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Mess with your minds: A wind powered craft going faster than a tail wind speed.
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Labrat101:

--- Quote from: electrodacus on December 10, 2021, 10:23:43 pm ---
--- Quote from: Labrat101 on December 10, 2021, 08:15:03 pm ---Wind is powering the propeller not the wheels .
The wind tread mill is not correct .
Sorry you can't emerlate wind with a tread mill

--- End quote ---

The propeller was replaced by the M wheel here not to have any confusion about what a propeller is (just a wheel for traveling trough materials instead of on the material surface).
People think propellers have magical proprieties so I prefer to use wheels as people have less misunderstandings about how those work.  :wtf: :-DD

--- End quote ---
I have no problem understanding a propeller . I was flying twin engine Doves out of Hurn airport UK  in the 60s . ( Not the white birds that flap around going tweet tweet )
WE used the wheels to keep the fuselage from scraping along the ground .  They also came in handy for Landing ..
A wheel is a wheel .. Propeller is a propeller that's it .
The design  of a propeller is an important factor the one they use was a variable pitch . ie the blades can have their pitch altered
this is not in your formulae..  There for you are wrong .  Angle , degree etc etc etc Please add these in .
Then the Bumble Bee will fly  :-DD

PS    Quote "" People think propellers have magical proprieties ""    and you don't understand the magic  IT's a Propeller
electrodacus:

--- Quote from: Labrat101 on December 10, 2021, 11:06:49 pm ---I have no problem understanding a propeller . I was flying twin engine Doves out of Hurn airport UK  in the 60s . ( Not the white birds that flap around going tweet tweet )
WE used the wheels to keep the fuselage from scraping along the ground .  They also came in handy for Landing ..
A wheel is a wheel .. Propeller is a propeller that's it .
The design  of a propeller is an important factor the one they use was a variable pitch . ie the blades can have their pitch altered
this is not in your formulae..  There for you are wrong .  Angle , degree etc etc etc Please add these in .
Then the Bumble Bee will fly  :-DD

--- End quote ---

I hope not to sound rude but unis something is different from understanding how it works.
Variable pitch is the equivalent of a gearbox before the wheel.
A propeller has no "magic" proprieties and it is the exact analog of a wheel just that a wheel is much more efficient than a propeller.
So if you wanted to be more efficient you will have just took the power from the back wheel on blackbird and put that in the front wheel. But doing so provides you with no energy storage as road is not compressible like air.
 
If someone suggested you take energy from back wheel and power the front wheel it will have been considered stupid (by most not all) but suggesting taking power and supplying a propeller is even worse if you exclude that energy storage in pressure differential that nobody seems to understand.
Kleinstein:

--- Quote from: electrodacus on December 10, 2021, 10:40:51 pm ---
--- Quote from: Kleinstein on December 10, 2021, 09:15:02 pm ---When going at the speed of the wind or faster than the wind, the wheels are driving the propeller, not the other way around.

--- End quote ---

What powers the wheels ?

--- End quote ---
The wind power the vehicle and thus the wheels. The power from the wind is given as thrust from the propeller times speed of the wind.



--- Quote from: electrodacus on December 10, 2021, 10:40:51 pm ---

I wanted to make sure is clear Pout includes Pin that is why a Pnet was need to show what the state of the vehicle will be.
Derek used the wrong formula with (v-w) instead of correct (w-v) and only looked at the case C so vehicle speed above wind speed.
The G wheel is a generator only and M wheel is a motor only same as with blackbird where wheel is only a generator and propeller is only for propulsion (they even have a freewheel device installed to make sure power from propeller can not be transferred to wheel).
In case B that is at the limit so in real world you can not get exactly zero speed but all power from generator is needed at the motor else vehicle will move backwards (decelerate if any power is generated at G wheel and not all of it is put in the M wheel).

--- End quote ---
For the math it does not matter if one has a motor or generator. Esepcially wheels and gears work in both directions. In the examples generator power was fixed positive and there is no porblem ignoring the possible extra power in case 1, it works without it too.
Whether one uses (v-w) or (w-v) is only a question of the direction of the force, so it depends which side of the balance to look at.
The case B is very easy: one needs no power to stop the motor. So here zero power for the motor is obvious.


Kleinstein:

--- Quote from: electrodacus on December 10, 2021, 11:26:16 pm ---If someone suggested you take energy from back wheel and power the front wheel it will have been considered stupid (by most not all) but suggesting taking power and supplying a propeller is even worse if you exclude that energy storage in pressure differential that nobody seems to understand.

--- End quote ---

This is not stupid, but the way the vehicle works.  Of cause it only works because the wheels are not on the same surface, but with a velocity between them.

Excluding energy storrage is just making it simpler - in the steady state the energy storage does not contribute to the power. So far I see no form of energy storage that stores more energy when slower. The kinetic energy and the energy stored in the pressure difference around the propeller both go up when the vehicle goes faster. So these forms of energy storage can no explain a jo-jo type movement. Instead of chasing the red herrring energy storage just try to understand the explaination given. There is nothing wrong with the experiment with the large wooden beam on the roler vehicle. Just accept what you see.
Labrat101:

--- Quote from: electrodacus on December 10, 2021, 11:26:16 pm ---
--- Quote from: Labrat101 on December 10, 2021, 11:06:49 pm ---I have no problem understanding a propeller . I was flying twin engine Doves out of Hurn airport UK  in the 60s . ( Not the white birds that flap around going tweet tweet )
WE used the wheels to keep the fuselage from scraping along the ground .  They also came in handy for Landing ..
A wheel is a wheel .. Propeller is a propeller that's it .
The design  of a propeller is an important factor the one they use was a variable pitch . ie the blades can have their pitch altered
this is not in your formulae..  There for you are wrong .  Angle , degree etc etc etc Please add these in .
Then the Bumble Bee will fly  :-DD

--- End quote ---

I hope not to sound rude but unis something is different from understanding how it works.
Variable pitch is the equivalent of a gearbox before the wheel.
A propeller has no "magic" proprieties and it is the exact analog of a wheel just that a wheel is much more efficient than a propeller.
So if you wanted to be more efficient you will have just took the power from the back wheel on blackbird and put that in the front wheel. But doing so provides you with no energy storage as road is not compressible like air.
 
If someone suggested you take energy from back wheel and power the front wheel it will have been considered stupid (by most not all) but suggesting taking power and supplying a propeller is even worse if you exclude that energy storage in pressure differential that nobody seems to understand.

--- End quote ---

Variable pitch is the equivalent of a gearbox before the wheel.   Your kidding for sure . 
This phrase just show how you have no idea of the properties and design that goes into a making a propeller .
 Its not a Fan that sits on the table in your house .
 There are many many factors that you have left out .
I suggest you take a course in aviation . . & leave the school book theory's to the kids with wind up elastic band planes  .

 Like every one here has already tried to explain this to you your maths is Wrong .
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