Installed panel to measure, magnetometer install | 1.3.2021

I'm rapidly running out of airframe tasks to do (that I want to do... there's still some sanding left), so I started thinking about the sub-panel for the avionics. Basically, this will be a tray that sits directly behind the panel to make room for some of the remote mount boxes for the avionics suite. I need to build this soon, so I need to order angle aluminum, so I needed to do some measuring, so I needed to mount the panel. Just the type of dependency chain that's normal in plane building. :)

Pretty straightforward install. Basically just finagle that thing in there, then secure with some clecos. Of note, this is the "canted" panel that came with the kit. Because of where we want the avionics stack and screens, we will be using a flat panel for the final build. That's been ordered from Velocity, but for now I can do simple measurements with the existing panel.

Once the panel was in, I couldn't help but print out most of the avionics to scale to 1) make sure everything we're planning will *actually* fit in real life instead of in a panel designer and 2) so we could sit in the plane and make engine noises. ;)

Here's the first sneak peak at the panel layout. I think the pilot screen will be moving left by 1/2 an inch or so, and the landing gear controller will be made into a more compact footprint.

Everything printed to scale.

After being satisfied sitting there making vroom noises, I moved on to mounting the magnetometer. Initially, I had planned to put this in the nose so that it would be more accessible. The only issue with that is that it violated nearly all of Garmin's mounting location guidelines. Namely it was really close to relays, high power draw items, ferromagnetic "things" weighing more that 1kg, high draw wires, radios, etc. All in all it's a terrible spot for a sensitive magnetic device.

Even though I guess quite a few people have mounted the magnetometer up there without issue, I just couldn't shake the "not quite right" feeling, so I decided to mount it out in the strake end. At worst, this will be within a few feet of the right gear when the gear is up. It'll also be within a foot of the strobe light power cable, but I'll run shielded cable to those in hopes that it will help.

The issue with the strake end (and why I wanted to put it in the nose initially) is that it's not parallel to the direction of travel of the plane, and the mount needs to be mounted *very* close to direction of travel. I think the allowance is <0.5 degree. To get it mounted straight, I'd have to get a straight line from the centerline of the plane transposed over onto the strake. This is harder than you might imagine, and I had to think about this way too long.

Here's what I came up with: I leveled and secured the plane in place. Next, I dropped a plumb bob off the tip of the nose and the centerline that I had drawn on the firewall already (halfway between wing bolt holes/center of main spar) and drew a mark on the floor. I then measured an equal amount from those initial marks to the side where I'm mounting the magnetometer and pulled a bright string line between those two points.

I then needed to transfer that mark up into the strake end somehow. This is the best I could do. First, I used my MK.1 eyeball to line up a t-square sitting on the strake itself with the line on the floor. This is hard to get a picture of, but you get the idea:

Once perfectly in line with the line on the floor, I drew a pencil line on the strake with the intersecting angle in case I needed to reference it again. I also duct taped the t-square to the strake itself along the line. Here's where things get kinda janky: I will then use this t-square to drop the plumb bob over and then measure in to the magnetometer itself when I go to glass this in. This also needs to be leveled fore/aft and left/right. This is the best I could come up with. Someone probably has a better idea, but this was mine. I also did some spot checking by eyeballing along the firewall and perpendicular-ness with the canard, and it seems spot on. I can always adjust it if it's off in the air later.

This still needs to be glassed in, but I cut the mount to fit and keep everything level. This mount will also keep the magnetometer out of any water that happens to get into the strake end.

That's all for today!
- Jeff