CrayPuppy page 2 Fin Can starts to take shape.... |
| After cleaning up the mess I made, I carefully inserted that old casing again. If you wipe all the excess JB Weld off, it ain't gonna stick... |
| Thread on the ring and e-clip, nice and easy does it... Then slop on more JB Weld on the outside and use the popsicle stick to push goop into the gap between tube and retainer. Set upright on its tail to dry for a day or two... |
| While the motor tube was drying, I cut four fins from 1/8" birch ply. Since I played a bit with the RockSim to optimize the shape while keeping the original looks I guess they are more like 'semi-scale'... Clamped them all together and made a lot of dust with a belt sander, then hand sanded my usual 45 degree bevel on leading and trailing edges... |
| Due to the Bullpup design, I had to notch the fins to clear the aft centering ring instead of just sandwiching the fin between rings. Long cuts were made with razor saw, then the tab was cut off by scoring with a hobby knife. Once the motor tube had dried, I tacked on two homebaked 0.5" birch ply rings and first pair of fins with 5min epoxy... |
| ...soon followed by the other pair, then added hefty fillets with 30min epoxy. Once that was cured, it was time to drill the holes for #8-32 threaded brass inserts for a semi-modular design. Fins are epoxied to motor tube and rings, but the whole assembly is removable for easy maintenance and repair work. Do not try to thread the brass insert directly to the rings, but thread it first on a screw with a few nuts on it... |
... and use that whole thingamabob to drive it in a little bit at the time, back and forth, back and forth... Brass is soft and breaks easy. Then just back the screw off - and Voila`! |
I cut the tip off of an extra Crayon nosecone that was left over from one of the previous projects, and whipped out my red hot razor saw again for some fin slots that I forgot to cut before spraying with Kiltz primer... Duhhh.... |
Trial fit of the body tube, fin can and the tailcone showed a few spots where I had to shave a bit more off here and there for a halfway decent fit. Its always easier to shave a bit more off than to put it back... Front got dressed up with a nice and shiny 1/4" stainless u-bolt. |