Down wind faster than the wind

[Modified]

The cart moves directly down wind, I think? Tacking devices move across the wind, forcing the craft to travel further ( that's one of a number of possibilities).

We've already resolved that. You can connect two boats that are tacking back and forth at opposite angles with a sliding bar system. The system as a whole can then travel straight downwind faster than the wind.

 

[Modified]

If the belt is the road, it represents a moving mass. Yes, the vehicle moves away at belt speed , but its kinetic energy is not equal to that of the car, would it be going at belt speed, because for one thing, it has much less mass than the car.

If you're riding the belt at belt speed and run into the car, or if you are still on the road and the car runs into you at the same speed, the kinetic energy of the car with respect to you will be the same, and the collision will have the same result. Now just replace "you" with "the air".

 

[humber]

If you're riding the belt at belt speed and run into the car, or if you are still on the road and the car runs into you at the same speed, the kinetic energy of the car with respect to you will be the same, and the collision will have the same result. Now just replace "you" with "the air".

There is still a problem. Momentum transfer during collisions depends not only on the velocity, but the contact time, the frictions relative to the ground, for example. I would need to have the same contact with the belt, as a car would with the road, just as a starter.
Also the total amount of kinetic energy seems to be low. Me traveling at 10mph, and a car traveling at 10mph.

Now just replace "you" with "the air".

Now there's a problem. The air is not moving.

 

[humber]

We've already resolved that. You can connect two boats that are tacking back and forth at opposite angles with a sliding bar system. The system as a whole can then travel straight downwind faster than the wind.

I see, we are not talking about the cart that is on the belt?

 

[Myriad]

The cart moves directly down wind, I think? Tacking devices move across the wind, forcing the craft to travel further ( that's one of a number of possibilities).

The propeller blades move across the wind. And they travel (in a helical path) considerably farther than the cart.

Humber, do you think it is possible for an entirely wind-powered vehicle to move directly against the wind, or would that have to be over-unity also? To be clear I'm talking about continuous straight-line motion directly against a steady wind, on flat ground, after accelerating from a standing start by wind power alone. And nothing fancy, no electric generators or motors, no multiple tacking vehicles connected by sliding rods. Just wheels, gears, linkages, and a conventional vaned windmill rotor.

Respectfully,
Myriad

 

[Michael C]

Yes, but I meant which output. Velocity..torque. Just not defined is what I meant.

?

Gears trade off velocity for torque, but the work done is always the same.

Agreed.

A machine that produced more work than put into it, would be over-unity.

Agreed, but that isn't the case with the vehicle presented here.

That gearing up is not possible, because speed will be traded for torque, so the same work will be done, but at a different prop speed.
Therefore no magical increase in velocity.

An increase in speed is traded here for a decrease in force. The faster the craft goes, the less load it can pull. No need for magic.

 

[GreyICE]

Do you mean watts or watt/hours?

I mean watts, obviously. Watt hours would be useful if... um... cost estimation? Seriously, no, when would I want to use those units for a heat load application.

Whether "power" = "heat" depends upon the load. For a purely resistive load, that is correct. For a reactive load, not necessarily.
All the input energy will be converted directly to heat unless stored, or to some other form, then dissipated. Heat to mechanical motion to heat, or sound to heat. Painless, but true, as long as you know your units.

I've had engineers argue it with me. Given how you're arguing my side, I'd say you just like showing off your knowledge and starting arguments where you feel superior. I enjoy arguments and am proud of my knowledge, but I think you'll discover on this board, at least, there are many people with equal or greater knowledge.

In this case, you're plain wrong. Wind provides power. There is no physical laws being violated. This is not overunity.

For an example, please consider heat. Elementary heat transfer would tell you if you had a heat source and an input at or above room temperature, the resulting temperature of all material moved through this heat source, absent any other power sources, would have a temperature between the two extremes.

This is very similar to your argument that the vehicle cannot outrun the wind, powered only by the wind as an input force.

I can assure you the above regarding heat is quite false.

 

[Modified]

There is still a problem. Momentum transfer during collisions depends not only on the velocity, but the contact time, the frictions relative to the ground, for example. I would need to have the same contact with the belt, as a car would with the road, just as a starter.

No, the car would have to have the same contact with the belt as it does with the road, and you would have to have the same contact with the belt as you do with the road. For a person getting hit by a car, of course, surface properties would matter little, unless they were bolted to the belt/road.

Now there's a problem. The air is not moving.

A vehicle moving with the belt will behave the same as one sitting still on the road in the wind.

 

[humber]

The propeller blades move across the wind. And they travel (in a helical path) considerably farther than the cart.

Humber, do you think it is possible for an entirely wind-powered vehicle to move directly against the wind, or would that have to be over-unity also? To be clear I'm talking about continuous straight-line motion directly against a steady wind, on flat ground, after accelerating from a standing start by wind power alone. And nothing fancy, no electric generators or motors, no multiple tacking vehicles connected by sliding rods. Just wheels, gears, linkages, and a conventional vaned windmill rotor.

Respectfully,
Myriad

Myriad,
This is possible. However, there is no reason not to consider an electrical device, with a "real time" generator and a motor. The same rules of Newtonian mechanics, and the conservation of energy would apply to this as to a purely mechanical device.

The reason why these sort of devices are regarded as contentious, is that they contradict our "folk physics" about things not going "against" the wind or uphill.
The same scientific ideas that inform us that these notions are often wrong, also inform us of what not possible.
In this case, the machine as first described in the original video, will not get to windspeed without additional energy. It seems that it cannot garner more than is available from the wind via the propeller, so to actually achieve windspeed, would require over-unity. I was pointing to a flaw in the argument, rather than saying that was a specific claim.

The "equivalency" argument is certainly nonsense. A car on a treadmill is not "the same" as a car in wind. Take a look at #682.

That is the equivalent to saying that bouncing a ball off the wall of a house, is the same as holding the ball and accelerating the house to hit it. This is done on the simple assumption that they will be "the same" because the reactive velocities are "the same".

Humber

 

[Brian-M]

It's the other aspect of the problem that doesn't make any sense what so ever and even the explanation that Brain-M gives is as cryptic as hell.

Sorry... I was trying to explain to Humber how it would start to work on a treadmill, to preempt any questions he might bring up.

On the road, the wind will simply push it forward. As it moves forward, the wheels begin to turn, which spins the propeller, pushing air back against the wind. As every action has an equal and opposite reaction, pushing air back pushes the cart forward even faster, which turns the propeller even faster... and so on.

 

[GreyICE]

Myriad,
This is possible. However, there is no reason not to consider an electrical device, with a "real time" generator and a motor. The same rules of Newtonian mechanics, and the conservation of energy would apply to this as to a purely mechanical device.

The reason why these sort of devices are regarded as contentious, is that they contradict our "folk physics" about things not going "against" the wind or uphill.
The same scientific ideas that inform us that these notions are often wrong, also inform us of what not possible.
In this case, the machine as first described in the original video, will not get to windspeed without additional energy. It seems that it cannot garner more than is available from the wind via the propeller, so to actually achieve windspeed, would require over-unity. I was pointing to a flaw in the argument, rather than saying that was a specific claim.

The "equivalency" argument is certainly nonsense. A car on a treadmill is not "the same" as a car in wind. Take a look at #682.

That is the equivalent to saying that bouncing a ball off the wall of a house, is the same as holding the ball and accelerating the house to hit it. This is done on the simple assumption that they will be "the same" because the reactive velocities are "the same".

Humber

Humber, a car on a treadmill in still air is certainly exactly the same as a car on a still road surface with a wind speed. To go to your house-ball analysis, lets consider the house and the ball. Does the system change if the 'wall' becomes the wall of a train moving at a constant 60 mph in a straight line? After all the wall you're throwing it into has considerable velocity.

Now lets change it a little. There's a 60 mph crosswind blowing when you throw the ball against the wall of a house. And the train is an open roof system on a still air day. And yet you STILL can't tell the difference, because it seems like a 60 MPH wind to you.

Sketch up the force diagram yourself. Trim all the irrelevancies and you'll see the ball-wall system is exactly the same whether the wind is actual wind, or if it's still air and the train is constant velocity.

 

[humber]

I mean watts, obviously. Watt hours would be useful if... um... cost estimation? Seriously, no, when would I want to use those units for a heat load application.
I've had engineers argue it with me. Given how you're arguing my side, I'd say you just like showing off your knowledge and starting arguments where you feel superior.

Then you will appreciate that I am not going to show you that you have just compounded the error.

I enjoy arguments and am proud of my knowledge, but I think you'll discover on this board, at least, there are many people with equal or greater knowledge.

What can I say? A veiled compliment. I would have to assume that I were the world's most knowledgeable person to hold out for that idea. I do happen to use electrical analoges, so I notice.

In this case, you're plain wrong. Wind provides power. There is no physical laws being violated. This is not overunity.
For an example, please consider heat. Elementary heat transfer would tell you if you had a heat source and an input at or above room temperature, the resulting temperature of all material moved through this heat source, absent any other power sources, would have a temperature between the two extremes.
This is very similar to your argument that the vehicle cannot outrun the wind, powered only by the wind as an input force.
I can assure you the above regarding heat is quite false.

Well, I have made no claims about heat, except to comment on your comment.
There is quite a distinction between force and energy, and the comparison you give is invalid. A device traveling through a medium such as air faces resistance. The energy or power if you wish, must overcome that resistance. There is a balance, a forced-feedback balance, between velocity and drag, which would require a sum total of more than 100% to go beyond the normally accepted barrier.

This is so trivial in comparison with the general claim. I could have said that there would not be enough force to achieve the same end.

I am bemused that this is seized upon, when the elephant in the room, is the sham that is the treadmill. A device used to promote an idea, with which it has but a superficial similarity.

 

[GreyICE]

Then you will appreciate that I am not going to show you that you have just compounded the error.

Translation: I have no practical experience in the real world.

What can I say? A veiled compliment. I would have to assume that I were the world's most knowledgeable person to hold out for that idea. I do happen to use electrical analoges, so I notice.

Well, I have made no claims about heat, except to comment on your comment.
There is quite a distinction between force and energy, and the comparison you give is invalid. A device traveling through a medium such as air faces resistance. The energy or power if you wish, must overcome that resistance. There is a balance, a forced-feedback balance, between velocity and drag, which would require a sum total of more than 100% to go beyond the normally accepted barrier.

Nonsense. Your claim is obviously ludicrous. You admit as much yourself. Energy is energy. It requires no overunity to extract energy from an energy source and use it to move a vehicle.

The normally accepted barrier for velocity is THE SPEED OF LIGHT. There is no other normally accepted barrier. If this vehicle claimed to exceed light speed, you might have a point. Otherwise, we're deep into 'define your terms' land.

You are making **** up at this point, and you know it.

This is so trivial in comparison with the general claim. I could have said that there would not be enough force to achieve the same end.

If it's trivial, show me the math.

I am bemused that this is seized upon, when the elephant in the room, is the sham that is the treadmill. A device used to promote an idea, with which it has but a superficial similarity.

 

[ynot]

Haven’t had time to read the entire thread so this may already have been said.

If a vehicle is travelling directly downwind at the speed of the wind then the vehicle is effectively in a calm and is not in a wind at all. To then travel faster than the wind the vehicle would have to get energy from a calm (no wind) and effectively move against a headwind. Not going to happen anytime soon.

There is a big difference between moving directly with a wind and moving at an angle to a wind (tacking). When a thing accelerates with a wind the wind speed effectively slows. When a thing accelerates at an angle to a wind the wind speed remains constant.

To travel faster than the speed of a wind you have to tack against the wind, not with it. The angle of the blades aren’t tacking against the wind when the blades are moving with directly the wind.

ETA -
A vehicle that could travel directly in the direction of a wind faster that the speed of the wind is a vehicle that could accelerate from a perfect calm in to it’s own headwind.

 

[humber]

Humber, a car on a treadmill in still air is certainly exactly the same as a car on a still road surface with a wind speed.

No it is not, Myriad. When a car is driven at any velocity above zero, the car must do work to make progress against that resistance. This does not happen on a treadmill ! Where is the wind?
It is not a matter of adding up velocities, because they are real objects that have mass and so forth. I understand the diagrams, no problem.

To go to your house-ball analysis, lets consider the house and the ball. Does the system change if the 'wall' becomes the wall of a train moving at a constant 60 mph in a straight line? After all the wall you're throwing it into has considerable velocity.

No, the wall is at rest.

Now lets change it a little. There's a 60 mph crosswind blowing when you throw the ball against the wall of a house. And the train is an open roof system on a still air day. And yet you STILL can't tell the difference, because it seems like a 60 MPH wind to you.

Sketch up the force diagram yourself. Trim all the irrelevancies and you'll see the ball-wall system is exactly the same whether the wind is actual wind, or if it's still air and the train is constant velocity.

It seems that this is a very difficult idea to dispel. I have mentioned this before. Drawing velocities as arrows, is to put it mildly, an oversimplification.

To take the ball from zero to, say the 10mph it achieves,when it hits the wall, requires the application of force to accelerate it to that velocity.

To do the same, to accelerate a house to the same velocity, requires a much greater level of force. Not only that, they will have different levels of kinetic energy when that velocity is reached.

No? Do you really not see the difference? If a car on a belt says it is doing 60mph, but standing still, and there is no wind, that that is "the same". I mean literally the same?
Why stop there? The light reflected off the body work is going at lightspeed, so the relative "velocities" is lightspeed +/- bit.

I will try and think of a better way of expressing this.

Humber

 

[Modified]

No it is not, Myriad. When a car is driven at any velocity above zero, the car must do work to make progress against that resistance. This does not happen on a treadmill ! Where is the wind?

When the car on the road is traveling at the speed of the wind, it also experiences no air resistance. Both must overcome rolling resistance. They are exactly the same.

 

[GreyICE]

No it is not, Myriad. When a car is driven at any velocity above zero, the car must do work to make progress against that resistance. This does not happen on a treadmill ! Where is the wind?
It is not a matter of adding up velocities, because they are real objects that have mass and so forth. I understand the diagrams, no problem.

Humber, the equations are equations of real OBJECTS. They are not numbers we pull arbitrarily out of the air. There is no difference between a 10 mph wind into your face while you're standing still and you standing on a moving surface that is traveling 10 mph into still air. None. The forces diagram the same because THEY ARE THE SAME. Stick your hand out of the car sometime. Feel that wind hitting it? The air is probably near still, so where is it coming from?

No, the wall is at rest.

Humber dear, the wall is on a train going at 60 mph. The train tracks are at rest. The wall is NOT staying in the same place relative to the train tracks. So how is it at rest?

It seems that this is a very difficult idea to dispel. I have mentioned this before. Drawing velocities as arrows, is to put it mildly, an oversimplification.

To take the ball from zero to, say the 10mph it achieves,when it hits the wall, requires the application of force to accelerate it to that velocity.

To do the same, to accelerate a house to the same velocity, requires a much greater level of force. Not only that, they will have different levels of kinetic energy when that velocity is reached.

Yes. However, what you are ignoring is that the EFFECT ON THE BALL IS THE SAME. The house may have all the kinetic energy in the world, but when it hits the ball at 10 mph, the ball is accelerated exactly the same as if it hit the house at 10 mph. You can try this any time you want with a ping pong ball and a paddle. Hold the paddle still, throw the ball into the paddle. Then drop the ball, hit it with the paddle. It appears to be... doing the same thing.

Doesn't really matter how big the paddles is.

No? Do you really not see the difference? If a car on a belt says it is doing 60mph, but standing still, and there is no wind, that that is "the same". I mean literally the same?
Why stop there? The light reflected off the body work is going at lightspeed, so the relative "velocities" is lightspeed +/- bit.

Yes. A car on a belt doing 60 mph, still relative to the observer not positioned on a treadmill, is exactly the same as a car driving on the road with a 60 mph tailwind.

 

[humber]

When the car on the road is traveling at the speed of the wind, it also experiences no air resistance. Both must overcome rolling resistance. They are exactly the same.

1. The "no drag" at windspeed idea, is a falsehood.
2. The rolling resistance of a vehicle on treadmill is much lower than that of a vehicle doing work against a load.
3. The argument assumes itself as a premise
4. The vehicle must get from zero to windspeed, a period of time in which it will
certainly experience drag.
5. See Ynot's post

Nothing to say about the treadmill?

 

[humber]

Grey_ice
Done all that. Read the posts.

If you are looking for something original to contribute, then you might try and find the flaw in my treadmill drawings that show it to be a sham.

 

[Brian-M]

Can you give please give an example of two simple moving masses, where the frames idea can be used to contradict Newtonian mechanics?

Um.... The frame idea is Newtonian mechanics.
Here's some links...

http://www.newton.dep.anl.gov/askasci/phy00/phy00726.htm
http://farside.ph.utexas.edu/teaching/336k/lectures/node25.html
http://www.britannica.com/EBchecked...wton-reconciled-different-frames-of-reference
http://www-istp.gsfc.nasa.gov/stargaze/Sframes1.htm

Everything about this cart is explainable using Newton's laws of physics.

That is a tautology of what is already the case. If each body finds a new frame when it accelerates to a new velocity, there must be a series of "interframes". Which coalesce to become the one frame that Newton knows.
Same thing. Different bodies at different velocities within the same frame.

That is complete gibberish.

There is no absolute velocity.
Velocity can only be measured from an arbitrary (non-accelerating) reference point.
Whatever reference point you choose to measure from, that is the frame of reference.

No. You have dome exactly what I claimed above. The "object" wind has been stripped of the source that generate it, its kinetic energy, and mass to become a numerical vector to be added or subtracted at will. Adding elephants and mice.

If you're using an object moving at airspeed as your point of reference, then the air has no kinetic energy in that frame of reference, no matter how fast it is moving relative to the ground.

(Although, if the air is moving relative to the ground, then the ground has a huge amount of kinetic energy in this frame of reference. On the other hand, using a reference point stationary to the ground, then the ground has no kinetic energy, but the wind does.)

But it's not that simple, because a car on a dyno or belt, is said to be equivalent to the real item in wind, when it is not. A car, on a dyno or belt, that remains in position as seen by the operator standing along side, has no kinetic energy. It has no velocity.
There is not one point from which this can be achieved. If the belt is the road, it represents a moving mass. Yes, the vehicle moves away at belt speed , but its kinetic energy is not equal to that of the car, would it be going at belt speed, because for one thing, it has much less mass than the car. The idea is internally inconsistent.
Can you name one "reference frame", where you can see motion between the car and the operator standing along it? No.

You fail to understand different frames again.
The operator and the car have zero relative velocities. As a result, they are traveling at identical velocities in all reference frames.

However, in the reference frame of the belt or dyno, both the car and operator have a high velocity (and high kinetic energy), while in the reference frame of the ground (and each-other), both the car and operator have zero velocity, and zero kinetic energy.

The reason why these sort of devices are regarded as contentious, is that they contradict our "folk physics" about things not going "against" the wind or uphill.
The same scientific ideas that inform us that these notions are often wrong, also inform us of what not possible.

I'm very glad Myriad asked you this question. I've stated at least twice before that the DDWFTTW craft uses exactly the same physics as an upwind craft.

Imagine if on an upwind craft, instead of a propeller, you had a wheel (or wheels), with the same orientation as the existing wheels (ie. parallel to the direction of travel).

Place this device on a treadmill, with a second treadmill (with a little bit of "slip" in the belt, so the system doesn't lock-up) suspended upside-down over it, making contact with the top wheel that replaced the propeller.

We'll call this upside-down treadmill with the slipping belt the "wind".

Turn on the "wind" and this "upwind" craft will travel in the opposite direction to the wind.

Turn the "upwind" craft upside down, and turn on the bottom treadmill instead. In this case, the craft will move in the opposite direction to the bottom treadmill, because the treadmill is now doing the same job as the "wind" was doing, and the "wind" is now doing the same job as the treadmill was doing.

Notice, this craft is now moving the opposite direction to the treadmill when the "wind" is still.

A DDFTTW craft moves in the opposite direction to a treadmill when the wind is still.

Turn off the bottom treadmill, and turn the "wind" on again.

Can you guess what will happen?

In this case, an upwind craft is an upside-down DDWFTTW craft. They're the same thing.

That is the equivalent to saying that bouncing a ball off the wall of a house, is the same as holding the ball and accelerating the house to hit it. This is done on the simple assumption that they will be "the same" because the reactive velocities are "the same".

In both cases, the ball will bounce off the house at the same speed, relative to the house. It is "the same".

What do you think would happen instead?