General > General Technical Chat
Mess with your minds: A wind powered craft going faster than a tail wind speed.
<< < (68/285) > >>
IanB:

--- Quote from: electrodacus on September 02, 2021, 02:36:41 am ---Is clear you do not know how a fan works or/and what air is.
There is a fairly sudden change in pressure, density and speed of air molecules from one side to the other of the blades.
--- End quote ---

In the diagram, the curve of "C" shows the velocity (speed) of the air flow. Since you say there should be a sudden change in speed, and yet the diagram shows no such change in speed, you agree that the diagram is bogus?
electrodacus:

--- Quote from: IanB on September 02, 2021, 03:13:30 am ---
--- Quote from: electrodacus on September 02, 2021, 02:36:41 am ---Is clear you do not know how a fan works or/and what air is.
There is a fairly sudden change in pressure, density and speed of air molecules from one side to the other of the blades.
--- End quote ---

In the diagram, the curve of "C" shows the velocity (speed) of the air flow. Since you say there should be a sudden change in speed, and yet the diagram shows no such change in speed, you agree that the diagram is bogus?

--- End quote ---

That is average speed of air molecules but all air particle hit by the propeller will change speed quite dramatically. Imagine a molecule at relatively low speed coming from upstream hit by a propeller at multiple time that speed will have a very serious change in speed from one moment to the other.
But I'm glad you look closer at that diagram.
bdunham7:

--- Quote from: electrodacus on September 02, 2021, 03:10:29 am ---So that is a good test that should convince anyone about pressure differential energy storage.

--- End quote ---

I'm not persuaded one bit by any of that....and you didn't answer the question about what an observer behind the vehicle would feel.

Here's one last thought.  If your theory about pressure accumulation behind the vehicle is true, then that pressure would dissipate equally in all directions, right?  If so, the least area that the pressure could be confined to would be a cylinder the diameter of the propeller and as long as the distance travelled during the storage phase.  Since the pressure is dissipating equally in all directions and only the part that represents the vehicles propeller can actually get any benefit from it, it seems that this would be very, very inefficient.  You'd have to calculate how far the vehicle would travel during the time it takes your pressure balloon to accumulate the needed energy (reduced by this inefficiency) but it seems to me you would only recover a tiny fraction of the total and the rest would just go off into space.
electrodacus:

--- Quote from: bdunham7 on September 02, 2021, 03:29:05 am ---I'm not persuaded one bit by any of that....and you didn't answer the question about what an observer behind the vehicle would feel.

Here's one last thought.  If your theory about pressure accumulation behind the vehicle is true, then that pressure would dissipate equally in all directions, right?  If so, the least area that the pressure could be confined to would be a cylinder the diameter of the propeller and as long as the distance travelled during the storage phase.  Since the pressure is dissipating equally in all directions and only the part that represents the vehicles propeller can actually get any benefit from it, it seems that this would be very, very inefficient.  You'd have to calculate how far the vehicle would travel during the time it takes your pressure balloon to accumulate the needed energy (reduced by this inefficiency) but it seems to me you would only recover a tiny fraction of the total and the rest would just go off into space.

--- End quote ---

You mean that you will not be convinced by a test showing blackbird or small scale model of that pushed to say 12mph and then released and results showing vehicle accelerating to say 24mph then slow down until it stops.
How then will you explain without energy storage that vehicle got from 12mph pushed speed to double that at 24mph ?
Most other people are saying that vehicle will not accelerate past 12mph and just slow down and stop. So if they will see vehicle accelerate past pushed speed they will know my theory is right.

No it will not dissipate equally in all directions as it can not do that where the propeller sweep area is that large 20m^2 disc created by the moving propeller and so air molecules hitting that will just give their energy to the vehicle.
It is relatively an inefficient energy storage device but there is enough energy to power the vehicle for as much as 2 or 3 minutes depending on design and amount of initial energy stored.
Keep in mind that most of that energy vehicle takes from the pressure differential (energy is stored in both sides of the propeller) will be put back in to increase the propeller speed and only a smaller fraction is used for accelerating the vehicle that is why it takes so long a few minutes instead of just a few seconds before the pressure differential drops to low.
Also losses from stored energy are higher at peak when you have the energy storage full and the losses will drop as the pressure differential drops so you will observe a decrease in acceleration rate as you get close to peak speed.
bdunham7:

--- Quote from: electrodacus on September 02, 2021, 03:46:30 am ---No it will not dissipate equally in all directions as it can not do that where the propeller sweep area is that large 20m^2 disc created by the moving propeller and so air molecules hitting that will just give their energy to the vehicle.

--- End quote ---

OK, please describe the area or whatever that stores the energy--the physical dimensions, the method of energy storage (pressure?), etc.  I'm not getting that part.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod