QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 34 Reply 4, posted (9 years 5 months 2 weeks 5 days 22 hours ago) and read 1925 times:
Heavier wings give less wing bending moment, which is a good thing.
While that's certainly true, I doubt it comes into play in terms of what get refueled when. Obviously, wing bending is only present when the wings are lifting, so relieving that bending is a mute point while on the ground (refueling).
Starlionblue From Greenland, joined Feb 2004, 16376 posts, RR: 66 Reply 5, posted (9 years 5 months 2 weeks 5 days 15 hours ago) and read 1862 times:
Hmmm, but eventually the plane will be in the air, and in case of a short trip it might dispatch with the center tank empty or partially filled. So that is relevant right? Or I may pf course be wrong It's all about learning.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 34 Reply 6, posted (9 years 5 months 2 weeks 5 days 15 hours ago) and read 1858 times:
You're completely right: in the case of a short trip, yes, wing bending considerations would certainly come into play (assuming you're not just topping up all of the tanks). I was just thinking more along the line of a "normal" (longhaul?) all-tanks-filled flight, for which fuelling order wouldn't matter in terms of wing bending. Sorry, I hadn't be very clear before.
Crosswind From United Kingdom, joined Nov 2000, 2592 posts, RR: 59 Reply 7, posted (9 years 5 months 2 weeks 5 days 9 hours ago) and read 1833 times:
Even on a long-haul - unless you're really pushing the aircraft's range limits, it's rare for the fuel tanks to be full. You will usually reach your MTOM due to the payload carried before fuel-voulume becomes limiting.
As such, the centre tank will always be filled last, even on short-haul. As OPNL/Starlionblue said, this is a structural requirement to minimise the bending moment of the wings, particularly in the initial stages of flight when the aircraft is haviest. A similar rationale is behind the max ZFM, which I believe is set with reference to the stresses on the wing/body joints, again too much of mass in the fuselage which then has to be supported by the wing/body joints puts additional stess on the aircraft, which is not healthy for them long-term.