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Mess with your minds: A wind powered craft going faster than a tail wind speed.
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Brumby:
There seems to be a lot of difficulty working through the maths for the situation when the Blackbird is travelling at wind speed - so let's back away from that for a moment.

How about we put together the equations that describe the system for the Blackbird when it is travelling at, say, half wind speed?

This will require consideration of all the components including wind input, propeller output, wheel motion and whatever power train is in place between wheels and propeller.  ALL things must be considered and nothing can be dismissed out of hand as they are all, very clearly, involved.

If done correctly, then we follow this mathematical model and see where it ends up.



If you can't be bothered to look at this, properly, then you've revealed yourself as a troll.
electrodacus:

--- Quote from: bdunham7 on December 21, 2021, 04:03:10 am ---That's some extraordinarily convoluted babbling, even for you.  Power literally has no definition other than energy per unit time, or rate of energy transfer.  An amount of energy can be stored (as potential energy, like a compressed spring) for an arbitrary amount of time.

--- End quote ---

There is nothing wrong with that definition if you understand what it means.
I will say that maybe an analogy may be Force vs Impulse where force contains no time component will be similar to Power vs Energy if that helps.
Same as force, power has nothing to do with time. When you add time to force or power then you are talking about impulse or energy.
bdunham7:

--- Quote from: electrodacus on December 21, 2021, 04:33:44 am ---There is nothing wrong with that definition if you understand what it means.

--- End quote ---

What definition?  ::)   Where have you 'defined' power other than to say that it has no time dimension?
electrodacus:

--- Quote from: Brumby on December 21, 2021, 04:09:51 am ---There seems to be a lot of difficulty working through the maths for the situation when the Blackbird is travelling at wind speed - so let's back away from that for a moment.

How about we put together the equations that describe the system for the Blackbird when it is travelling at, say, half wind speed?

This will require consideration of all the components including wind input, propeller output, wheel motion and whatever power train is in place between wheels and propeller.  ALL things must be considered and nothing can be dismissed out of hand as they are all, very clearly, involved.

If done correctly, then we follow this mathematical model and see where it ends up.



If you can't be bothered to look at this, properly, then you've revealed yourself as a troll.

--- End quote ---

Case A will be about that. It is not half wind speed is 1/3 but it should be a good case where energy storage is ignored as with wheels on solid surface there is no energy storage.

To relay look at blackbird you can not start from half the wind speed you need to start from zero and integrate all stored energy.

If you want me to demonstrate that without energy storage higher than wind speed is not possible then we can use the wheel model the one with two treadmills below case A.
If you are interested how blackbird works and want to look at those equations then you will need to accept pressure differential energy storage.
Since what happens is that wind power is split in two parts for vehicle one part accelerate the vehicle and the other part is transferred from wheel to propeller and then propeller will increase pressure differential with basically increases the available potential energy is if like wind speed has increased.
You need two numbers the ratio between vehicle acceleration and propeller and the propeller efficiency.  In theoretical model you can have this fixed ratios in real life both the ratio of power for propeller and acceleration will be different at each step and propeller efficiency will also be variable.
electrodacus:

--- Quote from: bdunham7 on December 21, 2021, 04:40:22 am ---
--- Quote from: electrodacus on December 21, 2021, 04:33:44 am ---There is nothing wrong with that definition if you understand what it means.

--- End quote ---

What definition?  ::)   Where have you 'defined' power other than to say that it has no time dimension?

--- End quote ---

I need to say that since you think it has a time dimension.  I was refereeing to the definition you provided.
Power is just the rate at which energy is converted to another form so it is not containing time. The thing that contains time is energy.

So when I say 10W of braking power and I do not mention any time interval for witch this power is applied then time is not involved at all and no work it is being done.
You may know speed as in case A 2m/s and you can calculate force 5N but that is about all you can know. You can not say about any changes to vehicle speed or kinetic energy as time is not mentioned anywhere.
As soon as I say the 10W is applied for 1ms then you have the time and also the energy 0.01Ws and thus you can calculate what happens to vehicle over that time period including change in kinetic energy and speed.
To me it just seems you do not see power for what it is and it just seems you confuse that with Energy.
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