Steampunk Protostar #10 - Finishing Up The Engine Mount / Tail Section

I don't have a lot of confidence in the use of cardstock centering rings for motor mounts.  Especially for withstanding the thrust load of a D or E engine.

Back in my old fleet days, I had an Estes Big Bertha that, on its 6th or 7th flight, the card stock engine mount broke loose during boost and shot straight up through the body tube.  The model crashed and crinkled up the top three inches of the tube.  I was able to cut off the damaged section and continue flying the Bertha in a bit of a shorter version.

I don't relish the idea of a similar thing happening to a model on which I will have invested a lot of time building and detailing.

Over on Hans Chris Michielssen's Model Rocket Building Blog  (I highly recommend checking this blog out if you haven't already), there is a very good solution to this very problem. 

Chris simply cuts out some braces from scrap balsa and glues them between the card stock centering rings.  These keep the rings from flexing during boost and add a lot more strength to the entire assembly.  Even though they add a little more weight to the tail end of the rocket, I think the trade-off is very good insurance.

Here is a pic showing that simple construction process:

One small task which I should have done before even assembling the motor mount is this:

I absolutely loathe the finger tabs on Estes' latter-day engine hooks.  I just think they stick out too far and detract from the looks of the models. Plus, they aren't really necessary. 

Real Model Rocketeers don't need any stinkin' finger tabs, right?

So, I simply cut them off. 

A good heavy duty plier/cutter makes short work of this task.  Actually, the hard metal is easier to remove if it first gets a good scoring cut with the cutter.  The end can then be easily removed by bending it back and forth until it just snaps right off at the score line.  The sharp edge of the remaining hook can then be cleaned up using a metal file.





A couple of other small procedures to finish up:

A line of CA gets applied to the fore end of the engine hook, just in case.

And some small chamfers are sanded around the top edges of the centering rings.  These are meant to retain a line of glue at the ring/body tube joint when the motor mount is installed later.







Lastly, it's a good idea to perform a dry assembly of the engine mount and tail assembly into the main rocket tube, just to make sure everything inserts and fits right before any glue is applied.  Once engine mounts are glued in, they are impossible to remove in order to fix things.

Perfect fit!



I am not going to install the engine mount at this point in the build, because the tail cone is destined to get some additional Steampunk detailing applied.

Also, the proposed painting operation will be better accomplished separate from the main rocket to eliminate having to perform a lot of complicated masking.