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The Rocket Formerly Known as Black
Step Six
Fin Installation
After all that glassing, shaping, and sanding, the next step is to start ripping into the airframe. Yowsa.
After carefully checking all the fin alignment lines again, the outline for the fin slots are drawn on the airframe. (The 'freckles' on the airframe are Bondo Spot Putty).
The end holes were cut with a 3/4-inch hole saw, and for the straight lines I used a Dremel tool with a cutoff wheel. The foam was removed from the slots with shop vac and a series of violent slicing and gouging motions with a long knife.
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Left is the first photo of the rocket fully assembled, with the parts just dry-fit together. The fin slots turned out to be such a perfect fit that I could almost fly it without bonding them on. Almost.
In case you've forgotten how large this rocket is, it stands over 54 inches tall from the aft edge of the fins to the tip of the stinger. The circumference is over 46 inches.
After the dry fit, the fins were removed and the airframe was remounted on the rotisserie stand. I mixed a batch of West Systems epoxy and West Systems Glass Microfibers to the consistency of molasses and poured the mixture into the fin slot, covering the exposed tube, then installed the fin. The slots through the foam were cut accurately enough that I didn't need a jig to keep them straight. I ran a bungee cord through the fin holes to clamp them together. Then I started the rotisserie motor to run while the epoxy cured so the epoxy would stay put.
After the epoxy cured I applied 2-inch fiberglass tape across each joint between the fin and the airframe exterior. Then came sanding, fillets of lightweight vinyl spackle, shaping, more sanding.
TRFKAB Index
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