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

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gnuarm:

--- Quote from: electrodacus on December 28, 2021, 01:37:58 am ---I hope you keep your microphone on the floor and I'm getting tired to explain the same thing multiple times to someone that will not understand power, energy and conservation of energy.

--- End quote ---

I'm sure you are getting tired, but you haven't explained anything.  You obfuscate and bicker, but never actually make sense.  When someone shows you proof, you ignore it and change the topic.  But you never, ever explain anything.  You also don't respond to anything that is a clear, simple explanation of how you are wrong.  You just repeat the same old tired assertions that you perceive as fact.

BOOM! [mic drop again]

gnuarm:

--- Quote from: fourfathom on December 28, 2021, 01:46:49 am ---
--- Quote from: electrodacus on December 28, 2021, 01:37:58 am ---Also to store that energy the vehicle will accelerate much slower when below wind speed compared to a sail vehicle that will not store anything other than kinetic energy.
--- End quote ---

I've asked you this before, but why does a sail not store energy when below windspeed, but a propeller does?

--- End quote ---

A sail "stores" energy in exactly the same way as the propeller.  ED doesn't actually understand either the sail or the propeller.  The propeller blades work best when they have an airfoil which creates a high pressure on the flatter side and a low pressure on the more curved side.  There is also an adjustable pitch to the blades which works more like a kite.  The blades move through the air pushing air behind creating a higher pressure behind and a low pressure in front.  This pressure gradient is what ED claims is storing energy.  It does, but not very much.  It dissipates very quickly, almost instantaneously, when the blades are stopped. 

The sail works very similarly.  The wind blows across the sail creating the same high pressure and low pressure for the exact same reasons.  This pulls on the sail dragging the boat along.  The resulting forces actually propel the boat faster than the wind and can even move the boat upwind.  If such a vessel were examined closely while moving, it would be found there is no periodic release of energy to make the boat move the way it does.  The ideal situation is for the sail to be trimmed so the boat is in an optimal state to get the maximum movement from the wind.  At that point unless the wind direction changes, everything is stable.

[mic drop]

Brumby:

--- Quote from: gnuarm on December 28, 2021, 03:24:29 am ---The blades move through the air pushing air behind creating a higher pressure behind and a low pressure in front.  This pressure gradient is what ED claims is storing energy.  It does, but not very much.  It dissipates very quickly, almost instantaneously, when the blades are stopped.

--- End quote ---

But the blades of the Blackbird never stop.  True?

electrodacus:

--- Quote from: Brumby on December 28, 2021, 05:03:26 am ---
--- Quote from: gnuarm on December 28, 2021, 03:24:29 am ---The blades move through the air pushing air behind creating a higher pressure behind and a low pressure in front.  This pressure gradient is what ED claims is storing energy.  It does, but not very much.  It dissipates very quickly, almost instantaneously, when the blades are stopped.

--- End quote ---

But the blades of the Blackbird never stop.  True?

--- End quote ---

They rotate as long as the vehicle moves as they are connected to wheels. But the vehicle will get to a peak speed / kinetic energy when all stored energy (pressure differential) is used up then it will start to slow down well below wind speed.

IanB:

--- Quote from: electrodacus on December 28, 2021, 05:34:20 am ---They rotate as long as the vehicle moves as they are connected to wheels. But the vehicle will get to a peak speed / kinetic energy when all stored energy (pressure differential) is used up then it will start to slow down well below wind speed.

--- End quote ---

This kind of response, overshooting and then coming back down again, can only be observed in a system with second order dynamics, and a second order system requires some kind of inertia or momentum term. A compressed gas is a first order system, so it cannot explain this kind of system behavior. Where is the second order inertial term found in Blackbird?

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