Building the Glencoe Jupiter C (PMC) (part 4)

Last night’s club presentation was good, and it gave me confidence that for the most part what I’ve been planning is reasonable. Quality of execution, that’s another matter, but at least I have the general idea. Looks like using the rear hole as a motor centering ring is fine, though I’ll plan on adding an epoxy fillet.

I said I didn’t want to follow the examples of a couple of builders who’d put in a BT-55 stuffer tube, and I pointed out one builder who used no stuffer tube at all, but I’d pretty much decided I wanted to put a tube in there, just not BT-55. The need for a paper tube to protect the plastic against the ejection gases was emphasized (repeatedly) last night. Confirmation.

I rolled up a piece of 8½”×11″ cardstock and put it in the (dry fitted) airframe.

IMG_3147 The rubber bands are because I was attempting to fix the worst of the misaligned seams — semi successfully. The launch lug taped to the model is because I have not yet found myself standing at the launch pad with a lug-less rocket and a sinking feeling, and I’m trying to postpone that inevitable day.

I marked the tube length for cutting and taped it to the diameter it wanted, then pulled it out, cut it, and taped up the outside seam. (This was actually the second attempt; the first one I tried to glue together, and got it too small. The second time I decided it didn’t need to be glued, just taped.)

Then I rolled up a 1¼” wide strip of cardstock and stuck it inside the first tube. This one I did glue together.

IMG_3148 Then I ran a bead of tube glue around the top edge and pushed the nose cone down over it and into place, and let it dry. That’s the shoulder.IMG_3150With the liner cut, I decided it was time to put the airframe together. Using tube glue I attached the liner to the top of the fin can and both tank sections, and I used the capillary applicator to put 7R in the seams between the fin can and the tank sections.IMG_3149And I re-glued one of the hoses I’d knocked off. Those things just glue to the surface of the tank section, there’s nothing but a square millimeter or so of cement holding each one on. Their life expectancy is really, really low.

 

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