Originally Posted by
57mm
The Russians used (maybe still use) the Libelle g-suit, which covers from neck to ankle and is formed of fluid filled bladders. Not sure of the mechanics of operation, but believe it to have been quite effective, more so than a traditional air inflated suit.
Just reading an autobiography of an FAA pilot from WW2, they trialled water filled g-suits, essentially as you pulled g the water was forced into the lower parts of the suit pressing against the legs. They didn't seem to have been in service long though, his suspicion being due to a fatality after a ditching with one on. The less dense fresh water in the suit caused the survivors legs to float to the surface eventually drowning him. There was also the disadvantage in hot climates that you soon found yourself wearing a few kilos of warm water.