Brief Description: Dirlled critical hole is Right side 405, and skin
Today was the big day for the right side of the HS 405 to 702 spar and 810 reinforcing angle attach holes. They turned out as planned with no edge distance issues with the forward flange and the 810 angle. I also drilled all the other holes for the 801 skin attach holes.
Once done I took everything apart and noticed I have a min edge distance issue with the forward most upper and lower holes of the 405 rib. In my effort to not have an edge distance issue with the 810 angle I did not look at this area, I also did not read about this on any other site. I made sure the flange was flat with the spar; aside from a more acute angle to this flange I am not sure how this edge distance could have been made better. I have consulted some builder sites and VAF forums to get some ideas. I will call VAN’s on Tuesday when I am back from a trip. But my preliminary assessment is that the edge distance is not 2D but more like 1.5D but since it is just these two holes and there are other parts at this joint it might be OK. I read that in the 50’s they routinely used 1.5D edge distance. The best answer is to analyze this joint in particular and determine if the rivet and joint will be strong enough. The 2D is just a guideline and the builder can engineer a hole to a different tolerance as long as it meets the strength required for the parts. I am hoping Van’s can help me with the engineering of this joint. I have read were others have had edge distance issues with the 405 rib and Van’s told them all is OK and to build on. My unprofessional opinion is the part will be plenty strong with the hole as is, but if not I guess I will be ordering new ribs, though I am not sure how I will get the hole any further from the edge since the part was snug up to the spar and the skin holes are pre-punched. Time will tell.
