I think i found a way to stop the fuel from boiling away without installing extra mods!
1. Go to your KSP folder and enter the "Game Data" folder.
2. Go into the "Real fuels" folder and then into the "Resources" Folder.
3. Look for a file called "ResourceHsps.cfg" and enter it with notepad.
It should look a bit like this:
@RESOURCE_DEFINITION[LqdOxygen]:FOR[RealFuels]
{
%hsp = 0 // specific heat capacity (kJ/tonne-K as units) // recalc, mols are for O2 on wiki
%vsp = 0 // heat of vapourization (KJ/tonne as units)
%conductivity = 0.152
}
...
4. Look for this:
@RESOURCE_DEFINITION[LqdOxygen]:FOR[RealFuels]
{
%hsp = 0 // specific heat capacity (kJ/tonne-K as units) // recalc, mols are for O2 on wiki
%vsp = 0 // heat of vapourization (KJ/tonne as units)
%conductivity = 0.152
}
@RESOURCE_DEFINITION[LqdHydrogen]:FOR[RealFuels]
{
%hsp = 0 // specific heat capacity (kJ/tonne-K as units) // recalc, mols are for H2 on wiki
%vsp = 0 // heat of vapourization (KJ/tonne as units) or 8.97 * 10^5 or 8.97E5?
%conductivity = 0.072
}
5. Change the value of "%vsp = ..." to 0 at both fuels.
6. Save and enjoy the game without fuel boiloff!
If somebody has a better solution please let me know!