I've tried to play around this in my -400 today.CG valid entry range from 4% to 32%,
it affect the MAX ALT a little but I didn't
notice the change in buffet on the speed tape
(may be not heavy or not high enough).I agree
that it affects the G load margin which in turn affect the MAX ALT.
-400's weight & balance datum is at 17.5% MAC
(648.5") from "0" station,thus 18% entry sounds good.
In most of my sectors,CG moves ~2% from T/O
to Top of Climb(index moves ~3 units and burn
~1600kgs of fuel).I remember some time ago there was a posting saying further aft CG requires less elevator down forces thus less drag => more economy.Now the question is,how
significant is it?Can we deliberately load the A/C to way aft CG(within limit)to safe
some fuel?How much?Hope there are experts
could help.Thanks.
