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

On Monday, February 26, 2018 at 12:07:49 PM UTC-8, krasw wrote:

Sorry but with "light test" you have no clue of the turtle deck material.

Dude, chill. They're trying to talk sense for ya.

* Radio waves and light are both electromagnetic radiation; the only difference between them is frequency. If light goes in through the turtledeck structure, then radio waves will almost certainly to in and out as well.

* It doesn't matter if the turtledeck is fiberglass or Kevlar (aramid) or basalt fiber. If light goes through it, so will radio waves. Light doesn't go through carbon or aluminum, and neither does radio waves. BTW that's one of the reasons UV-curing vinylester resins are kind of a dead-end, they won't play nice with carbon. Someday there might be x-ray-curing vinynlesters, though, so hang on to your lead apron.

* When I designed the HP-24 fuselage, I surveyed the field and found that many if not most manufacturers were using radio transparent fiberglass for the portion over the wing, and I did the same. I also made the rudder out of Kevlar, and developed a tuned dipole com antenna that is a standard part of the rudder kit.

* I specifically decided not to develop an internal transponder antenna for the rudder or fuselage; for that I recommend an external blade antenna. I have on my to-do list the development of a flush 1090 mHz slot antenna, but it's pretty far down the list.

--Bob K.

On Monday, February 26, 2018 at 12:07:49 PM UTC-8, krasw wrote:
maanantai 26. helmikuuta 2018 21.12.23 UTC+2 Darryl Ramm kirjoitti:
Name one where it is not.

Sorry but with "light test" you have no clue of the turtle deck material. Why an earth would factories go trough massive pain and expense of laying up turtledeck using different material instead of just rolling up carbon/kevlar? Instruments and their antennas tend to reside in the instrument panel.. Routing GPS antennas to behind pilots back, who does this, and why would factories be interested in this? Please give some reference to glass turtledeck in carbon fuselage, anything will do. RF transparence is different thing, antenna on the hat shelf sees sky trough canopy as I stated earlier.

An ASH26E has an all carbon fuselage but a fiberglass turtle deck. As does every other AS glider I have ever seen (20, 24, 25, 29, 31, etc.). Every Ventus and Discus I have ever seen has a fiberglass turtle deck. Ditto every DG and Lak. Rather, please point to a composite glider that does not. In a Pilatus, Schweizer, or Blanik you will have some trouble as they are aluminum.

On Monday, February 26, 2018 at 2:12:23 PM UTC-5, Darryl Ramm wrote:
Name one where it is not. Go do the light test Jon discussed. Every Schleicher fueslage I have looked at is this way. Pretty sure the DG1000 is, ...

You were claiming no glider fuselages have this, having used GPS antennas mounted under the turtleneck in several otherwise carbon fiber glider fuselages I know you are wrong about that.

Here is a game for the upcoming SSA convention... folks there can ask or look to check if the turtledecks in all the gliders on display are RF transparent or not.

Oh the anticipation for the advancement of human (well r.a.s.) knowledge is killing me.... :-)

'27 and '28 lamination schemes show no carbon in a portion of the turtle deck area. Low loads and it is easy to shape carbon layer during lamination. My ELT antennas are in this area for that reason.
UH

Le mardi 27 février 2018 14:47:14 UTC+1, a écritÂ*:
'27 and '28 lamination schemes show no carbon in a portion of the turtle deck area. Low loads and it is easy to shape carbon layer during lamination.. My ELT antennas are in this area for that reason.
UH

Actually, the ELT antennas are the reason why there is a glass part in the turtle deck. Otherwise you would have to put these antennas somewhere else, and you would need a cable to connect the antenna to the ELT. And that would be real stupid.

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