Here are a few photos covering the MMT installation process as well as the fin attachment.
First, I wanted to make sure my dowel rod I was using the apply glue to the inside of the body tube was long enough. It was (just barely), and I knew how far to wedge my fingers into the aft end (lol) to get glue in the right spot for the forward centering ring:
It almost looks photoshopped in, but the white/yellow-ish ring inside the body tube there is my ring of Titebond II, well forward of the fin slots:
At this point, you want to get the forward centering ring in past the location of the middle centering ring and rock the MMT assembly to the side to give you access to applying glue to the inside of the body tube for that middle ring. On this kit, that wasn't too difficult:
Once I had glue in place for both CR's, I just had to slide the assembly in, remembering to line up the Fin-lok rings with the fin slots as best I could. Sliding it in proved to be much more of a challenge than I thought (not enough dry fit testing I guess), so I had to enlist the services of some left over 38mm motor mount tubing. I literally held the 38mm tube up against the middle CR and hammered it onto my workbench until it was in position. The glue was already bonding pretty tightly given the friction condition, but it relented enough to allow me to fine tune the positioning just enough:
View of the Fin-Lok rings through one of the fin tab slots:
View looking down from the top. Seems like its probably enough coverage, but I could drip/dowel another layer of glue down there later for peace of mind:
Before letting the MMT assembly go for the full cure, I made sure to test the fin alignment. Everything seemed to check out:
After giving the MMT some more time to dry, I snapped the fins in. Per the instructions, I mixed some 5 minute epoxy and applied it to the root of each fin forward and aft of the fin tab where it contacts the OD of the body tube. All three fins went in pretty well with the exception of the forward lock on one of them. I'm not sure why it wouldn't go. I beat my hand up pretty good trying to get it seated, but no luck. That said, the root seated sufficiently to the body tube, so I'm just gonna leave it as is:
Lastly, I went ahead and drew the lines for the conduits using the supplied template:
Overall, this portion of the assembly went pretty well. My only criticism is that it seems like either these parts are all toleranced too tightly, or they were made at the edge of spec. The rings fit onto the MMT tube very snugly (even after removing the outer layer of paper), the CR's were reluctant to slide into the air frame, and the fins were pretty difficult to click into the fin-lok rings. The design is all great, I just could have done with less sanding and subsequent assembly force (despite said sanding).
Next up will be the conduit installation, assembly of the upper payload bay, and then its on to finishing touches, more sanding, and paint.
Thanks for watching!
Brian