Mis-aligned Wrap!

Oops.

I mis-understood one of the alignment instructions. It was plenty clear: I merely blew it.

The S-IVB has two wraps to model the ribs, one on the forward end of the stage, one on the aft end. There’s a tunnel cover that stretches between them (overlapping each). So, the alignment mistake—about 20° off, rotated around the body tube—is more than just cosmetic, since there are flat spots in the wrap where the tunnel covers attach.

What to do?

I thought about just cutting the wrap where the tunnel cover needs to go, perhaps using the cut piece as a graft over the molded-in flat spot. I considered cutting the body tube in half, making a stage coupler, and rotating the two pieces to align the wraps correctly. I briefly gave thought to ripping off the wrap and replacing it with a new one.

I decided to try to remove the wrap and reapply it.

Some parts of the wrap came off the body tube very easily, but some were extremely difficult to remove. Where the CyA didn’t wick very far under the wrap, it came off easily.

I used a hobby knife, very gingerly, to pry the wrap up, occasionally using CyA debonder to try to dissolve the CyA. (I’d tested it on some wrap scraps.) In a few spots, I had to cut a layer of the body tube away in order to lift the wrap off. There’s one bad tear, a nick, and a couple of very small cuts, but the wrap came off in a reusable condition!

It’s now back on the tube, properly aligned. Rather than wicking CyA again, I used canopy cement: I didn’t want to take a chance on the wrap dissolving or cracking more from the CyA, so I just applied a thin layer of canopy cement to the edges of the wrap, laid it up, and taped it to the tube. Back in business!

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