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a.s.elliott(at)cox.net
Guest

Posted: Thu Dec 21, 2006 8:21 am Post subject: Nav antenna location?

I am building a 601XL taildragger and have been mulling over where to put  the still-hypothetical NAV antenna.  You know, the two-rods-in-a-V  thing.  Since the 601 doesn't have a fixed vertical fin, I am thinking that  atop the rudder, while possible, may not be such a good idea.  Maybe  on the bottom of the fuselage just forward or aft of the access door?  I am  worried that such a position will lend itself to continuous damage from flying  pebbles in the propwash, etc.  Any other ideas or proffered existing  solutions?

  

 Thanks,

 Andy Elliott, Mesa, AZ

N601GE (reserved)

601XL/TD/QB, Corvair,  building...

   [quote][b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Thu Dec 21, 2006 8:40 am Post subject: Nav antenna location?

I've got mine on top of the rudder and it works just fine.



On Dec 21, 2006, at 11:20 AM, Dr. Andrew Elliott wrote:

 	  Quote: 	
		  I am building a 601XL taildragger and have been mulling over where to put the still-hypothetical NAV antenna.  You know, the two-rods-in-a-V thing.  Since the 601 doesn't have a fixed vertical fin, I am thinking that atop the rudder, while possible, may not be such a good idea.

	




 -- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

 



 [quote][b]

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Sat Dec 23, 2006 2:28 am Post subject: Nav antenna location?

The  turning of our rudder will not affect the direction your VOR will give  you.  Wind resistance is minimal...   the biggest problem, which  is no problem, is routing the coaxial cable.

  

 Merry  Christmas

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Sat Dec 23, 2006 3:01 am Post subject: Nav antenna location?

--------

dbortol

Joined: 02 Sep 2006
Posts: 46

Posted: Sat Dec 23, 2006 4:47 am Post subject: Nav antenna location?

Andy,



As Noel said, the direction on the VOR won't change as the rudder moves. The VOR reading depends on the position of the plane relative to the VOR station, but not on the plane's heading. I remember my instructor having me do a 360 while watching the needle to prove this out. 



Dino



On 12/22/06, Noel Loveys <noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)> wrote:[quote]          The  turning of our rudder will not affect the direction your VOR will give  you.  Wind resistance is minimal...   the biggest problem, which  is no problem, is routing the coaxial cable.

  

 Merry  Christmas

 

Noel [quote]   

   --

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sat Dec 23, 2006 7:51 am Post subject: Nav antenna location?

I have a home-made VOR antenna mounted on top of the rudder on my XL.  

I have test flown the plane to 200MPH and have seen no hint of  

flutter. The antenna is mounted just forward of the rudder spar, so  

the balance change in the rudder is minimal.

On Dec 23, 2006, at 6:00 AM, Bolding wrote:



 	  Quote: 	
		  

 I think you will find the BIGGEST problem to be the increased  

 potential for flutter that is introduced when you change the  

 dynamic balance of the rudder by this much. I would be surprised (I  

 CERTAINLY have been before)if Zenith would sign off on this mod.   

 LOW&SLOW   John Bolding


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Sun Dec 24, 2006 9:11 am Post subject: Re: Nav antenna location?

Screw the antenna. How did you get to 200MPH?

 	  bryanmmartin wrote: 	
		  I have a home-made VOR antenna mounted on top of the rudder on my XL.  

I have test flown the plane to 200MPH and have seen no hint of  

flutter. The antenna is mounted just forward of the rudder spar, so  

the balance change in the rudder is minimal. 	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.[/quote]

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Dec 25, 2006 3:46 pm Post subject: Nav antenna location?

I would agree with you if the weight of the antenna was significant and the

weight and physical dimension of the antenna were a lot further form the

centre of rotation of the rudder.  Also if the plane were a high speed

design then adding bits and pieces to a full flying rudder becomes more

critical.



I doubt Zenith would sign off a 25lb folded dipole like you will see on the

tail of your neighbourhood 747 or AN124.  A small dipole in the 200Kt and

below range shouldn't cause a problem.



Noel

 	  Quote: 	
		   

 I think you will find the BIGGEST problem to be the increased 

 potential for flutter that is introduced when you change the 

 dynamic balance of the rudder by this much. I would be 

 surprised (I CERTAINLY have been before)if Zenith would sign 

 off on this mod.  LOW&SLOW   John Bolding

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Dec 25, 2006 3:56 pm Post subject: Nav antenna location?

If you remember your basic  radio theory...  there is a loss of signal between vertical and horizontal  polarized antennas.  At VHF frequencies I think you will find this  signal drop is close to 20%.  (that one I haven't looked up)  The VOR  uses a horizontally polarized array  on the ground so for the best  reception the planes VOR antenna should be horizontally polarized ( horizontal  installation).  Com antennas on the ground were originally just a whip so  the antennas mounted on the planes were also vertical

  

 With an ADF you will actually  see the needle swing as the plane turns ... but it will always point at the  transmitting tower.

  

 Glad to see not every one had  junked their VOR for GPS.  A military flare up or a wayward meteor could  leave you lost for a place to land.  Today either one of these things are  possible.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

soarmoore2(at)yahoo.com
Guest

Posted: Mon Dec 25, 2006 6:53 pm Post subject: Nav antenna location?

For Andy Elliot

   

  Andy,

   

  Please contact me off list. I too am one of the few TD QB XL builders (barely started) and I'd like the opportunity to converse with a 'like' builder on various issues. Not sure how to contact you thru the list from this message. 

   

  BTW, I think GPS is the only way to go (other than basic pilotage) in the 21st century. If the GPS systems are all down, we probably won't want to go anywhere even if the VOR systems are still operational.

   

  Mike Moore (M2)

  Gardnerville, NV

  Soarmoore2(at)yahoo.com (Soarmoore2(at)yahoo.com)

   

  Do not archive



Noel Loveys <noelloveys(at)yahoo.ca> wrote:

  [quote]     If you remember your basic radio theory...  there is a loss of signal between vertical and horizontal polarized antennas.  At VHF frequencies I think you will find this signal drop is close to 20%.  (that one I haven't looked up)  The VOR uses a horizontally polarized array  on the ground so for the best reception the planes VOR antenna should be horizontally polarized ( horizontal installation).  Com antennas on the ground were originally just a whip so the antennas mounted on the planes were also vertical

   

  With an ADF you will actually see the needle swing as the plane turns ... but it will always point at the transmitting tower.

   

  Glad to see not every one had junked their VOR for GPS.  A military flare up or a wayward meteor could leave you lost for a place to land.  Today either one of these things are possible.

   

   

  Noel

  [quote]  

  --

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Dec 26, 2006 7:46 am Post subject: Nav antenna location?

There has already been one  satellite hit by a meteor.... one of the Anik satellites was hit years ago and  did disrupt a lot of communications up here in Canada.  The possibility  of  some of the GPS  constellation getting hit by debris increases  almost daily.  Are you sure you want to be over unfamiliar terrain with  nothing more than a compass and a map when the confidence flag on your GPS shows  up??  If you never fly over unfamiliar terrain and never fly IFR then it  all becomes inconsequential.  

  

 Ask yourself why the Transport  Category and piloted Military planes still carry conventional instruments.   When it comes to Military aircraft you will notice it is only when they remove  the pilot that they remove the instruments.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

billbutlergps(at)aim.com
Guest

Posted: Tue Dec 26, 2006 8:26 am Post subject: Nav antenna location?

I think that you should have a back up but then again with GPS is designed for 24 sats, and most of the time the DoD has extras running, last time I looked they had a total of 27. You have to have only 3 birds to give you x y and 4 to give you x y and z. It is very rare that you fall under 4. I have been dealing with GPS since the early 90s and in my previous life had to check GPS constellation daily. This is for survey grade GPS and I could then plan the day for the crews on when to travel, breaks, lunch and etc. Being that it is survey grade I wouldn't shoot anything under 4 sats. The longest that we would usually be under is no longer than 20 minutes. Also keep in mind that as long as nothing changes with the DoD that same constellation (high PDOP and low Sat numbers) will be 4 minutes earlier the next day. 

 As for Military they have ways to *#$(at) (starts with f and ends with ck and its not Fire Truck) with the enemy. The DoD knows that GPS is global and that the enemy has off the shelf products. They can send different levels of accuracy over different areas (remember here before 2000, when accuarcy was off 100 to 300 feet?). One example was in Gulf War I when the DoD sent incorrect GPS data to Iraq tank division and lead them into a trap. 

 So with all that said the DoD is shutting down GPS sats each and every day. You can check this out by going to the USCG website (USCG is the one branch of the military that handles the cilvilian end of GPS). From there you can take a look at the NANUs. The average life span of a bird is 7 years. They go up, they go down it is the nature of the beast. 

 Now if things go real serious in the world I would be worried about WAAS. This is the free DGPS that most off the shelf GPS products have. This give you the level of accuracy of about 3 meters. If the US found itself under attack and all commerical air traffic was grounded then you would see the plug pulled on WAAS and GPS would have SA turned back on. If that would happen then we would have to set up like we did before with our own DGPS then doing post process or spitting out DGPS via our own radio network. 

 But with that said relax, enjoy the day, fire up the GPS and don't worry but then again keep a map, and that compass handy in case....batteries go down or?

 Bill

 

   

  

 --

Jaybannist(at)cs.com
Guest

Posted: Tue Dec 26, 2006 9:05 am Post subject: Nav antenna location?

 	  Quote: 	
		  From the "been there, done that" dept.: About six or seven years ago, I was flying from Dallas to Little Rock, following the "dotted line" on my Garmin PGS III.  About a half an hour into the flight, my GPS signals disappeared (all of them). I recycled, moved the antenna several times and cursed, all without effect.  I was not alarmed nor lost, because I also had a VOR-based flight plan and a sectional on my lap, and I knew where I was from looking out the windows. After about five minutes, the signal returned and I went back to following the "dotted line".  On the return trip, the same thing happened about 15 minutes before landing.  The signal had not returned when I shut down.  


	


Moral:  "Belt & Suspenders" is as valid for flying as it is for britches.



All our nav systems are good, but any of them might fail, either at the source or at the receiving end.  So, it is wise to have more than one system in use at all times.  Pilotage, ded reckoning, VOR, GPS, ADF - Pick any two, or better, three, to assure that you know where your are and where you are going at all times, even if one fails.



Jay in Dallas [the "wise" one :>) ]

"Noel Loveys" <noelloveys(at)yahoo.ca> wrote:



[quote]There has already been one satellite hit by a meteor.... one of the Anik

satellites was hit years ago and did disrupt a lot of communications up here

in Canada.  The possibility of  some of the GPS  constellation getting hit

by debris increases almost daily.  Are you sure you want to be over

unfamiliar terrain with nothing more than a compass and a map when the

confidence flag on your GPS shows up??  If you never fly over unfamiliar

terrain and never fly IFR then it all becomes inconsequential.



Ask yourself why the Transport Category and piloted Military planes still

carry conventional instruments.  When it comes to Military aircraft you will

notice it is only when they remove the pilot that they remove the

instruments.



Noel



--

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Dec 26, 2006 10:18 am Post subject: Nav antenna location?

The British use the term "Belt and Braces"  Braces being the term for

suspenders.  Either way that was my point.



Happy New Year to all!



Do not archive



Noel



 	  Quote: 	
		   Moral:  "Belt & Suspenders" is as valid for flying as it is 

 for britches.

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Tue Dec 26, 2006 11:53 am Post subject: Nav antenna location?

Very carefully. 

During phase I testing, I went up several thousand feet and put it in  

a dive until I reached 200 MPH for a few seconds and gently pulled it  

out of the dive. This was just to verify the Vne of 180 mph. (The  

definition of Vne is 90% of the maximum demonstrated airspeed of the  

airplane.) This was after several flights of gradually opening the  

flight envelope and it was done in smooth air. I don't make a habit  

of flying that fast though.

On Dec 24, 2006, at 12:11 PM, Gig Giacona wrote:

 	  Quote: 	

 Screw the antenna. How did you get to 200MPH?

 bryanmmartin wrote:

> I have a home-made VOR antenna mounted on top of the rudder on my XL.

> I have test flown the plane to 200MPH and have seen no hint of

> flutter. The antenna is mounted just forward of the rudder spar, so

> the balance change in the rudder is minimal.

-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Eddie G.

Joined: 03 Nov 2006
Posts: 15
Location: Los Angeles, CA

Posted: Tue Dec 26, 2006 1:21 pm Post subject: Re: Nav antenna location?

Bryan,



Did you go with a 45* rabbit ear or 90*? What length? How is the reception?



Thanx...Eddie

 	  bryanmmartin wrote: 	
		  I have a home-made VOR antenna mounted on top of the rudder on my XL.  

I have test flown the plane to 200MPH and have seen no hint of  

flutter. The antenna is mounted just forward of the rudder spar, so  

the balance change in the rudder is minimal.



-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Tue Dec 26, 2006 7:53 pm Post subject: Nav antenna location?

I decided to try this question on Zenith for a  couple reasons, one I wanted to see what their answer was and 2 how long it  took to respond. I haven't asked them anything before and was pleased that Nick  took 4 hrs on the day after Christmas.  

  

 Oh Yeah,  he said don't put it on the moveable  surface, put it on the fuselage directly in front of it. He even sent a  picture.   John

 [quote]   ---

raymondj(at)frontiernet.n
Guest

Posted: Tue Dec 26, 2006 8:09 pm Post subject: Nav antenna location?

John,

  

     Please post the picture.

  

 Thanks,

 Raymond Julian

 Kettle  River, MN.

 do not  archive

 [quote]   --

ggower_99(at)yahoo.com
Guest

Posted: Tue Dec 26, 2006 9:57 pm Post subject: Nav antenna location?

Hello Bryan,



I apprecciate very much you did that Phase one test for me to 200 mph... 

Has been done,  Now I know I dont need to do it...       



Saludos

Gary Gower

Building a 601 XL  

Bryan Martin <bryanmmartin(at)comcast.net> wrote:[quote] --> Zenith-List message posted by: Bryan Martin 



Very carefully. 



During phase I testing, I went up several thousand feet and put it in  

a dive until I reached 200 MPH for a few seconds and gently pulled it  

out of the dive. This was just to verify the Vne of 180 mph. (The  

definition of Vne is 90% of the maximum demonstrated airspeed of the  

airplane.) This was after several flights of gradually opening the  

flight envelope and it was done in smooth air. I don't make a habit  [quote][b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Dec 27, 2006 5:33 am Post subject: Nav antenna location?

I cut down two FM whip antennas to about 26" (a little shorter than a  

1/4 wavelength at the middle of the VOR band) and mounted them at  

about 120° in a 3/4 inch PVC pipe cap. I used a "bazooka" balun. The  

reception is pretty good.

On Dec 26, 2006, at 4:21 PM, Eddie G. wrote:



 	  Quote: 	
		   

 <silentlight(at)verizon.net>



 Bryan,



 Did you go with a 45* rabbit ear or 90*? What length? How is the  

 reception?



 Thanx...Eddie


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

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