Sunday, June 18, 2017

Estes Apollo Little Joe II Build, Part 15, Fin Support

Well, I left out the post on the Fin Half Gluing. I've re-numbered the blog posts, scroll down to see a new post at #13. Everything should be in the correct order now.

The Little Joe II fins are surface glued on a vacu-form wrap, probably not the strongest joint. In post #229 of the TRF build, John Pursley showed an improved fin reinforcement. CLICK HERE

The first time he used a tapered wood dowel that went in the fin interior, through the body tube and glued to the side of the engine mount tube.
This revision used a square stick, Much stronger and the flat side lays against the right centering ring below it.
This allows the model to be flown without the nozzles if the lower ring and nozzle assembly is not glued in. Some flight reports have mentioned some melting of the plastic nozzles.The four square sticks will be very strong and also center the engine mount tube without the lower ring in place.

John Pursley used a 1/4" square stick, mine was 3/16". The length to start is 3" long. It'll be trimmed to fit later. Right now I'm just trying to get the taper to fit the inside of the fin.

The inside taper starts about 1 5/16" from the end.

Held up against a light you can see stick inside. It won't go all the way to to the outside edge. Don't press too hard or you could split the fin right down the glue line.

Fit the fin without the stick and you'll see the back edge is slightly above the end of the wrap. Take this into account when marking for the stick cut.

Rough up the wrap inside the fin guides with some 400 grit. A pencil won't write on the smooth plastic.
Press in the stick and set the fin on the body sideways. Trace the top and bottom of the stick with a pencil.


  1. So glad to see you writing this one up as it's next on my list to build.

    1. Hi Eddie,
      This one turned out to be a little more involved than I initially thought. The TRF build posts did most of the troubleshooting work ahead of me. Hopefully there will be a few tips that will help out your build.