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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
electrodacus:
--- Quote from: dunkemhigh on July 05, 2022, 05:32:57 pm ---
The equation you wrote gives the amount of power for some given sail area, right? By itself it is meaningless because you don't know how much power is needed to push the vehicle along. The entirety of your theory is that at windspeed the power available is zero, and for a sail type that would be true. But it ISN'T a sail type - it is a propeller.
As I pointed out, if it is rotating there is thrust, and when the vehicle is at wind speed that thrust is still pushing. The big question is how slow the wind speed can be be (relative to the vehicle) before the thrust from the prop fails to have an effect.
Your equation doesn't go anywhere near answering that. It is just considering one part of the problem to be solved, not the entirety. If you're relying on that equation to prove your theory then you are fooling yourself.
--- End quote ---
The way wind interacts with vehicle is the same no matter the type of vehicle.
Air particles have mass (thus the air density in the equation) and those air particles will hit the vehicle and so providing their kinetic energy to vehicle thus the vehicle area that is hit by air particles is also part of the equation and then particle speed relative to vehicle is the only other value needed in the equation.
The propeller blades and vehicle body are the sail and when propeller does not rotate it is very simple to calculate the wind power available to vehicle.
If propeller will not have been connected to wheels then all available wind energy (power integrated over time) will be converted in to vehicle kinetic energy minus a bit of energy needed for friction losses.
When propeller is connected to wheels part of the wind energy available is still use to cover friction and accelerate the vehicle but also a significant part is diverted to propeller and then propeller pushes against air (this will be completely ridiculous and useless if air was not a compressible fluid) but since air is compressible the energy taken from wind at the wheels is used to create a pressure differential (basically store energy).
But this stored energy is also used at the same time just that is used at a lower rate than it is put in so you get a net energy put in storage until around vehicle speed is at 20 or 30% of the wind speed at which point you take more out of the energy storage than you still get from wind and when I say get out I men use to accelerate the vehicle (increase vehicle kinetic energy).
When vehicle speed equals wind speed there is zero power available to vehicle from wind but there is power available from the stored energy (that pressure differential).
But the power available from the storage is still only in part used to accelerate the vehicle and cover the friction loss the other significant part is put back into energy storage as wheels and propeller are still connected.
Of course the stored energy net (pressure differential) will decrease as you take out more than you put back in. And so acceleration rate will drop until it gets to zero and from that point the vehicle will decelerate so the friction losses are provided by the vehicle stored kinetic energy meaning vehicle will start to slow down and will do so until it gets below wind speed.
So that equation is valid for any wind power vehicle.
The difference is that for a vehicle without energy storage all that power is used to accelerate the vehicle (faster acceleration).
While for a vehicle with energy storage only a part of that power accelerates the vehicle the other part is stored to be used a bit later. Since vehicle accelerates slower it spends more time in the region where high wind power is available so more energy from the wind is collected some to increase the vehicle kinetic energy and some to increase the pressure differential.
gnuarm:
This conversation has gone to the dogs, but I suppose that was inevitable with the givens...
electrodacus:
--- Quote from: gnuarm on July 06, 2022, 12:30:15 am ---This conversation has gone to the dogs, but I suppose that was inevitable with the givens...
--- End quote ---
I agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
Both are based on videos made by Derek (Veritasium) and both based on wrongly understanding of what energy is and ignoring completely energy storage.
For Blackbird the pressure differential energy storage was completely ignored and it is the thing allowing that vehicle to exceed wind speed.
For the transmission line the line capacitance was completely ignored and then the effects of that were misinterpreted as electrical energy not being delivered by electrons (charged particles) traveling through the wire.
gnuarm:
--- Quote from: electrodacus on July 06, 2022, 12:51:00 am ---
--- Quote from: gnuarm on July 06, 2022, 12:30:15 am ---This conversation has gone to the dogs, but I suppose that was inevitable with the givens...
--- End quote ---
I agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
--- End quote ---
The only thing they have in common is that you take a stance which shows you fail to understand an issue, then you weasel around without actually ever completing a line of thought and want to blame everything on effects that are essentially "invisible" and extremely hard to measure.
I know that was true of the wind car. I didn't bother to read your effluent on this issue because I quickly recognized the MO.
electrodacus:
--- Quote from: gnuarm on July 06, 2022, 05:01:40 am ---I agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
--- End quote ---
The only thing they have in common is that you take a stance which shows you fail to understand an issue, then you weasel around without actually ever completing a line of thought and want to blame everything on effects that are essentially "invisible" and extremely hard to measure.
I know that was true of the wind car. I didn't bother to read your effluent on this issue because I quickly recognized the MO.
[/quote]
All you need to convince me is provide an equation describing the available wind power to Blackbird.
There seems to be a lot of experts but no equation is ever provided.
You (many) claim you understand the subject but are unable to provide the equation.
Yes air molecules are invisible to human eyes and the electrons even more so but there are people that understand those exist and are able to make correct predictions.
So if you want to contradict me please provide the answer to most basic question: What is the equation describing the available wind power to Blackbird witch is the same as for any other wind powered vehicle that travels directly downwind and is also valid for directly upwind.
Once you provide that equation is super easy to test if it makes the correct predictions.
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