No one can explain WHY planes fly...

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Aerowerx

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See where he said "attracting each other when they are a little distance apart?
So air is attracted to the wing surface. And above that surface air layer the next air lamina is attracted to the surface air layer but not the wing itself which is too far, so these layers slide past. The surface layer stays attached. This way the attraction effects goes up to about a semi-wing span above the wing, I think.
But he was talking about atoms, not molecules.

And are the air molecules really "attracted" to the wing? Or are they there just as a result of their random motion?
 

dog

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Prove it.
Load a fly down with the same wing loading as a GA airplane and see what happens.
Whatever "makes a plane fly" isnt dependent on wing loading,or wether its tweety bird" i tawt i saw
a schodrers cat" its all the same phenominon,working with the exaxt same physics.
A GA plane is wildly primitive compared to life forms flying abilities.loaded down they are.
 

poormansairforce

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Whatever "makes a plane fly" isnt dependent on wing loading,or wether its tweety bird" i tawt i saw
a schodrers cat" its all the same phenominon,working with the exaxt same physics.
A GA plane is wildly primitive compared to life forms flying abilities.loaded down they are.
My oringinal response to henryk was in reference to the supposed efficiency of insects, etc using vortex lift. Increase the wing loading to GA loads and lets see if its still efficient. Next you'll be arguing that fighters are more efficient because they use vortex lift. Here is a suggestion for you...build a scaled man sized version of a spider silk and float away!
 

dog

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My oringinal response to henryk was in reference to the supposed efficiency of insects, etc using vortex lift. Increase the wing loading to GA loads and lets see if its still efficient. Next you'll be arguing that fighters are more efficient because they use vortex lift. Here is a suggestion for you...build a scaled man sized version of a spider silk and float away!

thats heavy
glad its your weight to carry
 

poormansairforce

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=many winged (birds,insects) can overcome big distances
(albatros) or fly very long time (swift,bat) iff to get some food...
From the article you posted:
"Aided by strong tailwinds"
Don't you think animals are tuned into their environment much better then we are? I think that is a common thing in the animal kingdom. They are going to find the best way to travel to ease the workload. Now you have to research how much free energy they pick up to determine how efficient they are. It doesn't work for us in explaining man made lift. Which is what this thread is supposed to be about.
 

henryk

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Now you have to research how much free energy they pick up to determine how efficient they are.
=we try to made similar way=f.e. Dynamic Soaring...

-the very prospective methode of soar in "bad" whather
(windy,dusty...) was discovered by polish/american pilot
Witold Kasper when tested his tailless glider BEKAS-N.

=possibility of soaring on flate land,NO thermiks need !!!
 

BBerson

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But he was talking about atoms, not molecules
Then study the physics of argon or some other atomic gas. I think he was mostly referring to water but he doesn't give detailed answers to your complex air questions.

Who knows what this means? "When they come close together, they can “see inside” each other and rearrange their charges, with the result that they have a very strong interaction. "
 

12notes

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I know it works.
But the question is why is air meeting a bottleneck in a tube so different than cars on Interstate 5 when reduced to one lane?
I think I've figured out a way to explain using the car analogy.

Lets deal with a 3 mile section of road, 1 mile of two lanes, a constriction down to 1 lane for 1 mile, then goes back to two lanes for the last mile. Each lane has a car entering every second at the beginning of the section, but staggered (e.g. Left lane has cars entering at seconds 1,2,3,..., Right lane at second 0.5,1.5,2.5,...) Pressure will be represented by the distance in feet between the cars, more distance = lower pressure. The key difference in this analogy is that it is a closed system, two cars are added and two exit this 3 mile stretch every second, no buildup is allowed before the restriction, and the 1 second spacing must be maintained throughout. The 1 car per second can be though of as the fluid density remaining constant. Obviously, this is a simplification.

If the cars are to remain 1 second apart throughout the 3 mile stretch, then when a car gets to the restriction, they need to instantaneously travel twice as fast to get 1 second in front of the car in the other lane which is only .5 seconds behind at that time, before the second car hits the restriction.The distance between two adjacent cars in the restriction will be greater than the distance between 2 cars before or after the restriction. This represents a lowering of pressure while the velocity increases. Similarly, the car will need to slow down to their original speed once back in their original lane after the restriction so the car originally following them will be exactly 1 second behind when it emerges from the restriction. the distance between cars compresses to the original value. Velocity goes down as pressure increases. Note that this situation never happens in normal traffic.

If the cars slow down at the restriction, then to keep the time between them at 1 second, the distance between them will to compress. The pressure goes up while the speed slows down. When they leave the restriction, the cars can return to their original speed, and the distance between them expands. Speed goes up as pressure decreases.
 
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BBerson

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I think I've figured out a way to explain using the car analogy.
Right, that's similar to my thought in post 190. But unlike cars, air atoms and molecules are linked in mysterious ways that keep them close but not too close. So I can imagine them as being interconnected before entering a Venturi and all through the Venturi. Forced to speed up at the Venturi neck and then slow back down again at the exit
 

pfarber

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I think I've figured out a way to explain using the car analogy.

Lets deal with a 3 mile section of road, 1 mile of two lanes, a constriction down to 1 lane for 1 mile, then goes back to two lanes for the last mile. Each lane has a car entering every second at the beginning of the section, but staggered (e.g. Left lane has cars entering at seconds 1,2,3,..., Right lane at second 0.5,1.5,2.5,...) Pressure will be represented by the distance in feet between the cars, more distance = lower pressure. The key difference in this analogy is that it is a closed system, two cars are added and two exit this 3 mile stretch every second, no buildup is allowed before the restriction, and the 1 second spacing must be maintained throughout. The 1 car per second can be though of as the fluid density remaining constant. Obviously, this is a simplification.

If the cars are to remain 1 second apart throughout the 3 mile stretch, then when a car gets to the restriction, they need to instantaneously travel twice as fast to get 1 second in front of the car in the other lane which is only .5 seconds behind at that time, before the second car hits the restriction.The distance between two adjacent cars in the restriction will be greater than the distance between 2 cars before or after the restriction. This represents a lowering of pressure while the velocity increases. Similarly, the car will need to slow down to their original speed once back in their original lane after the restriction so the car originally following them will be exactly 1 second behind when it emerges from the restriction. the distance between cars compresses to the original value. Velocity goes down as pressure increases. Note that this situation never happens in normal traffic.

If the cars slow down at the restriction, then to keep the time between them at 1 second, the distance between them will to compress. The pressure goes up while the speed slows down. When they leave the restriction, the cars can return to their original speed, and the distance between them expands. Speed goes up as pressure decreases.
I've always maintained that wings operate under Newtons laws, not Bernoulli's theory.

NASA has put out some papers that also run counter to the 'conventional' wisdom:

https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html

I mean symmetrical airfoils can generate left, as can a flat plate. Newton's laws make more sense than 'longer path' theories.
 

BBerson

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=gravitational forces between atoms are so weak,then in vacuum air molecules expand allmost ifinity...
Right. Gravity between atoms at short range is insignificant and no part of lift. (except without long distance gravity there would be no atmosphere)
So yeah, Gravity is why airplanes fly. :D
 

Aesquire

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Gravity is said to be an asymmetric force. It only pulls. Or curved space. We don't really understand it, we just have theories we like for their elegance.

Mass pulls mass. Why? Uh...

How about...Gravity is a Repulsive force. It pushes. From all directions, from the expanding shell of the Big Bang. Mass blocks the push. So if you stand on a big rock, like a Moon or Planet, it blocks the push from "below", and you feel pulled down.

The Earth doesn't suck. The Universe blows.
 

PagoBay

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Right, that's similar to my thought in post 190. But unlike cars, air atoms and molecules are linked in mysterious ways that keep them close but not too close. So I can imagine them as being interconnected before entering a Venturi and all through the Venturi. Forced to speed up at the Venturi neck and then slow back down again at the exit
I like the mystical expression and mysterious interconnectedness of all things but only to a point. Where does a Venturi neck come into a discussion of aircraft wings? Air foils just simply do not have any such venturi thing. Specifically as in...Asymmetrical airfoils fly and maintain altitude (produce lift) in inverted flight. Carburetors have venturis. For why planes fly, back to Prof. Babinsky's detailed, real world explanations, I suggest. Please don't take offense. Just sayin'.
 

BBerson

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Where does a Venturi neck come into a discussion of aircraft wings? A
The Secrets of Flight videos link posted on this thread shows a split Venturi in the wind tunnel to show the similarity of a wing (Venturi with top removed)
I never heard of Babinsky. Do you have a link?
 
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