Mess with your minds: A wind powered craft going faster than a tail wind speed.

[electrodacus]

Case A: The vehicle can move to the right with zero power from the generator and zero power at the motor.

Case B: The vehicle can move to the right with any power greater than zero at the motor. Less than 1 W would be enough.

Case C: The vehicle can move to the right with a power greater than about 4 W at the motor. Since this is less than 10 W, the generator can supply it.

In each case, the pictures clearly show the cart being able to move to the right.

Case A: If there is no power at the motor the motor will free spin there is no friction.  So in all cases if motor is not connected to generator vehicle will not move in any direction.

Case B:  Vehicle can only move to the right if there is an energy storage device and slip stick hysteresis.  In this theoretical analysis there is no specified energy storage device so no movement is possible as net power will always be zero.
You can only have 1W at the motor if you get that from the generator and the two are opposite so will cancel Pnet = Pout - Pin (conservation of energy)

Case C: There is no way for that vehicle to move to the right. Not quite sure how your intuition works but you have a vehicle with no on board energy source and is on two treadmills both moving from right to left.
 

[IanB]

Case A: If there is no power at the motor the motor will free spin there is no friction.  So in all cases if motor is not connected to generator vehicle will not move in any direction.

Incorrect, the wheel can be locked so it does not spin freely (a worm drive will do that). A wheel that is not turning requires zero power, since power = speed of rotation x torque.

Case B:  Vehicle can only move to the right if there is an energy storage device and slip stick hysteresis.  In this theoretical analysis there is no specified energy storage device so no movement is possible as net power will always be zero.
You can only have 1W at the motor if you get that from the generator and the two are opposite so will cancel Pnet = Pout - Pin (conservation of energy)

Again, incorrect. If the motor wheel is stationary then it consumes no power, the vehicle is stationary, and 10 W is available to be used from the generator. Take any small amount of power from the generator and supply it to the motor, and the wheel can turn clockwise, moving the vehicle to the right. We have a perfect system with no slipping anywhere.

Case C: There is no way for that vehicle to move to the right. Not quite sure how your intuition works but you have a vehicle with no on board energy source and is on two treadmills both moving from right to left.

This is the point. I don't use intuition, since intuition can give wrong answers. I use engineering analysis instead.

The cart can move to the right if the motor wheel turns faster than 4 m/s. There is ample power available from the generator to power the motor, since the generator wheel is turning at 10 m/s.

If you want a different way of looking at this, the "wind" and the "road" are moving at different speeds (4 m/s and 10 m/s), and the vehicle is in contact with both of them. The vehicle is therefore able to use the difference in speeds (10 − 4 = 6 m/s) as a power source to tap into, and it can use this power source to move in any direction it wishes by turning the motor appropriately.

[PlainName]

For direct upwind you can travel forever using those mini charge discharge cycles and stick slip hysteresis as you always have access to wind energy

Whoah! Have I read that correctly? You actually admit that going faster than the wind, with the wind directly behind, is doable indefinitely? I don't care if you have to butter it with this stick slip stuff, that simple acknowledgement makes this entire thread superfluous 

[electrodacus]

For direct upwind you can travel forever using those mini charge discharge cycles and stick slip hysteresis as you always have access to wind energy

Whoah! Have I read that correctly? You actually admit that going faster than the wind, with the wind directly behind, is doable indefinitely? I don't care if you have to butter it with this stick slip stuff, that simple acknowledgement makes this entire thread superfluous 

Maybe you did not notice upwind not downwind.
Directly upwind so against wind direction you always have access to wind power but for that case you still need energy storage and in this particular case also a way to trigger the discharge cycle so stick slip hysteresis.

[electrodacus]

Case A: If there is no power at the motor the motor will free spin there is no friction.  So in all cases if motor is not connected to generator vehicle will not move in any direction.

Incorrect, the wheel can be locked so it does not spin freely (a worm drive will do that). A wheel that is not turning requires zero power, since power = speed of rotation x torque.

Case B:  Vehicle can only move to the right if there is an energy storage device and slip stick hysteresis.  In this theoretical analysis there is no specified energy storage device so no movement is possible as net power will always be zero.
You can only have 1W at the motor if you get that from the generator and the two are opposite so will cancel Pnet = Pout - Pin (conservation of energy)

Again, incorrect. If the motor wheel is stationary then it consumes no power, the vehicle is stationary, and 10 W is available to be used from the generator. Take any small amount of power from the generator and supply it to the motor, and the wheel can turn clockwise, moving the vehicle to the right. We have a perfect system with no slipping anywhere.

Case C: There is no way for that vehicle to move to the right. Not quite sure how your intuition works but you have a vehicle with no on board energy source and is on two treadmills both moving from right to left.

This is the point. I don't use intuition, since intuition can give wrong answers. I use engineering analysis instead.

The cart can move to the right if the motor wheel turns faster than 4 m/s. There is ample power available from the generator to power the motor, since the generator wheel is turning at 10 m/s.

If you want a different way of looking at this, the "wind" and the "road" are moving at different speeds (4 m/s and 10 m/s), and the vehicle is in contact with both of them. The vehicle is therefore able to use the difference in speeds (10 − 4 = 6 m/s) as a power source to tap into, and it can use this power source to move in any direction it wishes by turning the motor appropriately.

I seen many of your comments on this forum and you look more like a troll thus not sure if is worth wasting my time.
If you think I'm wrong please provide the "correct" equation.
The one Derek provided in his video is clearly wrong as it will make bad predictions for both case A and case C sine his equation include (v-w) instead of the correct (w-v)   w-wind speed v-vehicle speed.

[IanB]

I seen many of your comments on this forum and you look more like a troll thus not sure if is worth wasting my time.

This is classical troll behavior, switching to ad hominem attacks when you can't debate the issue at hand.

So please don't waste your time. Please just go away and let this thread rest in peace.

If you think I'm wrong please provide the "correct" equation.

You are wrong. I provided the correct analysis above.

The one Derek provided in his video is clearly wrong as it will make bad predictions for both case A and case C sine his equation include (v-w) instead of the correct (w-v)   w-wind speed v-vehicle speed.

Kindly don't change the subject. We are looking at your pictures, not Derek's equations. This is classic troll behavior--when you don't like the answer, switching to a different topic.

[Psi]

Also there was never a sail based vehicle demonstrated to exceed wind speed directly down wind (not even close not even in ideal case).

True.  I don't think that a sailboat can beat a balloon to a goal directly downwind -- even if the boat jibes.

That doesn't sound right from what I have read, granted there is lots of misinformation out there and i have not looked into this much. But I was under the impression it was accepted scientific fact that a sailboat can beat a floating balloon in a race from point A to Point B by traveling much faster than the wind (at an angle) and periodically changing directions to enable navigating to point B indirectly. (verses the balloon that travels directly at wind speed).

Is that actually not true?

[IanB]

That doesn't sound right from what I have read, granted there is lots of misinformation out there and i have not looked into this much. But I was under the impression it was accepted scientific fact that a sailboat can beat a floating balloon in a race from point A to Point B by traveling much faster than the wind (at an angle) and periodically changing directions to enable navigating to point B indirectly. (verses the balloon that travels directly at wind speed).

Is that actually not true?

I think it's true. Actually, upon doing a quick search, I came across this article that attempts to unravel the puzzle:

https://www.lockhaven.edu/~dsimanek/museum/ddwfttw.htm

Among other things, the author mentions that sailboats can indeed sail downwind faster than a balloon, if they tack at the right angle.

[electrodacus]

I changed my strategy on a different forum so I will do the same here.

The claim of blackbird is that it can travel indefinite well above wind speed and even continue to accelerate.

Now imagine you are in your car traveling on a long strait highway directly downwind at 2x the wind speed and now you pop up a large propeller and connect that to the back wheels.
According to current theory you can stop the engine (no need to waste gasoline) and likely you have extra to even heat or cool the vehicle.

Does this seem reasonable to anyone ?   

[IanB]

I changed my strategy on a different forum so I will do the same here.

The claim of blackbird is that it can travel indefinite well above wind speed and even continue to accelerate.

Now imagine you are in your car traveling on a long strait highway directly downwind at 2x the wind speed and now you pop up a large propeller and connect that to the back wheels.
According to current theory you can stop the engine (no need to waste gasoline) and likely you have extra to even heat or cool the vehicle.

Does this seem reasonable to anyone ?

Again, you are trying to change the subject by making false comparisons.

The claim is that the Blackbird can do what it does.

Nobody is claiming you can stick a propeller on a big heavy car on the highway and achieve the same result.

So your question is irrelevant.

[electrodacus]

Again, you are trying to change the subject by making false comparisons.

The claim is that the Blackbird can do what it does.

Nobody is claiming you can stick a propeller on a big heavy car on the highway and achieve the same result.

So your question is irrelevant.

Blackbird plus driver has about 300kg.  That is not that far of from a lightweight car.
Add a larger propeller I do not care the question is still valid. Cost is no issue.

[Kleinstein]

If you think I'm wrong please provide the "correct" equation.
The one Derek provided in his video is clearly wrong as it will make bad predictions for both case A and case C sine his equation include (v-w) instead of the correct (w-v)   w-wind speed v-vehicle speed.

The correcrt equations / explainartions were given multiple time - just read them and understand or show, were you think they are wrong.

If a result is contradicting your intuition, this is no an argument to show that the equations are wrong.
We do the math way to get away from the intuition. Sometimes the real world is counter-intuitive.

Blackbird plus driver has about 300kg.  That is not that far of from a lightweight car.
Add a larger propeller I do not care the question is still valid. Cost is no issue.

The balckbird example showed that it works, with an optimized vehicle (low friction) and relatively large prop, though not at twice the speed of the wind, but still faster than the wind.
To do that starting with a normal car would need an even larger fan and may topple the car - so not really practical, but that is not the point.

The point is that there are experiments that show that things are possible that are against some peopel's intuition. Just accept that intuition some-times is wrong. If in doubt the math is more reliable.

[Brumby]

Are we back into this brick wall headbutting exercise again...?   

The simple fact is that the Blackbird can do what is claimed.  It has been proven experimentally - except someone doesn't want to admit something than runs counter to their intuition.

Many members have pointed out errors in their argument, yet they refuse to concede any of them.  Stubborn and ignorant ... it's a fool's errand to try and correct them.  I've not the time to waste any more on this silliness.


Dunning–Kruger is strong in this one.

[PlainName]

I've not the time to waste any more on this silliness.

Didn't you say that some while back (in the thread you had to duplicate this in)? Surely just skipping these threads would solve all your issues. Same in all the other threads where you strongly suggest it's closed, locked or otherwise terminated when you get bored of it.

[Brumby]

I've taken the time to add a comment regarding the futility of attempts to convince the recalcitrant involved.  I'm not inclined to invest any more of my time in trying to help them understand, further than I have previously.

So please - get off your high horse.

[Labrat101]

This is just an endless Loop of Insanity .
@ electrodacus  ."" would argue Black is white Because !!  ""
Plus he has a duplicate Thread that it also an endless Rabbit Hole Maybe someone should Lock it ..
As say ..

[fourfathom]

I see no need to lock either of the threads.  If you aren't interested in futile arguments, then just don't read the thread.  Me, I sometimes enjoy them.

[electrodacus]

If you think I'm wrong please provide the "correct" equation.
The one Derek provided in his video is clearly wrong as it will make bad predictions for both case A and case C sine his equation include (v-w) instead of the correct (w-v)   w-wind speed v-vehicle speed.

The correcrt equations / explainartions were given multiple time - just read them and understand or show, were you think they are wrong.

Have I not just done that ? Have you even read my comment ?

You care about the wind power available to vehicle as that is what allows you or not to accelerate and the correct formula for that in case of a vehicle traveling directly downwind is
0.5 * air density * area * (wind speed - vehicle speed)^3

The conclusion for this correct formula is that there will be zero wind power available to any wind powered vehicle traveling directly downwind.
So no wind powered vehicle can ever exceed wind speed unless it has an additional energy source or as is the case here an energy storage device.

[electrodacus]

Are we back into this brick wall headbutting exercise again...?   

The simple fact is that the Blackbird can do what is claimed.  It has been proven experimentally - except someone doesn't want to admit something than runs counter to their intuition.

Many members have pointed out errors in their argument, yet they refuse to concede any of them.  Stubborn and ignorant ... it's a fool's errand to try and correct them.  I've not the time to waste any more on this silliness.


Dunning–Kruger is strong in this one.

The blackbird vehicle works exactly the way I describe it and that involves energy storage.  I never claimed that blackbird test results are not exactly correct.
 The explanation Rick and Derek have provided is completely flawed and to justify their wrong intuition they changed a formula to look like data fits their description (it is not even with the wrong formula).

There is no power available from wind for a vehicle traveling at the same speed as wind speed directly downwind. This is a fact that only someone that has no understanding of the physic involved will make.
 

[IanB]

You care about the wind power available to vehicle as that is what allows you or not to accelerate and the correct formula for that in case of a vehicle traveling directly downwind is
0.5 * air density * area * (wind speed - vehicle speed)^3

And as I keep telling you, that is not the correct formula. The correct formula is:

available power from wind = 0.5 * air density * area * (wind speed − ground speed)^3

If you keep putting vehicle speed in there you will get the wrong conclusion.

The conclusion for this correct formula is that there will be zero wind power available to any wind powered vehicle traveling directly downwind.
So no wind powered vehicle can ever exceed wind speed unless it has an additional energy source or as is the case here an energy storage device.

And this is the wrong conclusion. The vehicle can draw power from the wind when going faster than the wind, because the vehicle is in contact with the ground using wheels that do not slip.

It has also been explained to you many times that there is no energy storage in the vehicle. It has no springs, batteries or flywheels. There is no possibility of "pressure energy" behind the propeller, as there are no walls and there is no containment. It works purely by drawing power from the wind, using a mechanical system to make the velocity component of the propeller blades in contact with the air be less than the wind speed.

[electrodacus]

And as I keep telling you, that is not the correct formula. The correct formula is:

available power from wind = 0.5 * air density * area * (wind speed − ground speed)^3

If you keep putting vehicle speed in there you will get the wrong conclusion.

ground speed relative to what ?

[fourfathom]

ground speed relative to what ?

Speed of the ground, relative to the ground.  In other words, zero.

[fourfathom]

the vehicle is in contact with the ground using wheels that do not slip.

And even if the wheels did slip, as long as there's some traction (friction) the vehicle can still draw energy.  Of course the system efficiency will be less with slipping wheels.

But for the sake of analysis, and for all practical purposes, the wheels do not slip.

[electrodacus]

ground speed relative to what ?

Speed of the ground, relative to the ground.  In other words, zero.

Then why even mention that?

[electrodacus]

the vehicle is in contact with the ground using wheels that do not slip.

And even if the wheels did slip, as long as there's some traction (friction) the vehicle can still draw energy.  Of course the system efficiency will be less with slipping wheels.

But for the sake of analysis, and for all practical purposes, the wheels do not slip.

Think about this way.  The thing that converts the wind power to kinetic energy is on the vehicle (you do not have an extension cord to a stationary location).
So wind speed relative to vehicle will be (wind speed - vehicle speed).

The wind power equation as you describe 0.5 * air density * area * w^3 is valid for a stationary device like a wind turbine or for a vehicle that travels perpendicular to the wind direction not directly downwind.