Feds Want to Equipe Gliders With Transponders and Radios

In article dSuRj.7182$r12.6971@trndny03,
Eric Greenwell wrote:

But, gliders have been made with carbon fiber for decades now, and even
fiberglass gliders have metal parts.

Is carbon more reflective than glass?

On Mon, 28 Apr 2008 22:34:56 -0400, Roy Smith wrote in
:


Is carbon more reflective than glass?

Carbon, being conductive, would be expected to be considerably
reflective of radar energy, IMO.

sisu1a wrote in
:

On Apr 27, 3:45 pm, Larry Dighera wrote:
On Sun, 27 Apr 2008 15:03:33 -0700 (PDT), WingFlaps
wrote in
:



On Apr 28, 9:32 am, Larry Dighera wrote:
On Sun, 27 Apr 2008 12:34:55 -0700 (PDT), WingFlaps
wrote in
68afa9fb-b4d2-4620-91e6-f0a85a75d...
@x19g2000prg.googlegroups.com
:

A radar reflector like they use on weather balloon ought be
sufficient. It is just a piece of foil with a large cross
section.

That's a constructive suggestion.

How large must such a radar reflector be?

It's a retroreflector, I have one in the form of a tube about 3
inches in diameter and 2 feet long. The corner cubes are inside
that. I have no idea how effective it is compared to a classic
reflector which occupies a cube about 1 foot across and
retroreflects the radar equally in all directions.
...

Interesting. Thanks for the information.

How do you think it might affect a sailplane's L/D?

Well, if the sailplane skin is transparent to radar a big reflector
could be mounted inside, they don't weigh much. On the other hand a
cylinder type reflector could be made quite aerodynamic and even
incorporated into (say) the wing tips?

Cheers

That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Unfortunately too simple. The problem is NOT ATC's equipment having
trouble painting a glider. The problem is the threshold of sensitivity
on their radars is set far too high to display us since they
intentionally filter out things as slow as a glider, particularly if
it's thermalling. We are simply filtered out as clutter (according to
the rep Reno sent to address PASCO last winter). That said, I'm sure
we don't all read the same on radar, but gliders are not the stealth
aircraft they are being made out to be. I believe cockpit alone has a
rather large signature, unless of course you paid the extra $1,000,000
for the one molecule thick layer of electrically deposited gold on
your canopy. There's more to a stealth aircraft then it being made of
fiberglass, or even carbon.



You fly Sisu?


Bertie

On Sun, 27 Apr 2008 23:24:48 -0700 (PDT), sisu1a
wrote in
:

[radar corner reflector suggestion snipped]


That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Unfortunately too simple. The problem is NOT ATC's equipment having
trouble painting a glider. The problem is the threshold of sensitivity
on their radars is set far too high to display us since they
intentionally filter out things as slow as a glider, particularly if
it's thermalling. We are simply filtered out as clutter (according to
the rep Reno sent to address PASCO last winter).

Perhaps it would be possible to modify ATC procedures or display
software to overcome that issue. That would certainly be preferable
to requiring electrical systems be installed in all gliders.

That said, I'm sure we don't all read the same on radar, but gliders
are not the stealth aircraft they are being made out to be. I believe
cockpit alone has a rather large signature,

What is there in the glider cockpit of a typical glass ship that
reflects radar energy? I suppose the instruments are metal, and some
of the control linkage and gear are metallic, but I would expect the
corner reflector to provide a much stronger return.

unless of course you paid the extra $1,000,000 for the one molecule
thick layer of electrically deposited gold on your canopy. There's
more to a stealth aircraft then it being made of fiberglass, or even
carbon...

Paul

I would think carbon-fiber composite would be nearly as reflective to
radar energy as aluminum.

The issue in equipping gliders with transponders, the way I see it, is
the high power consumption required by transponders. Here's a typical
glider transponder: http://www.airplanegear.com/becker.htm
It seems to draw 175W to 250W. That's not insignificant, and way more
than the comm radio consumes. Then there's the weight and antenna
that reduce performance, not to mention the cost of the equipment,
installation, and maintenance.

Larry Dighera wrote:


Perhaps it would be possible to modify ATC procedures or display
software to overcome that issue. That would certainly be preferable
to requiring electrical systems be installed in all gliders.

Not to ATC.

Larry Dighera wrote:
radar energy as aluminum.

The issue in equipping gliders with transponders, the way I see it, is
the high power consumption required by transponders. Here's a typical
glider transponder: http://www.airplanegear.com/becker.htm
It seems to draw 175W to 250W. That's not insignificant, and way more
than the comm radio consumes. Then there's the weight and antenna
that reduce performance, not to mention the cost of the equipment,
installation, and maintenance.


You may have made a small mistake: 175 to 250 Watts
is the pulse output power. In the same document, the
current consumption is about a half ampere at 14 V,
which is 7 Watts.

--

Tauno Voipio (CPL(A), avionics engineer)
tauno voipio (at) iki fi

On Mon, 28 Apr 2008 19:20:20 GMT, Tauno Voipio
wrote in
:

Larry Dighera wrote:
radar energy as aluminum.

The issue in equipping gliders with transponders, the way I see it, is
the high power consumption required by transponders. Here's a typical
glider transponder: http://www.airplanegear.com/becker.htm
It seems to draw 175W to 250W. That's not insignificant, and way more
than the comm radio consumes. Then there's the weight and antenna
that reduce performance, not to mention the cost of the equipment,
installation, and maintenance.


You may have made a small mistake: 175 to 250 Watts
is the pulse output power. In the same document, the
current consumption is about a half ampere at 14 V,
which is 7 Watts.

You are correct. Here's another with even less power consumption:
http://www.sportflyingshop.com/Avion...ansponder.html
Microair T2000 Transponder, $1,825
Wiring harness for T2000, $149
Ameri-King AK-350 Blind Encoder, $179

Power input: .25 amps @ 27.50 volts;
.4 amps @ 13.75 volts TX,
80 mA RX

I wonder if those power consumption figures include the heater in the
encoder.


Perhaps it's a good idea to require equipping all gliders with
transponders after all. :-(

In rec.aviation.soaring Larry Dighera wrote:
I wonder if those power consumption figures include the heater in the
encoder.


Perhaps it's a good idea to require equipping all gliders with
transponders after all. :-(

Keep in mind that the recommendation is not to require equipping all
gliders with transponders. It's to remove the exemption given to gliders
and give them the same rules as powered aircraft with electrical systems,
to require them to have a transponder for flight into a mode C veil or
above 10,000ft. In some places this would do almost nothing; where I fly
we are outside the veil (barely) and hit 10,000ft maybe a couple of times
a year. In other places it would severely limit activity for gliders
without transponders to the extent that it would essentially be required.

The power requirements are a secondary concern, the primary concern is
cost. Power requirements of course influence cost. There are gliders with
transponders out there, so obviously it can be done. But there are a lot
of gliders for which the cost of a transponder installation would be a
sizable fraction of the total value of the aircraft, and this change could
put their owners in a very bad spot.

--
Michael Ash
Rogue Amoeba Software

Larry Dighera wrote:


You are correct. Here's another with even less power consumption:
http://www.sportflyingshop.com/Avion...ansponder.html
Microair T2000 Transponder, $1,825
Wiring harness for T2000, $149
Ameri-King AK-350 Blind Encoder, $179

Power input: .25 amps @ 27.50 volts;
.4 amps @ 13.75 volts TX,
80 mA RX

I wonder if those power consumption figures include the heater in the
encoder.

No, that figure doesn't include the encoder. The heater can be 200-300
ma when it's fully on, but the typical unit won't be fully on unless
it's "really" cold outside. In my glider, that seems to be lower than
~10 deg F - winter wave flying for me. There are encoders with less low
temperature draw, but they tend to be expensive.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Apr 28, 7:44*pm, Larry Dighera wrote:
snip
The issue in equipping gliders with transponders, the way I see it, is
the high power consumption required by transponders. *Here's a typical
glider transponder:http://www.airplanegear.com/becker.htm
It seems to draw 175W to 250W. *That's not insignificant, and way more
than the comm radio consumes. *Then there's the weight and antenna
that reduce performance, not to mention the cost of the equipment,
installation, and maintenance.

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.