I was thinking more about forward/aft balance.I presume if you had a good CoG on take off and you feed equally from all tanks you would keep a good CoG.Concorde, my other pay ware add on is a more steam gauge 1960's bird and things like trim drag are too much at 60,000ft Mach2.02 so you have to use fuel to trim the CoG aft for cruise, rather than constantly have the elevons trimmed up and create drag. Then that reverses on the way down.I realised that descending or speeding up is all you can do with freezing fuel, but I was more interested in the fuel apparently losing a certain number of degrees per 1000nam at various cruise alts, and wondered if that would come into play in the 747 sim.

"presume if you had a good CoG on take off and you feed equally from all tanks you would keep a good CoG."Good point. Perhaps not equally from all tanks, but in a specified order. With all tanks full (including the tank in the Horizontal Stabilizer), fuel is firstly pumped from the Center Wing Tank (CWT)... to the point where you can pump fuel from the Horizontal Stabilizer Tank (HST) into the space made available in the CWT. This is done automatically. It's important that you get fuel out of the HST or you will end up with CoG problems for landing.With the CWT and HST empty, fuel starts coming from the inboard main wing tanks, then, when these are at a certain level, also from the (wing) reserve tanks... until the quantities in all four main wing tanks are equal. Then a sort of tank-to-engine configuration is adopted."but I was more interested in the fuel apparently losing a certain number of degrees per 1000nam at various cruise alts, and wondered if that would come into play in the 747"Over to PMDG insiders on this one ;-)Cheers.Ian.