Nick Thomas
... on shorter charter flights was there a mininium ammount of fuel that had to be loaded just to always have enough fuel for CofG movement...
Yes, 35,000 kgs, at take-off, for a short supersonic flight. This would allow sufficient fuel to be transferred rearwards in order to achieve a CG approaching 59%.
If the flight was to remain subsonic, the fuel figure dropped to 25,000 kgs, as the required CG for subsonic cruise was 55% not 59%.
Both these figures were at take-off, so the estimated taxy fuel had to be added to these figures in order to arrive at the minimum fuel figure required to be loaded.
...was it possible to be in a position where trip fuel, fuel to an alternate etc was less than the fuel required for CofG movement after take off?...
No, at least it should not have been!
However, a situation was sometimes reached in flight, generally only towards the end of the planned supercruise portion of a LHR-BGI sector, where, with the aircraft at M2.00 and FL600, it was no longer possible to maintain a CG of 59%, as the "ballast" fuel, which had been transferred aft into tank 11, was now required forward again as "fuel" fuel, to top up other tanks which had reached their minimum permitted levels.
In this case, once the forward transfer of fuel had begun, the CG would also be slowly moving FWD, and one would be compelled to commence the decel and descent earlier than desired, something
EXWOK touched on
here much earlier in this thread.
Best Regards
Bellerophon