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.
This conversation has gone to the dogs, but I suppose that was inevitable with the givens...
This conversation has gone to the dogs, but I suppose that was inevitable with the givens...
I agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
I agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
All you need to convince me is provide an equation describing the available wind power to Blackbird.
QuoteAll you need to convince me is provide an equation describing the available wind power to Blackbird.
Pw = (0.5 * air density * area * (wind speed - vehicle speed + wash speed)3) - Pp
where:
wash speed = velocity of air being pushed back by the propeller
Pp = power required to turn the propeller
Any equation that ignores the propeller (which is a pretty big part of the entire thing, you know!) is obviously missing something and not appropriate.
QuoteAll you need to convince me is provide an equation describing the available wind power to Blackbird.
Pw = (0.5 * air density * area * (wind speed - vehicle speed + wash speed)3) - Pp
where:
wash speed = velocity of air being pushed back by the propeller
Pp = power required to turn the propeller
Any equation that ignores the propeller (which is a pretty big part of the entire thing, you know!) is obviously missing something and not appropriate.The question that I asked was Wind power available to vehicle as vehicle is powered by wind power only.
QuoteAll you need to convince me is provide an equation describing the available wind power to Blackbird.
Pw = (0.5 * air density * area * (wind speed - vehicle speed + wash speed)3) - Pp
where:
wash speed = velocity of air being pushed back by the propeller
Pp = power required to turn the propeller
Any equation that ignores the propeller (which is a pretty big part of the entire thing, you know!) is obviously missing something and not appropriate.
The question that I asked was Wind power available to vehicle as vehicle is powered by wind power only.
The propeller itself is powered by wind so whatever contribution the propeller makes can not be added to wind power as it is already powered by the wind.
I did not asked about the Power available to vehicle to accelerate as that is not just wind power but after vehicle starts to move is wind power + power provided by the energy storage.
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.
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.
QuoteI agree that the direct downwind faster than wind is "slightly" unrelated subject.
But they have quite a bit in common.
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.
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.
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?
Getting off-topic here, but yes, "interestingly", what we commonly call "wind turbines" these days, in the common green vocabulary, are not really turbines.
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?
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.
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.
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.
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.
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.
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.
Your equation includes "wash speed" can you let me know what that is in an example ?
How do you calculate that ?
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.
The power is taken from the wheel in the sense that there is a significant friction on the tires, and this is the key for understanding how the car accelerates.
At the same time there is larger force forward given by the propeller (when you accelerate).
As I said before, it's a propeller not a turbine.
If wind speed+1m/s=vehicle speed, you can take 130 W from the wheel and get a large thrust from the propeller.
For example, if the propeller gets 10 kg/s of air, it can accelerate it to 2.7 m/s and get a thrust of 27 N.
If the vehicle speed is more than 5 m/s this is more than tire friction and your vehicle accelerate.
You get a large torque, which is why the vehicle is shaped like this.
Energy conservation is correct in a closed system. If you don't define the system, you can easily say wrong things, like here. And if you don't define the reference frame, ditto.
Bottom line is: both the atmosphere and the Earth are big, so there's a huge amount of energy in wind and if you neglect the annoying drag, you can go as fast as you want.
There are plenty of things going faster than the wind.
For example:
- all wind turbines.
It works in the same way as sailing boats which go faster than the wind, you just need to change direction regularly (tacking), and a rotor does this in an almost perfect way.
Well, at this point one has to ask "What the hell is the question you're asking!?!?" Clearly, the total power available is the wind acting on the surface, which is the equation you provided. There is no other power, so it is that which provides for the acceleration and everything else.
Also, I think you've failed to remember that the test vehicle had the prop blades feathered until it reached close to wind speed, at which point they were manually adjusted to provide appropriate thrust. I think you should consider that a significant clue.
However, what is very clear is that even when you get precisely what you ask for, you don't live up to your promise. There is no point or use in discussing anything with you because you are blind and immune to anything except whatever your mind has made up.
Both my equation and the one you provides shows that vehicle can not exceed wind speed unless and energy storage device is included.
QuoteBoth my equation and the one you provides shows that vehicle can not exceed wind speed unless and energy storage device is included.
Rubbish. The one you provided shows there is zero power at wind speed, but the proper version that I provided doesn't show that. It does show that power will reach zero but not the speed at which that happens. That will be dependent on how much power is taken for the prop and what thrust the prop provides.
From the equation as it stands, you cannot know if the vehicle will even reach wind speed or exceed it. To suggest otherwise means you are pre-judging based on only your bias, without thinking what the equation actually says.
If both values are zero you get zero wind power at vehicle speed equals wind speed.
All you need to convince me is provide an equation describing the available wind power to Blackbird.
Add any values you think are realistic for Pp and "wash speed" and let me know