Some progress has been going on, but an serious case of incredibly busy has slowed progress. However, the fins are tacked on, and here is how we arrived at that...
I glass all fins, partly for ease of finishing, but mostly because I love building rockets, however I HATE repairing rockets. I don't want a rocket where the fin breaks and I have to repair it, so if the fin breaks I expect the rocket to be a heap of confetti. Also, these things are huge and could use the reinforcement I think.
I am in the progress of upgrading my composite materials from LHS style to more serious stuff. The change for this project was ZPoxy to US Composites laminating epoxy. The cloth is the Hobbico 5oz from the LHS. I layed the fins out of wax paper, and mixed up a 4 oz batch of epoxy. The pot life is said to be between 20-25 min...it kicked at 23, so spot on. Fortunately I finished laminating at 22 m 45 s. It was about 80 F is the garage, so I should have used a water bath for the epoxy cup, but I didn't think it would take 20+ minutes to get things good. Anyhow, I laminated both sides, added a second sheet of wax paper, and sandwiched the whole thing between some hardboard under some power tools and bricks for weight. Most of this isn;t pictured because of limited time and epoxy hands (gloves).
The setup:
Now with ZPoxy wax paper peels right off, but with the good stuff not so much (fortunately I ordered some peel ply for my next attempt). To get the wax paper off the fins a great deal of time was spent scraping with fingernail, rubbing down with mineral spirits, and gentle sanding. Better epoxy calls for appropriate materials apparently. Also, this is indeed better epoxy. It is far less brittle than ZPoxy when cured, and doesn't chip when sanded at the edges, even if you catch it on the belt. I'm impressed.
Now this makeshift laminating method will leave you with an imperfect surface that is difficult to fill on the rocket, so I choose to take care of most of the imperfections now. As such the entire fin gets a coat of Bondo spot and glazing putty, and once dry it is sanded down with a palm sander being careful not to dig down to the glass. Once done, the edges were rounded using the belt sander, and a little and a little hand sanding at the larger curves. This went better than expected as there are no long flat edges on this the entire process was done on the edge of the belt, and was very freehand in nature.
The slots were then widened out to fit each fin snugly. The fins were also fitted to each slot by removing the excess tab length, and final shaping of the aft tip on the belt sander. And the step from the boat tail to the tube was blended with a couple cycles of bondo. It isn't perfect, but will need to wait until primer is applied to get much better. The fin tabs were roughed up using a sanding drum on the Dremel to prepare them for epoxy. The fins were then tacked in place with 5 min epoxy, which brings me up to date. Seeing the fin can together all I could think is this rocket is going to be really big (by my standards at least). Internal fillets next, these are going to take some time.