I also understood why people say that making modifications takes a lot of time - I've spent a few tens of hours doing the research I'm posting here (hopefully that'll save somebody else's time later, as other builders have saved mine), and even after that I'm not 100% sure this is correct and going to work.
I decided to use the SafeAir pitot-static kit, which comes with two nice static ports. One issue a friend recently had with his RV10's static system was water accumulation (which in his case, killed two avionics components that got flooded), so I plan to install them per instructions at the default location, then run the static lines up through the bulkhead, join them on top, then run the lines forward along one of the stiffeners all the way to the baggage bulkhead. Only at the baggage bulkhead they'll be routed down into the tunnel and all the way to the panel, where I plan to place the AHRS. With this, it will take a lot of pressure to make water get all the way to the front. I also considered adding a pitot static sump bottle to drain the water, like some Cessnas have, but it seems to be overkill.
Along the route, the lines will be attached with adel clamps, and the tee that joins the lines from the two ports will be attached to a small attachment fixture on the top of the bulkhead. This is similar to what has been done by Mouser and by Mike and Sarah, except I don't want mine to go to the back of the bulkhead (harder to inspect/maintain later), so I'll just use a nut to elevate the adel clamp over the lightening hole flanges.
From the bulkhead forward, I'll use adel clamps to secure the line along the top J channel. However, since I don't want to drill #10 holes into the stiffener to secure the adel clamps directly, I'll follow Justin Twilbeck's installation and use a small piece of aluminum with smaller holes to attach them:
BOM for this part:
|Static port install (photo by Mouser)|
|Static line routing (photo by Mouser)|
|Another tee bracket style for joining the static lines (photo by Justin Twilbeck)|
|Spacers for adel clamps that carry the static line (photo by Justin Twilbeck)|
- SafeAir1 static ports
- SafeAir1 L-shaped fittings (3)
- SafeAir1 T-shaped fitting (1)
- SafeAir1 static tube
- Tool for cutting static tube properly (SteinAir?)
- MS21919-WDG4 clamps for static tube (4)
- MS35207-260 screws for clamps (4)
- AN960-10L washers for clamps (4)
- AN365-1032A nuts for clamps (4)
- AN315-3R Nuts for clamp spacing (4)
- 0.1" wide wire ties
- .040 Aluminum for bulkhead T bracket and spacers
I reviewed once again the installation instructions for the GMU22 magnetometer from Garmin, given that a lot of people seem to install these inside the tailcone:
Others, still, install it in the aft deck (as is the recommendation for the RV7/RV9, but not the 10).
|Magnetometer installed inside the tailcone (photo by Terry)|
Looking at the Garmin G3X manual, it says "In general, wing mounting of the GMU 22 magnetometer is preferred", and they provide a table of things to avoid near it:
|Magnetometer disturbance avoidance from the G3X Installation manual|
Another document by Garmin, "AHRS/Magnetometer Installation Considerations" shows the same table for the GMU44 (used in other packages like the G900X), making it explicit that this list is ordered by priority. Given this, and given the number of motors and antennas I'll have in the tailcone, I've decided to indeed do the wingtip mount - having it close to the landing lights is still better than having it close to all the noisy equipment. The wingtip mount should look like this:
Also, to be safe, since I'll be installing the NAV and marker beacon antennas on the left wingtip, the magnetometer will go on the right wingtip.
|Wingtip magnetometer mount (photo by maus92 at VAF)|
BOM: nothing at this point
Autopilot and trim servosAs mentioned in the previous post, the autopilot servos have standard mounting kits, but those expensive and can change until I actually install the avionics, so at this point, the important part is to understand what space they're expected to take, so I don't plan to put anything there.
- The pitch autopilot servo takes up space aft and to the right of the bellcrank.
- The pitch trim servo takes up space just forward of the aft deck (and the cables go over the aft deck itself)
- The rudder autopilot servo takes up space further aft of the bellcrank and the pitch servo, on the center
|Idea for electric rudder trim (photo by Ernst Freitag from VAF)|
- Having the spring at the bottom, the regular rudder cable in the middle, then the servo's bridle cable at the top, with them all being connected at the same cable clamps
- Having the trim springs connect to the autopilot servo, at the same mounting screws as the bridle cables, but from the opposite direction. This requires attaching the other end of the fixed spring (on the right side) to the same screw as the pitch servo mount, and either using the standard AHRS platform or extending a small platform to mount the actuator on the left side.
At first I tried to pick the actuator and spring by doing the proper math to set my requirements, and found that I don't have all the input data (e.g. what is the force the rudder exerts on the cable depending on speed, load factor and deflection?). I then tried to eyeball it by looking for actuators with reasonable speed, low current and reasonable torque for this, and looked at A LOT of actuators, only to find that not a single one meets all those requirements. The closest two were the LD3Q (which goes to 1.2A, but otherwise moves at ~6mm/s and has way more torque than I need at 800N) and the P16P (which goes to 1A, moves at ~9mm/s with 90N of force). While the P16P doesn't support much sideloading, it supports more than the GSA28 will normally output even if they were connected at 90 degrees with the max torque setting, so that shouldn't be an issue. The L16P also seems to be similar to the P16 while supporting higher side loads, but it looks too hobby-grade for me.
Ultimately, I don't have to decide on the exact details until I mount the autopilot servos, so while I'm deferring that for now, this has made me decide to have a tall platform on the left side and a short one on the right side - that allows me to mount the linear actuator high or low, and the avionics on the other side.
BOM: nothing for now
AvionicsI've looked at several options for mounting the avionics, and revisited the original idea of mounting them to the corrugation:
|Avionics mounted to the bulkhead corrugation (photo by Elwell81 at VAF)|
I'm thus switching to avionics shelves (and keeping the corrugation available for any future upgrades):
On the right side, I'll rivet two F-1037 bellcrank rib angles to the stiffeners to make rails with nutplates, which I can later attach an avionics shelf with screws to.
On the left side, I'll use a modified version of the AHRS bracket by Vans, which extends all the way to the side and attaches to the side stiffener, much like Justin Twilbeck did on his, except I'll actually install the shelf rib from Van's to support it, and another F-1037 for the side-stiffener attachment:
|Idea for wider avionics shelf (mine will be on the right side - photo by Justin Twilbeck)|
|Attachments for avionics shelf (photo by Justin Twilbeck)|
- Van's AHRS bracket kit
- Van's F-1037 for the rails (2) - unfortunately F-1037A is not useful, but B and C are
- .040 aluminum for support brackets
- K1000-08 nutplates for the rails and brackets (21)
- MS35206-243 screws for attaching shelves
ELTI've also researched specific models, and so far I'm leaning towards the Kannad Integra AP, which continues to work using a second portable antenna if it's removed from the fuselage. It transmits on 121.5 for shorter than the fixed version (48h vs 100h), but if nobody has picked up your ELT after 48h, what are the odds they will in the next 48? I do plan to continue flying with my Spot Gen3 or something similar, too.
Plans on where to place the ELT remain the same. For a moment I froze when I saw this picture, which shows that the trim cables run through where I planned to place it:
|Trim cables running through where I planned to place the ELT (photo by Jemo)|
|ELT does fit even with the trim cables (photo by Ivan & Dianne)|
BOM: nothing for now
APU plugI tried to order the Aircrafters' APU plug, only to find out that they went out of business :/ I bought just the plug, and will fabricate a doubler to mount it to with a cover plate, similar to the one that holds the elevator cover plates:
Camloc fasteners. In addition to Aircraft Spruce, I also found three other suppliers: Quick Release Fasteners, MilSpec and Skybolt (each one was cheaper for some of the parts). My thought is that if I need external power to start, I can live with either needing someone to fasten it after start (I'll need someone to disconnect power anyway), or just flying without the cover. I considered making a proper door for this, with a Hartwell latch and all, but in reality I'll need to open it so rarely that it's not worth the time, effort and weight. Also, what are the odds that I'll have access to an APU but won't have access to a screwdriver?
I haven't figured out the right way to protect the input voltage (for one, against overvoltage, in case someone ever plugs a 28V APU into my 14V system), but I'm tempted to follow Vertical Power's suggestion:
|APU port wiring diagram (from Vertical Power)|
- .063 aluminum for the doubler
- .025 aluminum for the cover plate
- 91780A044 Female threaded hex standoff - 2 1/4" length, 10-32 thread, to attach the plug to the doubler
- MS24693-S274 flat-head screws to attach the posts to the doubler (4)
- MS35207-265 round-head screws to attach the posts to the plug (4)
- Camloc 2700-2S studs (4)
- MS213 Camloc receptacles (4)
- Camloc 2600-LW washers (4)
- Camloc tools
AntennasI had planned for many of the antennae to be on the center line of the tailcone, without realizing there's a stiffener there - those will be slightly offset to either side:
|ELT antenna marking and stormscope antenna|
|Top skin antenna locations marked|
|Transponder antenna location marked|
Another minor detail I noticed is that the Stormscope antenna requires applying Alodine to the skin where it's installed - this will be annoying.
Additionally, even though not a tailcone mod, I also found a wingtip marker beacon kit by SteinAir.
- Antennas (duh)
- .040 Aluminum for doublers
- In the future, RG-400 cable
Wiring conduitsI'll run one conduit all the way back until just before the F-1010 bulkhead for the ELT wires as well as any future wires that may be passed through the vertical stabilizer conduit. I'll also run another conduit as far back as needed for the transponder antenna.
From the tailcone forward, I'll likely have 3-4 conduits, like this other builder (if this is your photo, let me know in the comments so I can give you proper credit!):
|Conduit runs from the fuselage to the tailcone (photo from unknown source)|
|Wire tie anchors to cross the bellcrank ribs (photo by Mouser)|
|Clickbond fasteners to hold the conduits (photo by Mouser)|
|ClickBond CB4019 (photo by Clickbond)|
NACA VentsThis was an item I wasn't previously considering, but several reports made me want to have NACA vents on the back for overhead console ventilation:
|Side skin NACA vent (photo by Bob Leffler)|
|Aerosport NACA valve installed with the vents (photo by Ernst Freitag at VAF)|
|Flange for going from the tailcone to the overhead console (photo by Ed and Colleen)|
Also, to attach the valve to the center stiffener, I'll follow Ed and Colleen's suggestion of using a F-1048D:
|NACA valve with with F-1048D for attachment (photo by Ed and Colleen)|
Also, as another builder suggested on VAF, I plan to add a screen to the intake side of the valve, to prevent any bugs from coming in. It will be places inbetween the hose and the valve and held in place by the the same clamp that holds the hose.
- NACA SV-1 vents (2)
- Vent hose 2x6' (2)
- AN737TW-66 hose clamps (8)
- VENT DL-03 flanges (2)
- Aerosport NACA valve
- K1000-08 Nutplates (2)
- F-1048D fuel filter bracket (to attach the valve)
SummaryI'll be addressing the following items now:
- Right-side (tall) avionics shelf
- Rails for left-side (short) avionics shelf
- Conduits to the back
- Static lines up to the F-1006 bulkhead top
- NACA vents and valve
- APU plug and cover plate
Everything else will be left for later, possibly when I buy the avionics.