Friday, May 28, 2010

Forget the 6-pack, make mine a 12-Pack

Epoxy filler is drying, no pictures, feel like making a core dump...

I'm in the process of making a 12 x 18mm rocket that I'm calling the 12-Pack.  I had been eyeballing the 'stiffy' BT-20 tubes over at Uncle Mike's Rocket Shack for some time and when I saw a TRF thread where someone was going to build a clone of the USR Swarm C6-7, the gears started turning.

I bought 6 of the 18" tubes along with some other stuff and should point out that UMRS shipped the order the same day that it was placed and it arrived in good shape 3 days later.

The mount is constructed as follows.  The tubes were quickly hacked in half.  I wasn't even that precise since the rough ends would be hidden in a 3" body tube anyway. I then glued them together in one set of four, one set of two and two sets of three.  Once the glue had begun to set, these sub-assemblies were stacked and glued together.  This process was a tale of disaster and redemption.  When I glued the four sets of tubes together, the Titebond wood glue wasn't fully set.  The glue was set enough to hold them together and, when the group of 12 tubes was stacked on their flush ends, they seemed to be secure.  After several hours, I shuffled back down to the Dungeon and, to my horror, about half of the tubes were totally misshapen.  I assume that once the glue shrunk, it pulled and twisted on the tubes, but not enough to separate them.  I shoved motors in both ends of all the tubes and ran masking tape tightly around their circumference.  The next morning, the tape and motors were removed and it looks like I found the mistake just in the nick of time.  Whew! One tube looks a little squirrely but a motor fits nicely.  Did I say 'whew'?

So, I decided to mount the tube assembly in a 3" coupler.  I figured this would make plugging the outer tubes and the gaps between all of them easier and I could then easily slide it into the main body.  To allow the tube cluster to fit, I had to trim about 1/8" off 6 tubes where they abut the coupler.  This was easy with a diamond cut-off wheel on my Dremel clone.  To plug the outer 9 tubes, I cut plugs from corrugated cardboard, coated them with wood glue and then glued them in.  I mixed half an ounce of epoxy filler to cap the cardboard plugs and fill all the gaps.

The rocket will have three fins nestled in the joints between tubes.  The shock cord will be through the wall.  And, that's as far as I've gotten.  Will it look like a 'normal' rocket or be an odd-roc? I don't know...