On Tuesday, September 29, 2015 at 9:30:30 AM UTC-4, wrote:
I suspect you're right, T8. Would that also apply to the LNAV itself? That might make me finally address the issue of sharing a triple probe TE with my Winter backup vario, which has been the case since the glider was new in 1992. The biggest sin, I imagine, is using a "T" connection immediately behind the instrument panel rather than a "Y" farther back in the fuselage. Question: would you expect both varios to benefit from this, or just my LNAV?

Chip Bearden
ASW 24 "JB"
U.S.A.

I haven't played with an LNav in a long time. I think that's a flask/flow type instrument and those always seemed more tolerant of sharing TE with a mechanical.

We really started seeing problems when guys tee'd their new 302s in line with Winter & Sage varios. Didn't affect the mechanical, but the 302 acted lobotomized.

Whether splitting the TE line helps probably depends on the impedance of your probe. I've got one of those oldie but goodie venturi type triple probes and the venturi is mounted at the end of a rather small capillary. The impedance is high and I gave up trying to get a mechanical to play nice with a 302... solution was replace Winter with B400 for backup (pressure transducer instruments can share pneumatic sources, no issues here).

The other thing that can work is running your fancy primary vario off pitot + static with "electronic" compensation and leave the probe for your mechanical. In this case, the pitot and static need to be *really* good (fin mount triple probe) and not shared with mechanical instruments.

best,

Evan Ludeman