Estes Constellation Build Part 14, Fin Gluing

There is a light paint ridge where the fillet area was masked.

Lightly sand the ridge line with 400 grit sandpaper. 

The fins were glued on using my prototype Odd'l Rockets FinTool. 

(The Fin Tool never went into production and is not for sale.)

The fin trailing edge is even with the back end of the body tube.
The rear end of the launch lug is even with the front edge of the fins.

Estes Constellation Build Part 13, Fin Prep

Before spraying a white coat to check for flaws, a small bit of the root edge was masked off.

This was to keep some of the fillet area clear for a stronger glue joint.

After a light coat of gloss white the tape was removed.

You can see the fillet area is clear of white paint.

The pencil fin lines on the body tube were roughed up with 220 grit on a block.

After sanding off the lines they were drawn on again.

Estes Constellation Build Part 12, Primer Sanding

Here's the body tube and nose cone after the primer filler was sanded down.
The nose cone was slipped into the body tube for primer painting.
The clear payload section will be trim painted later.

The fin and fin pod transition joints looked pretty good after spraying with the primer filler.

The primer was sanded with 400 grit.

There is plenty of inside edges that need to be sanded.

TIP: Here's another use for the Q-tip swabs.
Roll a piece of 400 grit around the cotton tip.

This gives you a small, round cushioned sander with no sharp creases in the rounded end of the sandpaper.

Estes Constellation Build Part 11, Odds & Ends

This lug standoff probably isn't needed, the payload section isn't wider than the low end tube.
This style of standoff goes back to when Estes sold it's "C Rail". The dowel standoff fits the C Rail launch rod.

TIP: A BT-50 tube reinforcement coupler was made out of a split piece of body tube. This was glued in place in the tail end, pushed in place with the engine mount.

I'm tired of BT-20 and BT-50 models crimping and buckling right above the fins. That's a weak point when the model touches down.

This coupler should strengthen that weak area that's prone to bending.
After the strengthening coupler was pushed into place the engine mount was quickly removed.

Another line of glue was applied with a dowel end and the mount slid into place. The rear centering ring is even with the back end of the main air frame tube.

To be sure the ring is flush, the last 1/2" was pressed in place with the flat side of my sanding block.

The rear ring was "sealed" with some medium thickness CA applied with a Q-tip.

This hardens the outside surface and can be smooth sanded with 400 grit.

Estes Constellation Build Part 10, Nose Cone and Adapter Details

On the left is the nose cone and adapter from the Semroc kit.
You'll see these shoulders through the clear payload section when the model is finished. I usually sand these flat then round the edges.

On the right is the dry fitted payload section with the rough ends smoothed out.

TIP: To get a sharper edge on a balsa nose cone shoulder -

Brush on some CWF just slightly over the edge.
I'm not covering the entire nose cone yet, just the shoulder edge. this leaves the nose cone dry to hold on to it.

Slide the nose cone shoulder into a squared BT-50 tube.
Turn the nose cone and CWF on the shoulder onto the tube top edge.

Turning the nose cone base forces the CWF into the shoulder lip.
In the picture you can see the raised ridge of CWF at the bottom.
Slide the nose cone back out and let dry.
Sand off the raised CWF ridge with a block.
The nose cone shoulder lip will be stronger and the edges sharper.

Estes Constellation Build Part 9, Fin Pod Gluing

Each fin will be individually fitted.
Draw a line on the side of the pod side that will be glued to the fin.
Mark the outside edge of the fin with a "1" and the matching pod "1".

Match the edges of the pod and the outside curved edge of the fin. Lightly trace around the side of the pod.
(While not shown well in this picture, the tip of the pod should be even with the leading edge of the fin.)

Carefully cut off the pod recess.

After a bit of shaping checking against a bright light, the pods fits pretty well.

Glue fillets filled in the seams.
The fillets go from narrow at the tip to wide in the rear, the same shape as the teardrop shaped pod.

Estes Constellation, Part 8, Airfoiling The Fins

I used the rounded side of my old sanding block with 400 grit to sand the recess at the rear trailing edge.
This seemed to be the best way to get a round concave shape.

You could also use some 220 grit sandpaper wrapped around a 24mm engine casing for the round contour.

With the trailing edge facing up - 

Here's how that sanded recess looked after sanding.
You can see how the trailing root edge tip remains thick and less likely to break off. I still have to sand a "knife edge" to the remaining trailing edge.

With the fin held upside down,
On the left is looking directly at the root edge. The tip was rounded off.

On the right is the tapered trailing edge viewed from the rear of the fin.