PPRuNe Forums > Wannabes Forums > Professional Pilot Training (includes ground studies) > More fuel in tanks when colder temperature/higher density? PDA View Full Version : More fuel in tanks when colder temperature/higher density? WhySoTough9th Aug 2012, 12:11A friend of mine the other day was saying that he once did this. In winter time, the high density also affects the fuel, thus allowing you to carry some extra fuel in your tanks. Is this possible to do? How would you know how much extra you can carry? mad_jock9th Aug 2012, 12:17It does effect things but not by that much. You will find that the volume per hour burnt will change but the mass per hour will be the same for a given power setting. There are normaly performce figures provided when the difference is large enough to have any effect. peterh33711th Aug 2012, 07:33Avgas is about 0.1% per degC in volume so if you fill right up with fuel which ITSELF is say -10C then you are carrying 3% more energy than if the fuel was say +20C. In reality the only way to achieve that is to fill up, leave the plane outdoors at -10C and then when the fuel has shrunk you top off the tanks :) Then go flying right away before the tanks warm up and the juice leaks out of the vents :) mutt11th Aug 2012, 08:42It does effect things but not by that much. Kinda depends on how fuel you are talking about :):) This is one of the reasons we attempt to schedule long haul flights at night. NutLoose11th Aug 2012, 13:49That is why airliners measure their fuel quantities in weight, i.e Lbs and Kgs, a Gallon is a quantity that varies with temperature, but the weight of that Gallon remains a constant, so by measuring it by weight you know exactly how much fuel you always have in the tank.