What I was wondering is whether there are any gliders out there with
thermometers in the tanks. My hunch is that, together with non-leaking
valves, that would allow a great deal of added flexibility. It would also
reduce the amount of speculation in that thread

Best
--Gerhard

Can anyone share some wisdom on using water at high elevations for long durations? How do you know your fin or wing tanks will not freeze? If I am at 18K for 6 hrs in the Sierras, I really don't want my vertical stab splitting open in flight. Has this ever happened? Any guidance would be appreciated.