The COG (Center of Gravity) was calculated to be something about 8.6mm from Wing-Front, but that is to low, it can be some mm farer away, so you don't need so much lead in the nose :) I have "flown" this thing yesterday, only an small amount of throws on a meadow, and it shows that it will perform good on aq ridge with an good amount of wind... A guy on an other page asked what Slicer is was using, he used CURA and could not slice it right. If you want to use CURA, you need to make more parameters visible to slice these small walls. Its a parameter named something like "print thin walls" (is use the german version), you need to make this parameter visible and activate it, then the wing is sliced well. I have used Slic3r in the past, but i am not able to test it, cause an update has made it non working, i will keep you informed about parameters for Slic3r, too, when there are new updates that make it working again.