The Zipperless Rocket
OK, I've got a real good one for you this time. The name of the blog is The Thrifty Rocketeer , and I've got a great cost saving tip for you, provided that you use this method. Just bear with me... For years, rocketeers have been looking for an alternative to the Estes rubber-strip shock cord. And some people advocate totally skipping it in favor of a hard Kelvar string segment. Some even advocate a combination hybrid of half Kevlar and half rubber shock cord. Well, I'm not going to debate that here. What reared its head was the tendency for Kevlar string (or similar hard, thin cord) to pull a zipper down a cardboard tube when it snaps taut. The obvious solution is to either strengthen or pad the rim of the body tube, which is not practical, OR in some way, pad the string to spread the load and cushion the point where it bends over the body tube. Some people slip a short piece of rubbery insulated wire coating (like shrink tubing?) over the string and knot it into place. ...