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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
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electrodacus:

--- Quote from: Naej on July 06, 2022, 07:54:09 pm ---It's not a wind turbine, it's a propeller.
You'd use a wind turbine into the wind, not dead wind.

So the question you should ask is what's the force propelling the car for a given energy consumption.
With a mass flow of Q, and efficiency of 1, the energy consumption is 1/2*Q*Delta V^2; the momentum given to the car is Q*Delta V.
If Q is large (a big propeller), you obtain a high ratio between the 2, and a good efficiency overall.
Power is of course taken from the wheels.

--- End quote ---

Yes it is not a wind turbine but the propeller can only be powered by the wind and stored energy (with is actually the case and was ignored).
You need to ask what is the power available to propel the vehicle. Asking what the force alone is may get you to wrong conclusions.

You can not take power from the wheels.  What you call power from the wheels can only be from wind power or from stored energy like from pressure differential or vehicle kinetic energy or a combination or wind power and power from stored energy.

I think pressure differential energy storage is difficult for people to understand so here is an alternative model.
A sail vehicle that has an electrical generator at the back wheels and say a capacitor or rechargeable battery and motor on the front wheels (propeller replacement).

So initially when starting you have say an ideal sail (they are very close anyway for direct down wind).
So wind power available is 0.5 * air density * sail area * (wind speed - vehicle speed)3
Say wind power is 130W initially
If you do not take any energy from the generator all 130W will be available to accelerate the vehicle (increase vehicle kinetic energy).
If you take 50W at the generator wheels then only difference of 80W is available to accelerate the vehicle.
If you have no energy storage device just put this 50W at 100% efficiency in to front motor wheels then you are back to 130W for acceleration and it will not make sense to do that.
But if you have a supercapacitor or rechargeable battery you can put say 10W in to motor and 40W in to battery.
This way vehicle will spend more time at lower speed as it accelerates slower with just 90W (80+10) but as vehicle gets up to speed there is less and less wind power available so the only thing that still accelerates the vehicle are those 10W coming from the battery and powering the motor.

Hope you understand that no vehicle powered only by wind can exceed wind speed unless it has an energy storage device where it stores energy than is then later used to accelerate the vehicle for a limited amount of time above wind speed.
Any vehicle that is wind powered driving directly downwind without an energy storage device can not exceed wind speed as that will violate the energy  conservation law.
electrodacus:

--- Quote from: dunkemhigh on July 06, 2022, 09:23:44 pm ---I gave you exactly what you asked for. The propeller power is taken from the wheels and reduces the power available from the wind, but in turn it provides thrust.

The propeller does not take power from the wind nor provide drive to the wheels. If you think it does then that explains your inability to understand what's going on. Or inability to understand equations, but similar conclusion.

--- End quote ---

The thrust that propeller provides can only be smaller than the one wind will have provided if you did not take that energy from the wheels.

The only (and I mean only) energy source is the wind as this is a wind powered vehicle.  There is no such thing as ground power or power from the wheels.
Without adding an energy storage device the vehicle can not exceed wind speed as it is seen for any sail only vehicle.
The propeller is not just a propulsion device but it is also an energy storage device when used in air (a compressible fluid).

Your equation includes "wash speed" can you let me know what that is in an example ? How do you calculate that ?
Also you do realize that Wind power will be zero before vehicle gets to wind speed in your equation for any wash speed higher than zero.
Subtracting the propeller power (more correctly power you take at the wheel to provide the propeller if propeller is not 100% efficient) will just show the power available for accelerating the vehicle and not wind power available to vehicle.


So as an example wind speed 6m/s and afrea 1m2 to keep things simple

Vehicle speed = 0
Pw = 0.5 * 1.2 * 1 * (6-0)3 = 129.6W
Vehicle speed = 3m/s  (half the wind speed)
Pw = 0.5 * 1.2 * 1 * (6-3)3 = 16.2W   (so 8x less wind power already)
Vehicle speed = 6m/s
Pw = 0.5 * 1.2 * 1 * (6-6)3 = 0W

Now your equation will provide the same for wash speed = 0 and lower values for wash speed higher than zero.
As for subtracting propeller power again all the values will be lower than the ones above.
gnuarm:

--- Quote from: electrodacus on July 06, 2022, 05:46:25 am ---
--- Quote from: gnuarm on July 06, 2022, 05:01:40 am ---
--- 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.

--- End 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.

--- End quote ---

Lol!  It is YOU who has failed.  You have mis-attributed the quotes of your words to me!

I don't care about convincing you of anything.  Your failure is self-sustaining and you will live a rich, full life believing you are right.  So, enjoy.   
Alex Eisenhut:
What if there's lightning inside a tornado? Will the electons move faster if the lightning is going in the same direction as the tornado?
electrodacus:

--- Quote from: Alex Eisenhut on July 06, 2022, 11:02:42 pm ---What if there's lightning inside a tornado? Will the electons move faster if the lightning is going in the same direction as the tornado?

--- End quote ---

What ?
I guess this is related to the hairdryer question where the fan cooled the heating wires which meant  lower resistance and thus higher current as voltage is the same.
Higher current means more electrons traveling through the same cross section area in a unit of time.
Not quite sure what part you disagree with?  Turn on the fan on the hairdryer and you will see the heating elements glowing in visible spectrum meaning higher temperature and depending on what material the heating element is made out of is likely resistance will increase with increased temperature as the metal lattice will vibrate at higher frequency.
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