How does split flap increase lift?
Please don't just answer by saying "it changes angle of attack". if you say that then you may need to explain me the AOA. Ok we say that AOA is the angle between the relative wind and chord line of the wing and that's the concept we have learned mechanically.For me the AOA an imaginary angle doesn't seem to be affected by changes under the wing at trailing edge. because once the streamline hits the airfoil then the air flows on upper and lower area just from stagnation point. And this split flap neither increase the wing area nor changes the curveture to delay the separation of airflow. Then how this split flap can increase lift apart from increasing drang while brings no changes to surface area or curveture of the wing?