trex8 From United States of America, joined Nov 2002, 4786 posts, RR: 14 Posted (3 years 11 months 3 weeks 6 days ago) and read 2975 times:
Why isn't there a 238K MTOW A332F offered like for the pax version? You would think for a freighter a higher MTOW would be even more important. Airbus tech data shows 233.9 and 227.9K MTOW versions only.
Stitch From United States of America, joined Jul 2005, 31097 posts, RR: 85
Reply 1, posted (3 years 11 months 3 weeks 5 days 23 hours ago) and read 2949 times:
It may not be necessary if the aircraft is fuel-volume limited at the current 233t MTOW, though I know it flies farther with a lighter payload, so it might indeed be fuel-weight limited and a higher MTOW would help.
francoflier From France, joined Oct 2001, 3790 posts, RR: 11
Reply 2, posted (3 years 11 months 3 weeks 5 days 22 hours ago) and read 2867 times:
The important metric for a freighter is the MZFW.
I don't know about the A330 much, but if that MTOW extension to 238T on the pax version was done with no change to the MZFW (i.e: just to give it more range), then it would be a pretty useless feature.
Freighters don't need to fly far, they stop for fuel. The payload doesn't really care and it's more efficient that way.
[Edited 2010-10-29 18:35:02]
Looks like I picked the wrong week to quit posting...
trex8 From United States of America, joined Nov 2002, 4786 posts, RR: 14
Reply 4, posted (3 years 11 months 3 weeks 5 days 5 hours ago) and read 2612 times:
Quoting 747classic (Reply 3): AFAIK, the wing root bending moment is the limiting factor
For those of us who were stupid enough to do the social sciences at college, what does this mean??? The wings will break off if they have to sustain the higher load of a higher TO weight???
The freighters MZFW is higher than the pax version already, is this because of strengthened floor etc?
Another maybe stupid question. There is supposed to be a version of the freighter optimized for weight OR range. Are these structurally different? Seems to me, if you increase TOW with same fuel, your range goes down and if you take more fuel, your payload goes down, so its always a trade off of one against the other, or am I missing something?.
wn676 From Djibouti, joined Jun 2005, 1054 posts, RR: 4
Reply 5, posted (3 years 11 months 3 weeks 5 days 1 hour ago) and read 2549 times:
Quoting trex8 (Reply 4): For those of us who were stupid enough to do the social sciences at college, what does this mean??? The wings will break off if they have to sustain the higher load of a higher TO weight???
Basically, yes. The wing is like a big cantilever beam which, when loaded, will try to rotate around the fixed end (root). If the forces at that end become to large trying to counteract the loading on the wing, the wing will fail at that point.
Tiny, unreadable text leaves ample room for interpretation.
To explain it a bit differently, fuel in the wings doesn't load up the wing's mountings in flight, but payload does. This is why you cannot indefinitely offload fuel to increase payload. I'd be surprised if MTOW - MZFW was ever higher than wing fuel capacity. Of course, there are also limits to landing weight, but these are hit later.