General > General Technical Chat
Veritasium wrong about faster than wind direct down wind.
electrodacus:
I made a youtube video showing how Derek's explanation of the blackbird vehicle is completely wrong.
His explanation will violate the law of conservation of energy so it is in the end an electrical engineering problem more than a mechanical one.
It bothers me that I was not successful explaining how the vehicle works to anyone so I hope this video I made allows at least some people understand and then they maybe with much better skills at explaining stuff can do better.
The video is unlisted for now but will be on youtube in a few days. I gave Derek a chance to watch the video first and if he understands the problem and makes a I video I will be happy to keep mine unlisted.
It will be helpful if you can provide feedback maybe even notice some mistakes in my video that I can correct before release (sort of a peer review).
I'm sure no wind powered vehicle can exceed wind speed directly down wind unless it uses energy storage and that is what I try to prove in this video plus point that his explanation was done with wrong formula (I guess he needed that wrong formula to justify his explanation).
Labrat101:
Hi Nice video you have put a lot of work into this.
Yes I watched it but not being in my field of expertise .
Even though I still think its possible to travel faster than wind . As in sailing boats can do it even though they move in a zig-zag motion.
Some how the Laws of Nature are not always predictable . (Maybe they are not meant to be solved )
Such as a Bumble Bee can't Fly . and there are a few others that scientist will try to find a reason Why . without a conclusion .
Why is the universe expanding ?? .
wraper:
--- Quote from: electrodacus on December 08, 2021, 01:39:24 am ---I gave Derek a chance to watch the video first and if he understands the problem and makes a I video I will be happy to keep mine unlisted.
--- End quote ---
:-DD |O :palm:
heutnoch:
If you go directly in wind direction there is now relative velocity between the vehicle and the wind, when you reach wind speed. So, there is no energy to accelerate. If you go faster than the wind, there is relative velocity but no possibility to transform the energy in a forward acceleration.
It's different, if you go with an angle to the wind direction. There is a sidewards component of the wind and using Bernoulli's principle you can generate a forward pull. The air flowing along the curved side of the sail takes a longer way, must flow faster and as the dynamic pressure increases the static pressure decreases (like the wing of an airplane). You can use this principle to zigzag against the wind. And as far as I know you can zigzag against a relative contrary wind, you see by going faster as the wind, with a modern high-performance sailer.
electrodacus:
--- Quote from: heutnoch on December 10, 2021, 12:27:54 pm ---If you go directly in wind direction there is now relative velocity between the vehicle and the wind, when you reach wind speed. So, there is no energy to accelerate. If you go faster than the wind, there is relative velocity but no possibility to transform the energy in a forward acceleration.
--- End quote ---
Why is this obvious to you but not the majority of the other people ?
--- Quote from: heutnoch on December 10, 2021, 12:27:54 pm ---It's different, if you go with an angle to the wind direction. There is a sidewards component of the wind and using Bernoulli's principle you can generate a forward pull. The air flowing along the curved side of the sail takes a longer way, must flow faster and as the dynamic pressure increases the static pressure decreases (like the wing of an airplane). You can use this principle to zigzag against the wind. And as far as I know you can zigzag against a relative contrary wind, you see by going faster as the wind, with a modern high-performance sailer.
--- End quote ---
I have not looked in to zigzag idea as this vehicle is not doing that. It seems that may work especially in the ideal case where you have no friction since one you got the vehicle to any speed there is no friction to slow it down.
But this blackbird vehicle is not zigzagging so it can not take advantage of that.
The blackbird exceeds wind speed but is based on stored energy in the pressure differential created by the propeller.
So when it is below wind speed it can use as much energy as it wants and part of that energy it can use for propeller to increase the pressure differential and even well before getting to wind speed this pressure differential will start to be used so pressure differential will be reduced and when there is no longer enough to cover the friction losses the vehicle will slow down below wind speed.
Navigation
[0] Message Index
[#] Next page
Go to full version