So, I flew the glider! and it flew slower than I expected, more like a floater than an aerobatic glider.
CG is okay.... but the problem now is that the motor does not produce enough thrust
So, I mounted a bigger motor (2212). Now the glider is 50 grams heavier and the CoG is now nowhere on the wings but on the fuselage ! lol
So, now I have to put some ballast in the tail. But, instead of dead weight, I am going to install a rudder servo instead
Then I'll go fly it again this weekend.