philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Jun 19, 2015 1:40:27 GMT 1
Structurally, the center tank is part of the wing, not the fuselage. It counts as wing area. If I remember correctly, the central tank is inside the wingbox. Is this correct ?
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Baroque
in service - 2 years
Posts: 3,991
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Post by Baroque on Jun 19, 2015 4:36:59 GMT 1
TaliesinI shall have a look at that. Thanks. What happened was that I was going to refer to one of my own quotes in a previous post, and accidentally hit "edit" instead of "quote", and then it all went downhill from there... This is pretty much my thinking as well as it better demonstrates the aircraft's capability. This is exactly what Boeing is doing with the 777X. The wings and engines are being designed around the capabilities of the -9X and therefore become excessive for the 8X, which in that sense is a "pseudo-shrink". I'm not sure if this is what stealthmanbob meant, but the 77L for instance has provisions in the cargo hold for up to 3 optional auxiliary tanks. An A350-1100 stretch may be capable of having around 50-52 LD3 positions compared to the 44 of the -1000. That's an awful lot of cargo capacity which probably can be traded for some optional fuel tankage like the above if the range really needs a boost. Of course, the MTOW needs to be sorted out. They are said to be looking at wing modifications and engine fan size increase as well. They may lose a bit of commonality but I think some of these improvements can be moved back to the -1000. In any case, the -900, -1000 and the -1100 will all still have way better commonality than what exists between the 787 and the 777X. I read that it makes it less complex. No need for complex fuel systems and provisions so there's some maintenance and weight saving there. philidorWell, Boeing is doing it all for a cost close to $10 billion. I think Airbus can get away with a good alternative for just around $2-3 billion. They are talking to customers, so we will know in time whether it will happen. They say that a decision will come out by the end of this year or early next year, around the same time as the A380neo decision. The two decisions may be somewhat related.
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Post by stealthmanbob on Jun 19, 2015 10:13:56 GMT 1
thanks Baroque I think that was what I was remembering that ER and LR versions have extra fuselage tanks for the range at the expense of some cargo / luggage space.
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XWB
in service - 11 years
Posts: 16,115
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Post by XWB on Jun 19, 2015 10:55:47 GMT 1
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Post by stealthmanbob on Jun 19, 2015 11:42:08 GMT 1
Very interesting, I read the first 25 odd posts and I think I have got all the info my head can cope with
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s543
in service - 2 years
Posts: 3,957
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Post by s543 on Jun 19, 2015 12:08:27 GMT 1
Right interesting - but to sum it up - if I got it right ? - the whole thing is a problem, is complicated to run and maintain and the gain in capacity is not big, according to reply 14 on oooold VC10 - around 6%. The numbers are probably similar ?
It just let us know how complicated all the thing in an airliner are and we get better understanding why all is so expensive.
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Taliesin
Final Assembly Line stage 1
In Thrust we trust
Posts: 228
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Post by Taliesin on Jun 19, 2015 12:36:48 GMT 1
I'm not sure if this is what stealthmanbob meant, but the 77L for instance has provisions in the cargo hold for up to 3 optional auxiliary tanks. An A350-1100 stretch may be capable of having around 50-52 LD3 positions compared to the 44 of the -1000. That's an awful lot of cargo capacity which probably can be traded for some optional fuel tankage like the above if the range really needs a boost. Of course, the MTOW needs to be sorted out. They are said to be looking at wing modifications and engine fan size increase as well. And did any airline ever use this setup? I think not, for a very simple reason. This only makes sense for missions where the airplane is fuel volume limited and not MTOW limited. Even if you raised MTOW, on a typical mission, your tanks aren't full anyway and the additional tanks would go unused. For the 77L this is beyond 9500nm, for the 77W it's beyond 7750nm. With maximum passenger range already at 7900nm for the A350-1000, I just don't think this makes any kind of operational sense. It's possible, but for very obvious reasons it isn't routinely done.
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philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Jun 19, 2015 13:50:07 GMT 1
And did any airline ever use this setup? I think not, for a very simple reason. This only makes sense for missions where the airplane is fuel volume limited and not MTOW limited. It depends on the aircraft type/version. Some aircraft are fuel volume limited. I remember this is the case of some A330 versions intended for short range (with a desactivated central fuel tank). Likewise, the A321neoLR uses up to three additional tanks.
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Post by Jkkw on Jun 19, 2015 14:05:00 GMT 1
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mjoelnir
in service - 2 years
Posts: 4,089
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Post by mjoelnir on Jun 19, 2015 14:09:38 GMT 1
I did not mean that fuel is not stored in the fuselage. The wings are the preferred storage of fuel in an aeroplane because of the weight distribution. Distributed weight in the wing works as a stress relief on the wing joint with the center box. Number two area is the center box, does not take volume from possible payload little influence on trim. If those two areas do not meet the volume need for fuel you add tanks in the belly.
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