General > General Technical Chat
Mess with your minds: A wind powered craft going faster than a tail wind speed.
Kleinstein:
--- Quote from: electrodacus on September 17, 2021, 07:20:27 pm ---If I where to compete with a similar vehicle just using a round 5.3m diameter sail instead of the propeller I will win the race any time against the blackbird.
What will happen is that I will be the first to accelerate while blackbird will waste a lot of time initially to store energy and while blackbird will have higher top speed the average speed will be lower due propeller being less efficient than a sail.
So if the race is about top speed then blackbird can win but if it is about getting first to finish line then sail vehicle will win.
--- End quote ---
For such a race is depends on the lenght of the race. Initially the backbrid needs additional energy for the kinetik energy of the propeller - that is the main extra energy storrage. So in the acceleration phase to maybe 90% of the wind speed the sail drive may be more efficient, but later the propeller extra pushing action can give it an edge and finally reaching the higher sustained speed (e.g. 120% the wind speed), while the sail may only reach 95%.
If there is extra energy storred this extra would go up with higher speed. So that extra energy could not be used to accelerate - this would be the wrong way round, like using the gain in potential energy to go up faster up-hill, which obviously does not work. There just is not significant energy storrage that would help to accelerate the vehicle (only to slow down the slow down).
The energy storage is just there to confuse and maybe find an explaination for seeing the experiment but not believing. The idea with energy storrage just does not work.
The example with wheels can be calculated without, with very basic math - not even physics. The movement to the right is the only one compatible with the gear ratio and no slip at the wheeels. Trying to convince us of the opposite as nearly as crazzy as claiming that 3x3 is 7. :horse:
electrodacus:
--- Quote from: fourfathom on September 17, 2021, 07:46:00 pm ---Where is the energy storage in a lever? Where is it in a gear ratio? Energy storage is not required here.
--- End quote ---
Not quite sure what you are asking. In real world same as you can not get rid of friction you can not get rid of energy storage. You can reduce both friction and energy storage but you can not completely eliminate them.
If you are talking about the geared toy cart in my first video then as explained the frame of the vehicle torsion acts as an energy storage device again is like a spring same as with the belt elasticity just less pronounced but if you look closely in the video you will see how the metal pins on the side of the vehicle move up and down as the energy is stored and then used.
Kleinstein:
There is some parasitic energy storage, but it is not relevant. It is just too little to explain the experiments shown. The right explaination works without it.
It's just red hering - and a dead hering. :horse:
electrodacus:
--- Quote from: Kleinstein on September 17, 2021, 07:47:27 pm ---
--- Quote from: electrodacus on September 17, 2021, 07:20:27 pm ---If I where to compete with a similar vehicle just using a round 5.3m diameter sail instead of the propeller I will win the race any time against the blackbird.
What will happen is that I will be the first to accelerate while blackbird will waste a lot of time initially to store energy and while blackbird will have higher top speed the average speed will be lower due propeller being less efficient than a sail.
So if the race is about top speed then blackbird can win but if it is about getting first to finish line then sail vehicle will win.
--- End quote ---
For such a race is depends on the lenght of the race. Initially the backbrid needs additional energy for the kinetik energy of the propeller - that is the main extra energy storrage. So in the acceleration phase to maybe 90% of the wind speed the sail drive may be more efficient, but later the propeller extra pushing action can give it an edge and finally reaching the higher sustained speed (e.g. 120% the wind speed), while the sail may only reach 95%.
If there is extra energy storred this extra would go up with higher speed. So that extra energy could not be used to accelerate - this would be the wrong way round, like using the gain in potential energy to go up faster up-hill, which obviously does not work. There just is not significant energy storrage that would help to accelerate the vehicle (only to slow down the slow down).
The energy storage is just there to confuse and maybe find an explaination for seeing the experiment but not believing. The idea with energy storrage just does not work.
The example with wheels can be calculated without, with very basic math - not even physics. The movement to the right is the only one compatible with the gear ratio and no slip at the wheeels. Trying to convince us of the opposite as nearly as crazzy as claiming that 3x3 is 7. :horse:
--- End quote ---
Yes there is some kinetic energy stored in the propeller but that is much smaller in that initial phase than the energy stored in pressure differential energy storage.
There can not be a sustained speed above wind speed and that I what I try to make people understand.
No matter the length of the race the sail will win the race if wining means being first at finish line. If race is about top speed obviously blackbird will win.
Have you watched my slow motion video https://odysee.com/@dacustemp:8/wheel-cart-energy-storage-slow:8
The energy storage is fairly visible there and you can see vehicle peak speed even above paper speed but average speed is much lower. Same will happen to blackbird if you waited long enough to see multiple cycles then it will look the same as my toy cart.
fourfathom:
I am now halfway through this entire thread, and I apologize to all for beating a thoroughly dead horse.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version