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"