Van's RV-8 Build. Ep 102. Wings 31. Main skins prep and scarf joints - That Hippie Pilot In today's session, I got to work prepping the main skins (both top and bottom) for riveting to the wings. The outboard skins overlap the inboard skins. So, it's necessary to create a scarf joint at the corner where the overlapping main skins will abut the fuel tank skin. I think I'll be able to complete edge finishing and creating the scarf joints in one more work session.