any help?
You are really asking for the coefficient of thermal expansion of a family of kerosenes. It is given the Greek symbol “Beta” and is 0.95 – 1.00 per degree Celsius.
Unfortunately it does vary with temperature as indeed do the thermal expansion properties of plain old water.
Suppose you had a 1000 cc of kerosene at 15 deg C and it weighed 800gm. If the coefficient of thermal expansion is 0.001 per deg C then the change in volume down to 5 deg C and up to 25 deg C will be 1000 x 0.001 x10 = 10 cc
The weight of the kerosene is still 800gm, only the volume has changed.
So the specific gravity is 800/990 = 0.808 at 5 deg C for 0.800 at 15 deg C and 800/1010 = 0.782 at 25 deg C
Points to note are that a) coefficient of thermal expansion is not a constant over the whole range of temperatures you are likely to meet; b) at very cold temperatures the fuel is no longer purely liquid; c) what are the effects of the additives?
From memory F35 AVTUR is specified within a window of acceptable specific gravity of 0.775 – 0.840 but generally speaking pans out to be 0.803 and with the usual dyestuffs and additives has a coefficient of 0.99 per degree Celsius but I am none too sure about that last figure.