Autopilot hardpoints, cowl repairs | 11.21.2020

Started off the night by fabricating hardpoints for the autopilot servos out of aluminum. Specifically, I wanted to start installing the roll servo, but figured I'd make all 8 hardpoints while I was making them. Basically just cut squares of aluminum then drill and tap them.

Here's the extra four for the pitch servo.

Once that was done, I temporarily mounted the GSA28 servo in the bracket and attached the hardpoints. I had to add spacers to the front (nearest the whale tail) to get it to sit in line with the aileron bellcank, because of the curves in the fuselage. The spacers are made from the same stock, but drilled out to bolt diameter. Basically a big flat aluminum washer.

Hardpoints installed to the bracket. You can see the spacers I made here too, on the left side.

At this point I test fit everything with the bracket in place and drilled the bellcrank for the servo arm. I also ensured that the drilling location allowed for full range of motion with the autopilot overcenter safety bracket installed.

Bellcrank drilled

Once I was sure everything would work, I sanded the floor and used structural adhesive to bed the hardpoints. Once this cures, I'll glass over top with 2 plies BID.

This angle makes it look not parallel, but it is.

I also worked on repairing the cowls. Had some scrap triax, so I cleaned up around a few of the holes in the cowls and fabricated a backer out of aluminum tape (no duct tape around). I then glassed 1 ply triax over the holes. This will probably get another ply of something once I figure out how this comes out. Might just fill with micro and do a few layers of BID on the outside or something. I also added another ply of 5" wide BID to the flanges where the cowl attaches to the fuselage. The other 3" and 4" plies had been done, but the 5" wide tape called for in the plans was missing.

The rear holes will need fixed as well, but this was more of a test.

I also used some scrap triax to fabricate a mount for the magnetometer that will be mounted in the nose.

2x4s were my form.

- Jeff