So this is about intuitive explanations of flight. The complaint about using Newton's law is that it doesn't readily explain the low-pressure region above the

So this is about intuitive explanations of flight. The complaint about using Newton's law is that it doesn't readily explain the low-pressure region above the wing. Let me give it a try. Intuitively, all the forces on the wing are manifest as air pressure measured the wing surface and expressed as a force normal to the surface at that point. There are no other forces from the air. You sum them over the wing and the net force upward is called lift, the net force backward is call drag. If there is net lift, that means the net normal forces summed over the wing are upward, implying that the pressure is low above the wing relative to below the wing. The Newtonian explanation is that a force must be exerted to change the direction of the air. The net force on the air is in the direction that the air turns, and the reaction force on the wing is in the opposite direction. On the underside of the wing the air is diverted downward and the reaction force on the wing is upward, and this is measured by the air pressure on underside of the wing. On the top of the wing the air is again diverted downward and the reaction force on the top of the wing is again upward, and this is measured by a lowered air pressure, giving a net upward force.