November 15, 2019

Rear Floor Skins

After attaching the pushrod to my recently-completed rear torque tube assembly, I continued on with next steps on the fuselage. It looked like it was safe to install some of the rear floor skins, so I pulled those off the parts shelf. I’ve already riveted in the vertical close-out skins, but I only fit the floor skins in place and clecoed them for now. I think I need access to this area later to route brake lines, so I’m not going to rivet them in just yet. There is also a mystery row of rivet holes drilled into the floor skins (running across from left to right), with nothing underneath. I’m guessing they might be there for a non-existent channel to help strengthen the floor, or maybe this is a part shared with the Sling 2, where those holes serve a different purpose. Perhaps the answer will become apparent to me in the near future. In any case, this skin gets covered in carpet, so I won’t even see them once the interior is in. Originally I wasn’t going to prime these skins, but now as I’m typing this, I think I’ll prime them after all, since they’re right beneath the carpeting that wet shoes will be resting on, and I won’t have any other moisture barrier.

Vertical skins riveted in; floor skins are clecoed for now. I think I need access to this area later on to run brake lines.
Looking down at one of the rear floor skins: the red-circled holes are larger than the usual rivet sizes, so I assume I’m putting rivnuts here? Also, the blue-circled holes are grossly misaligned with the holes on the main gear channel, so I’m going to have to open up the holes on the skin and maybe switch to a larger rivet.
This appears to be the cover that goes over the cut-out in the rear floor

Craig and Ellen Maiman were recently over my house for dinner, and something that Craig pointed out to me were the holes in the rear wing spar uprights (used for attaching the parachute cables) are not drilled to the proper size. Craig said it was very difficult to fix later as part of the canopy installation. I looked in the canopy manual, and it calls for AN6 hardware for these holes (3/8″ OD). I took out my calipers and found the holes are indeed a bit too small. A quick check with a 3/8″ bolt confirmed that I cannot fit the bolt through these holes. This is not the first time I’ve encountered an undersized hole, and I imagine I’ll see more of this going forward, so I ordered a few more chucking reamers for all the common sizes of bolts: AN4, AN5, and AN6.

View of the rear spar upright, left side, looking forward. The circled hole is undersized and needs to be reamed open to 3/8″. Access to this hole is much more difficult after skins are installed!

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