How is that there is no leak through the fuel vents during aerobatics maneuvers?
There are 3 common solutions,

1) do nothing, unless the airplane is flown for an extended period of time inverted, there will be no appreciable vacuum created from fuel use and the vent is so small that there will not be appreciable fuel loss.

2) point the vent into the slipstream giving a ram air effect.

3) use two vent tubes (can be mounted either top &amp; bottom or same side), at least one extends to opposite side of the tank.


This picture is for RC or drone aircraft but the same principle is used for full scale aircraft.