Fiberglassing fins +/- expanding foam

[Zyzzyva1000]

So just curious on opinions. I just finished 2 layers of 6 oz fiberglass on 1/8 plywood fins (debating a third layer). Once I have them attached had been recommended to do a tip to tip layup.

Long ago I used PMLs expanding foam to strengthen my fin cans. Was debating that here instead of the tip to tip fiberglass (in part because I think it will be messier, whereas what I have done so far looks nice). Any thoughts on these 2 option for adding some strength around the fins? (Hyperloc 300 is the rocket).

 

[JackC]

If you’re not trying for Mach 1.5 or higher, I recommend the foam instead of tip to tip.

 

[Zyzzyva1000]

If you’re not trying for Mach 1.5 or higher, I recommend the foam instead of tip to tip.

Planning to keep it under 1000. Ended up going with the expanding foam, definitely added some stability. Guess I could still do a tip to tip, but I think its plenty strong now