3 ms·
If it's a 3D wing with finite span, then you're well into vortex-shedding and momentum-carrying plumes of gas. The usual way to avoid this is to make the wings
by wbeaty 5y ago
If it's a 3D wing with finite span, then you're well into vortex-shedding and momentum-carrying plumes of gas.
The usual way to avoid this is to make the wingspan be infinite, with no wingtips. But this is dishonest, because it transforms the problem into a "venturi effect," where the airfoil is producing an instant-force against the ground. Then, the Newtonian force-pair exists between wing and ground. (Yet real, non-infinite wings don't need any ground surface to react against. Their force-pair is between the wing and the vortices being launched downwards.)
To simplify: first explain a hovering helicopter. Wings work the same, acting as air-pumps, pulling in air from all directions, then creating a momentum-carrying plume launched downwards. (Helicopters and wings, both are examples of fluid propulsion, where Bernoulli doesn't apply.)