Perpetual motion proposal for criticism

[SteveThackery]

DWFTTW wasn't a fiasco - it was science in action. Despite what the "experts" expected, it worked. And those experts were forced to change their mind. That's how science works.

And who, exactly, had this "meltdown"? Who became unglued? The only unscientific thing to happen would be if the individuals in question denied the evidence in front of their eyes.

Having said that, this development did happen in an area where there was a high level of confidence, because it all fits comfortably in the realm of Newtonian physics. So we definitely did see a high level of scepticism. But that is not wrong: it is absolutely correct that where we have a high level of confidence, the bar is set high for any new claims that come along. And guess what - the claim of DWFTTW did, indeed, jump over that bar. Stuff was learned, and minds were changed.

By the way, I don't understand how it works, and I strongly suspect that some of the people who think they do, actually don't. But let's not get into all that again! 😄

[CatalinaWOW]

There may be some tricks around the OPs proposal that could allow some energy extraction.  For example curling the capillary tube down and treating the end with a material that has similar surface energy.   The existence of such a trick is obvious because some trees do weep sap and maple sugar taps do work without suction. 

The conservation of energy occurs on a larger scale.

The proposal fails on other grounds.  Limited scale and lousy economics.  Pouring buckets of maple sap through a turbine will generate trivial amounts of power and at costs shockingly higher than other methods.

Similar in that sense to an idea I had to generate fresh water and power for "free".  Simply put reverse osmosis membranes on a pipe running to deep seawater.   The difference in density between the fresh water in the pipe and seawater creates the pressure differential to drive the reverse osmosis and move the water through the pipe.  The physics works, but the depth required means many kilometers of pipe even in the most favorable locations, and servicing the filters at depth is also a real problem.   When I did rough numbers it didn't look appealing,  though it would be a sounder basis for a scam than most things out there.  Unfortunately for scam artists a real idea is easier to analyze than flim flam.

[SteveThackery]

There may be some tricks around the OPs proposal that could allow some energy extraction.  For example curling the capillary tube down and treating the end with a material that has similar surface energy.   The existence of such a trick is obvious because some trees do weep sap and maple sugar taps do work without suction. 

The conservation of energy occurs on a larger scale.

I think the conservation of energy operates at small scales as well. If it is ever possible to rig up something along the lines of your curled capillary tube, which drips water forever, then it must and will be extracting energy from something. Heat energy, maybe?

I'm reminded of those "drinking duck" toys. They appear to be perpetual motion provided the water supply is maintained. But in reality they extract heat energy from the air to evaporate the water.

[SteveThackery]

There may be some tricks around the OPs proposal that could allow some energy extraction.  For example curling the capillary tube down and treating the end with a material that has similar surface energy.   The existence of such a trick is obvious because some trees do weep sap and maple sugar taps do work without suction. 

I don't know enough to contradict you with confidence, but four different AIs insist that your method for continuous drips won't work, at least not indefinitely. They point out that weeping sap is driven by root pressure and maple sugar taps work on the pressure differentials arising from the freeze/thaw cycle.

The usual AI caveats apply.

[IanB]

I don't know enough to contradict you with confidence, but four different AIs insist that your method for continuous drips won't work, at least not indefinitely. They point out that weeping sap is driven by root pressure and maple sugar taps work on the pressure differentials arising from the freeze/thaw cycle.

The usual AI caveats apply.

You don't need AI. If you construct a device that continuously moves liquid uphill (by capillary action or otherwise), then it will require a continuous source of energy to keep working. If there is no source of mechanical energy, then it will necessarily use heat from the environment Whatever heat source it is using will cool down until the device stops working, unless you replenish the heat from outside.

(For a simple analogy, imagine a steam engine when the fire goes out. It will keep working based on its stored internal supply of heat and steam until it cools down too much, and then it will stop working until you add more heat.)

[IanB]

By the way, I don't understand how it works, and I strongly suspect that some of the people who think they do, actually don't. But let's not get into all that again! 😄

I know you don't want to get into that again, but really, the principle is not that complicated. It's all about gearing, like running a gearbox in reverse with a gear ratio greater than one. If you turn the input shaft slowly, the output shaft turns faster.

Similarly, the wind pushes at a slower speed, and through gearing the wheels turn at a faster speed. It's all about the gearing of the wheels in contact with the ground. If the craft were on a sled, on ice, it could never work, because there would be nowhere to apply the gearing against the ground.

One important thing to note: principles can be easy to understand, but that does not mean that an actual design is easy to accomplish.

For instance, I can describe the principle of operation of a wireless radio receiver, but that does not necessarily mean I can design and build a working example of one.

[SteveThackery]

Similarly, the wind pushes at a slower speed, and through gearing the wheels turn at a faster speed.

But when the cart is going faster than the wind, the wind isn't pushing at all. Rather, as the cart has a headwind, it's acting to slow down the cart.

[IanB]

But when the cart is going faster than the wind, the wind isn't pushing at all. Rather, as the cart has a headwind, it's acting to slow down the cart.

That's an (incorrect) statement, leading to a false conclusion.

If instead of making a statement like that, you were instead to ask a question, such as "How does the wind push the cart, when the cart is going faster than the wind speed?", then you could be enlightened.

[CatalinaWOW]

There may be some tricks around the OPs proposal that could allow some energy extraction.  For example curling the capillary tube down and treating the end with a material that has similar surface energy.   The existence of such a trick is obvious because some trees do weep sap and maple sugar taps do work without suction. 

I don't know enough to contradict you with confidence, but four different AIs insist that your method for continuous drips won't work, at least not indefinitely. They point out that weeping sap is driven by root pressure and maple sugar taps work on the pressure differentials arising from the freeze/thaw cycle.

The usual AI caveats apply.

Root pressure?  Giving a different name (and possibly different chemistry/physics) to the phenomena doesn't change the concept relative to being an energy source.  I suspect that root pressure is the real source of movement in maple sugar taps, though the freeze/thaw cycle may adjust the details of the process.  There is no fundamental reasons that the mechanisms involved have to be part of a biological system. But these added details are what I meant by energy being conserved on a larger scale.  To tally up the energy budget in these systems you have to go outside the simple capillary action in a closed tube and figure out how the water gets to the tube and how it returns from the capture cycle.  At a very fundamental level the source will turn out to be primarily the sun and possibly the stored thermal energy in the earth.  These mechanisms will place limits on the rate at which energy can be captured by processes of this type and I am quite sure that those rates will be low.

To say in a different way, a solar cell cannot deliver energy indefinitely.  There is an external source of energy, just as there are in these osmatic or possibly capillary systems.

[SteveThackery]

If instead of making a statement like that, you were instead to ask a question, such as "How does the wind push the cart, when the cart is going faster than the wind speed?", then you could be enlightened.

You mean the wind cannot push on the cart, but it can and does push against the backward-flowing jet of air from the fan?

[SteveThackery]

Root pressure?  Giving a different name (and possibly different chemistry/physics) to the phenomena doesn't change the concept relative to being an energy source.  I suspect that root pressure is the real source of movement in maple sugar taps, though the freeze/thaw cycle may adjust the details of the process.  There is no fundamental reasons that the mechanisms involved have to be part of a biological system. But these added details are what I meant by energy being conserved on a larger scale.  To tally up the energy budget in these systems you have to go outside the simple capillary action in a closed tube and figure out how the water gets to the tube and how it returns from the capture cycle.  At a very fundamental level the source will turn out to be primarily the sun and possibly the stored thermal energy in the earth.  These mechanisms will place limits on the rate at which energy can be captured by processes of this type and I am quite sure that those rates will be low.

To say in a different way, a solar cell cannot deliver energy indefinitely.  There is an external source of energy, just as there are in these osmatic or possibly capillary systems.

Of course, of course!

But: you used dripping sap and sugar taps as examples of capillary action producing continuous flow, with water/sap/sugar dripping out of the end, as the OP hoped would happen.

I pointed out that the motive force for dripping sap and sugar is not capillary action, it's root pressure, so your examples do not support the OP's idea.

All the research I've done says the same thing: pure capillary action cannot produce a continuous flow with water dripping out of the end.

[IanB]

You mean the wind cannot push on the cart, but it can and does push against the backward-flowing jet of air from the fan?

Almost, but not quite. The mathematics works that way, but the physics doesn't. The wind pushes on the moving surface of the fan blades, and due to the movement of the fan blades and the angle of attack, there is a net reaction force on the moving fan blades in the downwind direction.

[SteveThackery]

You mean the wind cannot push on the cart, but it can and does push against the backward-flowing jet of air from the fan?

Almost, but not quite. The mathematics works that way, but the physics doesn't. The wind pushes on the moving surface of the fan blades, and due to the movement of the fan blades and the angle of attack, there is a net reaction force on the moving fan blades in the downwind direction.

May I just question this? When the cart is going faster than the wind, I don't see how the wind can push against the fan blades. The fan - indeed the whole cart - is moving forward faster than the wind, so the wind cannot possibly push against anything physical on the cart. The wind gets left behind by the cart. The cart has a headwind, so there is no tailwind to push on any part of the back of the cart.

As I see it, the only thing which is not outrunning the wind is the air jet from the fan.

[paul cotter]

I haven't looked  into this at all and these are just my preliminary thoughts. I have no problem with thrust being generated, while traveling faster than the wind, once the prop is rotating fast enough- the problem with this is that the power to rotate the prop comes from the wheels and this will generate a braking force on the cart.

[IanB]

May I just question this? When the cart is going faster than the wind, I don't see how the wind can push against the fan blades. The fan - indeed the whole cart - is moving forward faster than the wind, so the wind cannot possibly push against anything physical on the cart. The wind gets left behind by the cart. The cart has a headwind, so there is no tailwind to push on any part of the back of the cart.

Even though the cart as a whole is going faster than the wind, the rear-facing surface of the rotating fan blade has a horizontal velocity component pushing back against the wind.

This is how a stationary desk fan is able to produce a breeze. Even though the fan as a whole is stationary, parts of the fan blade are pushing against the air and making the air flow away from the fan.

[IanB]

I haven't looked  into this at all and these are just my preliminary thoughts. I have no problem with thrust being generated, while traveling faster than the wind, once the prop is rotating fast enough- the problem with this is that the power to rotate the prop comes from the wheels and this will generate a braking force on the cart.

While what you say is true, the overall power balance on the cart is a net positive, so that the cart receives more energy from the wind than it loses to drag and other retarding forces, and therefore speeds up.

The basic situation is that the wind passing over the stationary ground creates a net velocity difference from which energy can be harvested. The cart, by having its wheels anchored to the ground by friction, and a fan engaged with the air through aerodynamics, is able to extract energy from the differential velocity between the wind and the ground, and is thus able to make itself go. By using careful selection of gearing between the wheels and fan blade geometry, the cart is able to do this even when it is moving downwind faster than the actual wind speed.

[SteveThackery]

May I just question this? When the cart is going faster than the wind, I don't see how the wind can push against the fan blades. The fan - indeed the whole cart - is moving forward faster than the wind, so the wind cannot possibly push against anything physical on the cart. The wind gets left behind by the cart. The cart has a headwind, so there is no tailwind to push on any part of the back of the cart.

Even though the cart as a whole is going faster than the wind, the rear-facing surface of the rotating fan blade has a horizontal velocity component pushing back against the wind.

This is how a stationary desk fan is able to produce a breeze. Even though the fan as a whole is stationary, parts of the fan blade are pushing against the air and making the air flow away from the fan.

But that's exactly what I said! The fan works as a fan, obviously. When it turns the fan blades push air backwards, again, obviously. But when the whole cart is moving faster than the wind, then the wind cannot push against any physical part of the fan. It CAN push against the backward jet of air from the fan.

[SteveThackery]

I haven't looked  into this at all and these are just my preliminary thoughts. I have no problem with thrust being generated, while traveling faster than the wind, once the prop is rotating fast enough- the problem with this is that the power to rotate the prop comes from the wheels and this will generate a braking force on the cart.

This is at the heart of why I suspect some people who claim to understand it actually don't. The wheels must subtract more energy from the cart than the fan can add to the cart.  And that must be true regardless of what gearing is used.

Having said that, I'm obviously wrong!

EDIT : What I would like to see is the whole experiment repeated under fully controlled conditions in a lab. In particular I want to see that there is no energy storage and release, giving a temporary FTTW speed. Outside, the wind direction and strength varies from moment to moment, so the lack of controls means it's not a very scientific experiment.

[IanB]

But that's exactly what I said! The fan works as a fan, obviously. When it turns the fan blades push air backwards, again, obviously. But when the whole cart is moving faster than the wind, then the wind cannot push against any physical part of the fan. It CAN push against the backward jet of air from the fan.

It's subtle, but that's not a correct explanation according to physics. To apply force to the cart, the air (wind) has to push directly against the cart itself. If the wind pushes against a backwards jet of air from the fan it cannot apply any force to the cart as air is a fluid, and when unconstrained it cannot transmit force. Imagine there is a balloon floating in the room, and you try to push it with your hand without touching the balloon. The balloon will not move, because the air is not rigid and cannot transmit the force from your hand. But connect the balloon to your hand with a solid rod, and now the balloon will move.

Similarly, if the forward flowing wind meets the backwards jet of air from the fan on the cart, the two air streams will tend to cancel each other out, but this will apply no force to the cart. Once the air has left the fan it is no longer in contact with the fan (or cart), and whatever happens to that air stream after that is no longer the cart's concern.

What actually happens is that the rotating fan blades push against the air in contact with them, and this generates a reaction force that pushes the cart along. Imagine putting a desk fan on a cart, and pulling the cart along in a downwind direction. Even though the cart is moving downwind faster than the surrounding air, it will still manage to blow air backwards.

[SteveThackery]

When I said "pushes against the air jet" I meant that the nett effect will be an increase in air pressure behind the fan. A fan increases the air pressure in front of it and decreases the pressure behind it. Moving air doesn't behave like a theoretically perfect fluid because it has mass (which gives it both kinetic energy and inertia) and viscosity, both of which slightly constrain it.  That is why a fan produces a "jet" of air, even though the air isn't constrained.

Put two fans face to face. Switch them on. They will push each other apart because they create a high pressure zone between them. Replace one of the fans with an air stream, and the other fan will still be pushed away. So yes, I think an air stream can push against a fan by interacting with the air jet from the fan, pushing the fan away.

[SteveThackery]

What actually happens is that the rotating fan blades push against the air in contact with them, and this generates a reaction force that pushes the cart along.

Which brings us right back to where we started. Your explanation doesn't take into account the reaction force the other way from the wheels. Forgive me for repeating myself, but the fan cannot add more thrust than the wheels subtract, because that would be over-unity.

[IanB]

Put two fans face to face. Switch them on. They will push each other apart because they create a high pressure zone between them. Replace one of the fans with an air stream, and the other fan will still be pushed away. So yes, I think an air stream can push against a fan by interacting with the air jet from the fan, pushing the fan away.

Replace one of the fans with a wall, and the other fan will still push itself along.

Remove the wall entirely, and the other fan will still push itself along.

Pressure is really the wrong intuition here.

The moving air leaving a fan actually has a lower pressure than the surrounding air. If you use a smoke generator, you will see the smoke getting sucked into the moving air stream.

[IanB]

Which brings us right back to where we started. Your explanation doesn't take into account the reaction force the other way from the wheels. Forgive me for repeating myself, but the fan cannot add more thrust than the wheels subtract, because that would be over-unity.

This does not imply over-unity.

On the contrary, having more thrust from the fan than the retarding force from the wheels is the only way the cart can accelerate. This is Newtonian physics.

No energy balances are violated, because in the overall system energy is transferred from the wind to the cart.

[IanB]

@XenaE

Since the forum says you have blocked personal messages, here is a public message instead.

I have read your note and responded to it by deleting/editing my posts to clean up the thread.

With sincere regards. I have no animosity towards anyone.

[SteveThackery]

On the contrary, having more thrust from the fan than the retarding force from the wheels is the only way the cart can accelerate. This is Newtonian physics.

But that's now a circular argument - it works because it obeys Newton's laws. Well of course it does. That doesn't explain how it works.

I don't believe it is possible for a wheel-driven fan to create more thrust than the drag from the wheels, otherwise it really would look exactly like over-unity.  The fan would need to be over 100% efficient. Such a vehicle would drive itself along even in still air. Impossible.