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  #1  
Old 05-31-2019, 06:20 PM
DavidHarris DavidHarris is offline
 
Join Date: May 2018
Location: Upland, CA
Posts: 32
Default RV-7A Antenna and Aft Avionics Bay locations

I'm building an RV-7A slider with a Dynon / Avidyne glass panel. I'm looking for advice about placing some of the remote avionics and antennae.

Regarding avionics placement, is it sensible to mount the following items on a 30” wide x 7” deep avionics shelf between the longerons behind the baggage bulkhead wall? I'm concerned about aft CG, but this seems as far forward as the ELT can go, and the other items are fairly light and would be more accessible than on the sub panel.

- ELT
- dual ADAHRS
- remote transponder
- ADSB

Regarding antenna placement, could you give me any feedback on this option for an RV-7A? With the option of a SuperTracks slider, there’s not a lot of space on the upper fuselage skin, and I worry about scraping anything too far back on the lower fuselage skin.

COM1: Under baggage tunnel
COM2: about 4 feet behind COM1 near F-707 bulkhead
AV-801 GPS: on top just ahead of F-708 bulkhead
GPS-250: on top just aft of F-708 bulkhead
ELT: on top aft of GPS-250 and forward of vertical stabilizer
AV-74 Transponder and ADS-B antennas: side by side 2’ apart laterally and 1’ behind COM1 under avionics shelf
NAV: Bob Archer wingtip antenna

I understand from the Skyview docs that the separation requirements are:

COM1 to COM2: 4’ minimum, 6’ preferred
COM to ELT: 4’ minimum
COM to GPS / transponder: 1’ minimum
ADSB to Transponder: 2’ mininum

Is there a separation requirement between the two GPS antennae? I see some folks mounting one forward of the firewall under the cowling, but would prefer to keep it away from a source of heat.

In my arrangement, the COM2 to COM1 and COM2 to ELT would be near or below minimums. Not sure of a better arrangement.

Thanks for suggestions!

David
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Old 05-31-2019, 06:44 PM
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sahrens sahrens is offline
 
Join Date: Jan 2007
Location: Northern CA
Posts: 469
Default

Hi David,

I have the dual ADAHRS, the servo, the strobe power pack and the ELT just aft of the baggage bulkhead. My RV-7 with CS has an aft CG such that I limit my baggage to 85 lbs. What you are planning is probably a little lighter but not much. So you may end up with the same kind of weight restriction.

As for the antennas my

transponder is located just aft of the firewall near the right gear leg, no complaints from ATC.

comm 1 & 2 are located under the seats as far outboard as I can get them, again no complaints. EDIT they are just aft of the center section with enough clearance for the flight controls.

My Dynon 2020 is just aftof the rear window but I have a tip up, half way to the vertical is the ELT antenna.

The ADSB-in is about 1/3 of the way between the baggage bulk head and the vertical, on the bottom of course.

My Garmin antenna is in the left wing tip.

As mentioned early, I have not had any performance issues.
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RV-7 N818BG (flying)
Bearhawk Patrol (building)
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  #3  
Old 05-31-2019, 08:46 PM
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scottmillhouse scottmillhouse is offline
 
Join Date: Apr 2007
Location: Madison, AL
Posts: 322
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I put the ADAHRS and transponder behind the baggage bulkhead and was easily able to get everything attached to the bulkhead behind the panel including extras like two fuse sub-panels, a strobe driver, Skyview network hub along with two backup batteries, transponder, ADSB and engine module. All supporting two 10" Skyview touch screens. 2020 GPS works fine under center of cowl just in front of firewall. Antennas were transponder front, Com middle, ADSB back with ELT on top in front of vertical stabilizer to give plenty of clearance for slider. Temp probe under horizonal stabilizer in the shade.
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  #4  
Old 06-02-2019, 09:15 AM
DavidHarris DavidHarris is offline
 
Join Date: May 2018
Location: Upland, CA
Posts: 32
Default GPS pucks

Thanks for this advice.

I've seen a picture of somebody mounting the two GPS puck antennae on top just behind the baggage bulkhead such that the sliding canopy rides over top. I'm still building my canopy and would like to see that there are no clearance issues before committing, but it seems like a graceful solution if it works. Has anyone found issues with such a placement?
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Old 06-06-2019, 12:29 AM
DavidHarris DavidHarris is offline
 
Join Date: May 2018
Location: Upland, CA
Posts: 32
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On further consideration, this avionics shelf plan is a bad idea. It looks like it will interfere with the seat belt anchor cables. It also puts the ADAHRS near other boxes that may generate magnetic interference.

My next plan is to use the Vans standard ELT mounting bracket for the ELT, move the transponder and ADSB up to the subpanel, and to build a tray for the ADAHRS like that of Dan Langhout.

http://www.vansairforce.com/communit...ad.php?t=62878
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Old 06-06-2019, 08:44 AM
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Raymo Raymo is offline
 
Join Date: Nov 2014
Location: Richmond Hill, GA (KLHW)
Posts: 2,045
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That's what I did but my AD-AHRS are simply mounted on two pieces of aluminum angle. Lots of room on the sub-panel for those items, unless you are installing IFR hardware, which will consume more space. The remote XPNDR could go under the seat pan.

The GPS antennas mounted on the glare-shield make for easy wiring but the glare on the windshield is a no-go. I have mine temporarily covered with black cloth until I can fab some fiberglass covers that will Velcro down to the loop Velcro, which will replace the gray cloth that is there now.

After replacing the ADSB-470 with the472 (left side of sub-panel), much more room there, as well.

ADS-B and XPNDR antennas are just inside the gear weldments on each side of the plane. This keeps them out of harms way and also made for easy, short RG-400 runs. One COM antenna is mounted in the first bay of the co-pilot seat pan floor.

ELT antenna mount:










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RV-7A - Slider - N495KL - First flt 27 Jan 17
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Last edited by Raymo : 06-20-2019 at 10:40 AM.
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Old 06-06-2019, 06:01 PM
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sahrens sahrens is offline
 
Join Date: Jan 2007
Location: Northern CA
Posts: 469
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Quote:
Originally Posted by DavidHarris;1351209
My next plan is to use the Vans standard ELT mounting bracket for the ELT, move the transponder and ADSB up to the subpanel, and to build a tray for the ADAHRS like that of Dan Langhout.

[url
http://www.vansairforce.com/community/showthread.php?t=62878[/url]
I have a similar panel to Dan's. It seems to be a common method although Dan's appears to particularly well done. If I had to do it again I would make the bottom of the tray removable from the sides. Once it is installed in that aft compartment it is not easy to reach for maintenance. Once the ADAHRS are installed on the tray all the cabling is connected on the rear of the ADAHRS and there is just barely enough clearance to get to the mounting screws. I used brass screws and nuts to attach the ADAHRS to the tray and would probably do the same to attach the tray bottom to the sides. That way I could remove the tray, do whatever was necessary and reinstall the tray.
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RV-7 N818BG (flying)
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  #8  
Old 06-20-2019, 09:54 AM
DavidHarris DavidHarris is offline
 
Join Date: May 2018
Location: Upland, CA
Posts: 32
Default SteinAir recommended antenna locations

I called Vans for some advice about antenna placement, and they pointed me to some sample drawings that SteinAir has posted. I wish I would have seen these earlier.

https://www.steinair.com/wp-content/...ent-RV-7_9.pdf

David
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