Estes Solar Sailer II, Kit # 2044, Step 4, Ring Prep & Engine Mount

The instructions don't mention it - 

Cut a shallow notch so the ring will slide over the engine hook.

The rings were too tight and required some sanding of the inside wall. 400 grit is wrapped around a used engine casing.

Note the penciled arrow. That points down to the glue sealed and sanded smooth, visible side.

The instructions have you place the lower ring over the middle of the engine hook. This places the lower ring too high inside with no easy way to add a glue fillet.

I did a wrap of electrical tape around the middle of the engine hook. The lower ring had a 1/8" piece cut out for engine hook flex. 

Setting the ring 1/4" from the bottom allows for a glue fillet from the bottom.

On the left - the notched ring is set into the BT-50 tube (dry) to hold it tight around the BT-20 tube as the glue dries

I didn't have to order the BNC-50J nose cone, it was in my spare parts drawer. I lucked out - I didn't even know I had it.

This nose cone is from Balsa Machining Service. 

There is a hole in the shoulder for the hardwood dowel to glue in.

A small hole is drilled into the dowel for the screw eye.

This screw eye attachment is very strong and won't pull loose!

The hole gets some glue and the dowel is pressed in.

My dowel extended out the back about 1/8".

I cut off the extensions and sanded it flat. Not necessary, just something I did.

Squirt a bit of glue into the dowel hole. Screw in the screw eye.