replacement for nav antenna from Narco type

gordonbunting · Post by **gordonbunting** » Tue Oct 23, 2007 3:54 am

Hello,
We're thinking about replacing the stanchion type narco antenna for our vor with something smaller/more streamline. The only option I can find is the cat whiskers dipole antenna mounted off the vertical stabilizer. It seems from reading posts that mounting on the tail can be problematic and or expensive. Any thoughts would be appreciated. Looking back at pics of other 170s is seems 1/3 or so have the narco- what are other folks using??
Thanks,
Gordon

1952 C170b N2354D

kloz · Post by **kloz** » Tue Oct 23, 2007 8:57 am

You could use the cat whiskers under the tail.

bsdunek · Post by **bsdunek** » Tue Oct 23, 2007 12:24 pm

I, too, would like to replace my old Narco nav antenna with something cleaner and smaller. Dorne & Margolin used to make a plastic/fiberglass version, but that was back in the 70's and maybe 80's. Nobody seems to make one now. I would like to find an old one, but have not been able to.

Post by **GAHorn** » Tue Oct 23, 2007 9:09 pm

This can be a challenging problem.
The cat whiskers are not easily mounted in the vertical stabilizer. (Internal structure is problematical, and lack of readily available parts...plus you're gonna have to route that wiring,...and you're gonna have to avoid poking yourself in the eye every time you move the tail around!)

Cat whiskers below the tail is a problem...subject to damage from grass runways, FOD., etc.

The original Narco antenna was actually a good plan, but the old antennas need maintenance after so many years. The cables are dry and shot with possibly excessive impedance. But...they can be rebuilt, beadblasted, repainted and/or powder coated and the radiant elements cleaned up and it'll be spiffy again!

Interal windshield mounts are possible, utilizing antennas designed for composite aircraft.

Me? I'd clean up my Narco (replace that RCA connector with a BNC while you're at it) and after restoring it, reinstall it.

gordonbunting · Post by **gordonbunting** » Tue Oct 23, 2007 11:27 pm

the question was more style than function so staying with the narco sounds good to me. Thanks for your help,
Gordon

blueldr · Post by **blueldr** » Wed Oct 24, 2007 12:14 am

Since I no longer fly in the IFR system, I long ago removed the antenna, the nav radios and the associated instruments. I've found that should I want to go to a VOR, my GPS is more accurate and provides me with the distance,bearing, and time to the station without having a DME,which provides only slant range anyway.

Post by **GAHorn** » Wed Oct 24, 2007 4:04 am

blueldr wrote:... should I want to go to a VOR, my GPS is more accurate and provides me with the distance,bearing, and time to the station without having a DME,which provides only slant range anyway.

If you got TO a VOR slant range is what you want. If you want to go OVER a VOR.....GPS may be all you care about....

blueldr · Post by **blueldr** » Wed Oct 24, 2007 5:45 pm

George,
Why would I ever want slant range, except it is the only thing offered using DME?
If I was flying "on top" at ten thousand AGL. with an allowable plus or minus four degrees of azimuth and two miles slant range, it doesn't seem to be nearly as accurate a position as available on GPS.
As I previously mentioned, I no longer fly in the IFR system, and haven't since leaving the airlines, so I guess the question is moot.

N2255D · Post by **N2255D** » Wed Oct 24, 2007 6:37 pm

George,
Why would I ever want slant range, except it is the only thing offered using DME?

One time would be the departure from Newark where the initial turn after departure is requires the turn to be made at 2.3 DME.

cessna170bdriver · Post by **cessna170bdriver** » Wed Oct 24, 2007 8:30 pm

N2255D wrote:
George,
Why would I ever want slant range, except it is the only thing offered using DME?

One time would be the departure from Newark where the initial turn after departure is requires the turn to be made at 2.3 DME.

Assuming this is the departure procedure in question:
TAKE-OFF RUNWAY 22L/R: Climbing left turn via heading 190, upon crossing 2.3 DME Rwy 22L ILS (use Rwy 22R ILS only if 22L ILS is not available). Turn right heading 220, maintain 5000 feet. Thence . . . .

This puts the DME station at the approach end of the runway. Also assume a 170 could climb 1200 ft (.2nm) in 2.3 nm, the slant range error will will be LESS THAN .01nm (60ft). (Pythagoras and all that stuff...)

Miles

N1277D · Post by **N1277D** » Wed Oct 24, 2007 10:12 pm

A few years ago we were flying in Mexico, with the 170 which has the Narco antenna. Like most airports there, you are greated by the Army for paper work checks. One of the servicemen noticed the Narco antenna and asked about it. After some discussion it appeared that they were under the impression it was a "NARC" antenna and wanted us to move on quickly. If you head to Mexico with a Narco antenna, it might be wise to make sure the labeling is well worn and it is difficult to read the letters.

Post by **GAHorn** » Thu Oct 25, 2007 4:24 am

Ha! That was probably GOOD for you! (That gives a new "slant" to things, don't it?)

mrpibb · Post by **mrpibb** » Sun Oct 28, 2007 5:11 pm

TAKE-OFF RUNWAY 22L/R: Climbing left turn via heading 190, upon crossing 2.3 DME Rwy 22L ILS (use Rwy 22R ILS only if 22L ILS is not available). Turn right heading 220, maintain 5000 feet

.

Unless you take off on 22R VFR and they isssue a "apon reaching 1200 feet turn to 270" which always put me aiming right for the control tower. However they are allways quick to amend and change it to maintain runway heading untill passing the control tower

To bad, always wanted to buzz the control tower.

PS. send me your narco nav antennas if you dont want them, I think their cool

Post by **GAHorn** » Mon Oct 29, 2007 1:59 am

mrpibb wrote:
TAKE-OFF RUNWAY 22L/R: Climbing left turn via heading 190, upon crossing 2.3 DME Rwy 22L ILS (use Rwy 22R ILS only if 22L ILS is not available). Turn right heading 220, maintain 5000 feet
.

Unless you take off on 22R VFR and they isssue a "apon reaching 1200 feet turn to 270" which always put me aiming right for the control tower. However they are allways quick to amend and change it to maintain runway heading untill passing the control tower To bad, always wanted to buzz the control tower.

PS. send me your narco nav antennas if you dont want them, I think their cool

Unless otherwise cleared, one is supposed to avoid all turns until passing the departure end of the takeoff runway.

cessna170bdriver · Post by **cessna170bdriver** » Mon Oct 29, 2007 4:03 am

I checked my cat whisker nav antenna on pre-flight today, and eye poking would not be a problem as the elements are in the very top of the vertical stab, and point forward and up, well above my 5'10" head. If they pointed rearward, they MIGHT be a problem, but I would think the horizontal stab/elevator would keep you from walking into them.

That antenna has always worked well. I have two splitters in my installation, using that one antenna to drive two nav radios and the glideslope receiver. It does appear that installation and wire routing would NOT be trivial, howver.

Miles