Oh I see now.
Sorry for jumping the gun on the issue
(hard to read a 3 page thread filled with information  )

But I still stand pat regardless 

A cambered wing with zero geometric AoA (angle between mean chord and relative wind) will provide lift since there is a net diversion of the air down.
The same wing profile, with zero effective AoA wont produce lift.
Zero effective AoA =  0 lift

(sorry for the crappy pic, mobilecamera  )

So in order to get the aircraft up in the air, it has to deflect the air downwards.

Sorry for borrowing your image  



If the vertical component (red) of the downwash, "thrust" vector was significant enough to provide enough lift to be holding an airplane up.. The horizontal component (green) would surely be enough add airspeed...

I still say  NO..   lol  

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I think it's more of a friendly debate than a fight, and it was established long ago in this thread that we're both right to some extent.
At least I'm willing to admit that...

I hadn't anticipated getting into a long scientific argument on this. It's a long time since I thought anything about aerodynamics & I must admit to not being familiar with these latest theories. In fact I'd not heard of them before reading the article from Jake's link. I've always thought there is more than one force at work here. It's quite possible the Newton/Coanda theory is valid in some circumstances but that doesn't appear to explain why there are so many different aerofoil sections or why they would be necessary. Not being a scientist I imagine several basic laws of physics apply here. I won't show my ignorance by continuing the argument but throw a few points into the discussion.

Most people tend to forget that it's the wing that's moving through the air & the term 'airflow' is a misnomer. This brings the whole argument about angle of attack into question as increasing the AoA involves lifting the nose of the complete aircraft & changing the direction of flight upwards. The thrust line remains constant so once a climb (or dive) is established the direction of the relative 'airflow' is no longer horizontal as shown in most diagrams.

I've dug out my old 'Flight Briefing for Pilots' that was considered the private pilot's bible for many years. I was given a signed copy by the author when it was first published in 1961 which is one of my prized possessions. I copied this short extract from the chapter on fundamentals. "If the Leading Edge of the airfoil is raised at a slight angle to the airflow, pressure will rise when the air makes contact with the undersurfaces of the wing because of its momentum. The net result is that the airfoil section will generate a lifting force approximately two-thirds of which is due to the decrease in pressure on top of the wing and one-third to the increased pressure below."

I suggest that this is only temporary during the change of direction & until the climb is established.

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I did a little more research into this, and apparently it's a desired airfoil for all "tailless" aircraft, not just deltas... this would explain why it was being studied in 1941, as there are tailless and even swept-wing designs going back quite a ways.
I'm still not exactly sure why it's desired, but that little schwoop at the trailing edge seems to help with (lateral?) stability at low airspeeds and high angles of attack. Why it works so well with gliders is another interesting question; maybe the narrow fuselage aft of the wing puts sailplanes in the same aerodynamic realm as tailless aircraft in some situations. I wish I had more time to study this, but unfortunately I'm not getting paid to play aerodynamicist; got to get ready for work now.

This has been fun; maybe next we can all have a whirl with the old "downwind turn" debate... LOL...

I'm Googling  "Downwind turn debate".. keepin' an eye open for the thread 

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Uhboy, here we go...

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Hmmm. Not sure I understand that now I come to think about it. I was quoting something I read while googling. I'll ask Chris to elaborate on the properties of reflexed aerofoils next time I see him. (In most cases I've seen the actual aerofoil is not reflexed. The effect is achieved by the angle of the control surface attached to it.)

I think you're right about the intuitive understanding. I was never convinced that all these scientific explanations are correct.