Estes Interceptor Build #1250, Part 9, Fin Gluing

The fin lines were marked and the glue lines were sanded down to the tube.
The sanded area was wide enough for the fin width and glue fillets.

After sanding off the pencil lines they were re-drawn for gluing.

The sub fins are glued on first.
Be sure the wide end is facing forward. It's easy to follow your first instinct and flip these.

The drawing on the upper right is incorrect. It shows the sub fin directly above the engine hook. The two sub fins are actually on either side of the engine hook.
I understand the point they are trying to make, the drawings just don't jive.
TIP: Where you can, try to center the engine hook between two fins. It's easier to install and remove engines without the fins in the way. This is especially true when longer fins trail past the end of the body tube.

Here's both sub fins glued on. Glue with the wide end forward. It's easy to follow your first instinct and flip these.
The rear edge is 1/8" from the end of the main tube.