Semroc MMX Blue Bird Zero Build, Part 2, Engine Mount

The centering rings are laser cut from Letramax material. The laser cutting chars up the parts. Wipe off the ash before gluing anything up.

The instructions say to tie a knot in the Kevlar and set it under the inside engine block inside the engine mount tube.
I went more mainstream and tied the shock cord outside around the engine tube and under the upper centering ring.
This required a notch to be cut in the upper ring.

GOTCHA: The instructions have you glue the engine block flush with the top end of the engine mount tube. With the engine block even with the top, a MMX engine goes in too far. It ends up almost even with the low end of the engine tube. There is very little of the engine hanging out the back end.
For me there's not enough of the casing exposed to easily remove it after a flight.

The engine block will have to be glued down inside the tube. In the picture above, notice the block set next to the engine mount. This is how far down the engine block should be recessed.

With the engine block recessed down from the top, the engine will extend out the back. Enough is exposed to grab and remove a friction fit engine with pliers.