Birch and Bramson kept things simple. Whatever the cause the airflow over the wing reduced in pressure (not in density so not a vacuum) and the flow below the wing increased the pressure. Displacement takes place and we call this lift. The effect could be demonstrated with a piece of folded paper or the back of a table spoon in the flow from a tap. It didn't pretend puritan truth but it taught the pilot the importance of angle of attack/lift force and speed of flow/lift force. The wing stall could also be demonstrated and so his method taught all the pilot need know.
The circulation theory whilst absolutely true is complex and difficult to grasp by ordinary folk, like me, who become pilots. The Circulation theory needs to be demonstrated in a wind tunnel. Reducing complexity into four vectors; lift/weight, thrust/drag can easily be drawn as a schematic diagram on the white board or by use of a model.
Last edited by Fl1ingfrog; 7th July 2023 at 21:44.