Pneumatic switching?

T o d d P a t t i s t wrote:
Marc Ramsey wrote:
If it were my glider, I'd always run the 302 off the nose pitot and
fuselage static, using the 302s (excellent) electronic total energy
compensation.


As MIke Borgelt recently pointed out, this produces two in
phase error signals. Running with the pitot and static both
on the nose or both on the tail, preferably with the pitot
twice as far from your CG, will produce canceling errors for
electronic TE.

Yes, I'm sure it makes sense in theory. In practice, I'm flying a
glider with an electronic TE vario (C302) on nose pitot and tail boom
static (which is all that is available), and I've never seen it shown
any "errors" that weren't also present on the B40 running on the TE
probe by itself. But, YMMV...

I've had problems in the past, in several different gliders, with the
combined pitot/static/TE tail probes (I've got 3 different types of
multi-probes gathering dust in the closet, right now) measuring
airspeeds that vary by several knots from the nose pitot, fuselage
static setup. It's, of course, hard tell which was more accurate
(unless you're Dick Johnson), but given that the POHs inevitably require
use of latter setup for the ASI and altimeter, I'd rather have
everything working off the same source...

Marc