STUFFER TUBE/MOTOR MOUNT
A BT50H provides the core of the rocket. I don't know why I do this to myself, I hate stuffing parachutes into BT50. Anyway, most of the action happens at the motor mount end, and that is where we'll start.
The cant angle of each BT60 segment is set at 4.4°, so I started at cutting an equivalent angle at the MM end of the tube, so it will match up with bottom BT60 segment.
And now I finally had to decide on how to assemble the motor mount. My goal was not just to build this motor mount, but to come up with a good, solid, repeatable process. After getting as much input as I could, I decided on a modified approach that was... well, not exactly the right choice. It worked, but I probably wouldn't do it this way again, or recommend it to anyone.
My general approach would be to cut the tube above the MM use a coupler as the thrust ring. I filed a notch in my coupler to provide room for the Kevlar to squeeze between the coupler and body tube:
So far so good. The next step is where I... "innovated". I poked a hole in the center of the coupler (where the pencil mark is in the above picture) and threaded the Kevlar through. Then I tied a nice beefy knot in it (to keep it from pulling through the hole and gave the whole interior mess a nice coating of epoxy:
Then I went a couple of steps without pictures as my epoxy was starting to set and I had some on my gloves and I just needed to get it done. But here's what I did:
1) The *far* end of the coupler in the above picture was glued into the motor mount, pushed up against the top of the hook.
2) The *near* end of the coupler, along with the Kevlar in the coupler notch, was pushed into the remainder (long piece) of the stuffer tube.
The whole thing was laid into a piece of angle to keep it straight while it cured.
My thought process was that by doing the Kevlar this way, the loose end of the Kevlar would emerge into the body above the coupler, which would give a couple inches of buffer from the ejection charge. That's fine, but what I failed to consider was that pushing the coupler in that direction meant that the Kevlar wanted to push back. I realized this once I started pushing it in, and then needed to try to pull on the Kevlar to keep is straight as the whole thing was going in. I think I was only partially successful, but since the whole thing will be hidden it's OK.
So I didn't come up with my clean and repeatable motor mount process, but I learned some things. Will do better next time. I like the coupler approach, but the Kevlar installation needs improvement.
Finally, I put a 5055 ring around the motor hook to secure it, and electrical tape to hold the top.
Final note: the motor hook was aligned (approximately) with the "short" side of the tube. That is where the thick side of the centering ring will go, so I have lots of wood to work with there to cut a slot for the hook.