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NAV Antenna


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What is the factory antenna that FD uses or has used for the NAV on the CTs that they installed a NAV/COM on?  Or has anyone retrofitted a NAV radio to their CT?  If so, what antenna and where was it mounted?  I just pre-ordered the GNC 215 and am looking for a good (see compatible with CT) NAV antenna.  I am thinking about the belly, but am a little worried about interference from the nose or if at a low pitch angle.

The vertical stabilizer would be ideal, but I really don't want to fight that battle if I don't have to.

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1 hour ago, GrassStripFlyBoy said:

There is a LS near me with factory nav antenna, mounted on the rear lower vertical fin

Now that's a thought.  I didn't consider the lower fin.  Easily accessible and should provide a mostly unobstructed view.

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9 hours ago, Madhatter said:

Being that the lower fin is fiberglass an internal antenna might be an option. I don't think it would be too difficult. Advanced Aircraft Electronics has a number of antennas that might be suitable. I use one in my cub.

I had heard about the internal ones, didn't realize the lower fin was fiberlgass.  That is definitely a great option.

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28 minutes ago, Garrett Gee said:

Ouch...  That price.  I like that style though.  I would love to go this style, but man that is steep.

You can get blade antennas much cheaper but there is an issue with them to be aware of. These blade antennas are aerodynamic and can put significant forces on the mounting surface. Enough so that the FAA had issues with them years ago. I have installed them but had to significantly reinforce the vertical fin. Also the blades must be aligned very close to the airflow direction produced in-flight  to reduce unnecessary aerodynamic forces.

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23 hours ago, Madhatter said:

Being that the lower fin is fiberglass an internal antenna might be an option. I don't think it would be too difficult. Advanced Aircraft Electronics has a number of antennas that might be suitable. I use one in my cub.

I know that the CTSW is fiberglass, but in the back of my mind I think the CTLS is carbon fiber. I know when I have added the tail bumper block before I have used carbon fiber cloth to reinforce the area. 

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My CT is an SW. I did some experiments with GPS signal strength with the antenna inside the fuselage or outside.  I was surprised that there was no difference.  Carbon fiber apparently varies significantly depending on different formulations . I guess the only way to know is to try. If an external antenna is considered I believe a towel bar type might work on the lower fin. 

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43 minutes ago, Tom Baker said:

You could probably build a little shelf in the sub fin and do something like this. https://www.aircraftspruce.com/catalog/avpages/av532.php  Position it so that it is under the stabilator.

That is exactly the one I am eyeing right now.  Being that the fin in carbon fiber, the internal one is out.  And Madhatter convinced me no to use the blade type.

 

Thank you everyone for the help and insight.

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I also can confirm my underfin is carbon fiber too, along with every CTLS model I have seen and i've repaired a few too.

As far as signals go for carbon fiber: it depends on frequency. Never seen a difference GPS wise.

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On 2/7/2024 at 5:23 PM, Tip said:

This is the way mine came from the factory. 2011

image.jpeg

I like that, and that would be how I would really like it done.  Honestly, I have never actually looked at the top of the vertical stab from above.  Is there access at the top to actually do that, or would that installation be somewhat "invasive" (ie removing the rudder)?  That location would the be the best I would think, but I would rather avoid having to go invasive (drilling into structure and removing flight controls) if I don't have to.  My current thoughts are still on the lower fin.  While still important, I would feel better about patching an issue (ie screw up on my part) on the lower fin rather than the vertical stab?

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It's invasive. Installing that style would be a lot more difficult than you think, you'll likely have to cut into the vertical stabilizer to be able to mount the anchoring.

Plus pulling the coax all through the tail, which would probably be even harder. Hope you got little kids!

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I have pulled shielded wire for the strobe through the vertical fin to comply with Garmin electrical interference requirements for G3X. It was a real challenge to thread the small wire down the vertical fin. I'm not saying it can't be done with coax but will take some work.

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3 hours ago, Anticept said:

It's invasive. Installing that style would be a lot more difficult than you think, you'll likely have to cut into the vertical stabilizer to be able to mount the anchoring.

Plus pulling the coax all through the tail, which would probably be even harder. Hope you got little kids!

That was my exact fear.  I kind of figured that was how it was, just from glancing at the vertical stab today.  While nice, probably not the option I am going to go for.  Thanks!

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1 hour ago, Tip said:

I’ll get you the measurements if you decide to go that way.

Thank you!  I will take a look at it next time I get to the hangar and really look at it.  I really appreciate the help!  The radio won't be in for a few months, so plenty of time to plan and figure it out which place to use.

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