RE: Zlin EP - What is the CG?
I don't quite understand why you have the rod and balsa above the wing?
The wing should sit against the curve of the fuselage, which the rod and balsa is preventing.
This will get the wing to sit with it's leading edge higher than the rear of the wing, producing a positive angle of attack.
In the air the wing will fly more level due to the angle of the tail plane ( stabilizer ).