The International Cessna 170 Association

In an attempt to make 81D IFR this year, I need to install a VOR antenna.

The location options seem to be a mast on top of the cabin, the to of the rudder or possibly on the belly under the tail.

Of them all, on the belly under the tail is the most appealing to me.
Has anyone ever mounted an antenna down there? Seems pretty straight forward to do but would like to hear of other examples.

Also, does anyone have any experience with the VAL INS 429?
http://www.aircraftspruce.com/catalog/a ... INS429.php

I wouldn't install the antenna under the tail, especially if you ever use unpaved runways. Every antenna that I've seen mounted that way had grass hanging from it and was covered in grime.

I'm doing the same sort of project. I've got a Narco mast and would like to install it for the old-time look, but it's heavy and draggy. I'll probably install a set of VOR whiskers at the top of the vert stab. It's a lot more work, but a cleaner installation. Of course, the extra coax to that antenna probably weighs the same as the Narco mast.

I had a Narco mast on the plane when I bought her. Starting to regret getting rid of it.

bagarre wrote:I had a Narco mast on the plane when I bought her. Starting to regret getting rid of it.

They are available I'm sure. I removed it from my first 170 in favor of an installation at the top of the vertical stabilizer. I pointed the V towards the back of the aircraft which is the preferred way to point it though not necessarily the way you always see them installed.

I can not tell you how many times I almost poked my eye out when working around the rudder untying the aircraft or whatnot. And each time I always regretted doing that. The Narco works, is out of the way and is period correct.

At 120mph, how much drag can the mast ACTUALLY be causing? I certainly didn't see any speed gains when I took it off.
I see them pretty cheap all the time on fleabay and they are dead simple inspect and get working again.
AND I already have the doubler installed on the roof (currently supporting the stress of a GPS puck).

I'm still not sure what NAV I want to go with.
The VAL INS 429 and Garmin 300XL (plus annunciator) for cost
or
A Garmin 430W and 106A Head for simplicity

They both cost the same to install but the 300XL setup would save me a couple grand in hardware.

Plenty of time to decide as I'm just starting my commercial and instrument now.

When you move the GPS antenna to reinstall the Narco antenna make sure you head the GPS antenna location instructions concerning the VOR antenna when relocating it.

Wouldn't a glass cockpit be nicer??

I may be a minority, but I absolutely adore the piano key design. If I had a 1953 or later airplane, I'd honestly rather have an Avion panel and at that point seriously consider some glass. Not sure a G500 would fit well, but it sure as heck would be cool.

The Comant GPS/comm antennas that John Barrett has on his airplane are pretty slick (along with everything else about his airplane). I'd rather have those and whiskers on the vertical fin than a Narco, as cool as it looks.

I'm a big fan of the piano keys as well. Thats' why I'd never convert my 170 to glass.

If I ever fly so much IFR that a glass panel seems appealing, I need to be in something other than a 170.

The tail is not my favorite place to locate a whisker-antenna for several reasons:
1- Bruce mentions the personal injury hazards....but it also subjects the antenna to potential damage due to the tail-low position where the antenna is easily contacted.
2-The lower tail will result in antenna damage.
3-The long cable-run will result in gain-losses not experienced by antennas mounted over the cabin.
4-The vertical fin and the lower fuselage requires extraordinary mounting brackets.

I favor the Narco mast type. Another possibility might include an interior antenna, or a split antenna mounted within composite wingtip fairings such as found in composite aircraft.

Do you think the stab-mounted antenna would be an eyeball hazard if it pointed forward instead of aft?

Coax loss is not significant. The total loss in a 20-foot length of RG-58 at 120MHz is less than 1dB. Not worth worrying about. At 330MHz glideslope frequency, the loss is about 1.6dB, also not worth worrying about.

Installing the antenna in the stab is a lot of work, which is a good reason to consider the Narco mast. So is the appearance of the Narco -- it just looks great.

DaveF wrote:Do you think the stab-mounted antenna would be an eyeball hazard if it pointed forward instead of aft?

No. But I didn't put it that way on mine because I wasn't willing to except less performance considering the work it took to do it.

I have my VOR antenna on the vertical stab and it has never been an issue as an obstacle, you would have to be in a very contorted position to have it poke you. Mine are pointed forward.

Arash, that sticker on your rudder might be enough to push the aircraft into the modified judging category.

So, what's the opinion on the value of a serviceable Narco Mast and whiskers?