Estes Super Mars Snooper #7309, Build Part 13, Gluing Up The Fins

Here's how those cut lines in the root edge line up with the nose cone/body tube joint.

The instructions usually recommend Super Glue (CA) for gluing wood to plastic joints.

This fin is a combination joint - 

Half is balsa to body tube, the other half is balsa to plastic.

I used Beacon Fabri-Tac for the plastic to balsa side and wood glue for the balsa to body tube side. See NOTE below.

Here's the fin assembly setting in the assembly jig.

Fillets followed - 

Wood glue on one side, Fabri-tac on the other.

Under a bright light you can see the Fabri-tac fillet on the plastic nose cone side. After a light coat of gloss white, the fillet ridges were sanded with 400 grit.

NOTE: I got an email from Bernard Cawley about some fin breaks on recovery. I used Fabri-tac for the balsa to plastic joints, but you might be better advised to use CA glue as the instructions recommend.