I have the 12 gal Wag tank in my left wing. I'm not sure what length to use for the arm when figuring wt. and balance. I was estimating that the center of gravity of the tank was perhaps 1 or 2 inches forward of the tanks front to back center line. I am using the leading edge for the datum so the number I am looking for is the distance from the datum to the tanks center of gravity. If the tank was out I could empirically measure the center of gravity but Alas, I need not reinvent the wheel.
Joe
Joe