Sorry.. I spent the day helping a friend install a water heater..

I didn't answer the question directly,  'cause I didn't understand the point being made, and thought I kinda answered it with that diagram.

You can apply infinite types of wing configurations to this discussion; and as underqualified as I am to be having it in the first place; I'd go past underqualified right on into genuine confusion.

True angle of attack becomes a complex issue too. A very complicated airfoil can "look" like it has zero or no AoA while indeed it DOES have a positive AoA  (that was the point of my very simple airfoil diagram) while looking plenty cool ..lol

Still though.. none of this refutes my position that there cannot be a net lift from Newton's 3rd, without positive AoA.  Repeat.. Redirecting air down the backiside of an airfoil  cannot yield a net lift without AoA...That type of lift can make the old barn door fly. Pressure differential (no matter how you wanna credit it in the entire process (pure additional lift OR assisting the redirection for N3 lift OR the magic puzzle piece that brings it all together ) it doesn't matter).. It's STILL what makes a wing a wing and an airplane fly.

Ok.. I think I'm seeing your point more clearly, and it makes me wanna make mine more clear.

Here's why I had a problem grasping it..

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Not true.. I'm fully aware that as the AoA increases, the net  "action/reaction" increases. The cancellation happens at or near zero AoA..

I discovered, admitted to and accepted (even said so when this thread was first active) that as far as pure, upward force; pressure differential is a mere fraction of what's needed. I think, for a C172 @ 100kias it worked out to be 60lbs (I'd prefer Newtons as the unit , but aren't up to doing the math).

I'm all for new math and proving old, accepted stuff wrong, but when I started to try to visualize redirected air, downwash and all that stuff... the conservation of energy haunted me. "How can you get a NET force out of it ?" ...  "You cant just move mass around and get more work out of it than you put in"...    Obviously, the sacrifice for the lift; no matter how you credit it; is drag. You're going to have the L/D deal no matter how you go about keeping the airplane aloft.

Now.. isolating the two components we're wrestling with....  The Newtonian lift is NOT a product of redirecting air. You're going to have redirection no matter what the wing shape. Air is gonna be moved more than once and in more than one direction. But you don't get "action/reaction" lift until there's a positive AoA. The Newtonian (N3) lift happens BECAUSE of the angle of attack, period, no debate....  The Bernoulli lift DOES happen because of how the air is redirected by the wing. It IS a product of the WING and DOES happen, even at zero AoA. Even Bernoulli opponents admit that the Newtonian lift relies on Bernoulli and usually end up settling this debate saying, "both camps are right.. "can't have one without the other"....

I'm saying...(even if isolated pressure differential force is a fraction of the brute AoA force).. (and even if ALL you credit Bournelli with, is allowing the barn-door-lift an aerodynamically more efficient way to happen... happen without stalling)...  that the difference between these two components (barn-door-lift and wing-shape-lift) is the pressure differential.  It's what makes a wing a wing... and what makes an airplane fly.

See why I can't answer this question  ?

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I'm not trying to dodge the question.. You yourself are pointing out the "near identical" performance and then asking we to say otherwise  

Two different wings will do stuff differently; have unique performance profiles.. but picking certain points in a profile doesn't change physics..

Brett_Henderson wrote on Jan 14^th, 2007 at 12:56pm:

Actually....No   ...Like I said...   I tend to think in very simple terms....

I was just trying to use two aircraft with nearly identical dimensions and performance but a different upper wing shape.

Maybe if I used a T-38 vs. an Ag-Cat....

Hmmmmm.....probably not....   Somehow, I think if NASA's word wasn't good enough, I'm just spinnin' my wheels here.

I was only trying to get you to reverse-engineer the scenario by comparing each example.

Me personally; I imagine what the flow over the top of a high performance wing looks like just prior to stall and then I imagine......what changes I might make to the upper surface of that same wing that might make the flow adhere to the surface at an even lower speed.....hmmmmm

beaky wrote on Jan 21^st, 2007 at 4:54pm:

Yes, I think us measly private pilots should stay out of this one 

beefhole wrote on Jan 21^st, 2007 at 5:49pm:


.....on the contrary....I think one of the most crucial attributes any aviator should possess, is modesty.

I'd be a fool to think that I know everything.  

Quote from Brett_Henderson on Yesterday at 8:34pm:
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From Ottol:
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No.. I might want to re-word it, but I won't.. we're both weary of this 

Good discussion. It took a while to read, and I skimmed in a few places, but here I am on page 9 of a months long discussion.

While there were discussions of flat planes, and barn doors, NOBODY mentioned the barn roof. This alone proves Bernoulli's force will provide all the lift, if necessary. A high wind will lift the roof off of a barn, with no lift provided from underneath, i.e. no Newton. It's all Bernoulli force acting on the top, like blowing across the top of the dollar bill example. Once it's lifted, however, Newton gets underneath it and moves it along. But the initial lift is all Bernoulli. There is no down wash.

In a normal wing, there are both forces in play, but I fall into Brett's camp. Bernoulli is the difference.