Pneumatic switching?

On a self-launch with pylon mounted prop, the prop wash can interfere with a
probe mounted on the vertical fin. One way to get around this is to use a
pneumatic switch to change from tail probe to nose pitot/fuselage static
when running the engine. Question is, what plumbing is best to switch,
pitot, static, TE or combination of these?

Glider in question is equipped with a 302 using pneumatic compensation (not
electronic) and Tasman electronic back-up vario (no flask). Currently tail
TE is plumbed to both varios direct (no switching). Two ganged pneumatic
switches are used for the 302 pitot and static inputs to switch these from
fuselage when motoring, to tail probe when soaring. ASI is connected to nose
pitot/fuselage static (no switching). This configuration seems to work okay,
but is this really the optimal configuration? For more sensitive detection
of lift during self-launching, would it be better to switch the vario/s TE
input from tail TE to cockpit or fuselage static, and forgo switching
either pitot or static to the 302?

Thanks for any input on this.

all the best,

bumper

bumper wrote:
This configuration seems to work okay,
but is this really the optimal configuration? For more sensitive detection
of lift during self-launching, would it be better to switch the vario/s TE
input from tail TE to cockpit or fuselage static, and forgo switching
either pitot or static to the 302?

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. The Tasman would always be connected to the TE probe, and
just ignored when the engine is running. There is no need to add the
complication of pneumatic switches...

Marc

I have my varios plumbed as Marc suggests, but in my case the other
vario is a Winter. It bounces all over the place while under power,
while the 302 provides an excellent aid in finding and centering a
thermal ASAP after launch.

-Tom

That's how my TwinIII SL was working. With a Peschges VP 6, that did
it's own thing with Pitot and static for TE compensation.
The ship did have a Pneumatic switch, and simply turned the Probe on
and off in the back. I think I was able to also feed the VP 6 with the
probe, but never did, and compared

Dieter