trex8
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A332F Higher Gross Weight Question

Fri Oct 29, 2010 11:44 pm

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.
 
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Stitch
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RE: A332F Higher Gross Weight Question

Sat Oct 30, 2010 12:03 am

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.
 
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Francoflier
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RE: A332F Higher Gross Weight Question

Sat Oct 30, 2010 1:34 am

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]
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747classic
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RE: A332F Higher Gross Weight Question

Sat Oct 30, 2010 12:07 pm

AFAIK, the wing root bending moment is the limiting factor.
Also on the A330-200 with increased MTOW (max 238.0) the MZFW is slightly lowered, compared to the same structure at lower MTOW.


WV057---------- MTOW 236,0 tons -----------MZFW 170.0 tons
WV058---------- MTOW 238.0 tons -----------MZFW 168,0 tons

The A330F comes in two versions :

WV000--------- MTOW 233,0 tons -----------MZFW 173.0 tons
WV001--------- MTOW 227,0 tons -----------MZFW 178,0 tons

see : http://www.airbus.com/fileadmin/medi...tech_data/AC/AC_A330_Jan2010v2.pdf

Scroll to pages 45 until/incl 51 (out of 458) for all certified weight combinations of the A330-200 and A330F.

For further MTOW increase with the same MZFW, Airbus has to increase the structural strength of the center wingbox and/or wing structure.

[Edited 2010-10-30 05:14:43]
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trex8
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RE: A332F Higher Gross Weight Question

Sat Oct 30, 2010 6:44 pm

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
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RE: A332F Higher Gross Weight Question

Sat Oct 30, 2010 10:15 pm

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.
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thegeek
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RE: A332F Higher Gross Weight Question

Sun Oct 31, 2010 12:25 am

Quoting trex8 (Reply 4):


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.

HTH

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