Estes Sandpiper, Kit #1389, Part 2, Engine Mount

The instructions have you set a line of glue 2" up inside the 3 1/2" long BT-20 tube. Then push the engine block up from the bottom.

The engine mount tube is only 3 1/2" long, I can add a glue fillet from the top.

Tape and engine casing with 1/4" extending out the bottom. Slide the engine block in from the top dry, no glue yet. 

Slide the block down until it stops against the top of the engine casing.

Add glue using a Q-tip making a fillet around the joint.

After it is dry, remove the engine casing.

The upper 2050 centering ring gets a notch for the Kevlar shock cord.

There is very little room between the tubes for a knot, I did a wrap.

Tighten the Kevlar, set it into the glue fillet.