The Physics of Wing Lift...Logic versus tradition.

[Trevor]

Yes but Allan I don't need to teach you how to crawl when you already know how to walk!
If I say wind tunnel, you already know what a standard wind tunnel is.
If I refer to the vacuum behind the camber of the wing you already know what sort of low pressure it is.
Although I prefer to use lay-mans language for the sake of clarity I don't want to treat you like a child but an intellectual.
Look,...I know what you mean, I am the same because I cannot take in my wife's story she is reading to me off her Blackberry, unless I know who she is talking about or where it is.LOL.

[Trevor]

Thanks Jim_mich,...I will try that when the time comes.

[johannesbender]

this is most likely wich brought my confusion , the use of the word vacuum .

to me without really researching (and not having something to read wich refers to a vacuum) when
you mention vacuum behind the camber of a wing is where i fall right of the bus here
because in my moment of reasoning i cannot concieve of any vacuum playing
a role here in the movement of fluid (air) over the wing , wich in principle
is all about a pressure difference in function (perhaps its this pressure you are refering to?)
you aswell as i and many here should know that for aerobatical planes
we use a wing with symmetry where the top and bottom both have
the same curve the top directing lift up and the bottom directing lift down
wich is needed for inverted flight wich is called a symetrical aerofoil
where is this "vacuum" ?

now as for your flat wing , any flat surface like roofs on a building or
a flat piece of balsa or foam or frame with cover can generate lift
with its angle of attack through the flow of air it travels in , this is fact
it was used on small inexpensive model airplanes before , it is nothing
new and does not defy any lift law , you can test this by holding a long flat
light surface in your hand and swing it horizontal through the air if you
have the slightest of upwards angle of attack it will lift and vice versa.

[Trevor]

Look guys ,...who cares about the exact details.
Call it a low pressure over the wing if you like, but the fact remains lift is generated due to the low pressure above the wing surface, allowing the wing to surf on the more positive atmospheric pressure under the wing.
My whole point was to debunk this theory that the low pressure over the wing is not caused by the high speed air near the surface but rather the reverse.
First the angular momentum over the camber causes a low pressure which is greatest near the surface. The thinnest air races to fill this space much fast than the more dense heavier air.
The high speed air is a result of its reduced mass being released into the space of lowest pressure.

[AB Hammer]

Yes but Allan I don't need to teach you how to crawl when you already know how to walk!
If I say wind tunnel, you already know what a standard wind tunnel is.
If I refer to the vacuum behind the camber of the wing you already know what sort of low pressure it is.
Although I prefer to use lay-mans language for the sake of clarity I don't want to treat you like a child but an intellectual.
Look,...I know what you mean, I am the same because I cannot take in my wife's story she is reading to me off her Blackberry, unless I know who she is talking about or where it is.LOL.

Trevor

We tend to take things for granted when we are speaking. But we also have people from all over the world on this forum. The mindset is self power so these test need clearer explanation. This is the question ( What does this have to do with ____ and how does this relate?) We also envision things from our own experiences. All to often someone describes something of how their wheel is, and when a picture or diagram is show it is something completely different from what is envisioned.

Don't assume every one thinks the same way. Perception!

[AB Hammer]

Look guys ,...who cares about the exact details.
Call it a low pressure over the wing if you like, but the fact remains lift is generated due to the low pressure above the wing surface, allowing the wing to surf on the more positive atmospheric pressure under the wing.
My whole point was to debunk this theory that the low pressure over the wing is not caused by the high speed air near the surface but rather the reverse.
First the angular momentum over the camber causes a low pressure which is greatest near the surface. The thinnest air races to fill this space much fast than the more dense heavier air.
The high speed air is a result of its reduced mass being released into the space of lowest pressure.

The wing scenario is well know and proved to our understanding of today. To question it "to test" is fine, and maybe it needs to be questioned for further understanding. For instance a helicopter can fly with only one blade, yet some would say no even though it has been proved. At least in small scale.

[Trevor Lyn Whatford]

Hi,

this is the quickest way to understand wings. If anyone want to feel wing lift first hand this is what you can do, get a spoon hold it by the handle so it pivot loosely between thumb and forefinger, run a tap and then enter the curved section into the flow of water and watch and feel the spoon being sucked into the flow ( wing lift ).

Trevor you can try different shapes and see how good they are.

Edit, as a sailor I constantly change the sails aerofoil shape of the sail to the wind strengths and angle of attack, flatter for stronger winds and sailing upwind, and fatter for lighter winds.

Edit, the best sailors are people who go out and experiment until they can get there sail trim and boat speed to the optimum in all wind strengths.

[Trevor]

I'm sorry guys,...The point I was making has not been addressed.
Let me refer to the erroneous statement on the net that gave rise to my argument.
It was stated that high speed air reduces it's pressure over the wing and this is what generates lift. I am sorry this is not the case.
It is the angular momentum of the air mass over the wing that generates lift through reducing the pressure.
This then gives rise to the highest speed air in the region of the lowest pressure.

[AB Hammer]

Well Trevor

Until the wing is propelled through the air by jet, prop, or future propulsion devices. The air mass is disturbed as the wing slices through the air. Before the wing slices through. there is no angular momentum of the air. But the reaction of the air over the wing causes lift. I can see where you are coming from and angular momentum like centrifugal force is created which creates the start of a vortex not unlike the inner edge of a tornado for the brief moment and a constant repeating of the new air going over the wing causing the wing space as like a void (low pressure) as far as the air effects.

Perception and viewpoint. The different ways people look at things.

Alan

[Trevor]

I quite realize that it is inertial delay due to mass of the air but it amounts to the exactly the same thing whether the plane is slicing into virtual air column or sitting in a wind tunnel.
The point has been missed again about crux of the argument so let's leave it there.

[eccentrically1]

what causes lift, a mechanical force, is motion of a solid through a fluid. no motion or no fluid, no lift. it isn't generated by a force field, or an electromagnetic field. it is improved by shape and size of the solid, span to area, velocity and inclination, and affected by the mass, viscosity, and compressibility of the air. so, the motion causes the shape to turn the flow in one direction, and lift is generated in the opposite direction, for any physical body able to produce a turning of flow. both sides of a wing shape contribute to the turn. it doesn't matter which is moving relative to the other. for tests, move the air. for flight move the wing. the motion differences, including the pressure, are represented by the equations.
quote nasa
"Lift depends on the density of the air, the square of the velocity, the air's viscosity and compressibility, the surface area over which the air flows, the shape of the body, and the body's inclination to the flow. In general, the dependence on body shape, inclination, air viscosity, and compressibility is very complex.
One way to deal with complex dependencies is to characterize the dependence by a single variable. For lift, this variable is called the lift coefficient, designated "Cl." This allows us to collect all the effects, simple and complex, into a single equation. The lift equation states that lift L is equal to the lift coefficient Cl times the density r times half of the velocity V squared times the wing area A.

L = Cl * A * .5 * r * V^2

For given air conditions, shape, and inclination of the object, we have to determine a value for Cl to determine the lift. For some simple flow conditions and geometries and low inclinations, aerodynamicists can determine the value of Cl mathematically. But, in general, this parameter is determined experimentally."

In the equation given above, the density is designated by the letter "r." We do not use "d" for density, since "d" is often used to specify distance. In many textbooks on aerodynamics, the density is given by the Greek symbol "rho" (Greek for "r"). The combination of terms "density times the square of the velocity divided by two" is called the dynamic pressure and appears in Bernoulli's pressure equation.

You can investigate the various factors that affect lift by using the FoilSim III Java Applet. (Have fun!) Use the browser "Back" button to return to this page. If you want your own copy of FoilSim to play with, you can download it at no charge."

[johannesbender]

trevor ,I think you based your argument on Bernoullis principle , but
there are other theorys of explanation where one fails to explain
another try to explain although at diffrent levels of complexity , they
can explain it with conservation of mass energy opposite forces react etc but
not every attempt of explanation are able to explain everything it takes into account
all we know is the air being forced over the wing produces lift ,
You can try and explain it diffrently or looking at it from a diffrent
point of view as long as it works but you cannot throw the current
point of view completely out of the window though , i get what you
try to discuss but without real proof and explanations etc it is a bit
like saying it is my feet that walks when another says no its your legs
Anyway , science have this type of argumentive subjects all over the place

[Trevor]

Johannesbender,...At last I have got a reply that addresses the point I am making,... congrats.
I know what you are getting at but I would like to assure you I can prove my argument both logically in depth and by practical demonstrations.
Perhaps it would be better if I put it all together in my book.
That way I won't get trapped with contradictory arguments by people who are stereo-typed into traditionally flawed theories which will confuse people.

[eccentrically1]

There aren't any flaws in theories of flight, good luck with your book though. sorry about confusing and trapping you with traditional physics!

[Trevor]

Eccentrically 1,... thanks for making me aware.
My problem is, I never know if people are on the same page of the one I am explaining.
I need to be careful to give them a point of reference first.