Apologies if i got it wrong, but it doesn't seem as if you are just conducting a poll. I gave my opinion (as you asked), backed it up with references, and then you go on to an un-related issue about NASA. That doesn't seem to be doing what an umpire does.
For another example of the scientifically demonstrated explanations, see
www.av8n.com/how/
This is a source referred to by a guy who created world record holding aircraft, Mark Drela of MIT.
Select to expand quoteChris 249 said..
un-related issue about NASA..
What is interesting about science that .
...rockets do fall of the sky not because you have things right 999 on 1000......
but because you had this 1 wrong.
Select to expand quoteMacroscien said..
Now there is very hard nut to crack for all our pushers and suckers here.
Lets imagine that we take a simple glass pane and water hose.
Lets perform following experiment.
1.- we keep the glass pane at the angle and pour water from hose on to it.
Water obviously spread on the glass and goes down.
2.-Now we till our glass pane to 90 degree, completely vertical.
Most of the water still "stick' to the glass and fall down
3.Now we tilt glass even further and now it is like 270 degree, almost upside down and water stream is still following this glass surface. Upside down!
Should fall off, one may say. What is causing this water to stick to the glass
? Is it glass sucking the water ?, air pressure pushing onto it? vacuum or pressure ? or something else?
Is it related to our sail example or not at all ?
Surface tension...
Select to expand quoteJupiter said..
Surface tension...
Now,
there are substances that lower or increase surface tension.
Suppose that you pour and mix water with your detergent - kitchen dish washing liquid to lower surface tension.
In such case your glass pane could
a) keep thicker water layer
b) less water
c) same as before
Lets all admit that the real question here is if plane wings create a lower pressure on top of the wing enabling lift and therefore flight, how do planes fly upside down??
+1 for a sail is pushed.
My unscientific Guess below.
An Aeroplane wing is not the same thing as a sail. The Aeroplane wing is used to force the plane up vertically not forward. The Engine drives the plane forward.
The two sides on a wing are a long way apart to make the air travel further on one side than the other and this is ajustable via the flaps.
A non cambered sail has the same distance from the mast to the clew on both sides. Is 1mm material thickness really going to make the air travel further down the backside and create lift ?
The sail is just re-directing air pressure from its original path creating force in a forward direction, with a lot of help from the fin.
I see windsurfers with over outhauled sails which are vertually flat still providing forward motion.
A piece of plywood at a 45 degree angle to the wind would work badly but still provide forward force. Visability may be an issue 
Select to expand quote
As I said I am not taking any sides , as a freelancer. Let see how we could tease NASA experts a bit.
We know that NASA planes (like space shuttle)
1. Fly faster then our sail
2. Fly much higher too.
We know also that maximum " sucking" force on the upper surface of our wing will be limited to 1 atmosphere at sea level.
if plane now is flying much higher altitude, where is less air the sucking force on the upper surface is much less then that.
If NASA engineers where as dumb to create a wing where the " pushing force" on the bottom where equal to the upper surface - such place will start from runway beautifully but then fall of the sky when reaching say 10 km flight level.
Simply stall and fall down, even where going with near hyper sonic speed.
So we know that upper limit on the upper surface will be limited by surrounding air pressure. On another hand there is no upper limit how much you could compress this same air at the lower surface. Now, one could say that at high altitude bottom airfoil surface works well , upper not so much.
So their returning to Earth space shuttle (that use wings) can not relay much on the upper surface, as much as on lower surface only.
Now Chris could use his PC computer and NASA experts their Big Blue Cray to calculate how much still incorrect is incorrect skipping stone theory ( that we called with Mark billiard balls molecules earlier 
) , and how far results very from beloved by Chris Newtonian version.
***Disclaimer 
Chris please read I use arguments above ,entirely for the sake of discussion and do not make any promise that are true or not , valid or relevant.
Wow, so many concepts got so wrong....
For one, anyone can design a straight-sectioned wing, like a flat plank, which (if I follow you) can be seen to have the "pushing force" the same on the bottom as on the top. Such a wing will still fly. Try building a simple balsa glider with a flat sheet as a wing - it will still fly. Secondly, look at aerobatic planes, which can have wings that are the same shape at the top as they are on the bottom. Of course, we usually use asymmetrical sections as they are more efficient.
Yes, the thinner air higher in the atmosphere limits aero lift - that's basic. That's why specialist high-altitude aircraft are different - there is no mystery about that, and it's not as if you have come to some conclusion everyone else has been too stupid to see for the last 120 years.
I don't know why you keep on going on about "sucking" force, or lift developed only from the upper surface, since I have not said that any such thing exists. You just keep on poking without reading the links provided so this I won't respond to any more of your silly trolling.
Select to expand quoteMcSailing said..
+1 for a sail is pushed.
My unscientific Guess below.
An Aeroplane wing is not the same thing as a sail. The Aeroplane wing is used to force the plane up vertically not forward. The Engine drives the plane forward.
The two sides on a wing are a long way apart to make the air travel further on one side than the other and this is ajustable via the flaps.
A non cambered sail has the same distance from the mast to the clew on both sides. Is 1mm material thickness really going to make the air travel further down the backside and create lift ?
The sail is just re-directing air pressure from its original path creating force in a forward direction, with a lot of help from the fin.
I see windsurfers with over outhauled sails which are vertually flat still providing forward motion.
A piece of plywood at a 45 degree angle to the wind would work badly but still provide forward force. Visability may be an issue
The guys who design world-record holding aircraft wings and Boeing aircraft wings, and also design America's Cup winning sailing rigs, say they are the same thing essentially.
The two sides on a wing are not a long way apart to make the air travel further - in fact thin wings are more efficient in some ways. Airliner wings are thick so they can do both low-lift cruising and high-lift takeoff and landing, and for structural and similar reasons.
As Professor Mark Drela, designer of world record holding aircraft and America's Cup rigs, says "Thin airfoils are capable of the highest CL (NOTE - that means lift) and CL/CD (NOTE - that means the lift/drag ratio) values, but only within a narrow CL range (or alpha range).... a soft sail allows the possibility of changing the camber of a thin airfoil, which can greatly extend the low-drag range if done appropriately. So a thin airfoil which always has the appropriate camber shape dialed in at any given operating point will in general be superior to a thick airfoil." He went on to look at a thin foil that had a max lift coefficient of 3, compared to the 2.3 of a thick foil.
<div>Tom Speer, Boeing wing designer and designer of America's Cup rigs, says;
<div>"the notion that because aircraft wings are very efficient and have thick sections, while sails have thin sections and generally lower lift/drag ratios, and therefore a thick sectioned sail will aerodynamically superior to a sail rig with a thin section simply because it is thick, is a mistaken idea. Airplanes have thick sections because they are structurally stronger and because they have to operate efficiently at low lift coefficients in cruise. This is generally not the case for most sailing craft, except for very high-speed craft like landyachts and iceboats.
A sail rig can operate at comparatively high lift coefficients even in high winds because it has the luxury of being able to reduce area. This makes the narrower operating range of the thin section acceptable."
Yes, the air on a sail can be said to be just re-directing air - but the same thing can be said of a wing.
Select to expand quoteChris 249 said..
You just keep on poking without reading the links provided so this I won't respond to any more of your silly trolling.
That is funny because I even copy pasted images from links you supplied and analyzed them aloud here.
But indeed I can not get intelligent discussion with the picture (while your scientific arguments boil down to stupid and silly. 
Look you troll - you haven't actually made an argument worth discussing. Instead you have just been wanking on about how you are smarter than everyone else by using bizarre theories that indicate that you don't even understand how you can increase aspect ratio or airspeed to compensate for low air pressure.
You haven't even noticed that the link you posted says that it is an incorrect theory. I'm not defending the "skipping stone" concept or your "sucking" fetish.
It is bizarre that you appear to believe that you are right and people who have spent years learning aerodynamic theory and won world records with their designs are wrong. it's like someone who has never windsurfed saying that they can do it better than AA ever did.
Select to expand quoteChris 249 said..
Look you troll -
Indeed I could not continue this dispute with you. Do you realize that if I use similar method of smearing I loose respect / esteem to myself first (?)
You supplied some link to useful info sites , and pictures but you don't seem to understand what actually on them.
When I do actually dispute with the merit of that picture, analyse content, you saying they are sacred , can not be disputed ,even if you don't know what there are actually means , you know /believe there are true and definitive ( because there are written by VERY SMART PEOPLE UNLIKE ME OR YOU)
I could not either argue with your religious approach or superstitions believes that superposition acutal knowledge on the subject.
In fact I don't require anybody here to has any specific knowledge on the subject - airfoils and lift !! I do encourage free discussion regardless of the knowledge and background , proximity to the actual truth etc.
Sad that instead disputing facts, theories everything you spew comes to personal attack.
It suppose to be fun for those the understand concept of free discussion and accept convention.
If we/you/anybody need pure educational thread, single post with single link to single wiki description will do the trick.
I will strongly advice you to create new thread on our SB forum;
The only truth about sailing and everything else, by Chris Almighty.
Select to expand quoteMcSailing said..
My unscientific Guess below..
...The Engine drives the plane forward...
Atought you don't claim almighty super knowledge by your self you pointed IMO to most crucial element that nobody mentioned earlier.
I am very glad to see that.
Our lift on air foil, wing ( or sails) could be only created if we have propulsion ( or anchor, resistance in sailing example)
If we jump into air - exposing our fin over water - we loose our lateral resistance -our lift, sail power eventually decline and we fall quickly back loosing speed.
Happen the the best in trade.
Macroscien, I am NOT claiming that I know everything. What I am asking you to do is to have some respect for OTHER people - not me - who have spent many years of their lives learning from yet more people, about how sails work. Some of the people who have spent years in a joint effort working out how aerofoils work have been good enough to share the knowledge with us, but you apparently think that you are smart enough to argue 'the merits' of what they have spent years working out with the aid of wind tunnels and computers.
It's got nothing to do with who is smarter. The fact is that if someone who is pretty smart spends 30 years or so learning about something, whether it is bricklaying or carpentry or brain surgery or aerodynamics, they will have 30 years more knowledge than you or I have if we have not been working in that area. I would therefore rather learn from them than dispute what they have learned. The odds are incomparably better that I will learn more that way than if I was arrogant enough to assume that I could poke holes in their ideas. As Isaac Newton said, "if I have seen more, it is because I stand on the shoulders of giants". These people have, for example, already spent a lot of time working out the implications of gliders, which seems to have just struck you.
Just to repeat - it isn't about me. I have never claimed to have special knowledge. All I am saying is that we should listen to those who have spent years getting that knowledge, instead of thinking that we are so much better than then that we can find flaws in their concepts.
It's really simple - these guys know better than anyone, which is why they break records and win stuff. We should learn from them instead of claiming that they will all give answers "further from the truth" as if we were smarter than they are.
Select to expand quoteChris 249 said..
Apologies
Apologies accepted bye
PS. re your comment above Sails are in use not in recent 30 years but for a thousands already. All your arguments above, about time spent and people that know better have been repeated over this thousand of years over and over again.
But we are still able to improve, step be step every year on something that is already so perfect as SAIL and known in every aspect.
Look ie Americas Cap.
Why do you assume I'm not already looking at the AC? The guys I quoted earlier, Speer and Drela, were designers for the America's Cup rigs, as the earlier posts said. They tell us about the theories behind the wing rigs - some of the information was in the quotes already given in this thread. They have been sharing their information on the AC rigs on other forums for years so there is no reason for you to assume that it is news to people who are interested in rig design.
The AC wings did not involve any major new theories. They were generally the application of standard theories and experience that have been developed since Austin Farrar did the first solid wing for "Bee" McKinnon in about 1951, and all the work that went into solid wings on Miss Nylex, Helios, Yellow Pages, Nicholas 150, Cogito etc.
Once again, this is a well-known area in which many smart people have been working for years. These people have been willing to share their knowledge with the rest of us, if we are willing to ask and to listen instead of trying to poke holes in their ideas because we think we are so much smarter than they are. By the way, plenty of us have had wing masts for decades.
The biggest development in rigs is not in new theory, but in materials and other developments that allow people to put established theory into practice.
Maybe you should try to meet and sail with the guys who do this stuff, or email them. You would probably learn to respect them like the rest of us do.
Select to expand quoteChris 249 said..
You would probably learn to respect them
I do 
If by any chance , by my innocent joke, I offended people like Decrepit at the beginning of the thread I will be apologizing willfully indefinitely. 
Because I respect the men. I don't even need to know how much he may know or achieved, but by the way the man present or talk on subject I may have nothing but ultimate respect.
Even if we don't have to agree on everything at first.
But great people don't get fussy as small one.
That is what make the difference on free discussion like that plausible.
Select to expand quoteMcSailing said..
+1 for a sail is pushed.
My unscientific Guess below.
An Aeroplane wing is not the same thing as a sail. The Aeroplane wing is used to force the plane up vertically not forward. The Engine drives the plane forward.
The two sides on a wing are a long way apart to make the air travel further on one side than the other and this is ajustable via the flaps.
A non cambered sail has the same distance from the mast to the clew on both sides. Is 1mm material thickness really going to make the air travel further down the backside and create lift ?
The sail is just re-directing air pressure from its original path creating force in a forward direction, with a lot of help from the fin.
I see windsurfers with over outhauled sails which are vertually flat still providing forward motion.
A piece of plywood at a 45 degree angle to the wind would work badly but still provide forward force. Visability may be an issue
If (1). the wind is strong enough, (2). The aircraft is light enough, (3). The aircraft's wings are long enough, and (4). The aircraft if light enough, then it can be lifted by wind alone. However, none of the conditions can be met, so the aircraft must provide its own forward movement in order to generate sufficient lift to take off. The same deal in regard to physics. Higher pressure from beneath the wing, and lower pressure above it, due to the wind speed differential between the two sides.
Regarding a sail craft, without a fin or keel, it will simply drift side-way.
Regarding a very flat sail that can still be able to provide forward motion, that is not really surprising, as long as there is a speed differential between the two sides of a sail/wing. In fact, ice-boats do have very flat sails. Once they get going, they generate incredible apparent wind.
Select to expand quoteMacroscien said..Jupiter said..
Surface tension...
Now,
there are substances that lower or increase surface tension.
Suppose that you pour and mix water with your detergent - kitchen dish washing liquid to lower surface tension.
In such case your glass pane could
a) keep thicker water layer
b) less water
c) same as before
When you mixed detergent with water, it will lower water's surface tension. You will find the mixture to spread over a wider area on the glass pane. Try dropping a tiny amount of detergent into a bucket of water, you will see the surface "opens" up as the detergent hit the water. This is because the surface tension of water is "weaken".
I believe the same amount of water will stick on the glass pane, but over a wider area.
Select to expand quoteJupiter said..
I believe the same amount of water will stick on the glass pane, but over a wider area.
Now the question could be if this water droplet on the pane upside down ( or ceiling ) remain there , hanging against gravity trying to pull its down:
a)- only by surface tension
b) -or combination of surface tension and air pressure that also press on this droplet against ceiling ? Like a succession cup don't require surface tension to remain sticking to the ceiling.
Now, lets see why it may be important.
Because if you lower surface tension, droplet spread over larger area and air pressure work now on larger area ( like a piston on your car - the bigger the better) .
So the question is if you lower surface tension, will you still have the same amount of water sticking to the ceiling , less or more?
I could see already people jumping here and shouting what this stupid question (chris will be first ) may have to do with our life at all?
Maybe not so stupid and you are a painter that want to paint the ceiling in one coat, and don't really want this white paint stuff to fall on his head. How much paint could he apply, and if he add surfactant to the paint - if it helps or not ?
Should he use water paint , because has higher surface tension or oil base or terpentine ?
Or you are sailor that took his sail just of the water and need to carry this sail back to car park. Then see this annoying water droplets hanging and ask himself : How much weight they do add to this f***g heavy stuff I need to carry ? If that help if next time I use some windows cleaner on my sails and board ? Will this eliminate this nasty water droplets or not ?
Select to expand quoteMacroscien said..Jupiter said..
I believe the same amount of water will stick on the glass pane, but over a wider area.
Now the question could be if this water droplet on the pane upside down ( or ceiling ) remain there , hanging against gravity trying to pull its down:
Macro
I believe you are placing too much emphasis on air pressure. In the case of water sticking on an inverted glass pane, surface tension between the glass and water molecules play a far more important part than air pressure asserted on the water film. Sure, there is a small influence by air pressure, but I doubt it is an over-riding factor.
As far as painting your ceiling is concerned, if you soaked your paint roller to the point of saturation, gravity will play havoc with your hair, unless you are well prepared and wear a hat, or like the hippies, a bandanna Once paint comes into contact with a surface such as the ceiling, surface tension certainly kicks in. For a start, the ceiling is porous, so some amount of paint will find its way into the pores. The rest of the paint will of course stick on the ceiling via a bond between the paint itself, and I suppose surface tension between paint and the ceiling. Imagine a piece of bread with hot butter. It will soak in.
I have never tried it. I suspect washing your sail window will actually make water stick more firmly on it. Too heavy to carry the sail back to the car park? Perhaps you want to give kites a go 
Select to expand quoteJupiter said..
I believe you are placing too much emphasis on air pressure. In the case of water sticking on an inverted glass pane, surface tension
I hoped that I could avoid that.
What would you say about gecko walking across ceiling ? or fly
Gecko have quite small feet to effectively employ air pressure.
Don't know about his surface tension ., or ceiling
If gecko is waling on the ceiling if the rougher surface helps he (to use his claws to grab gaps) or prefer smooth surface to suck in ( with suction his cups) ?
^ If the air can't get between the water and the glass it will definitely experience full on 1 atmosphere of pressure pushing it to the glass, but it's an unstable arrangement. The pressure also acts at the edges of the water pushing it inwards while surface tension also tries to pull it into some variation of a hemisphere. As it deforms it very quickly acquires a shape that allows air to get over the top and nip off a drop with the help of gravity.
Geckos hang from hair on their feet. That's all I know about it.
Select to expand quoteMacroscien said..Jupiter said..
I believe you are placing too much emphasis on air pressure. In the case of water sticking on an inverted glass pane, surface tension
I hoped that I could avoid that.
What would you say about gecko walking across ceiling ? or fly
Gecko have quite small feet to effectively employ air pressure.
Don't know about his surface tension ., or ceiling
If gecko is waling on the ceiling if the rougher surface helps he (to use his claws to grab gaps) or prefer smooth surface to suck in ( with suction his cups) ?
NotWal is right about the tiny hairs on the sole of their feet. I nicked this from my mate Goggle.
"The foot of a gecko is covered with about a billion tiny hairs called spatulae. Each is some 200 nanometers in length and width. A human hair is roughly 100,000 nanometers wide. The hairs work like Velcro. They are so small they wedge between the atoms of a surface and form molecular bonds with the wall or ceiling, putting the geck-o in direct contact with its environment."
So there is no suction cups, or air pressure involved. However, according to the above explanation, surface tension may be playing a part in a gecko's gravity defying feat. The surface tension is the bond formed between the hairs and the atoms of a surface.
May I ask, MacroScien, where on earth did you dig up such interesting questions? I quite enjoy them as they keep my brain ticking.
Now I have a question for you. If you freezed a bucket of sea water, will the ice be salty or not ? Then I have another. Are rain drops really come down like droplets ?
as Einstein once said.
Returning to our nasty droplets firmly attached to our upside down sail clear panel.
We reached consensus that there are stay there due to surface tension.
We know that we could
shake them off
wipe them of
but could we suck them off ??
If air pressure has nothing to do with droplet hanging on the sail or ceiling, if sucking off all the air around will make this drop let go an fall ? or still not ?
This short promotional video should illustrate how subjects we discussing above may found instant application in our ever day life www.facebook.com/1626076704335831/videos/1653873904889444/ 
PS if anybody know how we could better embed similar video on our SB . please advice
We need a new section called "very heavy weather" and this thread needs moving to it!
