Bridi Big Bee
Blackhawk I am using a 1.25 , .035 X 36 " aluminum tube with a phenolic tube installed in the wing halves. I came about that size from some advice from a friend who flies IMAC and has more experience than I do. Since the wing is flat on top I just stacked the ribs (4 on each half) with the top edges even and the spar slots lined up and jig-sawed the hole for the tube.
I got the tube from TNT, they sell tube/socket combos.
Adam