Originally Posted by stefanj
I sold a lot of my rocketry memorabilia when I was in grad school, for pizza money.
I have a file box full left, and I bet I still have some interesting stuff from the MRI / MPC / AVI era.
I'm building a Nike-Patriot right now. I'm really impressed by the body tubes. They were really thick, and also made of a really tough paper. It was fully wound, it that makes sense. No gaps or weak points. The slightly wrinkly outer shell sands beautifully, and you can hit it with sanding sealer to make it even smoother.
I wonder what it would take to recreate these tubes?
I wonder that too! Interestingly, the tubes in those MPC kits (the 18 mm motor powered ones as well as their 13 mm Minijet-powered Miniroc kits) are referred to in the kits' instructions as "fiber body tubes." While they aren't the same material as the fiber (or fibre, as Centuri spelled it to be fancy) fin material (that's beveridge board), the MPC fiber body tubes are of comparable strength and stiffness--even after all of these decades since they were made!--to the fiber fin stock. Now:
Not having an example of the MPC fiber body tubes in front of me at the moment (I presume AVI and AVI Astroport used the same tubes, since they got MPC's inventory), but recalling their appearance and how they dented, creased, or buckled (which required a lot of force!), my impression was that they may have been impregnated with some kind of resin (not necessarily something like an epoxy, polyester, or polyurethane resin, but maybe something that is appropriate for paper), and:
I once dented the end of a small scrap piece of the MPC fiber tubing with my thumb, and it made a faint "ch-ch-ch" sound as the creases at the edges of the dent formed. It sounded like how a thin (or wide and un-braced) piece of fiberglass (such as the floor of a cheap fiberglass shower stall, when one moves around while standing on it) sounds when it flexes or breaks. Not only that "acoustic similarity," but also a "cultural one," makes me inclined to think that the MPC fiber body tubes may have been resin-impregnated:
Back in the days when MPC was producing their model rocket kits, "fiber" things were considered modern, more efficient, cool, and futuristic (just as "digital" things were in later years). In issues of magazines such as "Mechanix Illustrated," "Popular Mechanics," and "Popular Science" in those years (and before), fiberglass was considered a 'wonder material,' and countless project articles in those publications (and in others) covered how to mold parts and items with complex curvatures, laminate boats and other wooden things, and patch damage to car bodies using fiberglass. In that "nomenclatural atmosphere," fiber body tubes (and for other model rocket companies, fiber [fibre] fins) would have sounded advanced and futuristic (and to me, they still do--the only difference is that today, the "buzz-word" for resin-impregnated fiber items is "composites"). In addition:
If a model rocket company re-created the MPC fiber body tubes (even in other sizes, although I'm perfectly pleased with the MPC/AVI/AVI Astroport/Quest Aerospace "5 mm increment" metric body tube sizes), I would pay extra (within reason) for kits that utilized them, because they're so much stronger, stiffer, and more durable than even brown virgin (having long fibers) kraft paper tubes (which are quite tough themselves--they're my close second-favorite body tubes!), BUT:
"Trailing the pack along the outside rail, in a distant last place," is my absolutely *least-favorite* body tube type--the white, recycled kraft paper tubes, which are made with short, chopped paper fibers that make them soft, weak, and easily damageable. If they could be made as strong and stiff as brown virgin kraft paper tubes by impregnating them with some type of resin, I would consider them good, but my preference would be for the even tougher MPC-type fiber body tubes, which were, I'm pretty sure, made using virgin kraft paper, whose long paper fibers (along with whatever was impregnated into the paper) made them the strongest of all.