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

[Naej]

The paper seems to concentrate on direct upwind witch uses different type of energy storage and can be debunked even easier.

Perhaps you should apply the wind turbine power equation now that it is a… wind turbine?

[electrodacus]

The paper seems to concentrate on direct upwind witch uses different type of energy storage and can be debunked even easier.

Perhaps you should apply the wind turbine power equation now that it is a… wind turbine?

Yes it is a wind turbine and yes that equation will apply for a theoretical ideal wind turbine and by ideal I mean 100% efficient not even Betz limit is applied.
But just to keep the vehicle in place you need all that generated power applied to the wheels.

So if wind turbine generates 1000W you need to apply all that to the wheels in order for the vehicle to remain stationary (assuming wheels have enough grip to handle that).

You can think at wind balls hitting the vehicle body (includes the propeller/turbine blades) and so for a 1m² area 6m/s wind you have the equivalent of 6 x 1.2kg balls hitting the vehicle every second and balls speed is 6m/s and are spaced 1m apart.
Now when the ball hits the vehicle it will transfer his kinetic energy to vehicle.

So for this case direct upwind say vehicle is 100kg and it is stationary then when one ball hits the ball transfers the kinetic energy to vehicle and that is 0.5 * 1.2kg * 6² = 21.6Ws
So now vehicle speed after the first ball hit will be sqrt(21.6Ws/(0.5*100kg)) = 0.657m/s in the same direction that ball was moving.
Now to get back to initial position and zero speed you will need to take all this 21.6Ws you got in ideal case form wind and apply to the wheels.
So ideal case you can stay in the same place and can not move upwind without storing the energy. 


Same ball hitting the vehicle is valid for direct downwind version so when vehicle speed matches ball speed no ball can hit the vehicle and when vehicle is above ball speed the vehicle hits the ball instead of the other way around.

The reality is that each 1.2kg ball is made of a huge number of air molecules Nitrogen and Oxygen mostly but the physics is exactly the same

[Naej]

Yes it is a wind turbine and yes that equation will apply for a theoretical ideal wind turbine and by ideal I mean 100% efficient not even Betz limit is applied.
But just to keep the vehicle in place you need all that generated power applied to the wheels.

So if wind turbine generates 1000W you need to apply all that to the wheels in order for the vehicle to remain stationary (assuming wheels have enough grip to handle that).

Damn 1 horse power in a car? It does not sound impossible to me.
And why would you want the car to remain stationary?

You seem to believe that energy in air flowing through a turbine/propeller = mechanical energy given to the car.
This is COMPLETELY WRONG, for example a wind turbine stays stationary.
The force applied on the turbine by the air can be computed (cf. my posts above) and then you multiply by the speed of the car/turbine to get the mechanical power.

If you put a propeller on a 1000W engine, it does NOT mean you'll get 1000W of mechanical power out of it. If, for example, you put the brakes on your aircraft it won't move and the kinetic energy is equal to 0, and you get 0W.

[electrodacus]

Damn 1 horse power in a car? It does not sound impossible to me.
And why would you want the car to remain stationary?

You seem to believe that energy in air flowing through a turbine/propeller = mechanical energy given to the car.
This is COMPLETELY WRONG, for example a wind turbine stays stationary.
The force applied on the turbine by the air can be computed (cf. my posts above) and then you multiply by the speed of the car/turbine to get the mechanical power.

If you put a propeller on a 1000W engine, it does NOT mean you'll get 1000W of mechanical power out of it. If, for example, you put the brakes on your aircraft it won't move and the kinetic energy is equal to 0, and you get 0W.

You want the car to move against wind direction and the best it can do without energy storage is to stay in place/stationary.

A 40% efficient wind turbine will act as a sail with area equal with 40% of the swept area of the rotor.
So say swept area of the turbine is 10m²  it will act as a 4m² sail as wind speed after the turbine will be lower.

So if you install such a wind turbine on your direct upwind vehicle and wind speed is say again a fairly strong 10m/s then your turbine will output
0.5 * 1.2 * 10 * 10³ * 0.4 = 2400W
But that will also result in a force pushing the vehicle in the wind direction (you want to drive against the wind direction as it is an upwind vehicle) and just to cancel that you need to use all those 2400W you produced.
In order to advance even at infinitesimally small speed against wind direction you need more than 2400W.

Think about how much power will a vehicle with 10m² projected frontal area and a 0.4 coefficient of drag  will need to travel at 10m/s
Equation for that will be
0.5 * 1.2 * 10 * 10³ * 0.4 = 2400W
If this seems familiar it is because is the exact same.
It is irrelevant if a vehicle drives at 20m/s with no wind or travels at 5m/s with a 15m/s headwind it will need the same power to deal with air friction. 

[Naej]

But that will also result in a force pushing the vehicle in the wind direction (you want to drive against the wind direction as it is an upwind vehicle) and just to cancel that you need to use all those 2400W you produced.
In order to advance even at infinitesimally small speed against wind direction you need more than 2400W.

It appears you don't understand the difference between force and power. Check these out in high school physics books.
For example, the concrete at the bottom of a wind turbine produces 0 W (as most concrete) and can "cancel" the 3MW produced.

Think about how much power will a vehicle with 10m² projected frontal area and a 0.4 coefficient of drag  will need to travel at 10m/s
Equation for that will be
0.5 * 1.2 * 10 * 10³ * 0.4 = 2400W
If this seems familiar it is because is the exact same.
It is irrelevant if a vehicle drives at 20m/s with no wind or travels at 5m/s with a 15m/s headwind it will need the same power to deal with air friction.

Lol and what if the "coefficient of drag" is 0.1 ?

[electrodacus]

It appears you don't understand the difference between force and power. Check these out in high school physics books.
For example, the concrete at the bottom of a wind turbine produces 0 W (as most concrete) and can "cancel" the 3MW produced.

Lol and what if the "coefficient of drag" is 0.1 ?

This exactly the problem but in reverse.

The reason a wind turbine attached to earth will not seem to move is because the power is applied to entire earth and yes earth will absorb that kinetic energy and spin a bit faster or slower but it all cancels out more or less as wind around the globe will be from different directions.
Plus earth is so massive and his density is so much higher than the very thin atmosphere that it makes no measurable impact (plus the random direction I mentioned).

To put this on another way. In a day with no wind how much power will a wind turbine generate if installed on a vehicle driving at say 10m/s and how much power will vehicle need to compensate for the drag produce by the turbine?

The 0.4 coefficient of drag was selected to match what a 40% efficient wind turbine look like. If wind turbine was just 10% efficient then yes you can consider coefficient of drag 0.1 and if you have a theoretical 100% efficient wind turbine (meaning no air on the other side of the swept area basically a sail) then coefficient of drag will be 1.

So the vehicle can have 0.1 (hard to do) coefficient of drag excluding the wind turbine. Then you install a wind turbine and if that is 40% efficient then the mechanical power it will apply to vehicle due to drag will be at least a theoretical 0.4 drag coefficient else you will claim to violate energy conservation.

So in order for a vehicle to be able to drive direct upwind (no matter how it is designed) it will require an energy storage device.
The simple way to think about this is vehicle applies brakes (basically anchors the vehicle to ground) stored the wind turbine generate energy then uses that to drive against wind direction until stored energy is used up then stops again or at least slows down (uses kinetic stored energy in vehicle mass to coast) charges again and can accelerate again for some time.
In reality there is no large energy storage device in a direct upwind version (as you have with direct down wind) so this charge discharge cycles happen very fast multiple times per second (so fast that you may not even notice with eyes and can only see on a high speed camera).
The other version of direct down wind uses much larger capacity pressure differential energy storage so there a charge discharge cycle take many minutes.     

[PlainName]

So the vehicle can have 0.1 (hard to do) coefficient of drag excluding the wind turbine.

It could have a 1.0 coefficient and not have a problem since there is no drag at wind speed, and negative drag below that.

[electrodacus]

So the vehicle can have 0.1 (hard to do) coefficient of drag excluding the wind turbine.

It could have a 1.0 coefficient and not have a problem since there is no drag at wind speed, and negative drag below that.

The discussion was about direct upwind version not direct downwind.
With direct downwind there is no drag at wind speed but there is also no wind power available.

[Naej]

It appears you don't understand the difference between force and power. Check these out in high school physics books.
For example, the concrete at the bottom of a wind turbine produces 0 W (as most concrete) and can "cancel" the 3MW produced.

Lol and what if the "coefficient of drag" is 0.1 ?

This exactly the problem but in reverse.

The reason a wind turbine attached to earth will not seem to move is because the power is applied to entire earth and yes earth will absorb that kinetic energy and spin a bit faster or slower but it all cancels out more or less as wind around the globe will be from different directions.
Plus earth is so massive and his density is so much higher than the very thin atmosphere that it makes no measurable impact (plus the random direction I mentioned).

To put this on another way. In a day with no wind how much power will a wind turbine generate if installed on a vehicle driving at say 10m/s and how much power will vehicle need to compensate for the drag produce by the turbine?

The 0.4 coefficient of drag was selected to match what a 40% efficient wind turbine look like. If wind turbine was just 10% efficient then yes you can consider coefficient of drag 0.1 and if you have a theoretical 100% efficient wind turbine (meaning no air on the other side of the swept area basically a sail) then coefficient of drag will be 1.

So the vehicle can have 0.1 (hard to do) coefficient of drag excluding the wind turbine. Then you install a wind turbine and if that is 40% efficient then the mechanical power it will apply to vehicle due to drag will be at least a theoretical 0.4 drag coefficient else you will claim to violate energy conservation.

So in order for a vehicle to be able to drive direct upwind (no matter how it is designed) it will require an energy storage device.
The simple way to think about this is vehicle applies brakes (basically anchors the vehicle to ground) stored the wind turbine generate energy then uses that to drive against wind direction until stored energy is used up then stops again or at least slows down (uses kinetic stored energy in vehicle mass to coast) charges again and can accelerate again for some time.
In reality there is no large energy storage device in a direct upwind version (as you have with direct down wind) so this charge discharge cycles happen very fast multiple times per second (so fast that you may not even notice with eyes and can only see on a high speed camera).
The other version of direct down wind uses much larger capacity pressure differential energy storage so there a charge discharge cycle take many minutes.     

No you don't compute the drag coefficient this way. 
Or are you claiming that the drag coefficient of a wind turbine is 0 ?

In general you seem to believe that whatever you want to be true about energy/forces must be true. It does not work this way. You must learn mechanics first.

[electrodacus]

No you don't compute the drag coefficient this way. 
Or are you claiming that the drag coefficient of a wind turbine is 0 ?

In general you seem to believe that whatever you want to be true about energy/forces must be true. It does not work this way. You must learn mechanics first.

Not sure what have you read or understood from my comments. So I better provide you the numbers are you seems to be the one having problems with classical mechanics and especially the energy conservation.

If all you have is a wind turbine on wheels say vehicle has negligible frontal area except for the wind turbine that faces directly the wind.
I do not care how the wind turbine is designed or what the wind turbine efficiency is as long as turbine outputs 100W then there will be at a absolute minimum 100W pushing against the vehicle trying to accelerate the vehicle in same direction the air particle move.
So whatever you do with those 100W from the wind turbine you can not advance at any speed against wind direction. The best you can do is stay in place.

The only way to drive upwind with a wind powered vehicle is to use an energy storage device.

You do not need to look at forces at all (you can but is not useful for this particular problem). All you need to know is power in (wind pushing against the vehicle and turbine is part of the vehicle) and power out (power applied at the wheels) which can never be higher than power in unless you add an external energy source or energy from an onboard energy storage device that was charged from available wind energy earlier.

But for direct upwind equivalent you do not even need to bother with air all you need is wheels.  And if you care about forces here it is


Let me know if you think this vehicle can move from left to right using energy from that treadmill that moves in the opposite direction right to left.
If you think that is possible without energy storage please write done the equation. 

[PlainName]

If you think that is possible without energy storage please write done the equation. 

1. It is no more energy storage than tightening a screw in a hole is - it's just friction. Use a lubricant.

2. That has bugger all to do with Blackbird or even a direct into the wind vehicle.

3. Even if there were an identifiable energy storage componet, so what? This entire thing was set off by you swearing blind that faster than wind travel was an impossibility, no ifs, no buts. Then you saw it happen yourself and the only way out of that bind is to preach energy storage. It's a great gag - dead easy to say it's the thrust (despite being unconstrained, and despite you saying it's not there) or it's the stretchy fixed-length band or tyres or... the world is your elastic band. requiring energy storage for it to work (that is, be sustainable).

4. Even if there was energy storage hidden somewhere, so what? If the average speed is higher than wind speed then it fits the spec and it doesn't actually matter how it does that so long as there is no other external input. And there isn't, but it's still a great gag because you'll say that however long we see this thing go faster than the wind, just around the corner it couldn't have gone on for very much longer.

[electrodacus]

1. It is no more energy storage than tightening a screw in a hole is - it's just friction. Use a lubricant.

2. That has bugger all to do with Blackbird or even a direct into the wind vehicle.

3. Even if there were an identifiable energy storage componet, so what? This entire thing was set off by you swearing blind that faster than wind travel was an impossibility, no ifs, no buts. Then you saw it happen yourself and the only way out of that bind is to preach energy storage. It's a great gag - dead easy to say it's the thrust (despite being unconstrained, and despite you saying it's not there) or it's the stretchy fixed-length band or tyres or... the world is your elastic band.

4. Even if there was energy storage hidden somewhere, so what? If the average speed is higher than wind speed then it fits the spec and it doesn't actually matter how it does that so long as there is no other external input. And there isn't, but it's still a great gag because you'll say that however long we see this thing go faster than the wind, just around the corner it couldn't have gone on for very much longer.

1. Tightening a screw will not be energy storage as the screw will not come back out after tightening.

2. It has little if anything to do with direct downwind Blackbird but it has a lot in common with direct upwind version of Blackbird.

3. When I have ever claimed that faster than wind direct downwind is not possible ? I never claimed that.
Also what powers the direct downwind version of Blackbird above wind speed is pressure differential energy storage nothing to do with elastic bands.

4. It does matter as if as Derek says vehicle is directly powered by wind when above wind speed it will be able to maintain higher than wind speed forever where if energy storage is used the vehicle will only be above wind speed until energy storage is used up.

So while I do not and never have claimed directly downwind faster than wind is not possible because it is and vas demonstrated in many ways (both blackbird and the treadmill model demonstrated that). The reason why that happen is super important as energy storage means vehicle is above wind speed for a very limited amount of time proportional with amount of stored energy and more importantly does not violate the conservation of energy.

[Naej]

If all you have is a wind turbine on wheels say vehicle has negligible frontal area except for the wind turbine that faces directly the wind.
I do not care how the wind turbine is designed or what the wind turbine efficiency is as long as turbine outputs 100W then there will be at a absolute minimum 100W pushing against the vehicle trying to accelerate the vehicle in same direction the air particle move.

You provided zero argument for this claim. You won't be surprise to learn that it is wrong.
What is providing the 3MW to a wind turbine?

I don't understand your example. Here is mine: imagine you have a giant gear above your hear, which is turning at constant speed. How fast can a vehicle go?

[PlainName]

1. Tightening a screw will not be energy storage as the screw will not come back out after tightening.

The model you show doesn't reverse. The screw jumps because of stiction, which is what's happening in your video.

3. When I have ever claimed that faster than wind direct downwind is not possible ?

Then what is this entire thing about? See 4. for your explicit claim that sustained faster than downwind speed isn't possible.

I never claimed that. [

I mispoke in that you claimed it was impossible and then modified that to include energy storage. It seems you needed energy storage from the off (but still claim it's not sustainable). I have modified my original.

4. It does matter as if as Derek says vehicle is directly powered by wind when above wind speed it will be able to maintain higher than wind speed forever where if energy storage is used the vehicle will only be above wind speed until energy storage is used up.

See.

So while I do not and never have claimed directly downwind faster than wind is not possible because it is and vas demonstrated in many ways (both blackbird and the treadmill model demonstrated that).

Ah-ha!

The reason why that happen is super important as energy storage means vehicle is above wind speed for a very limited amount of time proportional with amount of stored energy and more importantly does not violate the conservation of energy.

In other words, it can't be done.

[electrodacus]

You provided zero argument for this claim. You won't be surprise to learn that it is wrong.
What is providing the 3MW to a wind turbine?

I don't understand your example. Here is mine: imagine you have a giant gear above your hear, which is turning at constant speed. How fast can a vehicle go?

I guess you do not quite get what air is.  The analogy is not "giant gear above your head witch is turning at constant speed" but a large ball at constant speed hitting the vehicle or propeller blade or anything else in the path.

So a sail vehicle direct downwind or Blackbird can only have access to same amount of wind power as interaction between wind (moving air particles) and vehicle is by air particles hitting the vehicle and so exchanging kinetic energy.

When direct downwind vehicle (no matter the design) gest to wind speed those balls speed the balls can no longer hit the vehicle so no energy can be transferred to vehicle from wind.
And when vehicle exceeds wind speed it will encounter drag as now the vehicle will hit the balls and not the other way around.

[electrodacus]

In other words, it can't be done.

1. I see what you mean the screw has elasticity as any real screw will have but you apply the force in the direction the screw will move where with the vehicle the applied direction is opposite to vehicle moving direction.

3. It is not possible without energy storage. The main point I make is that pressure differential energy storage is what powers the direct down wind blackbird above wind speed. If you calculate the amount of stored energy based on volume of air at different pressure on each side of the propeller you will understand that there is exactly enough energy stored there to allow blackbird to get to accelerate up to the speed shown in the record test.

Here is the diagram showing the difference in pressure on each side of an axial fan



So yes it can be done and if the Blackbird will have continued for another minute or so you will have seen that it slows down as all stored energy was used.
The treadmill model is the same is just that treadmill is way to short to show how vehicle slows down to zero and starts to move backwards once the stored energy is used up.
But since treadmill is in a much more controlled environment with less variable you can just take a video from the side and see how acceleration rate drops.
Easy to calculate acceleration rate from the side video.

[Naej]

You provided zero argument for this claim. You won't be surprise to learn that it is wrong.
What is providing the 3MW to a wind turbine?

I don't understand your example. Here is mine: imagine you have a giant gear above your hear, which is turning at constant speed. How fast can a vehicle go?

I guess you do not quite get what air is.  The analogy is not "giant gear above your head witch is turning at constant speed" but a large ball at constant speed hitting the vehicle or propeller blade or anything else in the path.

So a sail vehicle direct downwind or Blackbird can only have access to same amount of wind power as interaction between wind (moving air particles) and vehicle is by air particles hitting the vehicle and so exchanging kinetic energy.

When direct downwind vehicle (no matter the design) gest to wind speed those balls speed the balls can no longer hit the vehicle so no energy can be transferred to vehicle from wind.
And when vehicle exceeds wind speed it will encounter drag as now the vehicle will hit the balls and not the other way around.

I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

And you didn't explain who is providing 3 MW to the wind turbine so that it can stay at the same place. So, who? A Diesel engine hidden in it?

[electrodacus]

I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

I do not think you understand what air is based on your analogy.

Of course a propeller can work in still air but what powers the propeller if there is no longer any wind power available when vehicle is at wind speed and above.
And please do not say that propeller is powered by the wheels. That is a very silly thing to say but I heard that so many times.

If you ignore the energy stored in pressure differential (pressure differential on each side of the propeller) that pulls and pushes the vehicle then you will never be able to explain how vehicle accelerates once vehicle speed equals wind speed.

And if you think there is no pressure differential then check this  https://en.wikipedia.org/wiki/Axial_fan_design  and how do you think that energy was stored there ? It was stored when vehicle was well below wind speed and starts to discharge way before vehicle gets to wind speed.


P1 is much lower than atmospheric pressure and P2 is much larger. This is what allows the treadmill model to run against the treadmill surface direction for some limited amount of time.

[Naej]

I know what air is, I just offered a mechanical analogue to help you.

You argument that a wind turbine cannot work in still air is correct. However it's a propeller. Propeller can work in still air, and even when the 'craft is moving.
Why don't you get this simple thing?

I do not think you understand what air is based on your analogy.

Of course a propeller can work in still air but what powers the propeller if there is no longer any wind power available when vehicle is at wind speed and above.
And please do not say that propeller is powered by the wheels. That is a very silly thing to say but I heard that so many times.

Yes the propeller is powered by the wheels. Yes it is silly. Many things in physics are silly yet correct.

If you ignore the energy stored in pressure differential (pressure differential on each side of the propeller) that pulls and pushes the vehicle then you will never be able to explain how vehicle accelerates once vehicle speed equals wind speed.

Yes air applies a force on the car, which pushes it. Amazing, no?

By the way, you didn't tell what was the engine providing 3MW to a wind turbine so that it can stay at the same place. 

[electrodacus]

Yes the propeller is powered by the wheels. Yes it is silly. Many things in physics are silly yet correct.

Yes air applies a force on the car, which pushes it. Amazing, no?

By the way, you didn't tell what was the engine providing 3MW to a wind turbine so that it can stay at the same place. 

Wheels are not a power source (they are not radioactive and not being burned to extract energy from them). Wheels are an intermediary but power to any part of the (wind powered vehicle) can only be provided by air particles hitting the vehicle body (any part of the body including the propeller blades).
When air particles hit the direct downwind vehicle from the back (wind speed higher than vehicle speed) the wind power is available to vehicle to accelerate in the desired direction and or store that.
When vehicle speed equal wind speed there is zero available wind power to vehicle and when vehicle exceeds wind speed the vehicle will now hit the air particles so wind power available to vehicle will be negative meaning will slow down the vehicle unless as it is the case here vehicle also has access to earlier stored pressure differential that will be used to cover vehicle friction losses including air drag. 

The stored high pressure and low pressure created by the propeller is called pressure differential energy storage.
That pressure differential was created by the propeller using wind energy while vehicle speed was well below speed then after that this stored energy is what powers the vehicle for the next few minutes (how many minutes or seconds depending on how high you set the acceleration rate).

The 3MW wind turbine is anchored to the ground so what is being accelerated is the entire earth and obviously a 3MW wind turbine will not make any measurable difference to such a large mass but it can be calculated as we know the mass and speed of air particles the equivalent area of the wind turbine and the mass of the earth.

You can imagine this 3MW wind turbine installed on a 4 wheel platform with say a weight of 1000kg including the wind turbine weight and then you can imagine this 4 wheel platform on a 200000kg 4 wheel platform that sits on the ground.
Wheels are ideal with no friction.

The 3MW for 1ms will provide at least 3000Ws (this is absolute minimum not to violate energy conservation) to the 1000kg 4 wheel platform
So starting from zero kinetic energy the platform will end up with 3000Ws
3000Ws = 0.5 * 1000kg * v²
So after this 1ms the platform speed relative to the large platform will be
sqrt(3000Ws/(0.5*1000kg)) = 2.45m/s  relative to both the large platform and ground.

Now if the small wheel platform is anchored to the large 4 wheel platform (say brakes are enabled).
Then that same energy will be transferred to the large platform
Now the weight is 201000kg
3000Ws = 0.5 * 201000kg * v²
so speed of the large platform after 1ms
sqrt(3000Ws/(0.5*201000kg)) = 0.17m/s relative to ground
Now if you apply the brakes to large platform also the energy will be transferred to planet earth and if you know the mass you can calculate the speed increase of the planet after 1ms.

[gnuarm]

In the wind powered car, the propeller is like a transformer, matching impedance.  The wind has a lot of power, but it is hard to couple that power to the car.  Using a sail causes the coupling of power to diminish as the car goes faster, reaching zero when the car speed matches the wind speed.  The power of the wind has not diminished at all.  It is just the coupling.

The propeller on the car is driven by the wheels, so it takes some power from the car motion to push back against the wind.  This allows the wind to push against the propeller more strongly at higher speeds.  While some power is required to produce the back pressure from the propeller, it is not so much as to make the car lose propulsion.  The wind can continue to push the car as the speed approaches and even exceeds the speed of the wind.  Why?  Because of the more appropriate coupling of the wind pushing the car, through the propeller.  It doesn't fall to zero as the relative velocity of the wind and car approaches zero.  In this case, what is important is the relative velocity of the wind and the exhaust from the propeller.

Has anyone already talked about the car that has multiple sails on a track?  The sails are moved towards the wind as the wheels power the track.  On reaching the back of the car, the sails fold up in some manner to be moved to the front of the car where they are unfolded again to catch the wind.  Since the sail will have a non-zero velocity to the wind as it moves backwards, the velocity of the car can rise above the wind speed while the velocity of the sails remains below the wind speed.  I expect this has already been talked about, no?

[electrodacus]

In the wind powered car, the propeller is like a transformer, matching impedance.  The wind has a lot of power, but it is hard to couple that power to the car.  Using a sail causes the coupling of power to diminish as the car goes faster, reaching zero when the car speed matches the wind speed.  The power of the wind has not diminished at all.  It is just the coupling.

The amount of power available to a wind powered vehicle (any design) is based on wind speed relative to vehicle so for direct downwind (wind speed - vehicle speed) as both this speeds are relative to ground and the equivalent area with witch the vehicle interacts with air particles.
And of course that means that as wind speed increases the available wind power to vehicle will drop with the cube of the air speed relative to vehicle.

P_w = 0.5 * air density * area * (wind speed - vehicle speed)³ for ideal case so best case scenario.

When vehicle speed relative to ground is zero the potential wind power is  P_w = 0.5 * air density * area * (wind speed)³ so highest possible depending on just area and wind speed.
When vehicle speed equals half the wind speed  P_w = 0.5 * air density * area * (wind speed/2)³ so 8x less wind power is available to vehicle
When vehicle speed equals half the wind speed  P_w = 0 so no wind power is available to vehicle.

The propeller on the car is driven by the wheels, so it takes some power from the car motion to push back against the wind.  This allows the wind to push against the propeller more strongly at higher speeds.  While some power is required to produce the back pressure from the propeller, it is not so much as to make the car lose propulsion.  The wind can continue to push the car as the speed approaches and even exceeds the speed of the wind.  Why?  Because of the more appropriate coupling of the wind pushing the car, through the propeller.  It doesn't fall to zero as the relative velocity of the wind and car approaches zero.  In this case, what is important is the relative velocity of the wind and the exhaust from the propeller.

So much wrong with this part of the comment that I will likely not be able to address all.
- Power taken at the wheel while vehicle still accelerates can only come from wind power, stored energy (like in pressure differential) or a combination of both depending on wind speed relative to vehicle.
- The amount of energy needed to create a very small pressure differential (say just 2 or 3% more air particles on one side of the 20m² propeller swept area say just 1m on each side so 20m³ volume) is about 100000Ws about 28Wh so almost 4x more energy than needed to accelerate the 300kg blackbird to the record speed of almost 13m/s which is about 7Wh
-So what you call exhaust from the propeller is stored energy in pressure differential and that will be used up then vehicle will start to slow down.

[PlainName]

The power of the wind has not diminished at all.  It is just the coupling.

That cuts to the chase perfectly, but he can't grasp it.

[PlainName]

so almost 4x more energy than needed to accelerate the 300kg blackbird to the record speed of almost 13m/s which is about 7Wh

Citation needed.

[electrodacus]

so almost 4x more energy than needed to accelerate the 300kg blackbird to the record speed of almost 13m/s which is about 7Wh

Citation needed.

I always provide all my claims with the proper math proof yet you all replay with opinions (strong opinions) and no evidence presented.
I guess it is true that the less you know the more confident you are.

So for the amount of energy needed to accelerate blackbird that has about 300kg to 13m/s
0.5 * 300kg * 13² = 25350Ws / 3600 = 7.04Wh
Now to this there is some rolling resistance and friction but there is also some help from wind before wind speed and then there is the low propeller efficiency when running from stored energy and we are above wind speed.

As for the energy that can be stored in pressure differential go to any online calculators say this one https://www.tribology-abc.com/abc/thermodynamics.htm
Set P1 to 0.105MPA so 5% above ambient pressure (is like having 2.5% on each side of the propeller) and that 2.5% will mean just that 2.5% more particles in a volume behind the propeller swept area and 2.5% less than normal ambient on the other side in total a 5% delta
Set volume to 20000 * 10^-3m^3 this will be just the volume on one side of the propeller if you consider 1m from the propeller witch has about 20m² swept area on Blackbird.

Leave all other data as default and push the solve button.
Result is in kJ and it is 102.5kJ so 102500J witch is the same with 102500Ws / 3600 = 28.47Wh