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Avionics locations

YellaDawg

Well Known Member
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I am laying out my avionics and harnesses and wanted to see what the group thinks of placing some modules on a shelf behind the baggage compartment? I have a fast back (not riveted yet) and can put a 19" long shelf on the longerons with stiffners etc. I am using Advanced (VFR) for the EFIS and the modules are Dynon of course. I was considering the ELT, ADSB, Xpondr, COM, EFIS back up battery to be mounted on the shelf. The ADAHRS I plan on using a RV14 mount in the left wing and the EMS module behind the instrument panel. Opinions please.... Thanks in advance.
 
The aft mounted avionics shelf seems ideal in the 8. It doesn’t seem any harder to get to stuff back there than stuff under the instrument panel.
Mike
 

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Thanks for the photo, since mine is a FB, I plan on using the top longeron, which gives me easy access through the baggage compartment. Nice prime job BTW.
 
Thanks
Another thing nice about the aft shelf is it lets you keep the transponder and UAT antenna coax runs short and away from everything else.
 
I'm at the brainstorming stage and planning to put the battery on the firewall. This leaves the rear battery area available for avionics. Anyone else do this, and able to share pictures?
 
I'm at the brainstorming stage and planning to put the battery on the firewall. This leaves the rear battery area available for avionics. Anyone else do this, and able to share pictures?

Depending on your engine, prop and landing gear choice a battery on the firewall may make W&B too nose heavy. I recommend you take a sharp pencil and do some calculations. Mounting stuff aft will compensate, but perhaps not enough.

I have the standard IO-360-M1B with the Hartzell CS BA prop and Grove gear. I have one PC-625 battery mounted in the forward baggage compartment well and another one mounted in the standard aft location. This provided for a good W&B.

Carl
 
Planning an EarthX battery (4lbs), and a composite prop. My concerns are more about an avionics shelf where the aft battery mount would be.
 
I built shelves both behind the instrument panel, and back where the aft battery would otherwise be. The aft shelf is where the ELT, ADS-B receiver, and transponder live, along with a network hub. The forward shelf has the com radio, Dynon backup batteries, SDS CPI2 and the SDS backup battery. I also have both voltage regulators and a few other items mounted to the forward baggage bulkhead.

The rear shelf has a bit of an odd shape in order to clear the bellcrank mount while also maintaining enough depth for the two larger units. I made it in three pieces (the "bridge" and the two "wings") and riveted the flanges together to make a single unit:

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The forward shelf mounts to both of the upper braces. It's the same width as the center panel cutout, so the entire shelf can come out that way if necessary (though detaching it would still be a bit of an operation):

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img_1893-1024x768.jpg
 
Thanks, I'm running a IO390 EXP119 with a Hartzell aerobatic prop so felt the need to go aft with as much as I could. I already have a Concorde battery I wanted to use so it needed to go back there for sure. I'm using Advanced so I'll mount the ELT, ADSB, Battery back up, SV-Com and Xponder back there. AdAHrs will go in the wing. I'll leave the EMS behind the instrument panel.
 
Thanks, I'm running a IO390 EXP119 with a Hartzell aerobatic prop so felt the need to go aft with as much as I could. I already have a Concorde battery I wanted to use so it needed to go back there for sure. I'm using Advanced so I'll mount the ELT, ADSB, Battery back up, SV-Com and Xponder back there. AdAHrs will go in the wing. I'll leave the EMS behind the instrument panel.

You may want to look at the wiring needed to move this stuff aft. Here I suggest:
Not too hard: ELT, XPDR (but need to run power and serial), ADS-B receiver (power and serial in a single four #22 conductor shielded wire) and associated antennas.
Hard: Dynon Comm (you need a bunch of wires to your audio panel, more wires to your mounted Comm head and such) and the SkyView backup batteries (again wiring). On this list I suggest the total weigh is in the margins.

So before you get carried away, run the W&B numbers. With that weak sister boat anchor of a battery back there you may be close.

Carl
 
Got it, I know wiring will be challenging (always is) and the weight marginal, I won't do anything until I have all my harnesses and all mocked up.

Thanks again for the inputs!!
 
You may want to look at the wiring needed to move this stuff aft. Here I suggest:
Not too hard: ELT, XPDR (but need to run power and serial), ADS-B receiver (power and serial in a single four #22 conductor shielded wire) and associated antennas.
Hard: Dynon Comm (you need a bunch of wires to your audio panel, more wires to your mounted Comm head and such) and the SkyView backup batteries (again wiring). On this list I suggest the total weigh is in the margins.

So before you get carried away, run the W&B numbers. With that weak sister boat anchor of a battery back there you may be close.

Carl

I don't think moving the SV batteries aft is workable. The installation manual has some pretty specific info about constructing your own harness:

SV_BAT 320 Connection

...

Wire: 22 AWG Tefzel, NO MORE THAN 24" LONG (emphasis not mine)

I'm not sure if the concern here is excessive voltage drop or what; if so, it might be something that could be mitigated. But the above is pretty explicit.
 
I am building a simple VFR RV8 with a single 10" Dynon Skyview with autopilot. I am able to mount the remote radio, transponder, ADSB, and EMS at the shelf immediately in front of the panel. The ADAHRS is at the rear battery location.

I did a rough weighing of my current avionics to the old six pack with panel mounted radio and transponder and my avionics is probably lighter as a group. The heaviest avionic is the 10" EFIS which is on panel.

My goal for grouping all the avionics next to the panel is to simplify the wiring runs which are complicated for my amateur knowledge at the time. The battery is mounted at the firewall. Mounting the battery to the firewall is fortunate because of all the short wire runs with the big cables.

I have the IO-360-M1B with the Sensenich ground adjustable carbon fiber prop which is lighter than a previous RV8 with the aluminum prop.

Another RV8A owner commented my setup should be close to neutral with the light prop and relative simple avionics. I hope he is right.
 
I don't think moving the SV batteries aft is workable. The installation manual has some pretty specific info about constructing your own harness:



I'm not sure if the concern here is excessive voltage drop or what; if so, it might be something that could be mitigated. But the above is pretty explicit.

Thanks for the heads up, I'm using Advanced, probably no difference but they did tell me it was OK to mount behind the baggage compartment. BTW, I enjoy your build log.

CW
 
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