I just did a little experiment with some 1/16th balsa and a 1" forsner bit. The bit cut through the balsa fine but there was one small issue. At the very end of the cut the bit tends to grab the waste from the middle and shear it out of the part, causing some of the wood to be a little jagged (Visible in the second photo, left side)

The problem is solved by boring half way through the part, flipping the part, then boring through the other side causing the waste to shear in the middle of the wood.

The two photos show a hole drilled using both methods. The holes on the left side show the same hole drilled in one continuous operation (Front view and back view). The holes on the right side of each picture show the hole made by flipping the part. The flipping caused a perfect hole but is a little more difficult to do.

I do have a fence on my drill press that will make the flipping and re-drilling a little easier as we will only need to worry about one axis when lining up the parts.

I don't have a 15/16" forsner bit but I could go get one. We can drill your parts and it is a good excuse to buy more tools.

Another issue is dihedral... If the wing has any we need to account for it when drilling the holes. We could just add a scale to the drill press table and the fence will allow use to line everything up via the scale for each rib.

Let me know when you want to do some drilling. I will need to go to Woodcraft to get the bit before hand. (Kinda like a kid in a candy store)

Phil<br type="_moz" />