Merged DDWFTTW in a “Real” Wind

[profpangloss]

So what you're saying is that you don't want to educate me as to the mistake as you see it, you just want to provide the information in as confusing a format as possible, obfuscate your point and then be sarcastic?

Fair enough, but it does seem to demonstrate that rather than have a reasoned debate in which you clearly say what you mean, you'd rather snipe from the sidelines and not present your information in the manner that has been traditional for years and that everyone is used to.

I thought that the whole point of your argument was to:



So now, when presented with the opportunity, you baulk?

I think it is more than clear enough to follow if you want to. The trouble is, you are invested in your belief, and no amount of cold hard facts, even mathematical facts, is likely to relieve you of your belief.

On the unlikely chance I am wrong about you, at least make an effort to read through and tell me what part you don't understand. If you come back and tell me the cart is using ground power, then I won't waste my time or yours trying to correct that delusion. You may keep it.

 

[humber]

And that reason is implicit in jduffy's post. A Cessna is not designed to go faster than the wind DDW, powered only by the wind on the ground.

Magical. A new set of physical laws for ddw. Not by accident, because that is what Spork is claiming.

 

[humber]

On the unlikely chance I am wrong about you, at least make an effort to read through and tell me what part you don't understand. If you come back and tell me the cart is using ground power, then I won't waste my time or yours trying to correct that delusion. You may keep it.

Yes. They do put rather a high premium on what is only their opinion, but are way to lazy to support it. Indeed, let them keep them in the dowry chest.

 

[Llyricist]

Yes of course, push that sucker because it won't go anywhere any other way!

No, I pushed it because you don't believe it could get there any other way.

That's the only energy there is, unless of course you believe in that magical mystical ground energy? You don't really do you?

Nope, the energy comes from the air's motion in the "ground's frame".

I have already done it correctly. There is no ground power, it does not exist, forget it.

Energy is frame dependent, but yes, in the "ground's frame", the ground has no power to give. And I didn't claim it did, you are arguing against a straw man.

The friction with the ground takes kinetic energy out of the cart.

No, the cart would have to slow down if that were the case, and it would have to slow down due to a net force acting against its motion. You have demonstrated no such force.

I delineated all the losses exactly as you specified them. The cart is leaking energy all over the place, and the wind does not have enough to give it even with the propeller trying to spin using the cart's own kinetic energy. The entire idea is ridiculous.

Yes, using the KE of the cart to spin the propeller would be ridiculous, which is why I didn't use the KE of the cart to spin the prop. I used the negative work of the propeller itself on the cart's forward motion to spin it.

 

[jduffy77]

I think it is more than clear enough to follow if you want to. The trouble is, you are invested in your belief, and no amount of cold hard facts, even mathematical facts, is likely to relieve you of your belief.

On the unlikely chance I am wrong about you, at least make an effort to read through and tell me what part you don't understand. If you come back and tell me the cart is using ground power, then I won't waste my time or yours trying to correct that delusion. You may keep it.

What is delusional is choosing a frame in which the cart is at rest and then posting silly equations which assume that the ground has no KE which a 6th grader could correct.

 

[humber]

Nope, the energy comes from the air's motion in the "ground's frame".
Energy is frame dependent, but yes, in the "ground's frame", the ground has no power to give. And I didn't claim it did, you are arguing against a straw man.

But, the submission report expressly uses it. However, there is no energy available from the ground, so can be completely ignored, leaving you with a prop that extracts energy from the wind, to drive itself faster than the wind, ddw. A theory that bases itslef on abstracted relative motion, but gratuitously includes the ground.

 

[jduffy77]

But, the submission report expressly uses it. However, there is no energy available from the ground, so can be completely ignored, leaving you with a prop that extracts energy from the wind, to drive itself faster than the wind, ddw. A theory that bases itslef on abstracted relative motion, but gratuitously includes the ground.

Another Humber reset post. He has been shown in great detail that this post is not what is happening. Everyone knows this is not what is happening. But he posts the statements anyway as if all the intervening explanations did not exist. He knows the ground is required in order to leverage the wheels.

 

[humber]

Another Humber reset post. He has been shown in great detail that this post is not what is happening. Everyone knows this is not what is happening. But he posts the statements anyway as if all the intervening explanations did not exist. He knows the ground is required in order to leverage the wheels.

The Catechism "reset post" only serves to demonstrate palpable levels of belief.

 

[Michael C]

But, the submission report expressly uses it. However, there is no energy available from the ground, so can be completely ignored, leaving you with a prop that extracts energy from the wind, to drive itself faster than the wind, ddw. A theory that bases itslef on abstracted relative motion, but gratuitously includes the ground.

For those who are interested in seeing what the submission report really says, it's here. There's a good explanation of how the cart works. Here's how it ends:

"The simple explanation is that the vehicle acts as a lever between two media (the ground and the air). Like any lever we can trade a small force over a large distance for a larger force over a smaller distance. This is how we get more thrust from the prop than we create drag at the wheels (since the wheels are moving over the ground faster than the prop is moving through the air –due to the tailwind)."​

There is also a succinct explanation of why the vehicle performs best when travelling directly downwind.

 

[3point14]

I won't waste my time or yours trying to correct that delusion. You may keep it.

Right back at ya.

 

[profpangloss]

No, I pushed it because you don't believe it could get there any other way..

Quite right, except for the word "believe". Based on the fundamentals of physics, and all known experience with sail craft going DDW, I know the cart won't get there any other way than pushing (or towing).

Nope, the energy comes from the air's motion in the "ground's frame"..

Neat trick, since the 295 kg cart @ 9 m/s has a hell of a lot more kinetic energy than that 72 kg of wind moving @ 7 m/s. Anyone here for reverse thermodynamics?

Energy is frame dependent, but yes, in the "ground's frame", the ground has no power to give. And I didn't claim it did, you are arguing against a straw man
..

Good, so we get the ground energy out of this, and the cart has more kinetic energy than that 72 kg parcel of wind. Now what?

No, the cart would have to slow down if that were the case, and it would have to slow down due to a net force acting against its motion. You have demonstrated no such force...

I have to demonstrate friction to you? Roll a coin across a level floor. The force that stops it is friction. Satisfied?

Yes, using the KE of the cart to spin the propeller would be ridiculous, which is why I didn't use the KE of the cart to spin the prop. I used the negative work of the propeller itself on the cart's forward motion to spin it..

Which is even more ridiculous. There is no useful wind force acting on the propeller above wind speed, unless the propeller is spinning. Now you want to use the wind force to spin the propeller for you just so it can act on it. Is there anything else you might want the wind to do for you? Is that how you perpetual motion gurus really talk; "I used the negative work of the propeller itself on the cart's forward motion to spin it". That is just nonsensical enough for some people to believe it. Nice work!

 

[humber]

For those who are interested in seeing what the submission report really says, it's here. There's a good explanation of how the cart works. Here's how it ends:

"The simple explanation is that the vehicle acts as a lever between two media (the ground and the air). Like any lever we can trade a small force over a large distance for a larger force over a smaller distance. This is how we get more thrust from the prop than we create drag at the wheels (since the wheels are moving over the ground faster than the prop is moving through the air –due to the tailwind)."​

There is also a succinct explanation of why the vehicle performs best when travelling directly downwind.

And the rest, which is also necsience. The "air lever" is a fantasy.

"The simple explanation is that the vehicle acts as a lever between two media (the ground and the air). Like any lever we can trade a small force over a large distance for a larger force over a smaller distance. This is how we get more thrust from the prop than we create drag at the wheels (since the wheels are moving over the ground faster than the prop is moving through the air –due to the tailwind)."


When the ratio of force to velocity changes, as with a lever, the power remains constant, so work/time remains constant.


The explanation of the ddw is best performance is totally bogus, but the power output of a turbine falls as the cube of the cosine away from the direct line with the wind. That makes the force from the opposing tailwind a maximum when ddw.

It seems to me that the post above by Profpangloss, says it all, really. A massive cart taking energy from the wind, where it has more energy than the wind.

 

[profpangloss]

And the rest, which is also necsience. The "air lever" is a fantasy.

"The simple explanation is that the vehicle acts as a lever between two media (the ground and the air). Like any lever we can trade a small force over a large distance for a larger force over a smaller distance. This is how we get more thrust from the prop than we create drag at the wheels (since the wheels are moving over the ground faster than the prop is moving through the air –due to the tailwind)."


When the ratio of force to velocity changes, as with a lever, the power remains constant, so work/time remains constant.


The explanation of the ddw is best performance is totally bogus, but the power output of a turbine falls as the cube of the cosine away from the direct line with the wind. That makes the force from the opposing tailwind a maximum when ddw.

It seems to me that the post above, says it all, really. A massive cart taking energy from the wind, where it has more energy than the wind.

Air levers, ground energy, I would really like to see them submit a paper for peer review with all these wonderful marvels of physics. I would suggest they add a sky hook, to keep that cart in the frame of the wind. That's about all the non-science and amusement I can take for today. I can't wait to see what they come up with tomorrow!

 

[Llyricist]

Quite right, except for the word "believe". Based on the fundamentals of physics, and all known experience with sail craft going DDW, I know the cart won't get there any other way than pushing (or towing).

In the case of this particular piece of crap cart, I would hesitate to say it would get there on its own myself, but for very different reasons than yours.

Neat trick, since the 295 kg cart @ 9 m/s has a hell of a lot more kinetic energy than that 72 kg of wind moving @ 7 m/s. Anyone here for reverse thermodynamics?

Anyone here know the difference between thermodymaics and mechanical systems?

A taxiing Cessna with a tailwind would have a lot more KE than the volume air it slows down, but it still gains energy from that air.

Good, so we get the ground energy out of this, and the cart has more kinetic energy than that 72 kg parcel of wind. Now what?

So now the wind loses 818 J of energy more than the cart gains.

I have to demonstrate friction to you? Roll a coin across a level floor. The force that stops it is friction. Satisfied?

I wasn't talking about friction, I was talking about the prop's negative work.

Which is even more ridiculous. There is no useful wind force acting on the propeller above wind speed, unless the propeller is spinning. Now you want to use the wind force to spin the propeller for you just so it can act on it. Is there anything else you might want the wind to do for you? Is that how you perpetual motion gurus really talk; "I used the negative work of the propeller itself on the cart's forward motion to spin it". That is just nonsensical enough for some people to believe it. Nice work!

Keep proving you don't understand how to do energy bookkeeping.

 

[humber]

Anyone here know the difference between thermodymaics and mechanical systems?

See Joule and how heat and work are equated.

A taxiing Cessna with a tailwind would have a lot more KE than the volume air it slows down, but it still gains energy from that air.

See "engine". See how a combustion engine is a heat engine.

I wasn't talking about friction, I was talking about the prop's negative work.

Tractor pulls plow. Plow does negative work on tractor. Tractor does work on ground via plow. Tractor does more work on the plow, than the plow does negative work on the tractor.

And you keep ignoring the failure of the theory against practice.

 

[Llyricist]

See Joule and how heat and work are equated.

No, you see it, and try to comprehend it.

See "engine". See how a combustion engine is a heat engine.

The engine is irrelevant, but its par for the course for you guys to bring up red herrings.

There is no principle that an object with lower KE cannot transfer energy to an object with higher KE, the case of the Cessna just serves to prove it actually happening.

 

[humber]

No, you see it, and try to comprehend it.

Physics4kids
Top line: heat is energy.
http://www.physics4kids.com/files/thermo_intro.html

The engine is irrelevant, but its par for the course for you guys to bring up red herrings.

"Engines in planes are irrelevant"

There is no principle that an object with lower KE cannot transfer energy to an object with higher KE, the case of the Cessna just serves to prove it actually happening.

Uh, huh.
http://zonalandeducation.com/mstm/physics/mechanics/energy/energy.html
http://en.wikipedia.org/wiki/Elastic_collision

 

[Jack by the hedge]

It seems to me that the post above by Profpangloss, says it all, really. A massive cart taking energy from the wind, where it has more energy than the wind.

Yeah, that pretty well sums it up. I mean - a sailing ship weighing hundreds of tons being pushed along by barely a ton of wind - who'd believe anything as crazy as that could work? You guys really got this science thing down.

 

[ThinAirDesigns]

JBTH - I believe humber is referring to the well known "conservation of speed" law.

JB

 

[Subduction Zone]

humber, heat is energy, you have that right. But you are implying an incorrect logical conclusion. Let me demonstrate. All goats are mammals. humber is a mammal. Therefore according to humber logic humber is a goat. Ooops, bad example. Oh well substitute almost anyone else' name and you will understand the error.