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