On Friday, March 22, 2013 3:02:43 PM UTC-7, Martin Gregorie wrote:
On Fri, 22 Mar 2013 09:46:45 -0500, Wallace Berry wrote:



In article ,

wrote:



On Thursday, March 21, 2013 2:32:42 PM UTC-7, WB wrote:

I am curious about Flarm installation in Libelles. I can see that I

will



have to install one at some point. Either a rental or bite the

bullet



and buy one. Where do you Libelle drivers mount the antennas?







Thanks







WB



H301 #19



Wally,

I put mine on an acrylic angle cantilevered off the front of the

instrument tray. With the libelle it's cramped and dark in there.

I'll have to see how folks receive me once the season gets going.



Regards, OD



Thanks, Dave, Uli,



Great suggestions. I was thinking along Dave's lines, since that I what

I initially did with the antenna on my pcas unit. I like Uli's idea

since it gets the antennas well apart.



I use a standard RedBox FLARM in a Libelle, rather than a Power FLARM,

but hopefully this will be a useful starting point.



I am using the optional dipole antenna mounted on a non-conductive

assembly I made from a section of fibreglass fishing rod and a moveable

wooden block using nylon screws to lock it onto the rod section and to

hold the dipole in place. This projects roughly horizontally forward from

the front of the instrument tray so the dipole is as high up as possible

inside the nose and roughly half-way between the front of the tray and

the rudder pedals. This is my version of a mount design I got from

Thorsten Mauritsen, a Danish Libelle driver. Details and the rationale

behind this set-up are he



http://www.gregorie.org/gliding/libe...ole_mount.html





I've checked the coverage using the FLARM tool at:



http://www.flarm.com/support/analyze/index_en.html



A little experimentation showed that the fore and aft placement is quite

critical: moving the antenna even 6mm (1/4") makes a noticeable

difference. The analyser shows my coverage is approximately 6km round an

arc that extends +/- 120 degrees from straight ahead. Behind that, the

coverage forms a roughly straight line between these points and with a

worst case range of 2km directly behind me. Even the worst case is twice

the recommended minimum for speeds of up to 200 km/h (110 kts).





--

martin@ | Martin Gregorie

gregorie. | Essex, UK

org |

I am getting similar results with my powerlfarm antennas installed in the nose of my 27a. IMHO the nose of the glider, if carbon free and far enough from the rudder pedals is probably the best place to put your antennas. I wouldnt worry too much about them being a bit tilted and a bit closer than the recommended distance. The most important is that they will have pretty much unobstructed half sphere view of the area in front of you which is where your threat will most likely be. An added benefit will be not to have to stare at antennas sticking out from the glare shield.

Ramy