Wha?
I've come across an interesting situation to do with finding the correct fuel burn for a certain part of a flight. Given this theoretical situation:
cruising FL330
mach .79
start zone weight is 70560
distance is 284
ground speed 543
(83kt tailwind)
and its ISA +3
u estimate a midzone weight say 69t
fuel flow for 69t .79 +3isa gives 4019kgph
so for this period of time (284/543) it's 2102kg.
endzone weight will therefore be 68458kg
(70560-2102)
so double checking the midzone weight u go 2102kg/2 + 68458kg gives 69509kg
which is closer to 70t
only by 9kg but its still closer
so u redo the fuel flow figures for 70t
same everything else
it's 4066kg an hour, for this distance it's 2127kg
therefore endzone weight:
70560-2127 = 68433
double check ur midzone weight 2127/2 plus 68433 gives 69496
which is then closer to 69t
only by 4kg but its still closer.
so you're going round in circles
Can anyone see an error in those calculations? I've rechecked them several times but still keep coming up with the same figures.
PS sorry for the abbreviated spelling - Copied and pasted straight from a chat window.
Cheers