ORIGINAL: MTK
...The thristiest powerplant around is the YS170-175. These models normally carry 20 fluid ounces fuel (of SG of around 0.87, or about 18 ounces fuel, weight basis) (Remember that 1 fluid ounce = 1.04 ounces water weight)
I'll be blunt. ANYONE carrying a full 20oz tank of fuel into a competition flight needs their head read.
If sombody needs more than 250g (10 fluid oz) of glow fuel to get through F3A then they should take the parachute off the back of their plane. NO electric flyer runs a flight with enough battery capacity for back to back rounds, there's no excuse whatsoever for IC guys to.
Looking at some of the weights for the top of the line Japanese YS powered planes they'd make 5kg WITH fuel. 5.5kg with fuel and that'd open up the door for a YS dz200cdi twin...