While I was studying my PPL today, I've encountered a question right below and I wasn't really satisfied with the answer.
Which statement about the airflow around an aerofoil is correct if the angle of attack increases?
- The stagnation point moves up
- The stagnation point moves down (correct answer)
- The center of pressure moves down
- The center of pressure moves up
Up here, α is the degree between the chord line and the oncoming airflow.
1) Stagnation point
2) Transition point
3) Transition point
4) Separation point
So, knowing all of these facts I just can't understand the question above. Why is the stagnation point moves down instead of going up while increasing the angle of attack?