Hi,
Vent holes are probably around 3/16" in each rib. Burned them through with a 1/8" rod that was heated. They vent into the fuse through the servo lead hole. Fuse has plenty of leaks that will allow it to vent. Canopy hatch cover, rudder cable exits, servo cutouts, etc... The weird part is it's only the right wing that does it. I keep thinking that since it's only on that wing, it's trying to tell me something, but I just can't find it.