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Topic: Direct Down Wind Faster Than The Wind (Read 24383 times) previous topic - next topic

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  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2250
"A couple of years back, Rick Cavallaro and his wind-powered car--Blackbird--silenced an online debate about whether its possible for a wind-powered vehicle to move downwind faster than the speed of the wind itself by going out and outrunning the wind."
 July 11, 2012
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2251
In 2020 one lone voice of reason will be still mocking everyone else for falling for this huge scam.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #2252
In 2020 one lone voice of reason will be still mocking everyone else for falling for this huge scam.

As I said earlier, as long as YOU believe in this, FX, the more sure I am that it is nonsense.
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

Re: Direct Down Wind Faster Than The Wind
Reply #2253
One of the more interesting arguments about the cart on the treadmill centers on the idea of relative motion. It seems that the believers in ddwfttw think that applying a force to move a belt under a wheel must be the same as applying a force to move a wheel over the belt.  While this kind of reciprocity is considered to be some sort of fundamental truth in mechanics, it may shock some people to learn it is not universally true!
It is true that if a force F is applied to one end of a sliding block, and then the same force F is applied to the other end of the same block, the resulting motions of the block will be symmetrical; the block behaves the same in both directions.
However, if the physical system is more complex, involving springiness and rotations, as the cart on the belt does, there is no guarantee that the motion will be symmetrical in such a non-linear system. In fact, there is currently quite a lot of research being done in this area, with several materials already being made that exhibit this non-symmetrical, non-linearity to motion.
That is just one more nail in the coffin for the claim that the treadmill cart, being powered by the belt, says something about a cart on a road powered by the wind.
Before anyone claims that this is denying Galileo, no, it is not! The GT of the cart on the belt is just changing the frame of reference while staying with the same situation; it is always a cart on a treadmill, powered by the belt.
What the carters are claiming is a magical transform; that a cart on a belt, powered by the belt, is the same as a cart in the wind, powered by the wind and that is total nonsense!





"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2254
haha
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #2255
One of the more interesting arguments about the cart on the treadmill centers on the idea of relative motion. It seems that the believers in ddwfttw think that applying a force to move a belt under a wheel must be the same as applying a force to move a wheel over the belt.  While this kind of reciprocity is considered to be some sort of fundamental truth in mechanics, it may shock some people to learn it is not universally true!
It is true that if a force F is applied to one end of a sliding block, and then the same force F is applied to the other end of the same block, the resulting motions of the block will be symmetrical; the block behaves the same in both directions.
However, if the physical system is more complex, involving springiness and rotations, as the cart on the belt does, there is no guarantee that the motion will be symmetrical in such a non-linear system. In fact, there is currently quite a lot of research being done in this area, with several materials already being made that exhibit this non-symmetrical, non-linearity to motion.
That is just one more nail in the coffin for the claim that the treadmill cart, being powered by the belt, says something about a cart on a road powered by the wind.
Before anyone claims that this is denying Galileo, no, it is not! The GT of the cart on the belt is just changing the frame of reference while staying with the same situation; it is always a cart on a treadmill, powered by the belt.
What the carters are claiming is a magical transform; that a cart on a belt, powered by the belt, is the same as a cart in the wind, powered by the wind and that is total nonsense!

Hyeveinz, you are a loon.

Re: Direct Down Wind Faster Than The Wind
Reply #2256
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2257
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2258
People who release helium balloons to end up in the ocean are murderers of animals.

"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2259
Somebody had to say it.
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #2260
One of the more interesting arguments about the cart on the treadmill centers on the idea of relative motion. It seems that the believers in ddwfttw think that applying a force to move a belt under a wheel must be the same as applying a force to move a wheel over the belt.  While this kind of reciprocity is considered to be some sort of fundamental truth in mechanics, it may shock some people to learn it is not universally true!
It is true that if a force F is applied to one end of a sliding block, and then the same force F is applied to the other end of the same block, the resulting motions of the block will be symmetrical; the block behaves the same in both directions.
However, if the physical system is more complex, involving springiness and rotations, as the cart on the belt does, there is no guarantee that the motion will be symmetrical in such a non-linear system. In fact, there is currently quite a lot of research being done in this area, with several materials already being made that exhibit this non-symmetrical, non-linearity to motion.
That is just one more nail in the coffin for the claim that the treadmill cart, being powered by the belt, says something about a cart on a road powered by the wind.
Before anyone claims that this is denying Galileo, no, it is not! The GT of the cart on the belt is just changing the frame of reference while staying with the same situation; it is always a cart on a treadmill, powered by the belt.
What the carters are claiming is a magical transform; that a cart on a belt, powered by the belt, is the same as a cart in the wind, powered by the wind and that is total nonsense!

Hyeveinz, you are a loon.

Do you have anything of substance to say about what I wrote?

Maybe you know of some law of physics which contradicts me?

Or is blathering idiocy all you have to offer?
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

Re: Direct Down Wind Faster Than The Wind
Reply #2261
People who release helium balloons to end up in the ocean are murderers of animals.



As compared to all the plastic bags in the oceans?
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2262
Plastic bags thrown in rivers  = animal murder
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #2263
Plastic bags thrown in rivers  = animal murder

For once I can agree. The amount of plastic in the oceans is astounding and it kills everything from the tiniest animals to the largest. It's a real problem.
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2264
One of the more interesting arguments about the cart on the treadmill centers on the idea of relative motion. It seems that the believers in ddwfttw think that applying a force to move a belt under a wheel must be the same as applying a force to move a wheel over the belt.
There is a problem with a treadmill vs moving over the ground being the same, and I brought this up several times.  For a cart powered by an engine it is certainly not the same. (why it doesn't matter in regards to the ddwfttw cart was also covered)

But to be fair the two are not the same for a runner, or a cart using a motor.  Because a cart that can do 10 mph on level ground with no wind will outrun a treadmill at 10 mph, because on the treadmill there is no headwind.  Same for running on  treadmill, you don't have wind resistance on a treadmill, and yes it matters.

I can run "faster" on a treadmill than on a track, because on a treadmill there is no apparent wind to deal with.  This really matters when you are running at top speed.  (this was discussed before)

A powered cart doing 20 mph on a treadmill will not use the same energy as the cart on solid ground with no wind, because on the treadmill there is no 20 mph apparent headwind to deal with.

Spork and other explained why this isn't an issue with the ddwfttw cart

The cart on a treadmill is the same as solid ground with a tailwind.  That's the difference. The cart isn't powered.  In fact, it is the apparent tail wind created by being on a treadmill that is the source of the power.  Not the treadmill moving. If you place a regular cart on a moving treadmill it will go backwards until it "feels" the virtual wind, at which point it will move backwards minus the "wind", but it will never advance against the treadmill.

It would be like a cart sitting in a wind.  Which is why we used an aircraft carrier moving as an example.

  • Last Edit: May 21, 2018, 09:41:21 AM by F X
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

  • F X
  • The one and only
Re: Direct Down Wind Faster Than The Wind
Reply #2265
At which point we are 10 years back in time arguing the exact same shit
"If you pick up a starving dog and make him prosperous he will not bite you. This is the principal difference between a dog and man."
― Mark Twain 🔭

Re: Direct Down Wind Faster Than The Wind
Reply #2266
The wind resistance isn't a problem since a cart that is at windspeed will have the same wind resistance as one in still air on the treadmill.

There is a real problem though, with the contact patch being different for a wheel that is rolling on the ground and for a wheel being turned by a belt. I have shown this several times now, with diagrams. People can deny it all they like but none can refute it with any sort of coherent argument.

That is just part of the problem though. The other part is the fact that the treadmill cart is held down on the belt to initially spin up the propeller. That act of holding the cart down is countering the reaction force from the belt driving the wheel. That force acts upwards. When the cart is released, that reaction force reduces traction and by extension reduces wheel drag. With reduced wheel drag the cart can advance. Nothing similar happens with a cart on a road in a wind. The simple math of Power = Force x Velocity says that with full traction the prop thrust will never be greater than wheel drag.

As I have just written, there is no law of physics that says that motion must be symmetrical in a non-linear system. That is, the motion does not necessarily act the same if the same force is applied at different ends of the system, due to things rotating and springs being compressed, which is what you have with a wheel on an elastic belt. The transform that is being claimed by the carters, from a cart on a treadmill to a cart on a road in the wind, is not a Galilean transform in any sense, it is just a load of horseshit.

Finally, there is no evidence in the outdoors to support the claim. The balloons offered a chance to provide such evidence and that was a failure.

All in all, ddwfttw remains a fantasy, nothing more.
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

Re: Direct Down Wind Faster Than The Wind
Reply #2267
At which point we are 10 years back in time arguing the exact same shit

You have a point there. Without any scientific evidence it really is a pointless argument, but somebody has to counter crackpots.
  • Last Edit: May 21, 2018, 10:03:13 AM by Heinz Hershold
"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

Re: Direct Down Wind Faster Than The Wind
Reply #2268
At which point we are 10 years back in time arguing the exact same shit

You have a point there. Without any scientific evidence it really is a pointless argument, but somebody has to counter crackpots.

Could you share with us what your definition of "crackpot" is?

Re: Direct Down Wind Faster Than The Wind
Reply #2269
The simple math of Power = Force x Velocity says that with full traction the prop thrust will never be greater than wheel drag.


Ahh, yes, the old Law of Conservation of Force. Can you provide references, a derivation, anything?

Re: Direct Down Wind Faster Than The Wind
Reply #2270
The simple math of Power = Force x Velocity says that with full traction the prop thrust will never be greater than wheel drag.


Ahh, yes, the old Law of Conservation of Force. Can you provide references, a derivation, anything?

You need a derivation for P=FV

No wonder you are a sucker for ddwfttw!

"When a true genius appears in this world, you may know him by this sign, that the dunces are all in confederacy against him." (Jonathan Swift)

  • uncool
Re: Direct Down Wind Faster Than The Wind
Reply #2271
You're making the same class of mistake humber, F_X, socrates, and Dave make there, Heinz.

semper isn't saying that p=fv is wrong. He's saying that your conclusion based on it is wrong, implying that the mistake is in your derivation. That p=fv is correct, but that your application is wrong.

Re: Direct Down Wind Faster Than The Wind
Reply #2272
Good god man, pull yourself together Heinz.
Love is like a magic penny
 if you hold it tight you won't have any
if you give it away you'll have so many
they'll be rolling all over the floor

  • MikeB
Re: Direct Down Wind Faster Than The Wind
Reply #2273
Guys, relax.  Earlier in the run, when I released the balloons, we were not quite directly downwind and the BB was prevented from turning (by a coned off area) to follow the balloons.  That is why I was remarking (in the video) that I should have waited until later, when the BB was free of the coned area, and I could have made a better job of it.  At that point, recording the video, we certainly were traveling essentially directly downwind.

We had been asking the BB driver, Steve, what the controls were like and if the variable pitch control had much force feedback.  He replied that it was surprisingly little.  Then he also noted that it seemed pretty easy to sense when he was angling off the wind direction, as that would have a noticeable effect in slowing the BB when he got more than some amount off.  He said that turning near a right angle with the wind would quickly bring the BB to a stop.

I had been keeping track of the wind direction, there were streamers and flags here and there to help, and I can assure you that in the part of the run I videoed we were close enough to directly downwind that we were getting full performance for that weak wind.  Angling off wind direction only hurts the BB performance.

If the BB ever get out to El Mirage again, I'll try to manage the balloon demo better, and will either take a less worried friend or just re-think it and do everything myself.

Edit - just noticed comments that if I drove 90 degrees to the wind direction, directly cross wind at 20 mph in a 20 mph wind, that the streamer would point straight back?  No, it would point 45 degrees from straight back.  This streamer was close to six feet away from the side of the car and well above the lake bed, so it would have been able to show that.
  • Last Edit: May 21, 2018, 04:38:45 PM by MikeB

  • Fenrir
Re: Direct Down Wind Faster Than The Wind
Reply #2274
Teehee.

Someone takes their cart for a belt on a lake. Cue 10 pages of abdominal discomfort.
It's what plants crave.