Jet A1 specific gravity at high temperatures

[Brakes...beer]

I have a friend who operates a business jet with auxiliary fuel tanks. The aircraft was refuelled somewhere hot, but the aux tanks have no gauges, so they only know how many litres went in. They have no SG tables on the aircraft and need to work out how many kilos they have in the tanks before they next fly. The standard 0.8 obviously won't work owing to the high temperature. Can anybody direct me to some tables on the internet (I've done a search to no avail) with this info? Failing that, what is the SG of Jet A1 at 30/40/50 degrees C?

I'm off for 3 days so can't look it up on our aircraft until the 8th.

Bizarre request but any help much appreciated.

[john_tullamarine]

Not that simple .. also depends on the source crude ... for a few dollars, you put an hydrometer in the aircraft and measure the SG directly .... ?

Try this page for a bit of a related read.

Amazing the stuff one can find on the Net ...

[Swedish Steve]

One thing to remember is that for small quantities the SG does not make a lot of difference. Our airline uses a standard SG for all short haul aircraft of 0.800. The difference for 8000kg from summer to winter SGs is only about 300kg. Obviously if you are putting 150000litres on a B747 it makes a difference, but not worth the effort on an aux tank on a business jet.

The refueller who fills up the tank will always give you the SG which will depend on the source of the fuel and where it is stored. If it comes out of a pipe line it will be well below ambient
temp.

[Mariner9]

A good rule of thumb is to subtract 0.0007 from the SG for every degree centigrade above 15C

[Brakes...beer]

Thanks, just the ticket.

[spannersatcx]

Uplift in litres X S.G gives you the weight.

i.e. 10000ltr X 0.8 = 8000KGs 10000lts X 0.793 = 7930 KGS etc etc