I considered fiberglass reinforcement on the fins, but between the through-the-wall construction (the fins are epoxied to the motor tube, and to two carbon fiber centering rings; they also have a good epoxy fillet along their joint with the outer body tube. They're 1/8" basswood, tough stuff. I can pick the rocket up by a fin and shake it with no fear of damage.
Plus, unlike the booster stage for Kandy Kolored Tangerine Flake Streamline Baby, Mr. Creosote II is meant to land under a parachute, not simply tumble to the earth.
Plus, I noticed he's lighter in the tail (and overall) than the first Mr. Creosote. Those epoxy clay fillets I built on the first fat bastard were overkill, and they probably added an ounce of weight. And tail weight is not what you want with a rocket. To much of that and your center of gravity moves aft of your center of pressure, resulting in the rocket equivalent of a violently fishtailing car. Worst case scenario, you take off unstable because the ass is too heavy, then with half the motor burned, the rocket becomes stable and hurls itself at hundreds of feet per second wherever it happens to be pointed at that time.
Since this new and improved glutton is going to fly on D and E motors, putting heavy clay fillets on the fins would risk having to epoxy lead shot into the nose cone to compensate, and at some point you'd end up with a rocket that performed as pathetically as the C powered Mr. Creosote I.
I did use some Z-Poxy (an epoxy specifically for fiberglass work) to seal up the fins. I was mounting the launch lug, and remembered how well epoxy worked at sealing up balsa nose cones. So before applying primer, I brushed on epoxy. I scraped the excess off so it's just what the wood would absorb and what would stick to the surface. Doesn't add much strength but it'll keep the fins from absorbing a bunch of paint which would only make them heavy and hairy.
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