I’ve been falling behind on regular posts, but I intend to return to a regular rhythm — if not daily, at least on the days when I work on the plane.. So, this post is a little longer as it captures work performed 8 – 13 July.
I’ve started to attach the right side skin to the fuselage. I measured and cut the insulation, making pieces for both sides at the same time.
I dimpled the forward part of the skin. This is optional for the Sling 4, but standard for the TSi. It may help performance a tiny bit (fewer drag counts), but mostly I’m doing it for appearance’s sake. Countersunk rivets sit flush with the skin when installed in the dimpled holes, rather than sticking out like the normal button-head rivets. To dimple the holes, I’m using a pop rivet dimpler for the skins, and a vise dimper for the longerons, and other places where space allows.
I decided to install the NACA scoop before attaching the skin to the fuselage. Rather than using Sika sealant recommended by the manual (hard to get in US), I’m using Dow DOWSIL 732 RTV Sealant, which is very easy to obtain here. As indicated in the (TSi) manual, the holes for the NACA scoop are also dimpled. You can’t dimple composite material, so instead I took a countersink drill bit to it. However, the flanges were so thin, it just enlarged the hole, so I made some reinforcement strips from 0.020″ Al sheet and dimpled those too.
I also completed a few small miscellaneous tasks: fit check of the seat belt reel (for front seats), designed & printed a seat belt grommet for the longerons, and drilled a hole in the skin for -3AN bulkhead fitting for the brake line.