Just recently I experienced a low battery situation which affected the
electronic vario in my club ship. The vario did not just fail, it started
giving me unreasonable readings. Eventually I figured it out when the needle
started swinging wildly - I knew the battery was getting low but it took a
few minutes to recognize the wierd behavior. The ship did not have a backup
vario installed, but I had an electronic micro-vario clipped to my hat.
DEFINITELY have a backup of some sort if you're going cross-country... as
others said, the choice of type is up to you.

Roger

"Bob Whelan" wrote in message
...
Jeff Runciman wrote:
This question was posted earlier but I was hoping for
a few more responses.

Do I put a mechanical vario or do I save space on the
panel.

Apparently I feel a need to start a religious war...

Electron movement can cease (open circuit, low battery, component
failure), become too energetic (short), pneumatics can fail (blockage,
leak). Everything has a life.

Which failure modes have you encountered most often? Which have you heard
people complain about most frequently? Have you ever heard of a
mechanical vario *suddenly* dying from an internal (i.e. non-pneumatic)
cause? Do you feel comfortable with all your panel eggs in an electronic
basket? How much thought to true redundancy have you given?

Your answers to questions as these may clarify your views.

Any approach is a double-edged sword, and there will be some who (rightly)
point out that frequency of failure is somewhat related to frequency of
use...and these days (both discrete-component based and IC-basd) electrics
are ubiquitous in sailplanes, and thus a frequency-of-failure based
assessment is to some extent invalid. That noted, when I got into
soaring, electric varios were still a newfangled item, yet despite the
relatively low frequency of them in panels, there seemed to me to be an
inordinate frequency of complaints about electric (radio, cario) failures.
IMHO, that's still true today, probably because electric systems a a)
ubiquitous, b) seemingly simple and relatively foolproof for any
basically-educated-hack to implement, but c) are in fact complex
(chemically, physically, electronically, conceptually).

Each of my personally-owned sailplanes when purchased had real electrical
systems in them, including the one I've flown since 1981. Eventually its
radio died, then its (uncompensated, used only for audio) Ball electric
vario. Today I use a handheld radio, and one day I hope to remember to
borrow my wife's Malletec for its audio. Only one person ever has
criticized my thermal etiquette (his experienced passenger later privately
told me he disagreed with the criticism), and my fun meter has never felt
seriously handicapped by the absence of electronic input. My Sage
continues to work perfectly, accompanied by the usual A/S, (sticky)
altimeter, and (little-used) whiskey compass. There are at least three
naked instrument holes in the panel.

Sometimes I feel like a dinosaur.

Regards,
Bob - a K.I.S.S. fan - Whelan