What Flarm really needs...

Flarm needs a box that is similar to that used by A&Ps to do transponder checks. Something portable that would allow you to test the send and receive range of your glider on the ground. Idally you would do sy 4 tests. Off the nose, behind, and left and right.

Range analysis tool is ok, but it's really pretty useless if you're trying to diagnose a problem.

If there were 10 of these boxes available in the US, I'd happily put down a significant deposit on the box and a reasonable rental to be able to check not just my glider, but all the gliders at my airport before returning the box to get my deposit back.

I must heartily second this suggestion.
One of the continuing problems with FLARM is antenna placement and function.. There are many gliders in my area that have significant blind spots due to antenna placement and glider construction. For a safety device this is totally unacceptable to me. A safety device must be predictable and consistent across the entire installation population.

A thought is that SSA might be a good organization to find a way to investigate and standardize the installation of FLARM in virtually every glider flying so that there is a predictable way to install the devices and have acceptable function. Finding someone with the skills and time like Dick Johnson used to do with flight tests is one possible way. The SSA should take the lead on this type of research, especially since they require FLARM devices in competitions.

My two cents.

On Monday, June 8, 2015 at 12:04:50 PM UTC-4, wrote:
I must heartily second this suggestion.
One of the continuing problems with FLARM is antenna placement and function. There are many gliders in my area that have significant blind spots due to antenna placement and glider construction. For a safety device this is totally unacceptable to me. A safety device must be predictable and consistent across the entire installation population.

A thought is that SSA might be a good organization to find a way to investigate and standardize the installation of FLARM in virtually every glider flying so that there is a predictable way to install the devices and have acceptable function. Finding someone with the skills and time like Dick Johnson used to do with flight tests is one possible way. The SSA should take the lead on this type of research, especially since they require FLARM devices in competitions.

My two cents.

I'm sure SSA would be pleased to know of a real expert that it could recommend to people for advice and expertise.
This forum has provided a lot of good information on the topic.
"They" (SSA) does not require Flarm in competition. The SSA contest board is on record as strongly encouraging contest pilots to use Flarm but has not made it mandatory.
UH

OK, here's a method that you could use to perform a PowerFlarm ground range test on the cheap...

Get a portable PowerFlarm unit (hopefully this can be borrowed from someone that owns one). Prepare a battery setup to power it. Connect a 40 dB RF attenuator between the portable unit and its antenna. The Attenuator will have the effect of simulating a 100:1 range reduction. Put your glider in an open field with the tail propped up to flying angle. Now walk out on various radials from your glider to determine the point of drop out -- multiply the drop out distance by 100 to get the approximate flying range.

At the portable setup, attach the attenuator on the PF unit with maybe 6 ft of coax hanging off to the PowerFlarm antenna. The antenna should be mounted on a stick and held vertical in the air to get it away from your body. Getting an RF attenuator configured with the right connectors might require help from a professional EE or tech or maybe an advanced HAM kind of guy.

This of course only gives you a zero azimuth range measure, but that's the most important for Flarm operation anyway. Ground reflection and any extraneous objects in the environs will introduce some error. There are many other caveats that make this an imperfect method for sure but it will get you reasonably close. Your attention should be focused on closely spaced radials in the forward angles from your glider as this is the direction which places the most demand on anti-collision range.

Nice suggestions.
I take issue with the zero azimuth as being good enough.
I worry about gliders under my belly and behind and above in my blind spots.
Pull-ups and diving for airspeed are part of soaring.

All the gliders with carbon cockpits and having the antennas under of on the glareshield means that there is a blindspot below the zero azimuth.

I should add that the professional or Ham guy should probably be part of the antenna on the stick design as well. There can be issues with respect to the type of antenna and the lead-in arrangement. I'd be inclined to use a PowerFlarm dipole antenna and set it up so that the lead in cable is orthogonal to the antenna for at least 6 inches or so.

On Monday, June 8, 2015 at 10:21:31 AM UTC-7, wrote:
Nice suggestions.
I take issue with the zero azimuth as being good enough.
I worry about gliders under my belly and behind and above in my blind spots.
Pull-ups and diving for airspeed are part of soaring.

All the gliders with carbon cockpits and having the antennas under of on the glareshield means that there is a blindspot below the zero azimuth.

Yes, under the belly is important. This is not really an important consideration for testing however. The reason is that it would be essentially impossible to create an installation that would so strongly attenuate in the under the belly direction compared to the zero azimuth directions such that acceptable range is found at zero azimuth and yet is not sufficient for good anti-collision operation in the very very close range that matter for under the belly, etc.

Steve, good idea for a first approximation. If under the belly and behind is really a worry that you'd go to some lengths, you could do what the radar boys do - put the glider on a pedestal. I still remember the F-18 I saw on a post 50 feet above the ground...

-John

On Monday, June 8, 2015 at 1:33:40 PM UTC-4, Steve Koerner wrote:
Yes, under the belly is important. This is not really an important consideration for testing however. The reason is that it would be essentially impossible to create an installation that would so strongly attenuate in the under the belly direction compared to the zero azimuth directions such that acceptable range is found at zero azimuth and yet is not sufficient for good anti-collision operation in the very very close range that matter for under the belly, etc.

On Monday, June 8, 2015 at 11:45:29 AM UTC-7, John Carlyle wrote:
Steve, good idea for a first approximation. If under the belly and behind is really a worry that you'd go to some lengths, you could do what the radar boys do - put the glider on a pedestal. I still remember the F-18 I saw on a post 50 feet above the ground...

-John

Again, I strongly believe that worrying about elevation angles is not worthwhile. Having said that, there's an easier way than building a pedestal into the sky. Take the wings off and pivot the fuse at various roll angles if you really must see what happens to range above and below your glider.

Awwww... Way too logical. I favor standing the glider on its nose and
walking around it to take up/down measurements! :-D

snip

Take the wings off and pivot the fuse at various roll angles if you really must see what happens to range above and below your glider.


--
Dan Marotta