Since I’m not going to have any traditional, panel mounted avionics, the radios, transponder, audio panel and associated boxes will all be mounted behind the panel. So I’m going to use a “Millin Shelf”. Named after Andy Millin because his is the first one I had seen. 🙂

First I made some brackets that are attached to the sides of the fuselage with structural adhesive and rivets.

Then two pieces of 1″x1″ aluminum angle stock are used to create the structure of the shelf.

Finally, a single sheet of aluminum is used to finish the shelf. Most of the devices will attach to the frame members so the aluminum sheet is used to bridge the frame members for smaller devices.

Once all the parts were assembled, I removed the shelf and began mounting the devices. Here I’ve mounted the VP-X Pro and the AHRS.

I made paper templates of the other devices (radios, transponder, GPS, etc.) and it’s going to require some careful planning to get everything to fit.

Connecting the primary alternator is pretty straightforward. Basically 3 wires. The “B” lead which supplies the power to the electrical system. The “F” (or field) lead which is what activates the alternator and a ground wire.

Here you can see the large B lead (with the white cover on it). The F lead is above and routed to the left. And the ground comes around the right side.

I wasn’t happy with how the alternator cover looked so I did some more filling and sanding. The purpose of the cover is for cooling. Air from the plenum flows into the alternator and then out the bottom through a port.

Here’s the alternator with the cover on.

And where the wires exit the cover.

More wiring…

The engine side terminal block and ground block is just about finished.

I have all the wires routed from the bottom of the co-pilot A-Pillar up to the overhead switch panel (OSP). Because the switches that I’m using a very small, I can’t use the standard Faston connectors that most people use. So I had to solder on short pieces of wire that I will then crimp in-line Faston connectors to.

Here’s the overhead switch panel with the terminated pig-tails. The two in the middle near the middle that are terminated are for the magnetos, and the one towards the bottom is for the G3i ignition (that I haven’t gotten yet).

Here’s the A-Beam where the OSP will fit with the wires terminated (except for the mags. Red=Right and Blue=Left).

And here’s one of the mag leads.

It may not seem like much, but the Master power switch and battery contactor are now wired up.  I don’t have anything running off the electrical system yet so I hooked up the multimeter so verify.

One of the reasons for this is that while I was pulling wires and hooking up the overhead switch panel, I decided to test every wire, terminal and switch. Out of the dozen or so circuits, I found one that had a bad crimp on the terminal.  It was relatively easy to troubleshoot and repair. Had I waited until everything was done, it would have been a major PITA.

So now, I test every single circuit when I install it.

Originally, I was going to use basic Molex connectors for the navigation and strobe light connections at the interface between the wing and strake. Then I found some weatherproof AMP connectors.

The wingtip light assembly has four wires (Ground, Navigation Light Power, Strobe Light Power and Sync) so I selected a 4-position connector.

Here is the fuselage side of the connection.

The red wire is the “sync” wire. This allows the strobe on the left to be synchronized with the strobe on the right.

Up until this point, I was labeling the wires with plain english (Oil Pressure, Starter, 24v, etc.). But after considering the number of labels and the cost of the heat shrink tubing, I decided that I should adopt the modified version of aircraft wire labeling standard. Hence the somewhat cryptic “L1-4B-20”.

Since the airframe is non-conductive fiberglass, I need a ground plane for the transponder antenna. Because the transponder operates on two frequencies, a circular ground plane isn’t optimal. I purchased a document from RST Engineering that provides the information needed to design antennas. But fellow builder John Tvedt had already built his some he sent me the template.

So I printed out the template and glued it to a piece of aluminum.

Then cut out the aluminum.

Drilled a hole and attached the antenna.

Now I just have to build the mount for the antenna assembly.

Instead of the traditional whiskey compass, I’m going to have an electronic magnetometer. And for redundancy, I’ll have two.  I was originally planning on having one in the outboard pocket of the right strake and the other in the left. But builder Andy Millin put both of his in the same location.  I was worried that there could be some interference issues if both were in the same location but it would appear that my worries were unfounded. 🙂

So I simply copied Andy’s design.  Imitation is the sincerest form of flattery, right?

The support bracket is a 2″ piece of 2″x2″ angle stock. That will be screwed into a hardpoint which will be mounted to the outer part of the strake.

This the spot on the strake where the hardpoint will go. The area has been sanded and structural adhesive and been applied.

Hardpoint positioned and adhesive is cured. Now it covered with 2xBID.

The mounting platforms (one for each magnetometer) are made out of 1/8″ aluminum (which is much stronger that needed) with holes to reduce weight.

Then I cut some 1/4″ aluminum tubing to create the spacers between the two platforms. Some 1-1/2″ brass screws, washer and nuts later:

When I was building the mount for the magnetometer, I forgot that the outer strake bulkhead is not parallel to the centerline of the fuselage. The documentation for the magnetometer says that is can be calibrated for up to 127 degrees, but it was fairly simple to ream out the mounting holes to allow for that.

Here’s the modified bracket which compensates for the alignment.

To get the front-to-rear and side-to-side level, I put in the bracket with just the bottom plate. I used a level to determine how far out it was. Then it was just a matter of adding a washer or two and a little sanding to remove some material.

The finished mount with both magnetometers installed and ready for cabling.

I have decided to mount the autopilot roll servo between the whale tail and the landing gear bulkhead on the pilot side.

I could have made some hardpoints out of 1/4″ aluminum but then the plane of rotation for the servo would not have been the same as the aileron bellcrank. So I used some 1/2″ aluminum for the forward hardpoints.

Once I had tweaked the alignment, I mixed up some structural adhesive with some flox & cabo then bedded the hardpoints.

Once it cures, I’ll cover it with 2x BID and that will be one more thing done.