Semroc Mini Optima Build, Part 3, Engine Mount and Interior Tube

The white, slightly narrower ring goes to the top of the engine mount tube. This fits into the ST-9 insulating tube.

GOTCHA: The instruction drawing shows the ring just covering the upper bend of the engine hook, sitting even with the end of the tube
The ring actually sits lower down the tube than the illustration shows.

Here's the finished mount with the lower ST-10 brown ring in place. Notice there is no Kevlar line used in this model.

The interior tube works like an insulator protecting the main airframe tube (and paint) from the hot ejection charge. It is slightly narrower than the ST-10 main outside tube.

The shock cord mount is old style, attached through slits cut into the body tube.

I used my long tweezers to depress the body tube in between the two slits.

You'll find it easier to feed the line through from the top. Pick up the line with tweezers and pull it through.

A knot is tied on the short inside end.
After the shock cord is at the correct position, press the tube depression back out and lock the cord onto the tube.
I applied a little wood glue to the slit areas.