Blunt trailing edge airfoil modification methods have shown that a compromise between aerodynamic performance and structural benefits can be achieved. Two modification methods are studied: the cutting off method and the added thickness method. Two-dimensional simulations were obtained in Ansys CFX® for a typical Reynolds number of 3.2 million. A Taguchi Method experiment is conducted for the study of the four-digit NACA airfoil family with the proposed modification methods. A detailed study for the NACA 4421 modified with several trailing edge thickness values was completed. The results obtained show that the increase in the maximum lift coefficient, the delayed stall and the drag coefficient increase are common to all modification methods studied, whereas it is proven that for the cutting off method the lift coefficient curve displacement to higher angles of attack is caused by the loss of camber. Finally, it was proved that the added thickness method produces larger maximum lift coefficients and larger critical angles of attack than the cutting off method.