This was a LOC tube with the glasine layer peeled. I got plenty good adhesion. I guess I should add that there was no delamination. Two wraps of
2oz fiberglass is not that stiff. The stiffness came from the tube, which was damanged > Alex Mericas wrote:
keep 'em flying!!!
Why what? 2-3 layers instead of one? Less overlap, better coverage. 45 degree bias adds additional fiber directions to the layup.
Read the book that comes with the system three starter kit, or a composites textbook. I've got one that came with an old Hexcel book for Rutan kits, and another by Lambie?
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Hexcel? The honeycomb core people? Mostly noted (or got their start) in the ski industry? What was the name of the book?
It's adding that second layer in a different direction that is the pain.
What I should have asked was: Is there any benefit to 2 wraps of lighter glass laid down the same way (no turning the cloth in a different direction) versus 1 wrap of heavier cloth?
I first heard the 45 degree bias rule when I took a class at the EAA "AirVenture" (aka Osh-Kosh Fly-In) about composite construction. The instructor presented it as the "right way" to do fiberglassing. It is done to improve strength.
I gathered that fiberglass has strength the direction that it's fibers run. By using two layers with a bias, you get best strength in 8 directions instead of just four.
I suspect most rocketry applications need strength along the vertical axis. Hey Drake: this might be an interesting experiment for your materials testing project.
An interesting tip from the class was to lay down a layer of, I believe, dacron on top of the fiberglass layup. The excess epoxy seeps through the dacron which can then be torn off after the layup has cured. The dacron has small holes with relatively strong fibers, so it can be fairly easily ripped off the layup, taking the excess epoxy with it. Sanding with light sandpaper will smoth out the texture from the material. I haven't tried this yet.
Anyone going to the EAA fly-in should consider taking the class. There was no additional charge for it, and while a lot of the material was pretty basic (stuff you'll hear on RMR glue threads, Info-Central and elsewhere) I found it interesting.
Glen Overby
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