Semroc Saturn 1B, Build, OOP #KS-1, Part 48, Central Engine Mount Assembly

Two thick walled ST-9 tubes run through the center line of the model.
The two 9" tubes are joined by a black coupler. An alignment line is drawn down the joined tubes.



The larger TR-115 ring is glued on top of the "clover shaped" cluster bulkhead.
The cluster bulkhead and TR-115 ring assembly is glued to the top of the four engine cluster tubes.

Note the picture on the right. The fit of the cluster bulkhead doesn't totally reach over the edge of the engine tubes. You can see light at the edges. I am concerned about ejection charge leaks charring the inside of the rocket. I may have to make some old style "tissue glue putty" to fill the corner gaps from the inside.

From the instructions - 

The top illustrations show the four engine cluster, the bottom is the single 24mm engine mount.

The end of the joined ST-9 tubes are glued into the TR-115 ring. The line drawn down the ST-9 tubes is set at the small notch in the cluster bulkhead.

The bottom "star" alignment piece is slid down from the top and glued to the top of the TR-115 ring.
Be sure the small notch on the inside of the star piece is in line with the line drawn down the ST-9 internal tube.

The top star is glued at the top of the mid joint of the two joined tubes. Be sure the inside small notch is also on the long pencil line.

Build time this post: 0 hour, 20 minutes
Total build time so far: 42 hours, 20 minutes