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VOR Antenna in Tail

sjjonesnz

Well Known Member
I've just rec'd my Comant CI-215 VOR/GS antenna which I'd planned on mounting at the top of the VS. Trouble is the hockey puck base of this is too wide for the VS tip.

I see 2 solutions....1) trim the puck so that it fits inside the VS tip or 2) trim the VS tip so the puck sticks out the side... the first is my preference as the other doesn't look as good (and we all know how important that is ;) ).

How have others dealt with this? Does 1) have any impact on the performance of the antenna?
 
Another alternative is to mount the antenna underneath the horizontal stabilizer, with the hockey puck in the fuselage, and the whips sticking out through holes. (This seems like a natural solution for someone from "down under" in fact....;))

This also serves to keep people from poking themselves in the eye with the antenna tips - a real danger with cat whiskers on the top of a tail dragger stabilizer....

Paul
 
The hockey puck contains electronics necessary for the operation of the antenna so it shouldn't be drilled or cut at all.
 
VOR antenna on VS

I did this on my RV-8 by building a custom bracket to mount the antenna just above the edge of the VS skin. I cut slots in the VS fiberglass cap to accommodate the extra width of the antenna base, and used a 90? BNC to make the connection. The antenna looks good and works great, and I can't detect any difference in speed with it on or off.

If you have a taildragger you'll want to mount the "V" pointing forward to avoid eye-poking (the antenna was designed to be mounted either way).
 
A varition of what Paul suggested is to mount it externally to the bottom skin under the HS. Not as cosmetically appealing as mounting the puck internally or in the VS, but simplifies the installation. A small fiberglass cover could be built to pretty it up, if you so desire.
 
Hockey puck fun

I've just rec'd my Comant CI-215 VOR/GS antenna which I'd planned on mounting at the top of the VS. Trouble is the hockey puck base of this is too wide for the VS tip.

I see 2 solutions....1) trim the puck so that it fits inside the VS tip or 2) trim the VS tip so the puck sticks out the side... the first is my preference as the other doesn't look as good (and we all know how important that is ;) ).

How have others dealt with this? Does 1) have any impact on the performance of the antenna?
Look I bolted it to the bottom of the fuselage under the Horz stab LINK. If you are handy with a little fiberglass, you could make a little "speed blister" or "speed bump" fairing to cover and stream line the hockey puck. I really like the aft belly under the horz stab location. It's almost invisible on the ground, especially with a tail dragger. VOR whiskers top of the Vert Stab on a tail dragger is an eye pokey outtie danger.

The top of the vert stab might be a tad better performance??? I had the bottom aft belly location; it worked well. I did not do any test for reception range, but I flew low altitude airways (at MEA or above) and it worked fine. I also did VOR/LOV/ILS approaches and it worked.

Drag wise we're talking such a small amount of drag regardless how you mount it, but every bit counts. For looks paint the hockey puck to match the plane? Trimming the hockey puck? Never tried it. Be careful. If you go with the external belly mount, may be chamfer the thickness front and back might look nice, plus a fiberglass speed bump faring. Regardless you are a winner. Here is a site of a RV-9'er that did the top-O-vert-stab LINK.

My RV7 is sans VOR, but the one on my RV4 was not as thick as compared to the one in the LINK. I don't remember the brand now, but I only mention it because it looks chunky compared to the one I had. It looks like a Rami (AV-532L). RV'ers may want to avoid the AV532 due to extra thickness? All the Comant VOR "pucks" are all about 2.5" diameter and 7/16" thick.
 
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VS tip

I installed my antenna in the VS tip. I made a special mount and riveted it inside the VS tip rib. I plan to route the cable thru a hole fore of the mount and loop it over the puck and back down thru the VS tip rib before connecting it to the puck so the cable won't just be hanging on the connector when done. Here are a couple of links to my builder's log:

http://www.aclog.com/rv-9a/index.php?c=1#918

http://www.aclog.com/rv-9a/index.php?c=1#920
 
Cat whiskers on the belly?

I did a search and this very old thread popped up, but I figured it was still relevant. It appears as though most people mount their cat whiskers VOR antennas either on top of the VS or under the HS. Is there a reason it couldn’t be mounted completely under the belly of the airplane where the whiskers aren’t sticking out at all? Would there be any problems with frequency interference? Also, does the VOR antenna need to be any certain distance from any other antennas….com, transponder, etc.? I’m installing the new carbon fiber wingtips that AeroLED is producing, so the Archer isn’t an option for me.
 
No matter where you mount it, put eyeball protectors on it when you park the plane. Even if mounted low on a tail dragger it is right at a dog’s eye height.

Do the same for all belly mounted antennas. The eyeball you save may be your own.

Carl
 
Mine is mounted on the belly under the horizontal stab. Whiskers pointing aft. Works great. Zoom in on the pic below and you can see the whiskers are protected by the stab and elevators. Can't walk into it. Just one of many options.

IMG_0794.jpg
 
My old 7 had it.
 

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Mine is mounted on the belly under the horizontal stab. Whiskers pointing aft. Works great. Zoom in on the pic below and you can see the whiskers are protected by the stab and elevators. Can't walk into it. Just one of many options.

View attachment 37052

This is basically what I’m talking about but I’m wondering if it’d work if it were mounted even further forward….close to the middle of the fuselage? Far enough forward where no part of the whiskers were sticking out from the side??
 
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