mjoelnir
in service - 2 years
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Post by mjoelnir on Nov 22, 2013 12:28:10 GMT 1
That's a good point, but as with all developments, plugging something new onto something old never yields the same gains as having everything developed together. I would be surprised if a folding wing extension with a new wingtip could yield that kind of gain in efficiency, but I'm prepared to stand corrected. I'm still not entirely sold on this folding wing extension, Boeing offered a folding wing extension for the 77W and 77L and as I'm sure everyone is aware, not a single customer bought it. A folding wing extension increases complexity and weight and it needs to be done in a way that even when the extension fails to fold back in for landing or even breaks off entirely, the plane can still fly. I'm pretty sure it would be an absolute nightmare to develop and certify, which brings me back to my original point.. I'm not entirely sold on the whole thing. The change for the A320 old fence to A320 new fence, sharklet, is about 4%. That, I think, is with a stage length of around 1,000 miles or about 1,600 km. www.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-launches-sharklet-retrofit-for-in-service-a320-family-aircraft/That is plucking something new on something old, and that is 4% and that is on a short haul frame, with the sharklet giving more advantage on longer flights. I expect the work with the A 350 has giving Airbus even more information to build on.
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mjoelnir
in service - 2 years
Posts: 4,089
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Post by mjoelnir on Nov 22, 2013 12:44:00 GMT 1
Regarding an engine change. I still believe that Airbus will not sling the XWB under the A380. The increased weight, I do not trust the numbers in Wikipedia not even having the same numbers in the English and German version, will force too many changes on the wing of the A380 especially the outboard engine. I think that we do not see thrust reversers on the out board engine is not only because of not blowing around debris but also because of weight constraints.
I can believe in a new engine with the XWB technology and also the RR next generation technology integrated in the right trust range and engine weight. That engine I would expect not before around 2020.
Or an upgrade of the T 900 including most of the XWB technology, added weight savings and not being downward compatible to older T 900. That could be perhaps around 2016/2017.
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Taliesin
Final Assembly Line stage 1
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Post by Taliesin on Nov 22, 2013 15:23:25 GMT 1
Regarding an engine change. I still believe that Airbus will not sling the XWB under the A380. The increased weight, I do not trust the numbers in Wikipedia not even having the same numbers in the English and German version, will force too many changes on the wing of the A380 especially the outboard engine. Apparently I stand corrected concerning the winglets, it would be kind of poetic if one day you stood corrected about the TrentXWB being offered on the A380
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Post by FabienA380 on Nov 22, 2013 15:37:49 GMT 1
Silly question, could that be ever possible to offer different engines on a single plane?... For example, XWB engines on the A380 for engines 2 and 3 and regular (RR) engines on the outboard, engines 1 and 4?... Fabien
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Taliesin
Final Assembly Line stage 1
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Post by Taliesin on Nov 22, 2013 16:04:33 GMT 1
Possible of course and it's been done in the past, I believe some versions of the 727 had newer engines on 1 and 3 and an older engine on position 2, because the newer engines didn't fit inside the fuselage structure. The TrentXWB's fan is only 2 inches wider than the Trent 900's, so I for one don't believe clearance to be an issue, but even if it were, this would never be done. The savings in fuel burn of the new engines would be eaten up by the increased costs of having to store spare parts for 2 engines and everything that entails.
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mjoelnir
in service - 2 years
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Post by mjoelnir on Nov 22, 2013 18:03:59 GMT 1
Regarding an engine change. I still believe that Airbus will not sling the XWB under the A380. The increased weight, I do not trust the numbers in Wikipedia not even having the same numbers in the English and German version, will force too many changes on the wing of the A380 especially the outboard engine. Apparently I stand corrected concerning the winglets, it would be kind of poetic if one day you stood corrected about the TrentXWB being offered on the A380 of course and it is of course only my humble opinion. But where would be the fun in discussing something if everybody would have the same views.
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philidor
in service - 6 years
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Post by philidor on Nov 23, 2013 0:23:26 GMT 1
So, the TXWB is one ton too heavy to re-engine the A380 (--> altogether, a 4 tons penalty).
Now, I have a question : would it be possible to fit the TXWB with a CFRP fan ? This might cancel out the weight penalty ! The upgrade would also benefit the A350 (saving two tons ?), improving the business case for the investment.
Does this idea make sense ? Could RR make it ? Would three years be enough ?
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Post by Flying Dutchman on Nov 23, 2013 3:25:01 GMT 1
[quote author= It absolutely defies logic to suggest that Airbus didn't know about this and didn't test a raked wingtip on the A380, at least in a numeric simulation. Something else must be going on here.[/quote]
There is a constant and relatively new development of these "vortex" effects on wings, so obviously there is a lot of improvements possible on the A380 wing, not only the wing-tips.(?) It does not have to involve folding wing tips. I believe traditionally Airbus has favoured larger wing area compared to Boeing and would that be the reason for them, Boeing, on the 777-x (That is a relatively old design = small wing area) to introduce the folding wing tips? Maybe the A-380 don't need that with their wider wings? Please advise me/us all technical people here!
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mjoelnir
in service - 2 years
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Post by mjoelnir on Nov 23, 2013 15:08:01 GMT 1
[quote author= It absolutely defies logic to suggest that Airbus didn't know about this and didn't test a raked wingtip on the A380, at least in a numeric simulation. Something else must be going on here. There is a constant and relatively new development of these "vortex" effects on wings, so obviously there is a lot of improvements possible on the A380 wing, not only the wing-tips.(?) It does not have to involve folding wing tips. I believe traditionally Airbus has favoured larger wing area compared to Boeing and would that be the reason for them, Boeing, on the 777-x (That is a relatively old design = small wing area) to introduce the folding wing tips? Maybe the A-380 don't need that with their wider wings? Please advise me/us all technical people here! [/quote] One has to define "need" for this question. The A380 has wings big enough to allow to lift quite a bit more than the current MTOW of 575 t. The A380 has not an excessive takeoff run at MTOW, inside of 3000m. In case we would have lower oil prices and less pressure to reduce greenhouse gases nobody would take a second look at the wings of the A380, they do a good job. But as we have high oil prices and fuel burn is the all overriding consideration one takes a look at the wings. As the biggest passenger plane in use she gets hit by a design restraint smaller planes have no difficulties with, the max wingspan of 80m. Increasing the wing span with winglets of many different construction possibilities will reduce fuel burn considerable perhaps up to 5%. But the wingspan is already at 79.75m. IMO it is rather a question how Airbus will do it than if.
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Taliesin
Final Assembly Line stage 1
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Post by Taliesin on Nov 24, 2013 0:19:35 GMT 1
The change for the A320 old fence to A320 new fence, sharklet, is about 4%. Not to re-open a settled debate, but the wingtip fence on the A320 was over 25 years old, replacing it with a sharklet supposedly yields 4% on longer routes. On the A380, the wingtip fence is a little over 5 years old and replacing it with "something new" supposedly yields 3%. I'm not saying it's impossible, but those numbers are to illustrate my point.. 3% under these circumstances is a lot. Folding wingtip extensions would benefit the A380 quite a bit in my opinion, because due the constraint of the 80m wing span, the A380's aspect ratio is significantly sub-par. While most competing aircraft have wings with an aspect ratio of around 10 or more, the A380 sports an aspect ratio of around 7,5. This increases induced drag and increases fuel burn. I'm not sure what exactly is achievable today with folding wing extensions, but quite a bit of the fuel burn reduction might come from this effect.
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