We decided to sew the fins to the FTC rocket. Hopefully this will provide additional strength for the expected G forces. Okay so it's not your ordinary needle and thread but the idea is the same. The wire threads through the split sleeve and through the fin. The wire does not go through the pressure chamber.
PL premium still provides the majority of the strength, but the wire is there to ensure the fin does not come off should the glue fail while the rocket stretches during pressurisation. The wire also keeps the fin in place while the glue dries.
Once the initial glue dries the wire is trimmed and the twisted part is folded down and a more glue is used to create a fillet on either side of the fin. We are trying a technique to minimise the amount of bubbling from the PL, as PL is not very nice for smooth fillets. After we form the smooth fillet with the PL we place scotch tape over the fillet to minimise the amount of atmospheric moisture entering the glue. Hopefully this will slow down the cure rate and won't produce the big bubbles we normally get. Will have to check tomorrow to see how it went.