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Newton's third law problem.

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wraper:

--- Quote from: Circlotron on November 27, 2022, 08:16:59 am ---
--- Quote from: electrodacus on November 27, 2022, 01:33:08 am ---Here a link to a proper vehicle physics calculator https://www.electromotive.eu/?page_id=12&lang=en

--- End quote ---
That calculator is next to useless. It has no facility to include coefficient of drag so it doesn't know the difference between a teardrop shape and a box shape.

--- End quote ---
It has.

Kleinstein:
That calulator is useless an using the wrong equations:  compare the case of 100 km/h headwind and 20 km/h with 110 and 10 and the calculator gives out the same result. The actual power needed would be half.

fourfathom:
And that calculator is irrelevant, or at least applicable to only a small part of the DDWFTTW discussion and that part can be ignored when studying the general principles. 

electro' still insists that the treadmill models are "transmission-locked" 
electro' still insists that his "wind turbine generator powering a motor that turns the wheels" is a valid analogy to the demonstrated DDWFTTW vehicles. 
Neither of these assertions is remotely true.

Pedaling bicycles upwind is a distraction that confuses rather than clarifies.

electrodacus:

--- Quote from: Kleinstein on November 27, 2022, 10:55:33 am ---That calulator is useless an using the wrong equations:  compare the case of 100 km/h headwind and 20 km/h with 110 and 10 and the calculator gives out the same result. The actual power needed would be half.

--- End quote ---

The calculator actually uses the correct equation and the result will be the same for vehicle at 20km/h with 100km/h head wind as it will be for vehicle at 110km/h and just 10km/h head wind.

Not quite sure where the wrong equation many of you are using originated.  Can someone point to a source for that equation and I'm not referring to Wikipedia.
That wrong equation seems to have significant implications and I will like to get rid of it. Anyone that will do an actual experiment will realize the correct equation is the one I mentioned hundreds of times and also the same used in that calculator.

Here is another website with the correct equation and definition https://scienceworld.wolfram.com/physics/DragPower.html
it reads correctly as v being the speed of the fluid relative to the body (vehicle in this case). 

electrodacus:

--- Quote from: fourfathom on November 27, 2022, 03:29:49 pm ---And that calculator is irrelevant, or at least applicable to only a small part of the DDWFTTW discussion and that part can be ignored when studying the general principles. 

electro' still insists that the treadmill models are "transmission-locked" 
electro' still insists that his "wind turbine generator powering a motor that turns the wheels" is a valid analogy to the demonstrated DDWFTTW vehicles. 
Neither of these assertions is remotely true.

Pedaling bicycles upwind is a distraction that confuses rather than clarifies.

--- End quote ---

The equation (correct one) used in that calculator is key to understand upwind version and also key to understand direct downwind version tho that will actually require even more understanding of fluid mechanics.
But I think once we can establish that is the correct equation (and there are relatively simple tests that can prove that is the case) there will be zero way to claim that direct upwind can happen without energy storage.
As that equation states that to move upwind you need more power than what is available to vehicle in ideal case from the wind.  Ideal case vehicle will be in equilibrium.

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