SM2 Booster Fins

This is a really crappy page that Mark sent to the other RTV members when he finished the booster fins. To his credit, it was probably about 3 in the morning when Mark slapped the page together after he'd worked all night on the fins.

This is being posted for two reasons: 1) It's better than nothing, and 2) Maybe Mark will become sufficiently embarrased that he will actually develop a page worthy of his abilities.

Here is his commentary:

First, I cut out all the frame parts. The insides of the triangle are uneven because I cut that part with a hand sabre saw.

Next, I clamped the spar in the frame using spring clamps and epoxied them in place. This pic shows the clamps. Note the lines drawn on the parts to help alignment.

With the spar epoxied in place, I masked off the fin tab prior to foaming.

The cavities were filled with low expansion foam and allowed to set.

The excess foam was trimmed with a bread knife. (Note: this works well and leaves no residue on the knife, but no amount of explaining will justify to the spousal unit why kitchen utensils are suitable tools for rocket manufacture.) In this pic, you can see how I align the knife with the edge of the frame and the edge of the spar. Under the piece being cut is a fin with the foam already trimmed.

Here is a close up of a trimmed fin.

And here is a piece with the skin epoxied on. When I do the remaining fins, I'll try to take pics of the skin assembly process. I just forgot with the first one.

Assembled fin from the bottom.

Assembled fin from the tip.

Assembled fin from the side.

The fins were wrapped with 4 oz. fiberglass after they were shipped to Phoenix.