If Newton’s third law sufficed, then the shape of the upper surface of the wing wouldn’t be important. In fact, it matters a lot.
There is no single explanation for why airfoils generate lift that works at a grade school level.
There is no single explanation for why airfoils generate lift that works at a grade school level.
The Navier-Stokes equations merely model fluid flows. Understanding them provides no understanding of the behaviour of such flows. That behaviour is emergent from the interaction of a great many particles.
But that doesn't have any explanatory power at all. If we assume Newton's laws hold, then obviously if there's a force upward on the airfoil then there's a reaction force downward on the air.
It'd be like explaining the combustion engine by saying "the drive shaft from the engine rotates this way, and the reaction force - because the engine is more-or-less rigidly mounted to the frame - is resisted through the suspension by the wheels being in contact with the ground". OK, sure, but I still don't know how the engine actually works.
Added: Or more Newtonish (no action at a distance), there is more upward vertical force contributed by the particles in both cases than downward force.
Planes fly by slicing through a lattice of air, with blades (wings) that only slice easily in directions that lie on a single plane. Orthogonal tail fins means that the vehicle doesn't go from side to side as easily, so it mostly keeps flying on a line. Take a `+`-shape and elongate it so you get a "dentastix" like shape, then hold that out the car window. It will go in whichever direction you point it.
Same idea of a boat rudder. And yet with boat rudders, we don't say "force of lift". The angle of attack changes, which means it now cuts through the water in a different direction (and the rudder piece wants to go straight in the direction it is pointing, since that way has comparatively little resistance in the water), which changes the way the rear of the ship moves which ultimately steers the ship.
... what do you mean by that? If you mean "you can demonstrate the aerodynamic force using a flat plate", then yes you can do that. If you mean "a flat plate is a good tool to explain the aerodynamic force", then that's much less true. If you mean "in the real world, airfoil shape is irrelevant to aerodynamics" that's obviously false.
Rudders are symmetric, i.e. don't have camber to create high/low pressure on one specific side all the time, and yet they work in redirecting (the relative) flow and thereby through Newtons 3rd redirecting the vessel!
The difference of shape between hydrofoils and airfoils is determined by the properties of the masses in which they move, explained by the same theories of fluid dynamics, rather than any fundamental difference.
That’s what the aerofoil does. It pushes air down but mimimizes wasting energy on drag. It’s still newtons law.