After weighings on a 1/2 scale template, I noticed that the plane was not at all loaded enough at the front. I chose a balance point at 30% of the leading edge of the wing, a pilot weight of 80kg and 40kg batteries (8kgx5)
If you want to keep these batteries behind the seat* you have to move the wings back almost 20cms, which reduces the wingspan by 40cms (8,40m instead of 8,80m)
To keep the same wing area (10,50m2), it is therefore necessary to increase the chord (125cm instead of 120cm). Obviously the fuselage has to be modified.
*We may be able to install some of the batteries in the front, but there is few space and I suppose this complicates the connections?