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GPS Antenna Under Cowl
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rv8a2001(at)yahoo.com
Guest

Posted: Wed Jan 03, 2007 11:28 am Post subject: GPS Antenna Under Cowl

Speaking of expensive GPS antennas, there was an article in Kit Planes a while back that had a roll your own antenna for about..........20 bucks? They had several different types and they worked just as well if not better than the expensive ones...........So if you do barbque the antenna find that article and make one for cheap!

 

Scott Bilinski

RV-8a



  ---

lors01(at)msn.com
Guest

Posted: Wed Jan 03, 2007 12:14 pm Post subject: GPS Antenna Under Cowl

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  I've long since deleted the original message on this subject but it was my  impression that the antenna in question was the Garmin GPS *XM* antenna which is  a different animal than the actual GPS antenna.  I could be wrong.

  

 BTW, I just installed my 496 and it only takes one flight while looking at  the weather around you in real time to get  hooked.  I'd feel naked  without it now.  

  

 Why didn't the FAA just buy a satellite channel for weather instead of that  silly, expensive, incomplete ground based system they decided  on?   Rhetorical question I guess.  They love ground based  systems for "turf reasons".

  

 Tracy Crook

 Rotary powered RV-4 & -8, 1600+ hrs.

  

  

 [quote]   ---

jimteri1(at)earthlink.net
Guest

Posted: Wed Jan 03, 2007 6:55 pm Post subject: GPS antenna under cowl

Not sure about the fragility of your chosen antenna, but I installed the factory antenna puck from my Bendix-King KMD-150 about 1 inch under the cowling, center mounted, just behind the baffels, on a supported aluminum plate.  No problems in 334 hours and I have lost signal only once in a heavy overcast.  The GPS locks on after startup in about 40 seconds.

Don't even think about mounting it on top of the glare shield - you will get the reflection in the windshield.  FWIW.

michele.delsol(at)microsi
Guest

Posted: Thu Jan 04, 2007 2:06 am Post subject: GPS Antenna Under Cowl

Dan,  

   

Thanks for pointing us to the McMaster single use temperature systems. I am impressed by the choices – they can be a great help in establishing peak temperatures in various locations under varying conditions.   

   

Michele  

RV8 - Finishing  

         

  

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Dan Checkoway

 Sent: mercredi 3 janvier 2007 16:35

 To: rv-list(at)matronics.com

 Subject: Re: GPS Antenna Under Cowl  

  

     

Interesting.  Still call me a skeptic, but I agree about measuring it.  I'll get some nonreversible temperature strips from McMaster and see what it hits.  

    

   

    

http://www.mcmaster.com/nav/enter.asp?pagenum=519  (middle of that page)  

    

   

    

)_( Dan  

    

   

  [quote]    

---

jmsears(at)adelphia.net
Guest

Posted: Thu Jan 04, 2007 2:20 am Post subject: GPS antenna under cowl

 	  Quote: 	
		   Don't even think about mounting it on top of the

 glare shield - you will get the reflection in the

 windshield.  FWIW.


	


When I built Scooter, the norm was to install the antenna on the glare 

shield, or on the fuse somewhere.  My instructions said to not paint the 

antenna; but, some did and found that the antenna still worked just fine. 

Mine is still white and has not been a problem on the glare shield, at all. 

In fact, I plan on installing the GPS antenna in the same location on my new 

one.  It works for me, even if some find it annoying.



I'd be somewhat concerned about having it under the cowl with all that heat; 

but, I guess it's a strong little critter.  I noticed some of you haves 

several hundred hours on your installations with no problems.



Jim Sears in KY

RV-6A N198JS (Scooter)

EAA Tech Counselor

mike.stewart(at)us.ibm.co
Guest

Posted: Thu Jan 04, 2007 3:48 am Post subject: GPS antenna under cowl

<Snip>

Don't even think about mounting it on top of the glare shield - you will

get the reflection in the windshield.  FWIW. 

<snip>



I disagree here. I have 4 of the small black hockey puck gps/xm antennas

up on my glare shield. No reflection what so ever. I would paint any

antennae black and stick it there. Easy to wire and service. 



I did have slight signal degradation with several gps antennas right

next to each other affecting only my 430. So I put the white garmin

antennae under the cowl, aft of the rear baffle, mounted to the engine

mount and it has worked fine there for 200 hours. I had the same

location on my 6 under the cowl for 1500 hours. 



Best,

Mike

michele.delsol(at)microsi
Guest

Posted: Thu Jan 04, 2007 4:22 am Post subject: GPS antenna under cowl

What about putting the antenna on the cockpit side of the firewall just

under a fibreglass covered cut-out which could be made into a trap? The only

problem I have with up front in the engine compartment is that I'd have to

plan for one more firewall pass through. I hate firewall pass throughs since

I plan to make each one as fireproof as possible.



Michele

RV8 - Finishing



--

jsflyrv(at)verizon.net
Guest

Posted: Thu Jan 04, 2007 5:38 am Post subject: GPS antenna under cowl

My 296 GPS antenna is on the glare shield and I do not  notice it is 

there. Of course my glare shield is painted black and my GPS antenna is 

black.

Jerry

Jim Sears wrote:

 	  Quote: 	

> Don't even think about mounting it on top of the

> glare shield - you will get the reflection in the

> windshield.  FWIW.

 When I built Scooter, the norm was to install the antenna on the glare 

 shield, or on the fuse somewhere.  My instructions said to not paint 

 the antenna; but, some did and found that the antenna still worked 

 just fine. Mine is still white and has not been a problem on the glare 

 shield, at all. In fact, I plan on installing the GPS antenna in the 

 same location on my new one.  It works for me, even if some find it 

 annoying.

 I'd be somewhat concerned about having it under the cowl with all that 

 heat; but, I guess it's a strong little critter.  I noticed some of 

 you haves several hundred hours on your installations with no problems.

 Jim Sears in KY

 RV-6A N198JS (Scooter)

 EAA Tech Counselor

Gary.A.Sobek

Joined: 09 Jan 2006
Posts: 217
Location: SoCAL USA

Posted: Thu Jan 04, 2007 6:43 am Post subject: GPS antenna under cowl

Michele:



Do you mean link this as was done with an RV-7? :



http://www.rvproject.com/hidden_antennas.html



Gary A. Sobek

"My Sanity" RV-6 N157GS O-320 Hartzell,

1,973 + Flying Hours So. CA, USA





----Original Message Follows----

From: Michèle Delsol <michele.delsol(at)microsigma.fr>

Reply-To: rv-list(at)matronics.com

To: <rv-list(at)matronics.com>

Subject: RE: GPS antenna under cowl

Date: Thu, 4 Jan 2007 13:24:45 +0100




<michele.delsol(at)microsigma.fr>



What about putting the antenna on the cockpit side of the firewall just

under a fibreglass covered cut-out which could be made into a trap? The only

problem I have with up front in the engine compartment is that I'd have to

plan for one more firewall pass through. I hate firewall pass throughs since

I plan to make each one as fireproof as possible.



Michele

RV8 - Finishing



--

michele.delsol(at)microsi
Guest

Posted: Thu Jan 04, 2007 7:36 am Post subject: GPS antenna under cowl

Yeah - that's the idea. Except that on an 8 half the front top skin is a

door into the forward baggage compartment. I plan to put the GPS antenna

under the other half and the brake fuel reservoir against the left side

(right side being the forward baggage well). The cut-out for the GPS antenna

should be rather large in order to minimize blanking. I figure that a 20°

mask is something that one can live with which means that the antenna would

have a 140° window instead of the 180° if it were to lay flat on the glare

shield. Since the GPS is looking at satellites only, no ground stations, I

would guess that this should be OK. 



Michele

RV8 - Finishing



--

LessDragProd(at)aol.com
Guest

Posted: Thu Jan 04, 2007 11:30 am Post subject: GPS Antenna Under Cowl

Kind of makes the fiberglass window in my carbon fiber cowl seem very  worthwhile.

 2 GPS antenna's mounted forward of the firewall just under the cowl  "window" in my "yet to be completed" modified RV-4.

  

 1 GPS antenna mounted forward of the firewall in my RV-6A.  1 year and  100 hrs.

  

 1 GPS antenna mounted forward of the firewall in my RV-3.  15+ years  and 650 hours.

  

 I seem to have established a pattern of placing the GPS antenna in the  cool section of the cowl.

  

 Regards,

 Jim Ayers

 BTW, Just as a sensory reference, the temperature that can raise a blister  on most people (touch temperature) is 140 degrees F.

  

 In a message dated 01/04/2007 7:56:19 AM Pacific Standard Time,  ktlkrn(at)cox.net writes:

  	  Quote: 	
		     Since I live in probably the hottest climate in    the US I feel I have a little experience is this area. Let me relate a couple    of things. One, in my law enforcement career I had the unfortunate opportunity    to supervise the investigation of the death of a child that was accidentally    left in a car in the summer time. In one case, we simulated the conditions the    next day, same time, OAT was within a degree, humitidy level the same. The OAT    was 112 degrees. The temperature inside the Chevy Tahoe was 166 degrees.    

    

   I guess temps above this are possible but not to    likely. Vehicle type, color, roof type are all variables.

    

   I believe the Sun itself is far more detrimental    to the equipment than the heat. UV rays are present regardless of the    temperature. In the Sun a Chrome finish can be hot to  the touch in 70    degree heat. So, you mount your GPS antenna under the bubble somewhere,    exposed to the sky, it is still getting the UV rays and the components are    getting heat from the sun and collecting that heat.

    

   Armed with this knowledge, I mounted my GPS and    XM antennas on a plate just in front of the firewall and near the top of the    cowl. Here, they never get direct sunlight and have constant air movement when    the plane is in motion.  When parked at an airshow or fly in I usually    keep oil door unlatched for a few minutes after shutdown. Also when flying at    altitude the air in the cowl is not very hot. Meanwhile the bubble mounted    antenna has the Sun on it.

    

   Unofficially, I spoke to a person who works in    the customer support area of a large Avionics company. He said the under the    cowl is probably one of the safest places to mount the antenna. There is it    protected from the sun and moisture. He said it should never be mounted     in the open as the moisture is the biggest killer of GPS  antennas.

    

   DArwin N. Barrie

   Chandler AZ

   RV7 N717EE

	


 

  

  [quote][b]

martin333(at)athenet.net
Guest

Posted: Thu Jan 04, 2007 12:11 pm Post subject: GPS antenna under cowl

 	  Quote: 	
		   



Jim
	


I have one of my GPS antennae mounted as below, however when I first

installed it I did not realize that the metal fleck paint on my cowl would

impede the reception. The fix was to sand off a 3" x 3" space above  the

antenna mount and repaint it with a grey paint without metal fleck in it.

No trouble since, 1400 hours .



Dick Martin

RV8 N233M

the fast one

 	  Quote: 	
		   Not sure about the fragility of your chosen antenna, but I installed the

 factory antenna puck from my Bendix-King KMD-150 about 1 inch under the

 cowling, center mounted, just behind the baffels, on a supported aluminum

 plate.  No problems in 334 hours and I have lost signal only once in a

 heavy overcast.  The GPS locks on after startup in about 40 seconds.

 Don't even think about mounting it on top of the glare shield - you will

 get the reflection in the windshield.  FWIW.

Bill Schlatterer

Joined: 09 Jan 2006
Posts: 195

Posted: Thu Jan 04, 2007 5:18 pm Post subject: GPS antenna under cowl

Anybody have any experience with a cowl mount under fiberglass with a

metallic topcoat paint job.   Someone noted before that this might be

trouble and that was exactly what I was planning to do!  Anyone actually

tried it?



Thanks 

Bill S



7a engine



Do not archive

ronlee(at)pcisys.net
Guest

Posted: Thu Jan 04, 2007 7:29 pm Post subject: GPS antenna under cowl

 	  Quote: 	
		  Anybody have any experience with a cowl mount under fiberglass with a

metallic topcoat paint job.   Someone noted before that this might be

trouble and that was exactly what I was planning to do!  Anyone actually

tried it?


	


I just read a post about that today I think from Mr Martin (The slow one)

or Mr Ayers.  Seems they had to remove some of it but check the web

archives.



There may be such a cowl at the airport that I can check in a day or so.

If so I will try a handheld receiver under it and report back.



Ron Lee



Do not archive

mike.stewart(at)us.ibm.co
Guest

Posted: Fri Jan 05, 2007 3:35 am Post subject: GPS antenna under cowl

Yes,

My RV8 has solid top coat metallic red. It's a 'pearl' coat, meaning the

metal flakes are fine and dense. No issues on the GPS under cowl for me.

Its 3 coats of this base coat paint.

Mike

--

michele.delsol(at)microsi
Guest

Posted: Fri Jan 05, 2007 5:19 am Post subject: GPS antenna under cowl

(long)



I believe the problem with satellite reception is that if the antenna is

inside an electrically conducting enclosure, then the radio waves do not

pass through. Correct me if I am wrong, electricians call such an enclosure

a Faraday cage. So, applying this reasoning, any surface which is

electrically conducting, such as aluminium, steel, copper, carbon fiber,

metallic paint and others will hinder reception.



As to temperatures inside the front baggage compartment on a very hot sunny

day, you have to consider two factors: direct sunlight on the surface -

color will be a determining factor, and the green house effect, ventilation

becomes the determining factor. If your front top skin is colored black and

you shut the canopy and not cover it than you have the worst possible

scenario.



Let me explain what the green house effect is and then it will be easy to

understand how to minimize it. I don't mean to be pompous but some of you

may not know the underlying principles. UV's will pass through glass and

will hit the inside of the airplane. That's energy going inside the cabin.

The surfaces heated by the UVs will radiate infrared light. It is the same

light as the UV except that the wavelength is a lot longer. The infrared

light will not pass through the canopy - it will bounce off and thus gets

trapped. The energy has consequently nowhere to go so things inside the

cabin wind up getting hot. Now, if you crack the canopy open hot air will

escape and will be replaced by cooler outside air, thus alleviating the

green house effect. Another solution is to cover the canopy with a

reflecting silver tarpaulin to prevent UVs from coming in. You can also put

a shiny reflecting surface inside the canopy so that the UVs should be

reflected outwards back through the canopy. The trick is to catch the UVs

and throw them back out before they get converted to infrared. You can

verify this with an experiment you can try now that it is winter. Go to your

fireplace, assuming that you have a good fire going. If there is nothing

between you and the flames, you will feel the heat. Now take a piece of

transparent glass such as is used for windows. Put it between the flames and

your hand. You won't feel the heat any more but you can see the flames

through the glass. Conclusion: low energy light which you can see does pass

through however high energy light, infrared, which feels hot but which you

cannot see, does not pass through. As a sideline, if you put a transparent

glass shield in front of your fire place, then you are throwing a lot of

heat out the chimney as very little will pass through the glass to heat up

your living room.



I enjoyed that - I hope I did not annoy anybody nor insult anyone's

intelligence with my technical meanderings.



Michele

RV8 - Finishing



--

GRWilliams2(at)bellhelico
Guest

Posted: Fri Jan 05, 2007 5:25 am Post subject: GPS antenna under cowl

Havent posted in awhile but here is my take on the matter if anyone really

cares. Just place the GPS antenna inside the canopy either on the glare

shield away from your view or behind you on the fuselage as the canopy will

slide right over it. This eliminates drag and it looks sexy too. Just my

opinion.



Glenn Williams A&P



--

davemader(at)bresnan.net
Guest

Posted: Fri Jan 05, 2007 7:31 am Post subject: GPS antenna under cowl

Same here,  three coats of metallic blue.  Heard the warnings but thought I

would try it just to see and its worked fine.

Dave Mader



--

dbris200(at)sbcglobal.net
Guest

Posted: Tue Jan 09, 2007 4:24 pm Post subject: GPS antenna under cowl

I think that most "metallic paint" today uses mylar for the flakes, not 

metal so there should be no problem, But you may still find paint that 

uses metal, so check before you use it.



Dave



PeterHunt1(at)aol.com wrote:

 	  Quote: 	
		   Bill S. asked if anyone had actually mounted a GPS antenna under the 

 engine cowl and then used metallic flake paint on the cowl.  I did 

 just that and mine works great.  I mounted my Garmin 530 GPS antenna 

 on a platform which I attached high and center on the engine side of 

 my firewall.  The cowl and much of the rest of my airplane is painted 

 with a beautiful teal metal flake paint.  I now have 200 hours on my 

 RV-6 and not the slightest problem with this GPS antenna 

 installation.  I lock into a GPS signal quickly (within 30 seconds of 

 start up) and never had a problem losing it in flight.  Further, 

 before I made this installation (during construction in 2004) I talked 

 with the Garmin people and they did not see any problems with my 

 installation.  I do open my oil access door after flying, but that is 

 more to just help the whole engine compartment cool down.

  

 Pete in Clearwater, FL

 RV-6, Reserve Grand Champion - Kit, 2006 Sun n' Fun

 *

 *

LloydDR(at)wernerco.com
Guest

Posted: Tue Jan 09, 2007 7:23 pm Post subject: GPS antenna under cowl

Mylar is reflective for RF, we used Mylar balloons in the Navy for

targeting practice, and when it is coated its reflectivity can be

increased to create chaff clouds or blooms. The only real way to tell or

not is to paint a like surface with the type of paint you are going to

use, place the antenna under it and test for signal acquisition.

Dan

--

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