According to Flight Airbus A350 programme chief Didier Evrard said for the A350-1000 wing that "there will be detail differences, for example to the high-lift system and the pylon".
http://www.flightglobal.com/articles...wo-years-to-refine-1000s-wing.html
Is it possible that Airbus might be looking at the possibility of lengthening the A350-1000 to close to 78 - 80m, and then if no engines support the bigger plane by the time they are ready, to go with a 4-engine approach?
An A350-1100 will be a good fit between the A350-1000 and the A380 and will compete with the B-777 replacement.
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- rheinwaldner
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
I proposed something like this several times. I know that the trend towards twins is huge and probably irreversible. But when looking at factors that could reverse the trend I see the possibility that smaller GTF engines could make a quad superior in TSFC. Together with the reduced requirements for total take-off-thrust this could lead to an other-than-VLA-quad that could win the efficiency-crown in the future.
In the end probably just some lazy predictions...
In the end probably just some lazy predictions...
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Thread starter): Is it possible that Airbus might be looking at the possibility of lengthening the A350-1000 to close to 78 - 80m, and then if no engines support the bigger plane by the time they are ready, to go with a 4-engine approach? |
I highly doubt that - the reference to pylon changes is probably due to the fact that the A350-1000 will have a heavier engine than the -800 or -900, combined with the fact that that engine produces more thrust. Theres no point in carrying that extra weight around on the bulk of the family.
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- futurecaptain
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Thread starter): An A350-1100 will be a good fit between the A350-1000 and the A380 and will compete with the B-777 replacement. |
How would a new quad compete with the 777 replacement? I would venture to say it would be the same as the current A340 vs 777 situation.
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- dl767captain
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
I don't think there is any need, I'm guessing that would turn into airbus' version of the 748 which so far isn't a hot seller on the passenger side. It seems like they would have another 777 vs A340 situation but this time they would be developing both planes. If there was no A380 them I think it would be a possibility but the 748 pretty much has this market taken care of I think
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Thread starter): and then if no engines support the bigger plane |
But such engines already exist! Ever heard of the GE90-115B? If GE can do it, why couldn't RR?
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
I would not be surprized if Airbus is considering a A350-1100 & 1200 or A370-200 and -300 using the CRFP fuselage, wing, cockpit and landing gear. It would incorporate a tail section as patented recently by Airbus:
A third 70-80.000lbs Trent / GENX class would not increase weight over e.g. two GE90's and provide sufficient power in case of an engine failure after V1. Important to carry serious cargo long haul (=Asia). A A340-600 style center gear would take care of additional MTOW / wheel pressure issues.
An additional 5-7 rows could lift capasity about 400 seats.
A third 70-80.000lbs Trent / GENX class would not increase weight over e.g. two GE90's and provide sufficient power in case of an engine failure after V1. Important to carry serious cargo long haul (=Asia). A A340-600 style center gear would take care of additional MTOW / wheel pressure issues.
An additional 5-7 rows could lift capasity about 400 seats.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Keesje (Reply 6): I would not be surprized if Airbus is considering a A350-1100 & 1200 or A370-200 and -300 using the CRFP fuselage, wing, cockpit and landing gear. It would incorporate a tail section as patented recently by Airbus: |
I'd be surprised if anyone launched a new trijet. Wouldn't you?
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Thegeek (Reply 7): I'd be surprised if anyone launched a new trijet. Wouldn't you? |
Its seems a good compromise to me.
2 x 150 lbs would become very big & heavy, making it unpracticlle under the wing.
I'm not sure if any OEM even wants to build it.
500 passengers on a single engine far above an ocean doesn't attract me neither.
Statictics on this show no reliability magic.
A&B both launched 4 haulers recently, trijets don't carry an emotional barrier I guess.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Keesje (Reply 8): A&B both launched 4 haulers recently, trijets don't carry an emotional barrier I guess. |
You can't count the 748 - it's an modification of an old design. But all those reasons would have applied to the A380, and Airbus obviously decided that the centre engine maintenance penalty was more than the fourth engine maintenance penalty. I presume that they did do this calculation.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Keesje (Reply 8): Its seems a good compromise to me. |
I see two problems:
1) the extra weight necessitated by both the twin vertical stabilizers and the extra structure that would be necessary in the horizontal stabilizers to support the vertical stabilizers, and
2) the usual problem, common to every trijet ever made, of time-consuming, expensive, and potentially dangerous mx procedures required for the No. 2 engine.
| Quoting Keesje (Reply 8): 2 x 150 lbs would become very big & heavy, making it unpracticlle under the wing. |
Remember that everyone said this about 80klb engines before the 777 was built. It went on to completely kill off its 3-engine competiton (MD-11) and nearly kill off the 4-engine competition (A340 and eventually 744 pax).
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting CJAContinental (Reply 11): What are the advantages of such a tail section? |
It was used on the An-225 because the An-225 was originally designed to carry the Buran orbiter on its back. Oversize cargo on top of the fuselage would prevent a conventional tail from being effective by interfering with the airflow.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting SeaBosDca (Reply 12): Quoting CJAContinental (Reply 11): What are the advantages of such a tail section? It was used on the An-225 because the An-225 was originally designed to carry the Buran orbiter on its back. Oversize cargo on top of the fuselage would prevent a conventional tail from being effective by interfering with the airflow. |
Many aircraft used this for various reasons. The A10 also for propulsion reasons. Studies into new NB design by both A & B have it. The tail shields of noise produced by engines.
Airbus foresees a segment for twin aisles larger the n A350XWB and B777-300ER in their latest market forecast. http://www.airbus.com/en/corporate/g...for-passenger-aircraft/twin-aisle/
Putting a bigger engine and the XWB would IMO require a redesign of wings, landing gears etc.
| Quoting SeaBosDca (Reply 10): 1) the extra weight necessitated by both the twin vertical stabilizers and the extra structure that would be necessary in the horizontal stabilizers to support the vertical stabilizers |
A 3 x 80lbs aircrafty would have 160.000 lbs (less asymetrical) thrust left if one engine fails during a critical flight phase. Hard to realize that with a twin. 3 GENX engines (240 lbs) weigh about the same as two GE90-115s (230k lbs)..
| Quoting CJAContinental (Reply 11): If its the one in the diagram shown, it looks exactly like the tail section used on the An-225. What are the advantages of such a tail section? |
| Quoting SeaBosDca (Reply 10): 2) the usual problem, common to every trijet ever made, of time-consuming, expensive, and potentially dangerous mx procedures required for the No. 2 engine. |
The patent Airbus got is about easy accessibility & replacement of the tail engine.
http://www.google.com/patents?vid=USPAT7240877
RE: A350-1000 New Wing To Support 4 Engines F0r -1
| Quoting SeaBosDca (Reply 10): I see two problems: |
A third: airflow into the middle engine during certain manouvers.
A fourth: CG issues with the long forward cargo hold this design has...
| Quoting Keesje (Reply 13): A 3 x 80lbs aircrafty would have 160.000 lbs (less asymetrical) thrust left if one engine fails during a critical flight phase. Hard to realize that with a twin. |
That is a case, yes. A longer fuselage and larger vertical stabilizer/rudder can help here.
| Quoting Keesje (Reply 13): 3 GENX engines (240 lbs) weigh about the same as two GE90-115s (230k lbs).. |
As I've shown you on another forum - the dry weight of three GEnx engines is a minimum of ~3klbs MORE than the dry weight of two GE90-115Bs. In addition, you'd get the additional strengthening and structural changes a tail engine would bring with it. It would end up weighing much more.
| Quoting Keesje (Reply 13): The patent Airbus got is about easy accessibility & replacement of the tail engine. http://www.google.com/patents?vid=US...40877 |
Both Airbus and Boeing file several patents each year, it doesn't mean that they're going to build what they patent.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Brendows (Reply 14): As I've shown you on another forum - the dry weight of three GEnx engines is a minimum of ~3klbs MORE than the dry weight of two GE90-115Bs. In addition, you'd get the additional strengthening and structural changes a tail engine would bring with it. It would end up weighing much more. |
~3klbs is more then enough for the additional thrust / MTOW performance.
- putting 160 klbs thrust engines under the wing of an A350 aint for free either to say it mildly. On top of that a 400+ seat big twin would need an enormous vertical tail.
I think we have to take the A350 XWB fuselage & wing as a starting point and then look for a 420 seat requirement.
GE says it has problem to break even on the GE90. A completely new even bigger engine is probably not on its wish list.. State of the art 80.000klbs engines are "off the shelf". The amount of engine per passenger wouldn't be more the e.g 787, 748i & A380..
Twin-engined aircraft are burdened by turbofans with "ever-increasing mass and size, thereby making it necessary for the aircraft structure [fuselage, wings and landing gear, in particular] to be designed accordingly," says the patent application.
This design "makes it possible to considerably reduce the previous acoustic problems, since the noise generated by the third engine of the fuselage is sucked up by the channel", the patent document says.
The tail structure and the third engine add weight and new structural complexity, but the Airbus inventors counter that the trijet can still beat a twin-engined type on fuel efficiency through offsetting improvements.
The added weight of the tail "is largely compensated for the by the drop in the mass of the landing gear, the reason being that the landing gear is dimensionally smaller and less voluminous given the smaller engines".
http://www.flightglobal.com/articles...-patent-for-new-trijet-design.html
I think people who have written any trijet because the 777 was a succes should wait a little longer..
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Thread starter):
Is it possible that Airbus might be looking at the possibility of lengthening the A350-1000 to close to 78 - 80m, and then if no engines support the bigger plane by the time they are ready, to go with a 4-engine approach? |
There's a very low chance... I don't think that plane would need anything bigger than a 115,000 lb engine, and we know that Rolls Royce knows how to make one.
That being said, its 100% more feasible than a trijet config.
| Quoting Thegeek (Reply 7):
I'd be surprised if anyone launched a new trijet. Wouldn't you? |
Absolutely shocked. A 4 holer would come first.
| Quoting Keesje (Reply 8):
Its seems a good compromise to me. |
Its the worst idea anyone has ever suggested. There is absolutely zero chance of it whatsoever in an A350 size airframe.
NS
[Edited 2008-05-26 11:04:33]
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Keesje (Reply 15): GE says it has problem to break even on the GE90. |
When did they say this? With all the recent sales of 77W's I'd think they must have done something really wrong to have lost money on the GE90-115B. And couldn't it have something to do with the cash they injected into Boeing for the 77L/77W.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Gigneil (Reply 16): Its the worst idea anyone has ever suggested. There is absolutely zero chance of it whatsoever in an A350 size airframe. |
I've been in airline / aerospace business for some time and tend to be less absolutely sure about future developments, just like the engineers that filled the patent. Others have suggested not so very good ideas in the past. https://www.airliners.net/aviation-fo...general_aviation/read.main/1010739
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- CJAContinental
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Brendows (Reply 14):
Both Airbus and Boeing file several patents each year, it doesn't mean that they're going to build what they patent. |
Seems very much like a game of chess, blocking and threatening each others paths, and having to think hard and carefully about future designs.
Quoting Gigneil
"Its the worst idea anyone has ever suggested. There is absolutely zero chance of it whatsoever in an A350 size airframe."
Is this due to the increased requirement for thrust of each engine as opposed to four smaller engines? Maintenance?
[Edited 2008-05-26 15:27:42]
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Keesje (Reply 18): I've been in airline / aerospace business for some time |
I somewhat seriously doubt that.
| Quoting CJAContinental (Reply 19): Is this due to the increased requirement for thrust of each engine as opposed to four smaller engines? Maintenance? |
Just the strengthening of the airframe alone and the requisite complexity therein is enough reason. That double tailplane? The weight necessary to build it all? None of it makes any sense.
Neither the A380, A340, nor 747 are trijets despite all being EASILY doable with three engines. They're just poor ideas, relative to twins and quads, but we didn't know that when building the first set and nobody could argue the MD-11 as a good idea.
Back to the topic, the A350-1100 would be NO trouble for a twin. A larger aircraft still shouldn't be a problem with twin engine technology today. A GE90 could be built tomorrow to do it.
NS
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- Starlionblue
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Thegeek (Reply 17): Quoting Keesje (Reply 15): GE says it has problem to break even on the GE90. When did they say this? With all the recent sales of 77W's I'd think they must have done something really wrong to have lost money on the GE90-115B. And couldn't it have something to do with the cash they injected into Boeing for the 77L/77W. |
Sales alone do not make profit. Those engines are viciously expensive to develop and manufacture. I think GE is investing in a long future of engines in the 100k+ class. Current low profits are the price they are paying.
| Quoting CJAContinental (Reply 19): Is this due to the increased requirement for thrust of each engine as opposed to four smaller engines? Maintenance? |
Maintenance and increased weight. Also issues with an engine close to many critical control surfaces.
| Quoting Gigneil (Reply 20): Neither the A380, A340, nor 747 are trijets despite all being EASILY doable with three engines. |
Indeed.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
I believe that the following should hold true.
1. It is getting prohibitively expensive to experiment with aircraft design anymore. (B787, A340, A380)
2. Airbus and Boeing can only afford up to 3 aircraft families (A320, A350, A380) (B737, B787, Y3) with some aircraft competing for as much as they can, because the other maker cannot deliver (A330 and B777)
3. Engine manufacturers are also feeling the pain of going along with aircraft makers for every design they have.
4. Airplanes with 4 engines can be successful and efficient as a 2 engine. (Just ask Boeing on how it feels about its A340-300s (yes, they have them) and look at the aircraft's fuel consumption at Lufthansa, which is the same as a A330-300)
Therefore, the need to extend families, such as the A350 to handle up to 420 seats, or the 787-10, will be done by making small to medium size changes focusing on reusing developed and paid for components such as engines, wings, etc.
1. It is getting prohibitively expensive to experiment with aircraft design anymore. (B787, A340, A380)
2. Airbus and Boeing can only afford up to 3 aircraft families (A320, A350, A380) (B737, B787, Y3) with some aircraft competing for as much as they can, because the other maker cannot deliver (A330 and B777)
3. Engine manufacturers are also feeling the pain of going along with aircraft makers for every design they have.
4. Airplanes with 4 engines can be successful and efficient as a 2 engine. (Just ask Boeing on how it feels about its A340-300s (yes, they have them) and look at the aircraft's fuel consumption at Lufthansa, which is the same as a A330-300)
Therefore, the need to extend families, such as the A350 to handle up to 420 seats, or the 787-10, will be done by making small to medium size changes focusing on reusing developed and paid for components such as engines, wings, etc.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Thread starter): Is it possible that Airbus might be looking at the possibility of lengthening the A350-1000 to close to 78 - 80m, and then if no engines support the bigger plane by the time they are ready, to go with a 4-engine approach? |
It's been speculated that the size of the A350's wing allows this stretch. It's wing is the same size as the 773ER's.
I don't see a need for this stretch to weigh any more than around 325 tonnes, though (assuming the others hit their weight targets), which would mean that around 105k lb would be plenty.
No. I think the changes are pretty much what they say they are:-
A more capable high-lift system to accommodate the weight of the A350-1000, and stronger pylons for the thrust.
| Quoting Gigneil (Reply 16): I don't think that plane would need anything bigger than a 115,000 lb engine, and we know that Rolls Royce knows how to make one. |
If that big 
Rgds
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Reply 22): 4. Airplanes with 4 engines can be successful and efficient as a 2 engine. (Just ask Boeing on how it feels about its A340-300s (yes, they have them) |
I'm pretty sure they don't have them anymore. Regardless, it was Boeing Capital Corporation that had them, not Boeing Commercial Airplanes. It was some part of the deal to get Boeing airplanes to a customer...I'm pretty sure that Boeing didn't actually want to have them as assets.
Tom.
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- hypersonic
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Thegeek (Reply 5): Quoting Panais (Thread starter): and then if no engines support the bigger plane But such engines already exist! Ever heard of the GE90-115B? If GE can do it, why couldn't RR? |
Hi Thegeek, Actually RR DID do it, or rather did have a GE90-115B equiv ready to produce.
However Boeing wanted the Engine manufacturer to share in the overall financial risk of the 777-300, which RR refused to do, thus shooting themselves in the foot.
GE's responce..... Sure, we'll share the risk, but we'll insist on exclusivity on engine type for this model of plane. thus the 777-300er only takes the GE. The RR engine would have been the Trent 8104 - but it was comparable to the GE90-115B
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- OldAeroGuy
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Reply 22): 4. Airplanes with 4 engines can be successful and efficient as a 2 engine. (Just ask Boeing on how it feels about its A340-300s (yes, they have them) and look at the aircraft's fuel consumption at Lufthansa, which is the same as a A330-300) |
No part of Boeing has any A340's, they were sold long ago.
I think Lufthansa would be shocked with this bit of news.
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Tdscanuck (Reply 24): Regardless, it was Boeing Capital Corporation that had them |
| Quoting OldAeroGuy (Reply 26): No part of Boeing has any A340's, they were sold long ago. |
Thanks for confirming that Boeing had the A340-300. I am sure that they are also aware of their performance as well.
| Quoting OldAeroGuy (Reply 26): I think Lufthansa would be shocked with this bit of news. |
Suggest that you read page 95 of the Lufthansa Balance report that talks about Sustainability.
http://konzern.lufthansa.com/en/down...ationen/lh_sustainability_2007.pdf
Specific fuel consumption per aircraft
A330-300 4.03 liters / 100 passenger km
A340-300 4.05 liters / 100 passenger km
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Panais (Reply 27): Specific fuel consumption per aircraft A330-300 4.03 liters / 100 passenger km A340-300 4.05 liters / 100 passenger km |
I think these fuel burn numbers reflect the different mission lengths(A343 longer, A333 shorter) both aircrafts are used for. For similar mission lengths, A333 should do better.
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- OldAeroGuy
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting LAXDESI (Reply 29): Quoting Panais (Reply 27): Specific fuel consumption per aircraft A330-300 4.03 liters / 100 passenger km A340-300 4.05 liters / 100 passenger km I think these fuel burn numbers reflect the different mission lengths(A343 longer, A333 shorter) both aircrafts are used for. For similar mission lengths, A333 should do better. |
I agree with LAXDESI, you need to compare the airplanes on the same mission length to understand what the differences in fuel burn are.
Even more important is to compare similar seat counts.
LH's A333's are all in a three class configuration of 221 seats, while their A343's come in two and three class versions.
The three class version seating is the same as the A333 at 221 while the two class version seats 266 or about 20% more. The two class airplanes skew the fuel burn per seat numbers shown above and render the comparison useless.
Note that the airplanes with the least fuel burn per seat shown in the referenced report are flown by Thomas Cook.
The best single aisle airplane is the 753 at 2.78 liters / 100 passenger km (280 seats)
The best twin aisle airplane is the A332 at 2.74 liters / 100 passenger km (354 seats)
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting Gigneil (Reply 20): I somewhat seriously doubt that. |
Well it aint the first time you missed things
| Quoting Starlionblue (Reply 28): However maintenance costs on the 343 are probably higher. |
I'm not sure for this particular case. The CFM56s proved incredible reliable on 737 and A320. The A340's CFM56's make much less cycles then NB variants. THe A330's GE CF6-80E1 are more typical. CFM56 components are overhauled lots of places all over the world. The CF6-80E1 in only a few places. So maintenance costs could be similar or even less..
RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
| Quoting OldAeroGuy (Reply 30): The best twin aisle airplane is the A332 at 2.74 liters / 100 passenger km (354 seats) |
Dramatic example of how these numbers tend to be misleading. Thank you, sir.
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- OldAeroGuy
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RE: A350-1000 New Wing To Support 4 Engines F0r -1100?
Relative to this comparison:
Please see these data in this thread:
333-6,000 kg/hr
772/343-6900 kg/hr
https://www.airliners.net/aviation-forums/tech_ops/read.main/229346/
The implication is that the A343 burns about 15% more fuel per hour in cruise than the A333.
This is not strictly comparable since the LH numbers are for block fuel while the CX numbers are cruise fuel flow. It does give a relative indication of the fuel flow differences between the two airplanes.
| Quoting Panais (Reply 27): Suggest that you read page 95 of the Lufthansa Balance report that talks about Sustainability. http://konzern.lufthansa.com/en/down...ationen/lh_sustainability_2007.pdf Specific fuel consumption per aircraft A330-300 4.03 liters / 100 passenger km A340-300 4.05 liters / 100 passenger km |
Please see these data in this thread:
333-6,000 kg/hr
772/343-6900 kg/hr
https://www.airliners.net/aviation-forums/tech_ops/read.main/229346/
The implication is that the A343 burns about 15% more fuel per hour in cruise than the A333.
This is not strictly comparable since the LH numbers are for block fuel while the CX numbers are cruise fuel flow. It does give a relative indication of the fuel flow differences between the two airplanes.
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