Netto

On 1 août, 18:24, Martin Gregorie
wrote:
On Mon, 01 Aug 2011 13:18:02 -0600, BobW wrote:
A few 'weird Libelle pilots' (and myself) aside, most glider cockpits
I've seen have (at least!) two varios, so I suppose a person might argue
that - when I still had the Ball in place - I was using two varios to do
what the C4 (with which I'm 100% ignorant) implements in a single
unit...save for the fact it 'continually subtracts' that aforementioned
200 fpm/2 knots when in cruise mode.

I'm also a Libelle driver, though of the two vario variety: I carry a
Borgelt B.40 as backup to the C4 and fins its extremely rapid response is
a useful addition to the C4, especially for finding the hot spots under
large clouds. *

I've wondered why the C4 uses super netto rather than plain netto in
cruise mode. My current best guess is that maybe the switch from netto to
TE modes causes the vario to step its reading. The C4 never produces a
sudden reading change that I've noticed when it switches between modes.

Anyhow, returning to the O.P.'s O.Q. (original question), my vote would
be to use 'unadjectivized "Netto"' for at least a couple of 'longish
soaring flights' or until such time as what I've tried to describe makes
conceptual/in-flight sense.

Agreed. I suggest the OP does a few flights with each netto setting, *in
each case staying with the same netto type long enough to get used to
what its telling him in cruise mode. Then he should simply use the one he
likes best.

--
martin@ * | Martin Gregorie
gregorie. | Essex, UK
org * * * |

Thank you for your for your answer.
The owner manuel says; netto is what the airmass is doing, relative
vario is what you would get if you stop for thermaling.
After 50 hours with netto I will try relative netto for a while.
The best of lift.
S6

On Jul 29, 7:05*pm, BobW wrote:
On 7/29/2011 11:19 AM, bish wrote:

Hi

This question has probably been ask many time!
My new to me LX 7000 offer the choice of Netto or Relative netto for
the vario needle.
Why should I choose one or the other?
Or which is most usefull?
Thank you
S6

Uh oh...one of those 'religious questions' on RAS. Everyone tighten your
seatbelts!

Disclaimer: I have absolutely Zero Experience/Exposure to an LX 7000. The rest
of this comes from a pilot having flown only w. a(n excellent) mechanical
netto display since 1981.

Further - displaying additional ignorance here - I'll admit to being uncertain
what 'relative netto' actually is or means. That noted, after being exposed to
*netto* 'way back when' and pondering on it briefly, my brain asked itself the
question, "What more do I need or want to know than what the air is actually
doing?" From that single piece of information, everything else I - as Joe
Glider Pilot - might *want* to do becomes immediately obvious.

Assuming your ship has decent speed compensation, a netto display instantly:
1) lets you accurately conclude if the air through which you're flying is
'climbworthy,' and 2) (when combined with a good, old-fashioned, speed-to-fly
ring, set as desired for the day in question, and, flying in descending air)
instantly/continuously points to the correct speed to fly, in a non-iterative
manner. Non-netto mechanical displays with which I'm familiar, achieve these
two things only via indirect/iterative means, IMHO. Joe Pilot has to do
considerably more mental work/instrument-gazing with a non-netto display.

All bets may be off with electronic?microprocessor-based indicators...though
just because something is electronic is no guarantee of 'new-&-improved' or
'simpler' or 'better' information display, in my experience.

To my way of thinking (being a simple kind of guy), an analog-displayed netto
(whether achieved mechanically or electronically), combined with a speed ring,
is simple and intuitive, and not obviously improved upon. (I'm aware of how
useful a well-implemented audio can be...)

Downsides?
1) You'll get 'somewhat bogus' information on tow, due to the influence of the
towplane's added energy...truly a minor deal to me. Certainly it never
hampered/bothered my "OK to release?" decision, since the first few moments of
towed flight - regardless of towplane or situation - quickly allows
determination of that particular tow combination's steady state netto
indication, hence anything above that is lift, of immediately known strength.
2) Some don't like not 'knowing' the actual climb rate when climbing, since
the needle displays air vertical motion, not glider vertical motion. Never
having had difficulty subtracting 200 from a needle indication, it never
bothered me. Besides, having begun soaring in the days before electronics, I
quickly developed the habit of timing my actual rate of climb (sweep second
hand and altimeter) anyway, from which I concluded most people were hopeless
optimists when it came to reporting *their* climb rates.

Use what works best for how your mind works, and go have fun!

Regards,
Bob W.

P.S. Kinda-sorta related, don't lose sleep over errors inherent in 'polar
uncertainties' (e.g. ballast or not, circling or not). From Joe Average
Pilot's perspective. this sort of 'stuff' is in the noise level compared to
the lift/sink strengths on which you'll be basing your 'thermic day' flight
decisions.

Slightly OT, but do you fly without an audio?

THAT is scary! Especially, if you are staring at a stopwatch and
altimeter, trying to figure out what your climb rate is, and watch the
vario needle to center the thermal. Doesn't leave much time for
looking out the window...

The beauty of modern gizmos is that they do all that "stuff" for you,
and let you concentrate on what is going on outside the cockpit, where
there be dragons!

As far as Relative (or Super) Netto, it just takes one more bit of
math out of the cockpit - just like regular netto takes some math out
compared to plain old TE.

So, I'm cruising along, waiting for a 5 knot thermal to climb in.
With a regular Netto, I've got to wait for a 7 knotter. With
relative, I just wait until I see 5 knots, and up we go!

Truthfully, I've tried both, and kinda prefer plain old netto,
especially when running under cloud streets...

Cheers!

Kirk
66

On 8/2/2011 11:56 AM, kirk.stant wrote:

Major snip...

Slightly OT, but do you fly without an audio?

Probably more than 50% of the time. Learned that way, have had ships with and
without audio, and find it useful and a convenience, but far from
'life-or-death crucial.' For that matter, having: 1) flown (including
thermal-XC) without functioning vario (several times...usually from water in
the plumbing); 2) flown (thermal XC again) without functioning ASI
(intermittent 'T/U' on a series of XC flights before 'indubitable death'); and
3) flown (once, thermal XC again) w/o vario *and* ASI (water, again), I've
found the first two conditions are pretty much non-events, while the last
combination took maybe 15 minutes or so to get accustomed to, but one's butt
and ears are actually quite sensitive if you pay attention to 'em. The butt in
particular is really good at detecting vertical acceleration *changes* which -
if Joe Glider Pilot learns to pay effective attention to it/'em - is far
quicker than any vario, which displays motion only after it has occurred, no
matter how short the vario's time constant.


THAT is scary!

Why?

Especially, if you are staring at a stopwatch and
altimeter, trying to figure out what your climb rate is, and watch the
vario needle to center the thermal. Doesn't leave much time for
looking out the window...

Ah! Who said anything about 'staring'? Peripheral vision works quite well for
noting (say) vertical passage of a sweep second hand and progression of an
altimeter hand on routine panel scans. (Anyone who thinks measuring a climb
rate over less than 30 seconds is 'XC valid' is indulging in self-deception; I
happen to prefer 60 seconds as 'more honest.' In any event, it's probably the
rare glider pilot who doesn't scan SOMEthing on the panel once or twice a
minute. Time yourself some time!)

Furthermore, my instructor pithily noted, "Staring at the instruments doesn't
make you climb any faster." He further noted, "Besides, climbing after a
mid-air collision is generally impossible." Both droll understatements made
perfectly good sense to me, even if I had NOT paid very close attention to
listening to and learning from what he sought to convey to me.


The beauty of modern gizmos is that they do all that "stuff" for you,
and let you concentrate on what is going on outside the cockpit, where
there be dragons!

Agreed on both counts, but especially the 'dragons' bit. Situational awareness
is the key.

That's true not 'merely' in sailplanes. Consider the drive to and from the
gliderport...I don't - in the absence of a functioning speedometer - have any
trouble driving a vehicle with which I'm 'a few drives worth' familiar and
remaining speeding-ticket-free. BTDT in lots of vehicles, from cars to big
rigs to buses over the years. 'Ear calibration' is real. Situational awareness
is real. Practice ought not to be only a sometime event.

Of course, I'm not about to claim ear/butt calibration is as precise/effective
as 'the latest-n-greatest instrumentation,' but I hope the point that - at
least in the intermountain west on any averagely decent day for a 'moderately
experienced' sailplane pilot - 'modern gizmos' while usefully enabling, are
far from absolutely necessary. Cat-skinning remains a multi-method activity.

As far as Relative (or Super) Netto, it just takes one more bit of
math out of the cockpit - just like regular netto takes some math out
compared to plain old TE.

Granted, but you don't get it 'for free.' The instrument designer is making an
educated guess as to your ship's 'circling sink rate increment.' Presuming
curiosity, Joe Pilot's own tests may disagree with the designer's guess. But
more to the point, is it *really* so difficult to always subtract 2 knots from
a glanced-at instrument reading? As non-mathematical a mind as is mine, that
subtraction quickly became second nature for me. This is one case where I find
the raw data more rapidly comprehensible/useful than massaged data.
Cat-skinning, again...

So, I'm cruising along, waiting for a 5 knot thermal to climb in.
With a regular Netto, I've got to wait for a 7 knotter. With
relative, I just wait until I see 5 knots, and up we go!

Truthfully, I've tried both, and kinda prefer plain old netto,
especially when running under cloud streets...

Cheers!

Kirk
66

Regards,
Bob - no harm, no foul? - W