Now that I have the instrument panel working and my RFI issues solved I returned to clean up items. I picked up my firewall forward items yesterday so my focus is going to shift to the engine. I need to get some loose ends on the electrical done, like all of the hot battery bus circuits among other things.
I decided to start with the speed switch that is part of the trim system, it senses the speed of the aircraft and will slow down the trim motor when you are going above a 100kts, this makes trim changes less sensitive. It needs pitot and static information to do this. I wanted to make a standoff bracket for the switch, it is very thin and I did not want it to be a pain getting the tubing on for the air data. I came up with a design that I hope will serve a dual purpose; it will hold the switch but will also be an anchor point for two antenna cables. I added some ¼ inch bushing to raise it off the bracket some.
The next thing was to install the heat valve. I wanted one with a flange on the inside so that I could run scat tube to bring the heat up closer to me, the standard valve has a cockpit side actuator and you can’t put a hose on it that way. I needed an engine side actuator. I had to have a special one made up; this style is normally two parts, one side like you see below and another with the hose flange. They get bolted and sandwich the firewall between them. There is a vertical support in the firewall on the RV-8 that makes this style not usable. I called Paul Bowmar at Plane Innovations, (they make the valve) the he offered to make one up with the 2”flange welded to the outer part. All I had to do was open the pre-punched hole just a bit to get the inside flange to go through.
There is a bead of fire seal around the flange and is compressed on the firewall side. The nuts are on the inside but I used high temperature ones anyways.
