barit1
...OF COURSE a stab tank will have CG trim implications ...
Yes, but I don't believe
Dan Winterland is in any doubt about that.
What he said was:
The 744 tail tank is just somewhere to stuff extra fuel. It is not designed to be a trim tank
a statement I completely agree with.
...There must be some reason the stab tank is used only on extremely long flights...
I thought I'd just given it, but let me try again.
The danger of getting fuel trapped in there - with the resultant AFT CG problems - means it is only used when necessary. It is only necessary with very high fuel loads. Very high fuel loads are only required on extremely long flights.
...its ability to trim for optimum cruise CG...
It can't actually
trim, not as such, it can only move fuel forward.
I've flown an aircraft which used a rear fuel tank as a trim tank, but that was a completely different system to the B744, which just uses the stabiliser tank as a place to store fuel.
Whether Boeing missed something by
not designing it as a trim tank is another question; however, on most of the ultra-long-range flights I've operated, the factor that has usually restricted our climb to sub-optimum cruise altitudes has not been a sub-optimum aircraft CG position, but a wretched Airbus, staggering along in pre-stall buffet, just above us.
Regards
Bellerophon