With this information in hand I proceeded to glass the real airframe and payload bay tubes. I decided that the easiest way to do them would be to mount them up adjacent to each other on a single PVC pipe, with a small gap between them. I then slid the fiberglass on them and secured it. When applying the epoxy I again found myself working excess fiberglass down the length of the tubes. Apparently the epoxy is acting as a lubricant and allowing the glass to slide along the tube and I suspect even more importantly along the weave.
I made what I feel was a mistake when I started putting the shrink wrap tubing on. Without thinking about it I started sliding the tube on from the end that I had worked the excess fiberglass down to. As I was pulling the tubing up I started seeing the fiberglass come off of the airframe tube as I was obviously pulling slack up the with the shrink tubing. I stopped and pulled the shrink tubing back off and then pulled it on from the opposite end.
I made sure my heat gun was on its low temperature setting to ensure I didn't overheat the fiberglass, due to my impressions from the practice tube. I shrank the tubing without any apparent complications until I got down to the payload tube. There I had a bulge that I could not get out.
I hung the tube up and let it cure. I then grabbed the practice tube and sanded it with 80 grit paper to prep it for a layer of epoxy per Soller Composite's recommended process. With the tube prepped I applied the epoxy and hung it up to cure.
Next I took the coupler tube and used the fiberglass sleeve to line it. This proved to be somewhat tricky, as the sleeve's natural tendency is to contract, not expand (think Chinese finger trap). This proved to be a real problem after I applied the epoxy. I ended up working the fiberglass until the epoxy got very tacky in order to get it adhered to the inside of the tube. Any force that pulled toward the ends of the tube would cause the sleeve to contract and pull away from the tubing. The ends absolutely refused to bond, particularly the end where I'd started applying the sleeve and had come hard around the end of the tube. It finally got to the point where the epoxy was so tacky that attempting to manipulate the fiberglass any further was doing as much harm as good due to it attempting to adhere to my glove.
Late in the day I was able to use the coupler tube as a gauge and determined that I could strip the shrink tubing from the airframe and payload bay tubes. I was really eager to do this in order to see my results and investigate the bulge on the payload bay. As you can see in the photos the bulge is an area that is not bonded to the underlying tube. My conclusion at this point is that when I smoothed the fiberglass back out after pulling the shrink tubing on from the wrong end that I missed a spot. I thought I had it all, but the evidence speaks for itself.
The main airframe tube looks great. I applied scotch tape over the pre-cut fin slots in order to prevent them getting filled with epoxy. It looks like I left a scrap of tape on the tube, though I really don't remember it. I don't see this as a real problem.
I don't think I'll be able to repair the bulge on the payload bay tube. I do have a solution though. The practice tube has plenty of good sections, so if the original payload bay is unsalvageable I'll cut a new one from the practice tube.
Photo Album: Fiberglassing 102
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