38mm4FNCDD for first scratch project

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Active Member
Sep 10, 2009
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Hey everyone. After much reading, research, and trepidation, I decided to try my hand at a nice slow build with my first genuine scratch project. So, I played around on Rocksim for a bit and came up with a fairly straight forward design. This is based around about 36" of BT-80 tubing (which will be glassed at some stage), a 38mm MMT, and one of the Apogee BT-80 nose cones. This will be a dual deploy design, and electronics and recovery is still not finalized.

Early design photo, which will probably change a bit during the process, is:


The fins are loosely based on the V-2 fin design, generally swept back without all of the detail.

I ordered the two BT-80 tubes (18" each) and 38mm MMT kit from Uncle Mike's online. For fin material, I went to the local hobby shop and grabbed a few small sheets of 1/8" basswood ply. I have a couple of couplers and the nosecone on order from Apogee, and they should be here by this weekend, not that I will need them that soon. As I said, this is a nice slow build for me, since I want to take my time and try to get a few things right.

On Monday night, I took the pattern for the fins from Rocksim and traced them onto the ply. I added an additional tab at the bottom of each so they could be mounted to the MMT. The fins were then cut on a bandsaw, then sanded to get them to the same dimensions and to remove any overly rough edges. These were tacked on with 5 minute epoxy.


Last night I added fillets to all of the MMT/fin connections, and let that dry.

Next on my list is to figure out what is next on my list. Being my first scratch build, I am feeling my way through the process. Even after all the reading of other builds, its just something I need to work out.

Initial Rocksim estimates are that it will reach the 3500-4000 ft mark.
Early builder estimates are that it will explode on liftoff. :rolleyes: