Mechanical Vario or not?

For the past 6 years I've been using an SN10, backed up with a (no
flask) Westerboer electric (with audio), running on two seperate
battery systems, either of which can run some or all of the panel. No
mechanical - traded in the Winter the glider came with for the
Westerboer.

Both varios match perfectly, which makes sense since they are plumbed
to the same TE probe. The only improvement I would like would be to
have one vario use electronic TE (selectable, ideally) and the other
the probe, for redundancy in case the probe failed (yes that has
happened to me, with both an earlier glider/probe combo and in the TE
plumbing in the current glider).

Personally, I would prefer to have big digital airspeed, altitude, and
angle of attack displays (with some form of analog trend information)
in place of the sticky and slow mechanical airspeed indicator and
altimeter. Without electrics, I'm going to land anyway, so I design my
electrics accordingly. And I know (from experience) that I can fly
500k+ without a working airspeed indicator. I also care more about GPS
elevation and height above ground than what the pneumatic altimeter is
lying about.

Caveat - I wouldn't even think about setting up a 1-26 or a primary
trainer this way! This is for serious XC and racing fanatics....be
sure not to tell the spousal unit of the cost involved!

66

My major concern was that of secondary battery failure due to low
temps. It's not like we even get the opportunity to reach such heights
where I fly, but, should the opportunity arise to explore some wave,
i'd hate to see the little 9V backup battery on the ILEC, decide to
have a rest when it was needed most.
Does anyone have any clues on the behaviour of lithium batts at lo
temps?


Fish

Fish wrote:
My major concern was that of secondary battery failure due to low
temps. It's not like we even get the opportunity to reach such heights
where I fly, but, should the opportunity arise to explore some wave,
i'd hate to see the little 9V backup battery on the ILEC, decide to
have a rest when it was needed most.
Does anyone have any clues on the behaviour of lithium batts at lo
temps?

Yes, they show significantly less degradation at cold temperatures than
alkaline cells or lead acid batteries. They are used in the Perlan
project for precisely this reason...

Marc

At 22:18 27 June 2006, Fish wrote:

My major concern was that of secondary battery failure
due to low
temps. It's not like we even get the opportunity to
reach such heights
where I fly, but, should the opportunity arise to explore
some wave,
i'd hate to see the little 9V backup battery on the
ILEC, decide to
have a rest when it was needed most.

That is a real problem. I lost my diamond height claim
because the new 9v battery in my EW barograph packed
in at 16000 ft, because of the cold. When we tested
it on the ground after the flight it returned to giving
8.6 volts.
A shame I did not fit the clockwork one we had.
Does anyone have any clues on the behaviour of lithium
batts at lo
temps?


Fish

Kirk makes an excellent point. There's a lot written about dual
batteries, backup electrical systems, mechanical vs. electronic varios,
etc. But the common point of failure for most of us is the TE probe. In
my last glider, I had completely independent varios...though both were
electric. One used a tail-mounted TE probe and a homemade netto device
connected to front statics. The other was driven by a Schuemann
TE/netto compensator connected to rear pitot and statics. Nothing short
of a lightning strike or water landing was going to take out my panel.


In my current glider, I've got a Winter mechanical backup vario but
it's driven by the same tail-mounted TE source as is the LNAV
electronic device. I've never done an analysis or survey but I suspect
losing the TE signal is not much less likely than losing a battery. Yet
this is the first mention I can recall on RAS of this subject.

Anyone know of a [relatively] inexpensive vario with electronic TE
compensation? I read an article some time ago (Dick Johnson?) about how
mounting a TE probe on the fuselage works better and is not nearly as
draggy as we once thought.

Chip Bearden'
ASW 24 "JB"

I like to use the 302 set up on electronic compensation and the winter or
backup electric on TE probe- no talking between the varios - IM

wrote in message
oups.com...
Kirk makes an excellent point. There's a lot written about dual
batteries, backup electrical systems, mechanical vs. electronic varios,
etc. But the common point of failure for most of us is the TE probe. In
my last glider, I had completely independent varios...though both were
electric. One used a tail-mounted TE probe and a homemade netto device
connected to front statics. The other was driven by a Schuemann
TE/netto compensator connected to rear pitot and statics. Nothing short
of a lightning strike or water landing was going to take out my panel.


In my current glider, I've got a Winter mechanical backup vario but
it's driven by the same tail-mounted TE source as is the LNAV
electronic device. I've never done an analysis or survey but I suspect
losing the TE signal is not much less likely than losing a battery. Yet
this is the first mention I can recall on RAS of this subject.

Anyone know of a [relatively] inexpensive vario with electronic TE
compensation? I read an article some time ago (Dick Johnson?) about how
mounting a TE probe on the fuselage works better and is not nearly as
draggy as we once thought.

Chip Bearden'
ASW 24 "JB"