Well, no sealing wax: just sealing thin CyA.

The large tube (S-IC, Interstage, S-II) is done, except for touch-up, masking, and painting. It’s on to the S-IVB now. First step is to build the transition between the S-II and the S-IVB (big tube and third stage). This requires building a centering ring-couple set between the small S-IVB tube and the large tube that comprises the S-IC and S-II.

Ideally, this is pretty easy: two centering rings, and a coupler constructed earlier (one of the first steps) by slightly sectioning a small piece of tube that’s the same size as the large tube so that it just fits inside the large tube. I made this coupler just a little too big, so out came the sanding block and, since I took off all the outer layers (the ones that coat the cardboard fibers to keep them from fraying), the thin CyA to reseal the coupler. Then, more sanding, since the thin CyA causes the outer fibers of the cardboard to swell, and the surface gets rough.

Just about done, though. Then, it’s on to attaching the wrap that gives me the most cause for concern: the third stage wrap, that overlays the transition’s taper.