Breaking Super Big Bertha In Two - Payload Section

Super Big Bertha is a very tall model. It's made of two lengths of BT-80 body tube joined by a coupler you glue into both tubes. I decided to turn the upper tube into a payload section, sealing one end of the coupler with a bulkhead and only gluing it into the upper tube.

This would have two practical benefits. First, I could fly a payload, like an altimeter, without worrying about the delicate electronics being fouled up by ejection charges.

Second was transportation. I take most of my rockets to launches in a large box.

A box of rockets large and small. You can lay towels between layers to protect the paint, but if
you don't jostle them too much, it's usually fine to simply lay them in and take them out gently.

It's a long box; you can see my Pro Series Nike Smoke and Ventris in there, as well as my North Coast Rocketry Archer in there. But the Bertha is just a still much too tall to fit in the box in one piece. Having it come apart in the middle makes it much easier to pack away.

I swore I had some BT-80 plywood bulkheads somewhere, but I couldn't find them.

I was taking out the recycling, when it dawned on me - these Madras lentils from Costco are not only cheap, tasty, and healthy, the carton they come in is made of very hard, finely corrugated cardboard, and would be perfect.

First step was to trace around the coupler. Then I cut the shape out with scissors, slightly larger than the finished product would be.

I then sanded the bulkhead round until it fit snugly inside the coupler. 

I reinforced one side with a bit of packing tape and punched two clean holes through the bulkhead.

A good glue bond with fillets on the inside would hold it in place. I ran some Kevlar through the holes and tied it in a loop.

Finally, I plugged the holes with some Titebond Molding and Trim Glue.

Once everything was dry, I glued the bulkhead halfway into the upper payload tube.

The finished product is very solid.

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