Tailcone mods and considerations

As I start to build the tailcone (post on that later), I'm looking at what kinds of mods I need to top in addition to what's on the plans.

As I mentioned in a previous post about antennas, I plan to have a few antennas with their respective avionics components in the tail: the ELT, the transponder, the ADS-B (GDL39R) and the Stormscope. These are mounted there in order to keep the cables to the antennas as short as possible, but it means I'll need to run cables to them for all the data connections - for those data connections, RS-232 standard says the maximum cable length should be 50ft, which is enough.

The ELT will go under the empennage fairing, in a location where it's easy to remove it and make it portable after a crash, probably like in this picture (source - Ivan & Dianne Kristensen's Albums):
ELT install position from another builder
The ELT antenna for it will still be mounted vertically, on top of the cone, but I like the idea of a smaller portable antenna as shown above.

For the avionics that will be mounted in the tailcone (transponder, ADS-B, Stormscope), the proposal from this VAF post seems to be good:
Avionics attached to the corrugation
The avionics are mounted to the corrugation, which means that no changes need to be made to the main tailcone structure - good for both postponing the final avionics choices/mounting and for any future changes to it (worst case, changing the corrugation for a new one would be easy). This also means I don't need either the AHRS mount nor the ELT bracket from Vans.

Also like in the picture above, I plan to run at least a couple of conduits to the tailcone for all the cables. The only cables going further than the servos will be antenna cables and the ELT panel cable - I'll provide attachments points for those, and have one conduit running all the way to the back (for both the ELT cable and any future use of the vertical stabilizer conduit, or a possible whisker-type antenna if I ever change my mind about the wingtip antenna).

As part of the G3X, I'll also have pitch and yaw servos in the back, which Garmin provides a mounting bracket for (specific to the RV10 - per their manual):
Pitch Servo Installation
Yaw servo installation
While the pitch servo only uses screws for attachment, the yaw servo requires some riveting (the lower part of the forward bulkhead) - those will require special attention later.

To allow charging the battery and/or powering up avionics with external power, I plan to add an external power port with an APU Doubler - those should go near the battery, probably to one of the sides:
APU doubler by Aircrafters
Mouser's blog shows that the oxygen tank can also be installed inside the tailcone, but I decided against that for a few reasons: first, I want mine to be removable (no need to carry the weight around all the time); second, putting a bottle of pure oxygen right next to a potential source of sparks (the battery/contactor) sounded like a bad idea; last, I'd rather not do any refilling myself (results can be quite tragic, I'm told), so I'll leave that to pros and instead have a removable tank that I can attach inside the baggage compartment, much like this one posted to VAF:
Oxygen tank NOT near the battery
Also like in the above VAF post, I may consider the access door for the maintenance/modification flexibility:
Tailcone access door
The bulkhead corrugation is only part of the fuselage kit, though, so no need to worry about it yet (plus, the whole corrugation is apparently screwed into nutplates (manual page 33-10), so it's also removable - just not as easily.

Two other components I decided against mounting in the tailcone are the AHRS and the magnetometer - the AHRS can be up front, in a rigid place behind the panel or close to the wing (pitot tubing). Garmin recommends against installing the magnetometer in the tail, in favor of installing it in the wings (which makes sense to me). The only downside is that, if I use the recommended static port position on the tailcone, I'll have to run static air ducts all the way to the panel (but I guess that's OK - just one more thing to provide attachment points for).

Last, the battery itself goes in the back, but I haven't decided on the specific model yet (don't need to decide, for now) - I'm hoping that something like EarthX will be available and more reliable than it is today when that time comes, so I decided against a custom battery box that would lock me to a specific battery at this point. I'm planning to use Vertical Power's Primary Power System if that's out in time (they say it will be), but it still suggests using a contactor if the battery is in the back, so that won't need modifications.

So, in summary, the mods I'm planning which affect the tailcone are:

  • Antennas (see previous post)
  • 2 conduits into forward part of the tailcone
  • 1 conduit all the way to the back of the tailcone
  • running 2 static port ducts from each side to a T, and from the T forward to the panel
  • APU port on the side of the tailcone
  • GSA28 brackets (implies not setting a few rivets for now)
  • ELT mounting bracket below the VS

Disclaimer: None of the pictures on this post are mine, but there are links to all their respective sources. If you own any of the images and would like me to remove it, just leave a comment and I'll do it.

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