Sunday, October 26, 2014

Estes Patriot Build #2056, Part 5, Coupler Bulkhead

I'm using the yellow section as a altimeter and payload section.
I'll have to make a coupler with bulkhead out of the second red coupler.

The red coupler fit can be tight so the edge that goes into the lower BT-60 section was rounded on the outside.
After rounding the edge got a coat of medium CA.
The edge was smoothed again with 400 grit.

Here's how the red coupler will fit into the upper white tube.
The coupler isn't glued in yet.
The red coupler is 1 1/2" long.
Instead of gluing it just halfway in, I want a little more length into the lower white BT-60.
5/8" will be glued into the upper yellow section, leaving 7/8" below.
I'll need a flat bulkhead to block the upper end and tie the shock cord onto.
A pencil tracing was made on heavy card stock around the outside diameter of the coupler.
This matte board is thick but can still be cut with scissors.

Build time:
CA tube ends = 5 minutes
Trace and cut disk = 5 minutes
Total build time so far = 1 hour 10 minutes


  1. Would it have been possible to glue the bulkhead nearer to the bottom of the coupler to make more room within the payload section? Basically cut the bulkhead to fit inside the coupler section, then use ring of body tube material (perhaps two layers) fitted inside the coupler to act as a support.

    1. Hi Naoto,
      Yes you certainly could glue the bulkhead nearer the bottom of the coupler. I glued it at the top overhanging the coupler edge. The bulkhead will be pulled down by the shock cord at ejection. The thick bulkhead has no chance of coming loose if it is glued over the top wall edge of the coupler.
      If I glued it in the center of on the bottom it might come loose.

    2. Basically my thought was to have the bulkhead glued inside the coupler ring, but slightly inset from the bottom edge -- then you would use some sort of reinforcement underneath:
      The simplest might be an epoxy fillet.
      Another idea would be "coupler-within-coupler" which would be glued inside the coupler at the bottom edge to act like a "shelf" onto which you glue the bulkhead.
      And of course the idea that could lead to madness -- the bulkhead would be inset within the coupler ring, then you glue a bunch of itty-bitty gusset pieces to act as reinforcement.