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Why Not A Twin A346?  
User currently offlineCubsrule From United States of America, joined May 2004, 22309 posts, RR: 20
Posted (6 years 6 months 2 days 14 hours ago) and read 8442 times:

On a (unnecessarily long) journey through ORD this afternoon, I spent some quality time staring at a beautiful IB 346 (EC-JLE, lest anyone cares). And that led me to wondering... if the 772 is a twin, when Airbus was developing the 346, why did it become the 346 instead of, say, the 334? While the wings of the 330 would almost certainly have needed to be redesigned, the 345 and 346 do not share wings with the 342 and 343.

Certainly the whole "4 engines 4 longhaul" mentality at Airbus had something to do with it. I'm also not so sure that the 345 would have been viable as a twin (perhaps I'm wrong). But even if that's true, the 345 is a niche aircraft, and TG is the only carrier that operates both 345s and 346s, so it's not like Airbus gains a lot due to the 345/346 commonality. Am I missing something? Or did Airbus miss the boat in the name of 4 engines 4 longhaul?


I can't decide whether I miss the tulip or the bowling shoe more
35 replies: All unread, showing first 25:
 
User currently offlineGigneil From United States of America, joined Nov 2002, 16345 posts, RR: 86
Reply 1, posted (6 years 6 months 2 days 14 hours ago) and read 8453 times:

They DO share wings with the 342 and 343 for the most part.

There's just an insert to increase span and some obvious strengthening.

NS


User currently offlineIkramerica From United States of America, joined May 2005, 21417 posts, RR: 60
Reply 2, posted (6 years 6 months 2 days 14 hours ago) and read 8438 times:

Because Airbus was shortsighted. That's my opinion. Well, actually, it should have been the A330-500 and A330-600 or something like that. The A330-500 a straight upgrade of the A330-300, like the 777-200LR is the 777-200, to give it 8800nm range. The A330-600 something more like the 350-1000, that is 350 seats and 7500nm range target (which likely would end up 7800 or so). I think they bought into their own quad hype, and it cost them in the long term...


Of all the things to worry about... the Wookie has no pants.
User currently offlineCubsrule From United States of America, joined May 2004, 22309 posts, RR: 20
Reply 3, posted (6 years 6 months 2 days 14 hours ago) and read 8424 times:

Quoting Gigneil (Reply 1):
There's just an insert to increase span and some obvious strengthening.

Correct; I should have been more clear, as saying that the 340s do not share wings is quite a bit different than saying that the 73Gs do not share wings with their older siblings. I stand by my previous point, though. Airbus could have modified the 330 wing in much the same way to enlarge the aircraft and increase the range, as the 330 basically has the 343 wing.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineLeskova From Germany, joined Oct 2003, 6075 posts, RR: 70
Reply 4, posted (6 years 6 months 2 days 11 hours ago) and read 8250 times:

Quoting Cubsrule (Reply 3):
Airbus could have modified the 330 wing in much the same way to enlarge the aircraft and increase the range, as the 330 basically has the 343 wing.

If I recall correctly, modifying the wing itself would not have been sufficient - the landing gear would have had to be lengthened to allow for the larger engines to have enough ground clearance.

However much I enjoy flying on A340s, I do have to agree that it would have been wiser for Airbus to not only expand the 4-engined line, but to at least also expand the twin line (if not only the twins): the A340 has, unfortunately, sold less than spectacularly, something that Airbus originally hadn't expected - according to a book I have in some box in the basement, they expected the split between the A330 and A340 to be something around 1:3... I think they weren't even wrong with the relation between the two, except that they were expecting the A340 to be the better-selling one.

Then again, European and Asian airlines took far longer to embrace the concept of twins than their US counterparts did, so Airbus obviously expected that to create more than enough selling-possibilities; but once the airlines outside of the US started realizing that ETOPS did not constitute a major step down in safety, but that it did - on certain routes - constitute a major step up in revenue, it was obvious that twins would be the way to go...



Smile - it confuses people!
User currently offlineGigneil From United States of America, joined Nov 2002, 16345 posts, RR: 86
Reply 5, posted (6 years 6 months 2 days 3 hours ago) and read 7766 times:

I don't think the plane being a twin or a quad has as much to do with it as the fact that the A330/340 family has shitty structural efficiency.

Perhaps some part of that is related to wing strengthening for the extra engines, but I don't really think the lion's share.

NS


User currently offlineNA From Germany, joined Dec 1999, 10365 posts, RR: 11
Reply 6, posted (6 years 6 months 2 days 3 hours ago) and read 7720 times:

Quoting Cubsrule (Thread starter):
Why Not A Twin A346?  

No thanks, I prefer a quad 777!
 Wink


User currently offlineTrex8 From United States of America, joined Nov 2002, 4494 posts, RR: 14
Reply 7, posted (6 years 6 months 2 days 3 hours ago) and read 7636 times:
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wasn't the problem the availability of the necessary engines which is why the A345/6 was on the market earlier as the 77W/LR needed GEs development of the latest GE90-1xxs

User currently offlineAirbusA6 From United Kingdom, joined Apr 2005, 2004 posts, RR: 0
Reply 8, posted (6 years 6 months 2 days 2 hours ago) and read 7502 times:

Quoting Trex8 (Reply 7):
wasn't the problem the availability of the necessary engines which is why the A345/6 was on the market earlier as the 77W/LR needed GEs development of the latest GE90-1xxs

Well Airbus could have lauched a slightly shorter A330-400 twin with Trent 892s, which would have produced a better 772ER rival?



it's the bus to stansted (now renamed national express a4 to ruin my username)
User currently offlineZak From Greenland, joined Sep 2003, 1993 posts, RR: 8
Reply 9, posted (6 years 6 months 2 days 1 hour ago) and read 7420 times:

Quoting Cubsrule (Thread starter):
. Am I missing something?

yes, the fuel price was not that big of a part of the equation when the 340NG was developed as it is these days.




10=2
User currently offlineCubsrule From United States of America, joined May 2004, 22309 posts, RR: 20
Reply 10, posted (6 years 6 months 2 days ago) and read 7251 times:

Quoting Zak (Reply 9):

yes, the fuel price was not that big of a part of the equation when the 340NG was developed as it is these days.

...but wouldn't carriers prefer to pay less for fuel regardless of what the actual price is?



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineVanguard737 From United States of America, joined Aug 2001, 680 posts, RR: 4
Reply 11, posted (6 years 6 months 1 day 20 hours ago) and read 6549 times:

I already asked this question a few months ago..and many said it was because the engines being so large would require so much structural changes to the wings as well as the landing gear that is would simply be to costly to be practical.


320 717 722 732 733 735 737 738 744 752 753 763 772 DC9 DC10 MD80 B1900 S340 E120 ERJ CRJ CR7
User currently offlineR2rho From Germany, joined Feb 2007, 2497 posts, RR: 1
Reply 12, posted (6 years 6 months 1 day 20 hours ago) and read 6483 times:

A similar aircraft (in the A343 size though) was, in fact, proposed. It was called the A350 (Version 1.0), and rejected by most customers...

User currently offlineZak From Greenland, joined Sep 2003, 1993 posts, RR: 8
Reply 13, posted (6 years 6 months 1 day 20 hours ago) and read 6483 times:

Quoting Cubsrule (Reply 10):

...but wouldn't carriers prefer to pay less for fuel regardless of what the actual price is?

indeed, but it becomes more important versus the other factors when the price per kg of fuel increases a few 100%.

Quoting Vanguard737 (Reply 11):
structural changes to the wings as well as the landing gear that is would simply be to costly to be practical.

apparently, airbus made the development decision with a different oilprice scenario in mind. who knows, if they had known that the barrel would appraoch 100$, they may have concluded that its time for a large twin before.
lufthansa is interesting in this regard, as their well over average fuel hedging allows them to operate on "good ol days" fuel prices, and for them the a346 was good enuff to order quite a bunch of them. one can assume that operating economics with the hedged price did play at least one variable in that decision, even if it might not have been the key factor.



10=2
User currently offlineSEPilot From United States of America, joined Dec 2006, 6682 posts, RR: 46
Reply 14, posted (6 years 6 months 1 day 20 hours ago) and read 6423 times:

Quoting R2rho (Reply 12):
A similar aircraft (in the A343 size though) was, in fact, proposed. It was called the A350 (Version 1.0), and rejected by most customers...

But that was against the 787, not against the 767/777.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineTrex8 From United States of America, joined Nov 2002, 4494 posts, RR: 14
Reply 15, posted (6 years 6 months 1 day 18 hours ago) and read 5371 times:
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Quoting AirbusA6 (Reply 8):
Well Airbus could have lauched a slightly shorter A330-400 twin with Trent 892s, which would have produced a better 772ER rival?

but weren't they after a 747 classic replacement and not a better competitor to the 772ER?


User currently offlineCJAContinental From United Kingdom, joined May 2006, 459 posts, RR: 0
Reply 16, posted (6 years 6 months 1 day 18 hours ago) and read 5037 times:

Quoting Leskova (Reply 4):
However much I enjoy flying on A340s, I do have to agree that it would have been wiser for Airbus to not only expand the 4-engined line, but to at least also expand the twin line

Expanding both lines would be silly. If you had a 330-500, 330-600, then that would probably kill off 340-300, 340-500 and 340-600. You can only do one or the other. Personally, I would have expanded the 330 line, would've taken away a lot from 773ER, more than the present 346.

I think the reason airbus has not done this can be traced to inaccurate, and somewhat unfortunate predictions in the early stages of this decade; with factors like 9/11, the war, increasing oil prices have damaged the four engine popularity if we compare the A340 to the 777.



Work Hard/Fly Right.
User currently offlineMD-90 From United States of America, joined Jan 2000, 8494 posts, RR: 12
Reply 17, posted (6 years 6 months 1 day 18 hours ago) and read 5011 times:

Quoting Gigneil (Reply 5):
I don't think the plane being a twin or a quad has as much to do with it as the fact that the A330/340 family has shitty structural efficiency.

The A332/A333/A343 do not have shitty structural efficiency.


User currently offlineCJAContinental From United Kingdom, joined May 2006, 459 posts, RR: 0
Reply 18, posted (6 years 6 months 1 day 17 hours ago) and read 4523 times:

Quoting MD-90 (Reply 17):
Quoting Gigneil (Reply 5):
I don't think the plane being a twin or a quad has as much to do with it as the fact that the A330/340 family has shitty structural efficiency.

The A332/A333/A343 do not have shitty structural efficiency.

Well, we don't know that for sure, the engineers came clean about the A346 to the concern of some airlines, though this surely has to be exclusive to the 346 due to the length. I'm scepticle that the engineers didn't realise that by creating a flying pepperami, they may jeopardise the structural quality, though I think airbus may have been reluctant to widen the fuselage on the A346 because their lazy (from A340-200, through to 600, diameter is 5.64m), (I suppose this could not be done on the A345, as range deliberately made this aircraft a niche product, and increasing fuselage diameter would have increased weight, making the aircraft pointless). Although they have to save money where they can, it shouldn't come into practice when the structural quality is seriously affected, which in my opinion, regarding the 346, the quality was affected.



[Edited 2007-10-22 17:04:20]

[Edited 2007-10-22 17:09:51]

[Edited 2007-10-22 17:10:35]


Work Hard/Fly Right.
User currently offlineLemurs From United States of America, joined Mar 2005, 1439 posts, RR: 4
Reply 19, posted (6 years 6 months 1 day 16 hours ago) and read 3947 times:

Quoting Cubsrule (Reply 10):
...but wouldn't carriers prefer to pay less for fuel regardless of what the actual price is?

Not necessarily. It all depends on where the greatest percentage of your cost is. If one plane burns a few thousand pounds liters of fuel per average sector versus another, but has half the long term operating and maintnance costs, it could be the much better airplane if fuel only costs a few cents per liter.

Essentially: Saving thousands of something worth very little is different than saving a few of something worth a whole heck of a lot. If you're going to run into a burning building to save some bags of money, are you going to grab the huge sack of $1s because "there are so many more!" or are you going to grab the small sack of $1,000s?



There are 10 kinds of people in the world; those who understand binary, and those that don't.
User currently onlineBurkhard From Germany, joined Nov 2006, 4361 posts, RR: 2
Reply 20, posted (6 years 6 months 1 day 5 hours ago) and read 3015 times:

I still do not understand why it is inevitable that a quad is less effective than a twin.

Fact is, given the same MTOW, a twin needs more power than a quad if an engine fails during takeoff. So, in the approximation that the weight of the engine is proportional to its power, a quad should be more efficient.

So this is not an inherent explanation. In the case of A345/6 things are more clear. The Trent 500 is a slightly shrinked version of any Trent, still a large engine and so has more than half the weight of a Trent 900. It is the only engine available in this class.

What I wonder more is that comparing the numbers for CF6 vs CFM56 as example, again the smaller engines are not so much lighter - anybody has an insight why?


User currently offlineBRxxx From Taiwan, joined Aug 2007, 113 posts, RR: 0
Reply 21, posted (6 years 6 months 1 day 5 hours ago) and read 3002 times:

IF it is really made a twin at that time, how is Airbus going to answer the airlines that don't like flying two-engined aircraft over big ponds?


Flown on:A320,A332,A333,B737,B738,B763,B744,B77W,B773,E175,E190,MD90,MD11
User currently onlineBurkhard From Germany, joined Nov 2006, 4361 posts, RR: 2
Reply 22, posted (6 years 6 months 1 day 5 hours ago) and read 2977 times:

It turned out that the number of "airlines that don't like flying two-engined aircraft over big ponds?" was smaller than expected - good old "Safety first!" has been replaced by "Profit only!" in most parts of the world.

User currently offlineRichard28 From United Kingdom, joined Aug 2003, 1595 posts, RR: 6
Reply 23, posted (6 years 6 months 1 day 4 hours ago) and read 2941 times:

Quoting Gigneil (Reply 1):
They DO share wings with the 342 and 343 for the most part.


The A346 wing was a new design to the previous A340/A330 wing.

Quoting CJAContinental (Reply 18):
I think airbus may have been reluctant to widen the fuselage on the A346 because their lazy

I think cost was more of a factor than laziness

if you widen a plane, then its practically a whole new design. to lengthen a plane is a lot lot cheaper.

[Edited 2007-10-23 05:29:00]

User currently offlineSEPilot From United States of America, joined Dec 2006, 6682 posts, RR: 46
Reply 24, posted (6 years 6 months 1 day 4 hours ago) and read 2912 times:

Quoting Burkhard (Reply 20):
I still do not understand why it is inevitable that a quad is less effective than a twin.

Weight, for one. One large engine weighs quite a bit less than two small ones, even though the two smaller ones need less total thrust. Also, the larger you can build a jet engine the more efficient it becomes in terms of thrust per unit of fuel with all other things being equal. The weight and drag of support structures is also less. The only area where a quad has an advantage is in wing structure, because distributing the engine weight over the wingspan instead of concentrating it near the root allows a lighter wing structure.



The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
25 Burkhard : This seems to be the case, but why? Thrust is proportional to the inlet area in first approximation - more air makes more thrust. Efficiency increase
26 SEPilot : I am not an expert in jet engines-perhaps Lightsaber could give us more info. But I do know it to be the case. The column of air exiting the engine e
27 Gigneil : No, it really wasn't. NS
28 Post contains links CJAContinental : The point I was trying to make is that although widening the plane would mean a whole new design, and more hassle, money etc... losing out on develop
29 Gigneil : The A340-500 and -600 are PERFECTLY safe aircraft. They have obviously been EXTENSIVELY strengthened, hence my comments about structural efficiency. T
30 Cubsrule : Airbus had no choice, though. The 777 family beats the pants off of the 340 in every mission save the few long range missions for which the 345 was d
31 Post contains links and images AirplaneFan : I taught TG & VS already operated that type. Modified Airliner Photos: Design © Abdullah M. Template © K.H. Ng - HKAEC Modified Airliner Photos: De
32 Post contains images Flysherwood : Now that would have been one hell of an aircraft!!!
33 Post contains images Flysherwood : That was because the 787 was already around.
34 Burkhard : To my understanding, the main purpose of the A345/6 was to keep in the large aircraft race until the VLA race gets won. It never was intended to blow
35 Tdscanuck : Because the TSFC of each individual engine is lower for a quad than an equivalent twin. The twin will burn less fuel for the same trust. It's not pro
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