On Saturday I got the mounting for the trim servo done and was ready to install it into the left elevator. However one last thing remained to do, add the wiring to connect it up through the horizontal stabilizer and so it can be wired up to the control stick eventually, but that’s after the fuselage gets built.

Here is the servo on it’s mounting plate, you’ll notice that the leads are a little short to reach the cockpit at this point.

The first part is to extend the leads on the servo so that they have enough length to reach through the HS and make it to a connector I will mount in the tail of the fuselage.

For people not familiar with wiring, here’s a brief tutorial… first I figure out how long the wiring need to be to reach from the servo’s mounting position into the fuselage through the HS, I leave it a little longer than I estimate, just in case. Then I cut some of the appropriate size wire for the amount of current that will be on the wire and for the length of the total cable run. For the trim servo it’s not much current on two leads that operate the motor and the other three leads are for position signalling and have even less current so the guage [wire is sized in ‘guage’ or AWG] of the wire doesn’t have to be much. I’ve selected 22 AWG for this application.

Also note that the wire is white… that means that I have to put tags on each lead so I can tell them apart later in the wiring harness. Not much problem now but later on I’ll have hundreds of wires and tracing them out if they were unlabelled would be a major pain. The wire is white because it has insulation sheathing made of Teflon. Ordinary plastic wire isn’t allowed in aircraft since the plastic burns and produces toxic fumes in a fire or a short. Don’t wan’t to add that to any potential in flight emergency.

Next all the wires are stripped to expose the conductor, the and each extension are twisted together neatly. Solder is applied to make a good solid mechanical and electrical connection. After each wire is soldered heat shrink tubing is slipped over and shrunk with the heat gun to insulate the connection. Finally all of the wires are fed into a larger piece of heat shrink tubing to gather them into a neat bundle and they are fed through the grommets in the elevator.

Here is the servo installed in the bottom of the left elevator. One remaining task is to fit a small fairing over the pushrod. Every little bit of drag reduction and streamlining makes the plane go faster and saves fuel!