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Finishing up Tailcone - Questions Antennas, Magnetometers and riveting top skins

BrianDC

Well Known Member
Well, it's time to ask for some advice from "the collective" as I'm basically trying to decide my next steps. (Regardless of the advice, I realize I am responsible for my own decisions :D )

Currently I have finished the tailcone (Section 10), but have not riveted either of the two top skins on yet. I had a local EAA Tech Counselor visit that suggested that I determine what antennas I want to install (including magnetometers) and to NOT rivet on the top skin (F-1075) until much later.

While I can see the benefit of maintaining mostly full access to the tailcone, has anyone else done this that can provide some advice? I'm leaning towards riveting it on before I attach the tail feathers for better rigidity (and following the plans).

My other questions are regarding antenna choices and mounting locations. All along I have wanted to get a G3X Touch system, however I didn't plan to purchase any avionics or antennas until I basically done with the aircraft. Looking at some other build-logs (Looking at you rdamazio), it seems that I really am not thinking far enough ahead in my build! :eek:

I'm currently plowing through the G3X Touch install manuals and trying to spec out what I would purchase today if I had to pull the trigger and I feel like I'm missing something regarding the GMU-22 and GMU-11. I see quite a few posts of RV pilots using the GMU-22, however based on the current install manual, the GMU-11 is recommended unless my RV-10 will do over 300Kts. Is the GMU-11 just a newer option or is there a reason to go with the GMU-22?

For antennas, and things like ELT's, when is it recommended to purchase / install? I guess there is nothing wrong with holding off to install this stuff much later in the build. Worst case is I have to stuff myself in the tailcone to mount these items once everything is buttoned up?
 
NOT rivet on the top skin (F-1075) until much later.

That's correct. I didn't rivet mine on until almost the VERY end of the build. It was nice for tailcone access, and it does get riveted on TOP of the fiberglass cabin top. The other top skins can be installed per plans.

While I can see the benefit of maintaining mostly full access to the tailcone, has anyone else done this that can provide some advice? I'm leaning towards riveting it on before I attach the tail feathers for better rigidity (and following the plans).

You can install the tail feathers now to check the fitment, but again, you don't need to install them onto the plane (for the final time) until you're almost totally done with the build.

My other questions are regarding antenna choices and mounting locations. All along I have wanted to get a G3X Touch system, however I didn't plan to purchase any avionics or antennas until I basically done with the aircraft. Looking at some other build-logs (Looking at you rdamazio), it seems that I really am not thinking far enough ahead in my build! :eek:

I'm currently plowing through the G3X Touch install manuals and trying to spec out what I would purchase today if I had to pull the trigger and I feel like I'm missing something regarding the GMU-22 and GMU-11. I see quite a few posts of RV pilots using the GMU-22, however based on the current install manual, the GMU-11 is recommended unless my RV-10 will do over 300Kts. Is the GMU-11 just a newer option or is there a reason to go with the GMU-22?

For antennas, and things like ELT's, when is it recommended to purchase / install? I guess there is nothing wrong with holding off to install this stuff much later in the build. Worst case is I have to stuff myself in the tailcone to mount these items once everything is buttoned up?

You really don't need to worry about any of that stuff for quite a while. It's all very do-able waaaaay down the road. My only suggested possible modification during the tailcone build is if you want to cut in a rudder trim, or add a conduit in your vertical stab for a future tail-cam or nav whiskers on top of the VS (under the rudder horn).

Everything else, and even those things I just mentioned, can be done at a much later time in the build.
 
That's correct. I didn't rivet mine on until almost the VERY end of the build. It was nice for tailcone access, and it does get riveted on TOP of the fiberglass cabin top. The other top skins can be installed per plans.

Just to confirm, I'm talking about not riveting either of the two top skins for the Tailcone. Fully understand you don't want to rivet the forward top skin till after the cabin top is installed.

You really don't need to worry about any of that stuff for quite a while. It's all very do-able waaaaay down the road. My only suggested possible modification during the tailcone build is if you want to cut in a rudder trim, or add a conduit in your vertical stab for a future tail-cam or nav whiskers on top of the VS (under the rudder horn).
That was my thought as well. Thanks for the confirmation. I did run a conduit in the Vertical Stab already for a possible tail camera, and plan on having sufficient conduits for any future equipment.
Thanks!
 
Just to confirm, I'm talking about not riveting either of the two top skins for the Tailcone. Fully understand you don't want to rivet the forward top skin till after the cabin top is installed.

I think you'd want to rivet them in place, per plans, just to maintain structural rigidity... even just for storage. They don't really impede any work going forward.

I installed mine when the plans called for it, and didn't have any issues.
 
I think you'd want to rivet them in place, per plans, just to maintain structural rigidity... even just for storage. They don't really impede any work going forward.

I installed mine when the plans called for it, and didn't have any issues.

Perfect, thanks for the clarification. I was thinking this was the way to go, but just wanted to confirm with some other builders. Appreciate the advice!
 
You can think about antennas (antenae?) now without selecting you final avionics, just based on capability. Doublers only need to go in before the floors go down for good for belly mounted stuff. You'll need one comm antenna for each radio you have, something for VOR/ILS if installed, two xpdr antennas for ADSB, one for the ELT and then one per GPS (G3X counts as one, unless you put up an additional antenna for each screen). As far as placement goes, there's a lot of advice if you search; internal vs external, top vs bottom for comm (or one each). My setup is as follows (with no claims made about being better) - GPS (GTN 650) is on top of the cabin; the G3X gps (only one with 3 screens) is on top aft of the cabin top, and I decided to get a combined VHF/GPS antenna (comant) (spendy) so the comm side is my 'other' radio; the GTN comm is a belly mounted bent whip and the VOR/ILS is bottom tail mounted. Two blades on the bottom for XPDR/ADSB and the ELT is mounted inside under the cabin top. Ed is right, though, that you have herds of time...

==dave==
N102FM
 
As others have suggested, avionics and/or builder preferences change faster than anything else. Postpone those choices as long as possible. When you get to the baggage area, run extra wires, or leave space in conduits with pull wires, to account for later changes. Antennas on the belly under the aft seats or baggage area you will have to plan for prior to closing those areas.
As to the tailcone, I followed the plans. In my early 60's at the time, I didn't find crawling back there for this and that too hard to do.
 
I'm at that stage now with the partially completed -10 kit I bought.

I think getting as many wires in now is a good idea, and in my case a bit easier since I have settled on Dynon equipment due to familiarity.
In my kit it's a little more complicated due to the fact that the baggage floor is riveted down and the rear seat bottoms are partially riveted too. I plan on adding multiple conduits from the flap drive area to aft of the baggage bulkhead.

Here is my list of all of the wires that need to pass rear of the baggage bulkhead -

AFT OF BAGGAGE BULKHEAD
Battery #2 heavy cable
Network cable to Dynon ADHRS
4 lines (22g) cable to Dynon ADSB box
Dynon Network SERVO cable to pitch servo
LED Tail light/strobe power
Elev. Trim servo cable - 5 conductor
ELT telephone cable to ELT panel control
ELT GPS position cable
PITOT TUBING + AOA TUBING from wing
Battery contactor Master Sw power
Power to overhead console lights
Com 1 and Com 2 – 2x RG-400 co-ax
Garmin GTN GPS antenna RG-400 co-ax


There's a lot of stuff listed so putting it in now and routing it to the general panel area will remove a lot of future work in the tail cone.

The list doesn't include wires that stay in the tail cone and don't pass forward through the baggage bulkhead -

ELT antenna cable
ADSB box to antenna
ADHRS box to OAT sensor


Even if you don't add the wires/cables now, allow for enough conduit space to get all of the above taken care of. :)
 
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As to the tailcone, I followed the plans. In my early 60's at the time, I didn't find crawling back there for this and that too hard to do.

Not to hijack the thread but how did you protect the bulkheads and the J channels on the floor? I'm worried about folding them over.
 
Cut some lengths of plywood to lay across the ribs to use as a platform. Should bear your weight easy and allow you access. At least that is my plan.
 
Not to hijack the thread but how did you protect the bulkheads and the J channels on the floor? I'm worried about folding them over.

I used some old pillows to build up and over the bulkheads. Those start to hurt after laying on them for awhile.

I've had to crawl back there three times after I've been flying to replace a variety of components. It's not a fun task.

I did leave the top piece that gets riveted to the cabin cover off until the last possible moment. That allows you to stand on the floor and work on the battery/servo areas.
 
Thoughts

One piece of advice I was given was...get the structure built then do the wiring/equipment choices and placement. If you seal something off during the build, how will you be able to service it during maintenance later on. I have made several notes as to where my equipment will be laid out and am planning ahead for them. The only one I am really isolating is the antennae mounts under the rear seats. Why waste time running wires / building mounts if at a later time they will be changed / modified or moved.
Just my 2 cents
 
Not to hijack the thread but how did you protect the bulkheads and the J channels on the floor? I'm worried about folding them over.

I cut swimming pool noodles to go against the skin with cut to fit plywood pieces on top. Then packing blankets on top of that for comfort.
 
I cut swimming pool noodles to go against the skin with cut to fit plywood pieces on top. Then packing blankets on top of that for comfort.

Oooh, I like that idea. *yoink* Mine now! :p

I didn't rivet the aft top skin until just before joining the fuselage up. Of course, my tailcone is crowded with all the A/C stuff. I agree with Dave about wiring for what you know will go in there. It's true that avionics will change, but it's a pretty safe bet that much will not. The elevator and, in my case, rudder trim servos are not dependent on what's in the panel. Neither was my ELT or my strobe power supply and the tail strobe. One poster had a good thought about accessibility after closing up, but rarely do you have to replace antenna or other wires. It's the equipment at the end that gets replaced. You can overplan for accessibility.
 
Plywood

Yeah plywood works but if you are a ?bigger? guy, it is not a pleasant experience going in that tailcone. Actually, getting into the cone is not so bad. Getting out, well that?s another story ...:eek:
 
Oh and...

If you are a ?bigger? guy, don?t use 7/16 OSB. It will support you until you need to put weight on just an elbow or hand...then it won?t...:D
 
Top forward skin

Leave the top forward skin off and you may only need to get in there a couple of times...the only things I was in there for that I could not reach were the tail light/strobe wires and the pitch trim wires...I think pretty much everything els you can reach...
 
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