Feds Want to Equipe Gliders With Transponders and Radios

On Tue, 29 Apr 2008 13:15:46 -0700 (PDT), "kirk.stant"
wrote in
:

Larry Dighera obviously hasn't been around a modern
glass glider recently or he would understand that most have electrical
systems and many have transponders.

As a percentage of the entire sailplane fleet, how many would you
estimate are "modern glass gliders?"

You can't put the antenna on the inside of a carbon fiber fuselage, well,
you could, but it would not work.
Not all gliders have excess usable weight available to carry water.

BT
_____________

You need to find the overall consumption, not what is used when it is
squawking.

As to weight - since we frequently put water in gliders to improve
performance, I can't see a problem there, and the antenna will be
inside the glider so won't increase drag.

But you are right that buying and installing a transponder isn't a
cheap thing.

On Apr 30, 8:40*am, sisu1a wrote:


It is my understanding though, (as already mentioned) it is NOT out
lack of a readable signature as a primary target (I'm not saying we
have huge signatures, just that they are already readable for the most
part, some better than others...), but our slow/erratic flying gets us
weeded out of the picture the same way it filters out buildings and
mountains. Again, this is from MY recollection from the Reno ATC rep
while addressing this very subject last winter.

As far as I know, fixed returns from stationary targets are removed by
simple sweep differencing and thresholding. It may be that target
doppler shift is used to selectr/reject moving targets so the issue
would then be the threshold for that rejection. I read that an
interceptor radar had a threshold of about 20 knots for this purpose
but I can't find any statement (via google) as to what threshold ATC
usually uses. Measurement of small doppler shift is aided by a strong
signal, so weak slow targets would be doubly rejected so to speak. I
doubt they see flocks of birds, but then they mostly fly at less than
30 knots I think (even the african swallow :-) so the could be set to
30knots without degrading system performance (maybe?).

I suspect that if the "powers that be" want to see gliders for traffic
avoidance and gliders don't want transponders it would be in their
best interest to make sure they can be easily seen by passive means.
Beaurocrats like being given options that are win win for both pasties
If offering to mount a really cheap reflector inside the fuse could
assure detectability, it could be a way to go forward (assuming
gliders want $ savings from avoiding the purchase and regular testing
of transponders)...

Just trying to help, I'm not a regular glider pilot.
Cheers

"Peter Dohm" wrote

I 'm confident that the installation is the biggest part of it--especially
when you include enough solar panels to power it all reliably.

Why solar cells? A 7 amp hour lead acid gel cell can be had for about 20 bucks,
and would run a solid state transponder for a whole flight.
--
Jim in NC

In article "Morgans" writes:
"Peter Dohm" wrote

I 'm confident that the installation is the biggest part of it--especially
when you include enough solar panels to power it all reliably.

Why solar cells? A 7 amp hour lead acid gel cell can be had for about 20 bucks,
and would run a solid state transponder for a whole flight.

One doesn't want to run the lead acid battery down past about 1/2 its capacity
to get a reasonable service life from it, so that limits you to 3.5 AH.

Given that they are also probably running some of:

o A com radio.
o An elecronic variometer.
o A gps.
o A flight logger.

and that they are wanting these to run for flights of 5 - 8 hours or more,
it is fairly clear that the 7 AH battery cannot do it.

I would expect they have already trimmed the list of electronic items
in order to get their flight time from the battery, so a transponder would
need another battery, or giving up some of the other equipment.


More thoughts on the basic issue of protecting IFR aircraft from gliders.
How about designating that area as having fairly low speed limits all the
way up to 18,000 feet (where wave windows would take over for separation),
only in this case note that if the aircraft is unable to fly that slowly,
they have to go around the airspace.


Alan

On Apr 29, 5:35*pm, Larry Dighera wrote:
On Tue, 29 Apr 2008 13:15:46 -0700 (PDT), "kirk.stant"
wrote in
:

Larry Dighera obviously hasn't been around a modern
glass glider recently or he would understand that most have electrical
systems and many have transponders.

As a percentage of the entire sailplane fleet, how many would you
estimate are "modern glass gliders?" *

Been to a glider field lately? Or a contest, or fun meet?

At my club, we have 5 older generation, non-glass gliders. The rest
of our fleet, club and private, totals perhaps 12 glass ships - all
with electrical systems (and one with a transponder). So that is a
pretty high percentage.

I would estimate that by flight hour, the majority of glider flying in
the US (and the rest of the world) is done in "modern glass gliders".

So if your idea of a typical American glider is a beat-up 2-33, you
might be surprised. While you will still find a lot of them around,
it's amazing how little they fly (with some obvious exceptions, of
course!).

Kirk

In rec.aviation.soaring Alan wrote:
In article "Morgans" writes:
"Peter Dohm" wrote

I 'm confident that the installation is the biggest part of it--especially
when you include enough solar panels to power it all reliably.

Why solar cells? A 7 amp hour lead acid gel cell can be had for about 20 bucks,
and would run a solid state transponder for a whole flight.

One doesn't want to run the lead acid battery down past about 1/2 its capacity
to get a reasonable service life from it, so that limits you to 3.5 AH.

What kind of unreasonable service life do you get if you use the full
capacity, and at $20 each do you care if you use it up faster? Unless you
can count the number of cycles on your fingers that may be the simplest
and most cost effective way to go, although of course I may be overlooking
something important.

--
Michael Ash
Rogue Amoeba Software

wrote:
On Apr 29, 5:35 pm, Larry Dighera wrote:
On Tue, 29 Apr 2008 13:15:46 -0700 (PDT), "kirk.stant"
wrote in
:

Larry Dighera obviously hasn't been around a modern
glass glider recently or he would understand that most have electrical
systems and many have transponders.
As a percentage of the entire sailplane fleet, how many would you
estimate are "modern glass gliders?"

Been to a glider field lately? Or a contest, or fun meet?

At my club, we have 5 older generation, non-glass gliders. The rest
of our fleet, club and private, totals perhaps 12 glass ships - all
with electrical systems (and one with a transponder). So that is a
pretty high percentage.

I would estimate that by flight hour, the majority of glider flying in
the US (and the rest of the world) is done in "modern glass gliders".

So if your idea of a typical American glider is a beat-up 2-33, you
might be surprised. While you will still find a lot of them around,
it's amazing how little they fly (with some obvious exceptions, of
course!).

Similar in Boulder. 60% of our club fleet is glass (OK it's only three
out of five, but still...) Mile High Gliding is about 50:50, then there
are the 30 or so private ship. I believe there are one or two HPs, the
rest are composite.

Shawn

"Michael Ash" wrote

What kind of unreasonable service life do you get if you use the full
capacity, and at $20 each do you care if you use it up faster? Unless you
can count the number of cycles on your fingers that may be the simplest
and most cost effective way to go, although of course I may be overlooking
something important.

I have found that using 60% or perhaps 70% does not seem to limit their life
noticeably. What does kill them is to charge them too fast, or most
importantly, leaving them sitting around in a discharged state. Doing that one
time could be the end of them.

The better question than asking how much more quickly a higher discharge kills
them for the price, is to ask why not buy an extra one, or two.

Larger gell cells are also available, but I'm not sure where the economics of
buying more small ones versus buying a single larger one come into play.
--
Jim in NC

In article Michael Ash writes:
In rec.aviation.soaring Alan wrote:

One doesn't want to run the lead acid battery down past about 1/2 its capacity
to get a reasonable service life from it, so that limits you to 3.5 AH.

What kind of unreasonable service life do you get if you use the full
capacity, and at $20 each do you care if you use it up faster? Unless you
can count the number of cycles on your fingers that may be the simplest
and most cost effective way to go, although of course I may be overlooking
something important.

It depends on the details of the battery. Lead acid batteries come in a
lot of sub-types, with varying ability to handle deeper discharges. The
better ones cost more.

Other factors include the output voltage under load at discharge -- a
lead acid battery is rated to 10.2 to 10.5 volts for a "12 volt" battery
at discharge. Unfortunately, most 12 volt radios and devices are designed
for a charging electrical system, with a voltage of about 14 volts. When
the battery is down to 75% of the expected voltage for the radio, not all
of them work. I have had aircraft radios that would not transmit below
about 11.5 volts, at which point the battery would be still above 50% charged.

Lead acid batteries are normally rated for capacity at a 20 hour rate of
discharge. A 7 AH battery would deliver 7000 / 20 = 350 mA for 20 hours.
Faster discharge rates result in less capacity being available (look up
Peukerts exponent for more details). Discharging faster than that, reduces
the amp-hour capacity of the battery.

Lead acid batteries have less capacity when cold. One guide suggests that
for every 10 degrees centigrade below room temperature, you should add 10%
to the battery capacity needed. High altitude flight tends to get up into
cold places.


Alan