RE: Jett Boubbless tank
The tetra bubbless tanks can be setup 2 or three line. Both are described in the instructions I received. If you go 3 line you fill through the line to carb and open vent line that goes to top of tank. Using a manual or electric pump this purges the air out of the top. When done filling close off vent. When emptying, empty from carb line with vent line closed. The pressure tap that comes with the tank is into the hard tank outside of the bladder, so air is not introduced there. I have used this for sport club racing since we are not allowed any syringe fillers (there was an incident of someone adding something to the tank) as we use club provided fuel and everyone fills at a common can with pump.
This method seems to work very well. Try it outside of the plane and you'll see how the air comes out so there is no air left. Not as bullet proof as 2 line and syringe I am guessing, so I guess that is why pylon racers generally go that route.
- Joe.