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

--- Quote from: IanB on December 11, 2021, 10:32:58 pm ---

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.

--- End quote ---

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:

--- Quote from: electrodacus on December 11, 2021, 11:23:29 pm ---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.
--- End quote ---

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.


--- Quote ---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)
--- End quote ---

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.


--- Quote ---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.

--- End quote ---

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:

--- Quote ---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
--- End quote ---

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:

--- Quote from: dunkemhigh on December 12, 2021, 12:08:06 am ---
--- Quote ---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
--- End quote ---

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  :-+

--- End quote ---

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:

--- Quote from: IanB on December 12, 2021, 12:05:58 am ---
--- Quote from: electrodacus on December 11, 2021, 11:23:29 pm ---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.
--- End quote ---

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.


--- Quote ---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)
--- End quote ---

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.


--- Quote ---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.

--- End quote ---

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.

--- End quote ---

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.
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