Did some assembly today. Some of it went well.
First, I built the motor mount, which is really just the end of the long BT50 that runs through the whole rocket. This is what it looks like:
The ring is positioned at the back of the fin can (more on that later). I realized, nearly at the last minute, that I couldn't wrap the hook with tape because that tape would be under the rear fins, and therefore would interfere with the TTW attachment. So I did something I've done before, which is just blanket the top half of the hook, and the bit just on the other side of the centering ring, with 30 minute epoxy. It's not going anywhere, the TTW locations are clean, and hook has enough room to bend and allow for motor insertion. So far so good.
The front centering ring was positioned about a 1/2" behind the front of the fin can.
Next I glued on the fin can:
Here's a close-up of the back end:
I let the centering ring (1/8" light ply) extend just a bit behind the BT, to give a "shoulder" for the transition to anchor to. I don't know if that's enough of a shoulder, but that's about all I could do.
The front looks like this:
Here, I took a short (~1/2") piece of BT55 and sliced out a small piece so it could be squeezed into the end of the fin can. This provides a quite nice shoulder for the front transition. This is why I put the front ring 1/2" behind the front of the tube.
Now for these guys:
I made these using a modified version of Chris Michielsson's "super shroud" technique (I will document this technique at some point); they are made from 2 layers of 65 lb cardstock and came out quite good on my first try. The longer front transition was easier, so I went to install that one first. I applied glue to the tube and the shoulder and got ready to slide it on:
Approximately one minute later, I was looking at this:
That is not a result of frustration (although I was frustrated), but of the fact that the front glue bead grabbed too quickly and left me unable to get the whole transition into position. So, with the glue setting, I had no choice but to rip the whole thing off. I'll make another and try again; next time I will not put a glue bead on the body tube, only on the shoulder. The front of the transition will be secured only with a fillet after the fact. I should have learned this lesson on my last build, but I forgot.
So, let's look at the rear transition. This one has to provide room for the motor hook, so I cut a nice little slot in it like so:
I put some CA around the edges of it and sanded it to make nice clean and reinforced edges. It provides just enough room for the hook to go through and be able to bend outward to insert or remove the motor. Actually, it could probably stand to be a little bit deeper; when the hook is fully extended it is pulling *slightly* on the transition.
But after further thought I'm not sure I'm actually going to use that transition. The large end of it is a tiny bit too big, and fits a little sloppily. I applied some CA to the edge and will try to sand it down, but if I'm not happy with the fit I'm just going to make another one of those as well.
Lucky it is quick and easy and cheap to make more transitions.
I kind of wish I had made this rocket one click larger (BT55/BT60); would have been easier to work with the slightly larger pieces.