I had a question regarding the direction of the pitching moment.
To make sure we are on the same page, here is what I know so far (please correct me if I am wrong).
- Lift acts through center of pressure
- Normally moment is taken around Aerodynamic Center because then the moment does not vary with angle of attack.
- In a cambered airfoil, the aerodynamic center and center of pressure are not at the same place, so the lift created also generates a moment at the aerodynamic center.
- In a symmetric airfoil, the aerodynamic center and the center of pressure are at the same place, so you do not have a pitching moment.
- Location of Aerodynamic Center is fixed for an airfoil, it does not change with speed.
Thanks for your help,