Microburst
but I'm growing old...
Know the feeling
What is on the vertical axis, exactly? Anyway I think I understand what you mean. Comes to my mind a graph with those lobes of pressure in the upper and lower surfaces.
Vertical axis is pressure difference relative to ambient pressure divided by freestream dynamic pressure - negative values are suctions, positive values are pressure above ambient. So the +1.0 is where the local pressure equals stagnation pressure. It is in fact one of those graphs with lobes of pressure on upper and lower surfaces. You just have to be aware that at negative AoA the pressure on the lower surface LE is the one that is negative.
So symmetrical airfoils never create any couple, but cambered ones always do, Right?. I will accept that as an empirical fact, because a theoretical explanation of it can be extremely complicated, I deem.
Yes, and I am darned glad you don't want a theoretical explanation
Can we consider the effect of the airstream on the wing as producing a total reaction plus a pure moment (a couple)
Yes
that we call Aerodynamic Moment?
Maybe I've misread your intent, but aerodynamic moment is usually used for the
combined effects of reaction (lift) and couple, referred to some chosen reference point e.g. 25% chord or aircraft CG rather than just the couple.
In case this is affirmative, the point at which the Lift is considered to be acting (i.e. the CP)... Does it take into account that couple, too? or you have to consider the moment of Lift (acting on the CP) about the CG and then add "the couple" or aerodynamic moment to find the total pitching moment effect?
The point at which the lift is considered to act (cp) takes the couple into account, which is why the cp is calculated as Cmo/CL chords away from the 25% chord point (assuming that to be the chosen reference).
I think that maths are a kind of language but it is is good to frequently translate it into normal words
Agreed, but I think you need to retain the discipline of mathematical conventions in your "normal" wording.