If pitching moment creates drag, how can high and low moment airfoils have similar drag polars?
Let's call a symmetrical airfoil like NACA0015 a low moment airfoil having no moment at an AOA of 0.
Let's call NACA 2415 a medium moment airfoil. Let's say it has a medium moment at an AOA of 0.
Let's call Eppler399 a high moment airfoil, and it has a high moment at an AOA of 0.
I understand pitching moment creates drag. While the above airfoils have vastly different moment polars at an AOA from -10 to + 10, they almost identical drag polars,at an AOA from -10 to +10.
How can this be?
See pics below