?

Have I been wasting my time reading this thread about something that's nothing more than a poorly conceived perpetual-motion machine?
It's not the "propeller pushing the air backwards which supplies the forward momentum". At below wind speed it is the wind blowing the craft itself downwind with force. The prop is then powered with some of this force through the wheels so the the wind relative to the craft remains faster than the wind relative to the ground even when the craft exceeds ground wind speed.
__________________
Peace to all people of the world. The evidence indicates that this is best accomplished through a skeptical approach.
my_wan is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 05:48 AM   #301
sol invictus
Philosopher
 
sol invictus's Avatar
 
Join Date: Oct 2007
Posts: 8,613
Originally Posted by technoextreme View Post
Nope. Nice try though but that cart aint moving at all with respect to the air.
I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.
sol invictus is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 05:59 AM   #302
ThinAirDesigns
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,058
Humber:
Quote:
JWideman has seen the light.
-
[quote]When someone familiar with your stuff says:
"The treadmill is merely a misdirection"
That's a winQUOTE]


LOL -- JW is not even "familiar" with the basic premise of inertial frames of reference, let alone "our stuff", but if you wish to consider JW as a win for you, excellent. He must make you very proud.

JB
ThinAirDesigns is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 06:00 AM   #303
sol invictus
Philosopher
 
sol invictus's Avatar
 
Join Date: Oct 2007
Posts: 8,613
Originally Posted by casebro View Post
No, still air vs a moving treadmill is NOT the same as moving air vs still pavement. You forgot that the drag of the slope will be exactly equal to the power being input from the treadmill's belt. That power input is what moves the cart 'relative' to the belt.
If there's a slope, the situation when you first let it go is identical to a car moving up (or down, depending on how you tilt it) a slope at the speed of the wind. The wind is blowing parallel to the slope.

This is absurdly easy to see. Just take every velocity that's relevant - in this case car, air, and treadmill belt - and subtract the velocity of the belt from it. That new situation is completely and totally identical to the original (so long as nothing else with a different velocity, like the floor, gets into it). Done.
sol invictus is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 06:13 AM   #304
ThinAirDesigns
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,058
Originally Posted by sol invictus View Post
I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.
-


I know Sol -- I have no idea how to explain it better either. Forget whether the device works, or has a motor -- let's just work on the treadmill/street thing.

We are going to mount a wheel driven speedometer and a *chassis mounted* air speed indicator on the device.

Let's just take the case of "as fast as the wind" and compare:

Case "A": cart is going down the street at 10mph in a 10mph tailwind.

Speedometer: 10mph
Air speed indicator: 0mph

Case "B": cart is on the treadmill(TR) which is set at 10mph and is neither moving towards the front of the TR nor to the rear of the TR.

Speedometer: 10mph
Air speed indicator: 0mph



Is there any chance that JW or humber sees the similarities in those two readouts?

humber, since you disagree, tell me what the readouts will be on those instruments in *your* world.

JW, since you disagree, tell me what the readouts will be on those instruments in *your* world.

Remember, I don't give a rip if device is powered by a Hemi right now -- and I don't care if it's being towed -- I only care about the speedometer readout and the wind speed indicator readout.

Case "A" numbers please.

Case "B" numbers please.

Thanks

JB

Last edited by ThinAirDesigns; 13th November 2008 at 06:14 AM.
ThinAirDesigns is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:19 AM   #305
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
[quote=ThinAirDesigns;4198248]Humber:
[quote]When someone familiar with your stuff says:
"The treadmill is merely a misdirection"
That's a winQUOTE]

LOL -- JW is not even "familiar" with the basic premise of inertial frames of reference, let alone "our stuff", but if you wish to consider JW as a win for you, excellent. He must make you very proud.

JB
Quote:
Hello again JW. Did you read my post #134?

If your interested in an exchange on the subject of inertial frames of reference, I would love to have one with you.
You must have changed your frame of integrity.
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:21 AM   #306
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Originally Posted by ThinAirDesigns View Post
-


I know Sol -- I have no idea how to explain it better either. Forget whether the device works, or has a motor -- let's just work on the treadmill/street thing.

We are going to mount a wheel driven speedometer and a *chassis mounted* air speed indicator on the device.

Let's just take the case of "as fast as the wind" and compare:

Case "A": cart is going down the street at 10mph in a 10mph tailwind.

Speedometer: 10mph
Air speed indicator: 0mph

Case "B": cart is on the treadmill(TR) which is set at 10mph and is neither moving towards the front of the TR nor to the rear of the TR.

Speedometer: 10mph
Air speed indicator: 0mph



Is there any chance that JW or humber sees the similarities in those two readouts?

humber, since you disagree, tell me what the readouts will be on those instruments in *your* world.

JW, since you disagree, tell me what the readouts will be on those instruments in *your* world.

Remember, I don't give a rip if device is powered by a Hemi right now -- and I don't care if it's being towed -- I only care about the speedometer readout and the wind speed indicator readout.

Case "A" numbers please.

Case "B" numbers please.

Thanks

JB
Elephants are gray
Mice are gray
Mice are elephants

Where's my $100K ?
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:35 AM   #307
technoextreme
Illuminator
 
technoextreme's Avatar
 
Join Date: Jun 2007
Posts: 3,785
Originally Posted by sol invictus View Post
I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.
I can comprehend it. The problem is that the end result is the car going slower than wind speed. Windspeed is the break even point. After that you have only momentum which is being slowed down by the drag which then means negative acceleration which then means your back to zero relative speed with the air.
__________________
It's amazing how many of these "paranormal" icons seem to merge together. There always seem to be theories about how they link together in some way. I'm sure someone has a very good explanation as to how Bigfoot killed JFK to help cover Roswell.-Mark Mekes
This isn't rocket surgery.-Bill Nye

Last edited by technoextreme; 13th November 2008 at 07:38 AM.
technoextreme is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:36 AM   #308
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by casebro View Post
No, still air vs a moving treadmill is NOT the same as moving air vs still pavement.
Well Galileo, Newton, and Einstein thought they were the same, but those guys are dead, so maybe you've worked out something new they hadn't thought of.

Quote:
You forgot that the drag of the slope will be exactly equal to the power being input from the treadmill's belt.
How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?

Read the thread, study some physics, build the cart as I describe here, and then get back to me.

Quote:
I think I'll need to see some air speed indicators, hull speedometer, and independent verification before I'll lose my skepticism here.
Excellent! Please post that all on youtube as we have with the cart we built.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:39 AM   #309
sol invictus
Philosopher
 
sol invictus's Avatar
 
Join Date: Oct 2007
Posts: 8,613
Originally Posted by humber View Post
Elephants are gray
Mice are gray
Mice are elephants

Where's my $100K ?
I see - so now not only is this device impossible, the laws of physics are wrong too. Ironically it's on the basis of those laws that you think it's impossible... yuck.

For the last 450 years or so physicists have understood that all motion is relative and that the laws of physics are invariant under boosts (i.e. identical in all situations that differ only by an overall shift in velocity). That's referred to as Galilean relativity - the "Galilean" part should give you a hint how old it is. Apparently that hasn't been enough time for it to percolate into some people's brains.

Anyway, we finally know where the difficulty lies - it has nothing to do with this device, it's just a failure to understand the basics of physics.
sol invictus is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:41 AM   #310
technoextreme
Illuminator
 
technoextreme's Avatar
 
Join Date: Jun 2007
Posts: 3,785
Originally Posted by spork View Post
How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?
I'm an engineer too and the one thing I remember from my physics class is that this is the easiest problem on the face of the earth to screw up.
__________________
It's amazing how many of these "paranormal" icons seem to merge together. There always seem to be theories about how they link together in some way. I'm sure someone has a very good explanation as to how Bigfoot killed JFK to help cover Roswell.-Mark Mekes
This isn't rocket surgery.-Bill Nye

Last edited by technoextreme; 13th November 2008 at 07:43 AM.
technoextreme is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:42 AM   #311
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Originally Posted by spork View Post
Well Galileo, Newton, and Einstein thought they were the same, but those guys are dead, so maybe you've worked out something new they hadn't thought of.



How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?

Read the thread, study some physics, build the cart as I describe here, and then get back to me.



Excellent! Please post that all on youtube as we have with the cart we built.
While you are at it, why not build a craft powered by the torque of the first three mentioned gentlemen, as the spin in their graves.

Where's my $100K?
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:43 AM   #312
Modified
Philosopher
 
Modified's Avatar
 
Join Date: Sep 2006
Posts: 6,401
Originally Posted by spork View Post
The fact that an ice boat can exceed the wind speed in certain directions doesn't necessarily imply that it can exceed the wind speed in all directions (steady state).
It implies that a connected system of such vehicles can do so. If a vehicle can average faster than the wind in some direction, then a connected pair or system of such vehicles which together constitute a single vehicle can maintain steady travel at (close to) that average speed. That step is a given, but you can come up with an actual construction if you like, such as attaching several boats with sliding connections to spokes with free-turning connections to a big center axle. Given semi-ideal components, a trivial amount of energy would be required to maintain the boat positions relative to the spokes such that the center of the axle moves at a constant speed in a straight line.

What I'm showing is that, starting from facts someone with limited physics knowledge can agree on, there is no theoretical reason that a DWFTTW vehicle is impossible (or any direction faster than the wind, now that you bring it up).
Modified is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:44 AM   #313
sol invictus
Philosopher
 
sol invictus's Avatar
 
Join Date: Oct 2007
Posts: 8,613
Originally Posted by technoextreme View Post
I can comprehend it. The problem is that the end result is the car going slower than wind speed. Windspeed is the break even point. After that you have only momentum which is being slowed down by the drag which then means negative acceleration which then means your back to zero relative speed with the air.
You just contradicted yourself. Either you end up at windspeed - which means zero speed relative to the air, which means the cart stays at fixed position on the treadmill - or you go slower. Make up your mind.

Of course you'll be wrong either way. You can't seem to understand that the motion of the cart is not powered by the wind alone, it's powered by the difference between the speed of the wind and the speed of the ground. That difference has nothing to do with the speed of the cart, and (in principle at least) one can always extract energy from it.
sol invictus is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:48 AM   #314
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by my_wan View Post
The "tacking" used by sailors is used as an example model of how ground wind speed vs apparent wind speed relative to a craft can produce craft velocities greater than the wind speed relative to the ground. By itself it doesn't prove this craft works
It does if you understand the kinematics of this craft and how the prop blades are directly analagous to the sail of the ice boat on a downwind tack.


Quote:
I do have some differences with some pro people here concerning the equivalency of a bidirectional analysis of force vectors, but only wrt efficiency.
That's because we are saying there is no "bidirectional analysis of force vectors". You can put whatever instrumentation you like on the cart - accelerometers, pitot-static system, measure the torque in the transmission, etc. and you will not find any difference between the cart on the belt and the cart on a stationary roadway with a tailwind. The first hint that should prove this case is that there is no such thing as a stationary roadway - not even remotely.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:53 AM   #315
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by my_wan View Post
the resistance of an object to motion through a fluid increases as the cube of the velocity.
Assuming a constant coefficient of drag, the resistance increases with the square of velocity. It's the power required that increases with the cube of velocity.

Quote:
So even though it is always possible for any given design to be improved to add some amount of top end speed, larger prop cross-section, etc., there remains an approximate practical limit.
The theoretical top end speed of this cart (relative to the wind) is given by the advance ratio (i.e. the distance the prop would theoretically carve forward through the air vs. the distance the wheels would drive it forward given one rotation of the prop). All other factors would simply reduce that top end.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:53 AM   #316
humber
Philosopher
 
Join Date: Dec 2007
Posts: 5,928
Originally Posted by sol invictus View Post
I see - so now not only is this device impossible, the laws of physics are wrong too. Ironically it's on the basis of those laws that you think it's impossible... yuck.

For the last 450 years or so physicists have understood that all motion is relative and that the laws of physics are invariant under boosts (i.e. identical in all situations that differ only by an overall shift in velocity). That's referred to as Galilean relativity - the "Galilean" part should give you a hint how old it is. Apparently that hasn't been enough time for it to percolate into some people's brains.

Anyway, we finally know where the difficulty lies - it has nothing to do with this device, it's just a failure to understand the basics of physics.
I see. We have 450 years of understanding, yet it seems that you are suggesting that the understanding of these laws is yuckky?
humber is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 07:59 AM   #317
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by humber View Post
Where's my $100K ?
I don't have the faintest clue. But if you find it you can put it in an escrow account with my $100K and we'll bet on what this cart does.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 08:02 AM   #318
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by technoextreme View Post
I'm an engineer too ...
I find that disturbing and terrifying if true.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 08:05 AM   #319
spork
Graduate Poster
 
Join Date: Nov 2008
Posts: 1,356
Originally Posted by Modified View Post
If a vehicle can average faster than the wind in some direction, then a connected pair or system of such vehicles which together constitute a single vehicle can maintain steady travel at (close to) that average speed.
Yes, but unless you show that the vehicles in question can average a downwind velocity component faster than the wind, connecting such vehicles doesn't get you there.
spork is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 13th November 2008, 08:06 AM   #320
technoextreme
Illuminator
 
technoextreme's Avatar
 
Join Date: Jun 2007
Posts: 3,785
Originally Posted by spork View Post
I find that disturbing and terrifying if true.
Same here buddy. Same here.
Quote:
It does if you understand the kinematics of this craft and how the prop blades are directly analagous to the sail of the ice boat on a downwind tack.
No the prop blades are directly analagous to a sail boat running directly into the wind. Your going backwards.
__________________
It's amazing how many of these "paranormal" icons seem to merge together. There always seem to be theories about how they link together in some way. I'm sure someone has a very good explanation as to how Bigfoot killed JFK to help cover Roswell.-Mark Mekes
This isn't rocket surgery.-Bill Nye
technoextreme is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Reply

International Skeptics Forum » General Topics » Science, Mathematics, Medicine, and Technology

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -7. The time now is 07:07 PM.
Powered by vBulletin. Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
2014, TribeTech AB. All Rights Reserved.
This forum began as part of the James Randi Education Foundation (JREF). However, the forum now exists as
an independent entity with no affiliation with or endorsement by the JREF, including the section in reference to "JREF" topics.

Disclaimer: Messages posted in the Forum are solely the opinion of their authors.