A "Fat wing" with 0 AoA may of course produce a "suction", but as above, and I believe this is an important and pivotal point, there cannot be a "suction" absent a "push".
Hi Bearfoil,
I absolutely agree and so does Bernoulli:
There is a push.
In static air, a push is performed on the wing with 10^5 Pa from all sides (at Sea Level).
Now that the wing is moving through the air, Bernoulli says, that there is still a push of 10^5 Pa.
And now comes what I falsely quoted as 'suction' :
On the upper side, the static push has dropped below 10^5 Pa.
That is due to the sum of static + dynamic pressure being constant.
The air has been accelerated above the wing, because at the end of the chord the air wants to merge again at the same point where it separated in front of the wing. Otherwise you would get a 'hole' in the air at the end of the chord on the upper side.
The profile of the speed of the air above the wing depends on viscosity of the air.
Very basically, along with theoretically, I am trying to demonstrate that as the Cl moves aft, its bottom component (push) is directly under the top component, the "Suck", and the wing will not produce the desired effect per Bernoulli. The upward movement of the after portion will be met with a downward movement of the forward portion.
I have to disagree.
And so does NACA:
If you look at the moment coefficient around the Quarter Chord line of an airfoil in free air, you will see that it is roughly the aerodynamic center, i.e. the axis around where a chnage in Alpha does not increase the pitch up moment.
If you take the mid chord, the moment coefficient is hugely positive, i.e. any posiitive change in Alpha increases further dramatically the pitch up moment of the foil around this axis. It won't stabilize.
Putting the axis of rotation (in a plane that would be the Cg) in front of the aerodynaimc center (which is for most foils close to the 25% chord calculated from the LE) is the basic priciple of aerodynamic stability as the tail fin is pushing slightly down and equalizing the moment of the Cg.
As the tail fin is excerting a mostly linear force (due to working closer to Alpha = 0 than the wing which has an incidence) the Cg in front of the aerodynamic center causes a negative moment coefficient, i.e. with an increasing Alpha, the pitch up moment on the main wing reduces more than the down force on the tail.
Edit: Flying Wings achieve this with an S- shaped foil, where the TE section provides the downforce.
/Edit
That's basically how the plane stabilizes itself