Thirsty - I totally get your weight concern. I like to keep my builds light too!!!
I usually get centering rings from Bill at
Balsa Machining Service. I'm not sure where he gets his Lite Plywood from, but I'm willing to bet its about the same weight as cardstock "fiberboard".
I have some BMS part #
CR52H80-W in my Box-O-Parts. They weight
3.1 grams each, and his price is
$0.55 each. Bill also sells sheets of 1/8" lite Plywood. His Lite Plywood is
NOT bullet-proof, but it's only a few grams heavier than the same size balsa.
P.S. - I wasn't kidding about the "I" motor either. :dark: Plain un-reinforced BT80 is
really very strong. I have yet to shred any BT80 based rocket.
(I did have one burn-up on the pad, but it didn't shred)
Here's my proof - Big Honkin' ply fins on a BT80 Cherokee-I. I flew this at LDRS33 to 3200 feet on a CTI 29mm 6-grain I-204 . The Big draggy fins kept it below mach.
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