GPS anetenna location OK in baggage area of a fiblerglass glider?

On Monday, February 26, 2018 at 6:40:27 AM UTC-8, krasw wrote:

Well there is not, this is simply not true.

Read The Fine Manual... From the ASW-27 flight manual:

"Since the whole airframe ex cept for the fin and a small area above the baggage compartment contains carbon fibre which screens electromagnetic radiation, the ELT's antenna must be fitted in the top of the baggage compartment and extend into the canopy area."

On a sunny day, have a friend place their hand on the outside of the fuselage and look inside. If you can see the hand's shadow, it's not carbon.

5Z

This may or may not be related, but...

I mentioned GPS dropouts to my avionics technician since I had several
GPS pucks under the fiberglass glare shield on my Stemme. They were
mounted directly under my Flarm antennae so I moved them to the top of
the glare shied and to the canopy frame up front. This took care of most
of the dropouts but there is still an occasional dropout.

The tech said he's seen this on power planes as well and he thinks it's
a failing GPS antenna.Â* He said that one antenna failing could
(apparently) transmit interference which could take out others.Â* He
suggested disconnecting my antennae one at a time and flying with that
system down and see if there are problems with the others.Â* It might be
less painful simply to get another GPS antenna (they're cheap) and swap
it around the cockpit from system to system and see if that fixes the
problem.Â* ...Or maybe an antenna combiner...

OBTW, there should be no problem with mounting an antenna underneath a
fiberglass cover.

On 2/25/2018 7:44 PM, Dirk_PW wrote:
I'm doing a little housekeeping with instrument panel this winter with the intent to eventually install an ADS-B solution (whatever that may be). The panel is quite cluttered right now. I'm considering one option of moving the FLARM GPS antenna (and eventually a ADS-B GPS antenna) back behind my head somewhere in the baggage area. I'm curious if anyone has done this and has had any problem acquiring a GPS signal (on a fiberglass glider). I'm currently having no problems acquiring a signal with the GPS antenna under the fiberglass front panel. Thanks.

--
Dan, 5J

On Monday, February 26, 2018 at 6:28:31 AM UTC-8, Dan Marotta wrote:
This may or may not be related, but...

I mentioned GPS dropouts to my avionics technician since I had several
GPS pucks under the fiberglass glare shield on my Stemme. They were
mounted directly under my Flarm antennae so I moved them to the top of
the glare shied and to the canopy frame up front. This took care of most
of the dropouts but there is still an occasional dropout.

The tech said he's seen this on power planes as well and he thinks it's
a failing GPS antenna.Â* He said that one antenna failing could
(apparently) transmit interference which could take out others.Â* He
suggested disconnecting my antennae one at a time and flying with that
system down and see if there are problems with the others.Â* It might be
less painful simply to get another GPS antenna (they're cheap) and swap
it around the cockpit from system to system and see if that fixes the
problem.Â* ...Or maybe an antenna combiner...

OBTW, there should be no problem with mounting an antenna underneath a
fiberglass cover.

On 2/25/2018 7:44 PM, Dirk_PW wrote:
I'm doing a little housekeeping with instrument panel this winter with the intent to eventually install an ADS-B solution (whatever that may be). The panel is quite cluttered right now. I'm considering one option of moving the FLARM GPS antenna (and eventually a ADS-B GPS antenna) back behind my head somewhere in the baggage area. I'm curious if anyone has done this and has had any problem acquiring a GPS signal (on a fiberglass glider). I'm currently having no problems acquiring a signal with the GPS antenna under the fiberglass front panel. Thanks.

--
Dan, 5J

Check for electrical noise on your mains. In my case it was caused by switching power supplies for the Oudie and Colibri II. I was seeing occasional dropouts in my IGC traces. Liberal use of ferrites stopped the problem cold.

I fly out west with a Powerflarm and a garmin 196 with remote antennae.The antennae are seperated by at least a foot or so under the glare sheild. At first and for years I had the 196 feeding my SN10B and without fail at exactly 00:00 UTC, I was usually on final glide or a long way from home, I would get about minute or three of dropouts. These would last for 5 to 30 seconds but very annoying. They would not show up on the 196, but I would get the warning on the SN10.If looking at the signal on the 196 it was always good and it would be updating its position constantly. After switching to the powerflarm as a gps source it has stopped. Still dont know why it was happening.

CH

Not sure how many Discus 2 and Ventus 2 fuses I made, but none of them have a glass turtle deck.
Radio antenna located in the fin which is glass, except the Nimbus 4 where it is located in the rudder.
This however doesn't help your issue

On Tuesday, February 27, 2018 at 7:16:13 AM UTC-8, Ross wrote:
Not sure how many Discus 2 and Ventus 2 fuses I made, but none of them have a glass turtle deck.
Radio antenna located in the fin which is glass, except the Nimbus 4 where it is located in the rudder.
This however doesn't help your issue

Has anyone tried putting a transponder antenna like the T2glued to the inside the turtle deck? does the antenna require a downward view? 250 watts of RF too close to your head? This would make install on an ASW27 MUCH simpler than a fin or stinger on the outside behind the gear, not to mention more aerodynamic.

On Tuesday, February 27, 2018 at 4:20:51 PM UTC-8, Matt Herron Jr. wrote:

Has anyone tried putting a transponder antenna like the T2glued to the inside the turtle deck? does the antenna require a downward view? 250 watts of RF too close to your head? This would make install on an ASW27 MUCH simpler than a fin or stinger on the outside behind the gear, not to mention more aerodynamic.

There is little if any scientific evidence one way or the other. But the general consensus seems to be that a 1/3 horsepower gigahertz ping next to the noggin is a lot more likely to be bad than good. You might hit the jackpot and mutate into a master of clairvoyance and psychokinesis, but the odds aren't in your favor on that.

And, yeah the view down seems to be more important than the one up.

One possibility might be a slot antenna, which are said to work well in the gigahertz range. I have it on my to-do list to try it, but it's pretty far down the list:

http://www.antenna-theory.com/antenn...rture/slot.php

--Bob K.

On Tuesday, February 27, 2018 at 4:20:51 PM UTC-8, Matt Herron Jr. wrote:
On Tuesday, February 27, 2018 at 7:16:13 AM UTC-8, Ross wrote:
Not sure how many Discus 2 and Ventus 2 fuses I made, but none of them have a glass turtle deck.
Radio antenna located in the fin which is glass, except the Nimbus 4 where it is located in the rudder.
This however doesn't help your issue

Has anyone tried putting a transponder antenna like the T2glued to the inside the turtle deck? does the antenna require a downward view? 250 watts of RF too close to your head? This would make install on an ASW27 MUCH simpler than a fin or stinger on the outside behind the gear, not to mention more aerodynamic.

Can't you put it in the nose of the 27? I mounted an L2 there on my 26, ahead of the rudder pedals. The nose it also not carbon, it's kevlar and glass.. I believe the antenna wants to be vertical for the correct polarization, that might add to the problems putting it in the turtle deck. I have the L2 transponder antenna on one side and the Flarm A on the other, works fine.

On Tuesday, February 27, 2018 at 5:26:55 PM UTC-8, jfitch wrote:
On Tuesday, February 27, 2018 at 4:20:51 PM UTC-8, Matt Herron Jr. wrote:
On Tuesday, February 27, 2018 at 7:16:13 AM UTC-8, Ross wrote:
Not sure how many Discus 2 and Ventus 2 fuses I made, but none of them have a glass turtle deck.
Radio antenna located in the fin which is glass, except the Nimbus 4 where it is located in the rudder.
This however doesn't help your issue

Has anyone tried putting a transponder antenna like the T2glued to the inside the turtle deck? does the antenna require a downward view? 250 watts of RF too close to your head? This would make install on an ASW27 MUCH simpler than a fin or stinger on the outside behind the gear, not to mention more aerodynamic.

Can't you put it in the nose of the 27? I mounted an L2 there on my 26, ahead of the rudder pedals. The nose it also not carbon, it's kevlar and glass. I believe the antenna wants to be vertical for the correct polarization, that might add to the problems putting it in the turtle deck. I have the L2 transponder antenna on one side and the Flarm A on the other, works fine..

I think the '27 is different from the '26 there and does not have the clear spots in the nose.

On Tuesday, February 27, 2018 at 4:20:51 PM UTC-8, Matt Herron Jr. wrote:
On Tuesday, February 27, 2018 at 7:16:13 AM UTC-8, Ross wrote:
Not sure how many Discus 2 and Ventus 2 fuses I made, but none of them have a glass turtle deck.
Radio antenna located in the fin which is glass, except the Nimbus 4 where it is located in the rudder.
This however doesn't help your issue

Has anyone tried putting a transponder antenna like the T2glued to the inside the turtle deck? does the antenna require a downward view? 250 watts of RF too close to your head? This would make install on an ASW27 MUCH simpler than a fin or stinger on the outside behind the gear, not to mention more aerodynamic.

Ah no, no and no.

Bad on all counts...

Irradiating yer noggin.

The antenna needs to be as vertical as possible.

You don't want the pilot able to affect it by stacking stuff near it in the luggage area. Like say bottles of RF opaque drinking water.

The carbon fibre spars and rest of the fuselage will block much of the RF. If you don't have a carbon fibre fuselage, go ahead and stick an antenna inside there elsewhere.

Aerodynamics? Uh you flying a world record in an Eta?

But start with... KISS, just follow the glider manufacturers instructions for the transponder antenna install they recommend. The main goal is to have the transponder works as best as it can. Over the last decade or so the major manufacturers have worked this out pretty well. Back in the 1990s some of them had just awful transponder antenna installs.