Estes Odyssey #7235 Build, Part 14, Inside Rear Engine

Here's how the two centering rings fit over the BT-5 tube on the rear inside engine.

I followed the ring position measurements closely. More on this coming up -

If the ring has a good friction fit, I won't set a ring of glue on the tube as shown in the instruction drawing. 

I'll slide the ring into position -

Then add a glue ring and smooth out the glue making a fillet.

I used one of the 1 1/4" long launch lugs (not glue yet) to double check the ring position before applying any glue to the ring/tube joint.

The lug is even with the end of the BT-5 tube. Slide the ring until it butts up against the lug end - then apply glue to the other side of the centering ring joint.

Notice the lug seams were filled already with CWF and filler/primer.

The vanes are glued on the pencil lines on the forward side of the engine. Fillets were smoothed with a Q-tip.

I added pencil lines to the face of the centering ring to make alignment easier.

I skipped every other vane leaving space to make the initial glue fillets easier. 

The vanes are close together and getting a smoothing fingertip in there is tight.

Go light on the glue and use a Q-tip if it is too tight.