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Mess with your minds: A wind powered craft going faster than a tail wind speed.
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IanB:

--- Quote from: electrodacus on December 19, 2021, 06:10:35 pm ---There are multiple resources here is one
http://web.mit.edu/wepa/WindPowerFundamentals.A.Kalmikov.2017.pdf
The equation can be applied anywhere starting with wind turbine design, power available to any wind powered vehicle, drag power needed for vehicle design .....

--- End quote ---

No, I want you to derive it yourself, and give your assumptions in the derivation.

If you cannot do that, you are merely quoting facts and equations from others, which in your own words shows a lack of understanding.


--- Quote from: electrodacus on December 19, 2021, 04:53:51 am ---Unfortunately school is mostly for those that can memorize facts and equations an understanding is completely irrelevant.   

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electrodacus:

--- Quote from: IanB on December 19, 2021, 06:14:48 pm ---
--- Quote from: electrodacus on December 19, 2021, 06:03:09 pm ---One part will be stored as kinetic energy the other part will be stored as both rotational kinetic energy in the rotating propeller and pressure differential  by increasing the difference in pressure between upwind side of the propeller and down wind side.

Then this stored pressure differential energy storage is what will allow blackbird to exceed wind speed for some limited amount of time.

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But the pressure after the propeller is lower than the pressure in front of the propeller: https://www.quora.com/Why-is-the-static-pressure-before-a-fan-higher-than-after-the-fan

I have shown you a video illustrating this. Do you think that video was manipulated or faked in some way? Every engineer knows that video shows the truth. You can do the same experiment yourself. Just use any household fan. You will find the pressure in the moving airstream is lower than the surroundings.

You should stop looking at that Wikipedia article. It does not say what you think it says.

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Not sure what you mean by after and front. Here is the graph for pressure difference.
Never claimed that anything was faked. It works exactly as shown from the equations and theory I presented.
electrodacus:

--- Quote from: IanB on December 19, 2021, 06:19:08 pm ---
No, I want you to derive it yourself, and give your assumptions in the derivation.

If you cannot do that, you are merely quoting facts and equations from others, which in your own words shows a lack of understanding.


--- Quote from: electrodacus on December 19, 2021, 04:53:51 am ---Unfortunately school is mostly for those that can memorize facts and equations an understanding is completely irrelevant.   

--- End quote ---

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Do not be afraid just open the pdf and look at page 4.
IanB:

--- Quote from: electrodacus on December 19, 2021, 06:20:03 pm ---Not sure what you mean by after and front. Here is the graph for pressure difference.
Never claimed that anything was faked. It works exactly as shown from the equations and theory I presented.


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I mean, if you do the experiment, yourself, with a real fan, you will find that P2 < PA.


--- Quote ---Never claimed that anything was faked.
--- End quote ---

But you did. I showed you a video where Matthias Wandel did the experiment, and you said you didn't believe the video. If you disbelieve a video of an actual, real world experiment, showing what actually happens, then you must think the video was somehow faked?
fourfathom:

--- Quote from: electrodacus on December 19, 2021, 06:03:09 pm ---The difference is that sail vehicle (an ideal one) takes all this available power and stores it as kinetic energy thus not able to exceed wind speed.
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So why is there no pressure differential energy stored behind the sail?


--- Quote from: electrodacus on December 19, 2021, 06:03:09 pm ---Blackbird will split this available wind power in to two. One part will be stored as kinetic energy the other part will be stored as both rotational kinetic energy in the rotating propeller and pressure differential  by increasing the difference in pressure between upwind side of the propeller and down wind side.
Then this stored pressure differential energy storage is what will allow blackbird to exceed wind speed for some limited amount of time.

--- End quote ---
Stored rotational kinetic energy can not cause a fixed-geometry propeller to increase rotational speed.  It can at best reduce the rate that the propeller rotation will slow down.
In your models and equations, stored pressure differential energy will not cause the vehicle to accelerate to above windspeed, since any pressure differential will diminish to zero at windspeed, and go negative when the vehicle is above windspeed.

Your errors in analysis have been explained many times.
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