Cambridge 302 and Super netto

Can some-one please explain the difference between netto and Super Netto as
used on the Cambridge 302 variometer.
Also what should the 302 be set to?
Thanks
Ross

Yes. This is an area where the 302 is weak and something
I wish Cambridge would rectify.

'Netto' should display the vertical motion of the air
mass (as opposed to the vertical motion of the glider)..so
in still air, it would show zero, even if your glider
is decending at 130 feet per minute. In gently rising
air, it would start to show, say, 0.5 up, in sinking
air, it shows down. This display means you can seek
out rising air and so maximise your glide angle, without
the need to stop and turn. It displays what the airmass
is doing irrespective of the sink rate or speed of
your glider.

'Super Netto' shows the climb rate you could achieve
if you stopped to circle at your best climb rate...in
effect this means it only functions differently from
a t/e vario at higher speeds, when it removes the additional
sink rate caused by you flying at 100kts rather than
50kts.

Netto is a really useful function in countries with
weaker lift (like the UK) and it is a real issue not
having this function in an otherwise excellent vario....come
on Cambridge, implement the *****function properly!

Chris




At 05:54 12 September 2003, Ross Biggar wrote:
Can some-one please explain the difference between
netto and Super Netto as
used on the Cambridge 302 variometer.
Also what should the 302 be set to?
Thanks
Ross

Chris,

You can select netto, super-netto or always TE in cruise
mode for the 302 using the 300 Utility or a 303.

John Galloway

At 06:48 12 September 2003, Chris Davison wrote:
Yes. This is an area where the 302 is weak and something
I wish Cambridge would rectify.

'Netto' should display the vertical motion of the air
mass (as opposed to the vertical motion of the glider)..so
in still air, it would show zero, even if your glider
is decending at 130 feet per minute. In gently rising
air, it would start to show, say, 0.5 up, in sinking
air, it shows down. This display means you can seek
out rising air and so maximise your glide angle, without
the need to stop and turn. It displays what the airmass
is doing irrespective of the sink rate or speed of
your glider.

'Super Netto' shows the climb rate you could achieve
if you stopped to circle at your best climb rate...in
effect this means it only functions differently from
a t/e vario at higher speeds, when it removes the additional
sink rate caused by you flying at 100kts rather than
50kts.

Netto is a really useful function in countries with
weaker lift (like the UK) and it is a real issue not
having this function in an otherwise excellent vario....come
on Cambridge, implement the *****function properly!

Chris




At 05:54 12 September 2003, Ross Biggar wrote:
Can some-one please explain the difference between
netto and Super Netto as
used on the Cambridge 302 variometer.
Also what should the 302 be set to?
Thanks
Ross

Chris,

I usually use the super-netto but I have tried the
netto on a couple of flights.

To be honest I find the super-netto a bit confusing
because if I set the 302 time constant to 3 seconds
my 302 and back up Borgelt B40 needles seem to always
closely match each other no matter what speed I fly.
However with the 302 on the bench and the airspeed
inlet pressured to simulate flight the super - netto
seems to be correctly set up.

The netto itself works on the bench and seems to make
sense in flight. And yes, the 1.5 knot up on the ground
(and on the bench) is compatible with the netto being
switched on.

My own gripe about the 302 is the lack of a bugs adjustable
speed to fly in the vario. From past reactions to
this observation noone else seems to think that is
an ommission and are happy to have a bugs adjusted
final glide height calculation on Glide Nav/Winpilot
and then fly cruise speeds based on a different polar;-)
I would prefer to fail to follow accurate data than
to fail to follow inaccurate data.

John Galloway


At 18:12 12 September 2003, Chris Davison wrote:
John, do you use Netto and does it work? I have just
had one of those 'I may be an idiot' moments....the
issue being when I have set the vario to Netto in the
past, with the glider on the ground, the needle points
to about 1.5kts up....which I have just realised it
what it should do...as it is assuming if the glider
is maintaining altitude it must be in rising air eauivalent
to the sink rate.....DOH.

Chris


At 15:18 12 September 2003, John Galloway wrote:
Chris,

You can select netto, super-netto or always TE in cruise
mode for the 302 using the 300 Utility or a 303.

John Galloway

At 06:48 12 September 2003, Chris Davison wrote:
Yes. This is an area where the 302 is weak and something
I wish Cambridge would rectify.

'Netto' should display the vertical motion of the air
mass (as opposed to the vertical motion of the glider)..so
in still air, it would show zero, even if your glider
is decending at 130 feet per minute. In gently rising
air, it would start to show, say, 0.5 up, in sinking
air, it shows down. This display means you can seek
out rising air and so maximise your glide angle, without
the need to stop and turn. It displays what the airmass
is doing irrespective of the sink rate or speed of
your glider.

'Super Netto' shows the climb rate you could achieve
if you stopped to circle at your best climb rate...in
effect this means it only functions differently from
a t/e vario at higher speeds, when it removes the additional
sink rate caused by you flying at 100kts rather than
50kts.

Netto is a really useful function in countries with
weaker lift (like the UK) and it is a real issue not
having this function in an otherwise excellent vario....come
on Cambridge, implement the *****function properly!

Chris




At 05:54 12 September 2003, Ross Biggar wrote:
Can some-one please explain the difference between
netto and Super Netto as
used on the Cambridge 302 variometer.
Also what should the 302 be set to?
Thanks
Ross

On 12 Sep 2003 20:26:36 GMT, John Galloway
wrote:



My own gripe about the 302 is the lack of a bugs adjustable
speed to fly in the vario. From past reactions to
this observation noone else seems to think that is
an ommission and are happy to have a bugs adjusted
final glide height calculation on Glide Nav/Winpilot
and then fly cruise speeds based on a different polar;-)
I would prefer to fail to follow accurate data than
to fail to follow inaccurate data.

John Galloway
The B50 does this properly and has done since its inception in 1995.

Mike Borgelt

Borgelt Instruments

On Fri, 12 Sep 2003 17:48:03 +1200, "Ross Biggar"
wrote:

Can some-one please explain the difference between netto and Super Netto as
used on the Cambridge 302 variometer.
Also what should the 302 be set to?
Thanks
Ross



Please see the article on our website under articles called "basic
glider instruments"
That will explain all.

Mike Borgelt

Borgelt Instruments
www.borgeltinstruments.com

What I got from Cambridge is that both of you are partially
correct. Yes, you can transfer a bugs setting to the
302 and you can also read it back out. However, I
was told by Cambridge that the instrument does not
'currently' use the bugs setting to degrade the polar
information that the 302 contains. That was about
a year ago though so perhaps that has changed with
one of the later firmware versions. Later!-MarkAt 03:06 13 September 2003, Eric Greenwell wrote:In article , says... My own gripe about the 302 is the lack of a bugs adjustable speed to fly in the vario. From past reactions to this observation noone else seems to think that is an ommission and are happy to have a bugs adjusted final glide height calculation on Glide Nav/Winpilot and then fly cruise speeds based on a different polar;-)Are you sure of this? The vario has a page for setting
bugs, so I assume it is used for the speed fly. Since the vario
doesn't have a final glide calculation, and the bug setting in Glide
Nav is transferred to the vario if you set it there, I can't
think of any other reason for having that page. -- !Replace DECIMAL.POINT in my e-mail address with just
a . to reply directlyEric GreenwellRichland, WA (USA)

That's my point - you can configure winpilot/GlideNav
for a bugs adjusted final glide height calculation
on your PDA but there is no capability for the 302
to accept a bugs adjusted polar from either the PDA
or a 303. This is confirmed by CAI who, when I queried
this, said there was no need for a bugs page on the
302 or the 303 because the 302 couldn't use it.

It seems such a simple capability to add to the 302
- just add another bugs page to the vario, like the
ballast one, and calculate the adjusted polar for the
STF. To me it is extraordinary that something all
other speed directors do (including the L/S-Nav) cannot
be done on a 302.

After several attempts to discuss this with CAI I did
get a reply that the subject would be put to the developers
for consideration. This was before the most recent
reorganisation.
Perhaps some other owners might like to take this up
if they feel the same as I do.

Maybe you don't get bugs or rain in US but we sure
as hell do here in Scotland:-)

John Galloway

At 05:36 13 September 2003, Eric Greenwell wrote:

Nope. I got confused - it's the ballast setting that's
on the vario,
not the bug setting.

--
!Replace DECIMAL.POINT in my e-mail address with just
a . to reply
directly

Eric Greenwell
Richland, WA (USA)

"John Galloway" wrote...
That's my point - you can configure winpilot/GlideNav
for a bugs adjusted final glide height calculation
on your PDA but there is no capability for the 302
to accept a bugs adjusted polar from either the PDA
or a 303. This is confirmed by CAI who, when I queried
this, said there was no need for a bugs page on the
302 or the 303 because the 302 couldn't use it.

The 302 accepts, but ignores, the bug setting. The 302 data protocol includes a
command to send a new polar, if the authors of the PDA wanted to, they could
send an updated polar each time the bug setting changes. Apparently, some don't
want to...

Marc

Marc,

That is a very interesting and, to me, surprising piece
of information. Here is what Peter Rogers sent me
on Feb 10th in answer to a query about using a 302/303
combination which I had found had no setting for bugs
at all:

'Hello John -
As you know the 303 does not currently have a 'Bugs'
screen. The reason
for this is the 302 does not utilize any 'Bug' information
in determining
final glide. We may at some point implement it but
it has not been a high
priority. Since it's not used we didn't see a point
of making a screen for
it since it would give our customers a false impression
that we were using
the value in our calculations when in fact we were
not.

Pete'

Which software does send a new bugs adjusted polar
to the 302? Will it make the PDA software, the 303
final glide altitudes, and the 302 speed to fly all
use the same polar?
I know that GlideNav and PocketNav do not because if
I fly in buggy conditions and put a bug factor in GlideNav
the GN final glide altitudes and the 303 final glide
altitudes diverge subsantially so the bugs setting
on GN is only being used there and not sent to the
302/303. The ballast setting is sent.

Thanks,

John Galloway





At 09:48 13 September 2003, Marc Ramsey wrote:

'John Galloway' wrote...
That's my point - you can configure winpilot/GlideNav
for a bugs adjusted final glide height calculation
on your PDA but there is no capability for the 302
to accept a bugs adjusted polar from either the PDA
or a 303. This is confirmed by CAI who, when I queried
this, said there was no need for a bugs page on the
302 or the 303 because the 302 couldn't use it.

The 302 accepts, but ignores, the bug setting. The
302 data protocol includes a
command to send a new polar, if the authors of the
PDA wanted to, they could
send an updated polar each time the bug setting changes.
Apparently, some don't
want to...

Marc