Wing Spar Location: Aerodynamic Center - S1223 Airfoil

[pegus]

Hi, I wonder where is the best location for a wing spar thorugh its cord. Up to where I know it is on the Aerodynamic center (approximately 1/4 of the chord from the leading edge) because is the point on the chord where the lift acts. I am using a 17in chord S1223 airfoil.

 

[SteamKing]

The best location for a wing spar is where the airfoil is thickest. The strength of a given spar is proportional to the square of the depth of the spar. That's basic strength of materials.