There is a great difference between thermal expansion of water
splitting the wing and trapped air (at altitude) splitting the wing,
this could happen regardless of the amount of water (air is the
significant factor). The amount of water that could heat and cause a
problem would be dependent on the wing being completely full. (I only
fill mine half way)

Gary Kemp
Andreas Maurer wrote:
On Mon, 23 May 2005 22:26:11 GMT, Gary Emerson
wrote:

Hopefully thermal expansion will not become an issue....splitting a
wing
open because it warmed up in the sun could ruin your day.... Your
"check valve" has the potential to allow such a situation...

This is very likely to happen. I once heard a report of a pilot (iirc
Helmut Grix) who had plugged his water drains before he went up in a
wave. The over-pressure of the air in his waterbags broke his wing
shells in the thinner air - he needed completely new wings
afterwards.


Bye
Andreas