WingedMigrator From United States of America, joined Oct 2005, 1944 posts, RR: 57 Posted (5 years 3 weeks 10 hours ago) and read 8303 times:
I noted in Airbus presentation materials on the A350XWB that the wing area was 442 m2.
Leaving aside for the moment the many slightly different ways of measuring wing area, this seems like a huge wing for an airplane with MTOW as low as 245 tonnes. The A358 will have an MTOW / wing area almost 20% less than the A388, which is itself noted for its uncommonly low wing loading.
What reasons can there be to make the A350 wing so large, even larger than the 777's?
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 1, posted (5 years 3 weeks 10 hours ago) and read 8305 times:
Quoting WingedMigrator (Thread starter):
What reasons can there be to make the A350 wing so large, even larger than the 777's?
Payload, it is designed to have a higher structural payload than the 777, or the same payload with a lot more range, higher cruise altitudes, better runway performance with smaller engines.
Flagon From France, joined May 2007, 126 posts, RR: 0 Reply 2, posted (5 years 1 week 2 days 12 hours ago) and read 8019 times:
Note that the 245T aircraft is the lighter version of the 350XWB (version -800)
the baseline aircraft is 265T (a350xwb-900) and there is also the version -1000 which is 295T with the same wing as far as I know.
American 767 From United States of America, joined May 1999, 3068 posts, RR: 16 Reply 3, posted (5 years 1 week 1 day 23 hours ago) and read 7957 times:
Quoting Zeke (Reply 1):
Payload, it is designed to have a higher structural payload than the 777, or the same payload with a lot more range, higher cruise altitudes, better runway performance with smaller engines.
That is correct. It is the lift capability that is enhanced. Higher coffin corner (it means max ceiling in the jargon of airline pilots), slightly less runway length required at take off even in hot conditions, improved fuel efficiency and higher range like you say. The only thing is, gate spacing, when the aircraft is parked at the gate between two other aircraft, the wing has to fit in. But I don't think that the wingspan of the A350XWB should be any larger than that of a B777, please don't hesitate to correct me if I'm wrong about this.
Ben Soriano
Brussels Belgium
"Aimer jusqu'a l'impossible, c'est possible". Tina Arena.
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 4, posted (5 years 1 week 1 day 18 hours ago) and read 7916 times:
Quoting American 767 (Reply 4): But I don't think that the wingspan of the A350XWB should be any larger than that of a B777, please don't hesitate to correct me if I'm wrong about this.
You are correct, the span is a little over 2' less, but it has a larger wing area then the 777.
Astuteman From United Kingdom, joined Jan 2005, 8612 posts, RR: 96 Reply 5, posted (5 years 1 week 1 day 17 hours ago) and read 7900 times:
Quoting Zeke (Reply 5): You are correct, the span is a little over 2' less, but it has a larger wing area then the 777.
As I understand it, you're right, but both of these figures are very, very near to the 77W's wingspan and area.
I'm guessing the larger area is a function of "the bit in the middle" (fuselage) being a tad narrower on the 777.
So effectively the same wing for the 295t max -XWB as the 350t 777.
I think a function of the CFRP wings is to take advantage of the material to give bigger, and bigger wingspans, to the great benefit of the cruise drag.
It'll have a serious L/D ratio
Of course, a bigger wing is heavier, but I'm guessing CFRP moves the trade-off point to a bigger span.
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 6, posted (5 years 1 week 1 day 15 hours ago) and read 7869 times:
Quoting American 767 (Reply 4): But I don't think that the wingspan of the A350XWB should be any larger than that of a B777, please don't hesitate to correct me if I'm wrong about this.
Can't post the pdf to the site, but it's stated as 3 meters wider relative to the A330, but then 64 meters in parenth so it's between 207' 8" and 209' 11"/210'. Most long haul international gates will be ADG-V in gate span (25' wingtip clearance) which is 239-240'.
Text from the pdf. :
Relative to A330:
3m larger wingspan (64m)
(ICAO Category E)
20% more wing area (442m2)
3° sweep increase (35°)
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 7, posted (5 years 1 week 1 day 10 hours ago) and read 7823 times:
Quoting Boeing7E7 (Reply 6):
Can't post the pdf to the site, but it's stated as 3 meters wider relative to the A330, but then 64 meters in parenth so it's between 207' 8" and 209' 11"/210'. Most long haul international gates will be ADG-V in gate span (25' wingtip clearance) which is 239-240'.
It is still 2-3 feet shorter that the 777 wing span, or 1-2 feet shorter than the 744 wing span.
WingedMigrator From United States of America, joined Oct 2005, 1944 posts, RR: 57 Reply 8, posted (5 years 1 week 12 hours ago) and read 7759 times:
Quoting Astuteman (Reply 5): So effectively the same wing for the 295t max -XWB as the 350t 777.
You could even say, effectively the same wing for the 245t A358 as the 350t 77W, and furthermore, the former designed with some 15 years newer CFD tools.
If the structural rigidity of the CFRP panel approach is as good as many think it should be, an additional stretch would be possible (and really needed to match the 777-300ER when the 777 is in 10-abreast Economy).
Astuteman From United Kingdom, joined Jan 2005, 8612 posts, RR: 96 Reply 10, posted (5 years 6 days 15 hours ago) and read 7690 times:
Quoting WingedMigrator (Thread starter): The A358 will have an MTOW / wing area almost 20% less than the A388, which is itself noted for its uncommonly low wing loading.
Just some further thoughts about this that might or might not be correct.
As far as I can calculate, the extra span will give the A350XWB-800 some 3% less cruise drag than the 787-9 at MTOW (c.7% better lift drag, offset by higher wetted area drag and slightly larger engines).
If RR are correct, and the Trent XWB is 2% more efficient than the 787's engines, then the A358 will burn 5% less fuel than the 787-9.
Boeing say the 787-9 has a range of 8 500Nm with 250 pax, and 8 000Nm with 290 pax.
Interpolating, with 270 pax as per the A358, range would be 8 250Nm, near on the same as the A358.
However, the A358, if my calcs are correct, would need about 5.5t less fuel to do the mission.
As it's 2.5t heavier, (545 000lb vs 540 000lb - please correct if wrong), the A350 should have an OEW some 8t heavier than the 787-9 (as you would expect, with a bigger wing, bigger engines and clamshells), and yet burn 5% less fuel for essentially the same mission.
Of course, these are just my fag-packet musings, but if I'm anywhere near, they're not bad numbers for the supposedly most inefficient model......
WingedMigrator From United States of America, joined Oct 2005, 1944 posts, RR: 57 Reply 11, posted (5 years 6 days 12 hours ago) and read 7666 times:
Quoting Astuteman (Reply 10): As it's 2.5t heavier, (545 000lb vs 540 000lb - please correct if wrong)
I believe the A358's MTOW is 245t, or just about the same as the 789.
Quoting Astuteman (Reply 10): the A350 should have an OEW some 8t heavier than the 787-9 (as you would expect, with a bigger wing, bigger engines and clamshells)
I'm having trouble getting the range calculations to close with that much of an OEW spread.
If as you say, the cruise L/D is 3% better for the A358 and cruise SFC is 2% better, and the OEW spread is 8t (118t for the 789 and 126t for the A358), my model (a first order computation based on the Breguet range equation) has the max range of the 789 at 8250 nm with 263 pax -- so far, so good -- but the A358 at only 7750 nm with 270 pax (versus 8500 spec). To hit the range spec, the A358 would have to lose 6t.
Under those conditions, an 8000 nm mission would take 88,950 kg of fuel for the A358, versus 93,600 kg for the 789-- indeed the 5% difference you point out. Factoring in the difference in pax load, the A358 would come out with 8% better fuel burn per seat-mile.
Another possibility is that Airbus's 8500 nm range figure is a tad optimistic... with an 8t OEW difference, the A358 would come out only 3.5% ahead of the 789 on fuel burn per seat-mile.
Quoting Astuteman (Reply 10): Of course, these are just my fag-packet musings
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 13, posted (5 years 5 days 15 hours ago) and read 7564 times:
Quoting Zeke (Reply 7): It is still 2-3 feet shorter that the 777 wing span, or 1-2 feet shorter than the 744 wing span.
And your point is? I gave a spec. Don't have a fit.
Except for the 200LR and 300ER, the 777 wing is 60.93 meters, not the A350's 64. The 200LR and 300ER is 64.8. The 744ER is 64.44 to 64.92 depending on fuel load.
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 14, posted (5 years 5 days 8 hours ago) and read 7508 times:
Quoting Boeing7E7 (Reply 13):
And your point is? I gave a spec. Don't have a fit.
I didn't have a fit, the only long haul gates that I go into that are constrained are at American airports where they do not spend any money investing the the future.
It is a fallacy to say "Most long haul international gates will be ADG-V", it maybe the case in the USA, but in the real world international airports don't have problems fitting in ICAO cat E aircraft such as the 744 at gates.
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 15, posted (5 years 4 days 17 hours ago) and read 7459 times:
Quoting Zeke (Reply 14): I didn't have a fit, the only long haul gates that I go into that are constrained are at American airports where they do not spend any money investing the the future.
Quoting Zeke (Reply 14): It is a fallacy to say "Most long haul international gates will be ADG-V", it maybe the case in the USA, but in the real world international airports don't have problems fitting in ICAO cat E aircraft such as the 744 at gates.
An ADG-V gate supports aircraft with a 214' wingspan and 25' of wingtip separation, that aircraft being a 744/772LR/773ER - and by extension the A350. I don't know of any US international gateway that doesn't use this standard for it's widebody FIS facilities and they have no problem supporting 747's. I think you might want to re-think your BS assertion because clearly you have no idea what you are talking about.
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 16, posted (5 years 4 days 7 hours ago) and read 7410 times:
Quoting Boeing7E7 (Reply 15):
An ADG-V gate supports aircraft with a 214' wingspan and 25' of wingtip separation, that aircraft being a 744/772LR/773ER - and by extension the A350. I don't know of any US international gateway that doesn't use this standard for it's widebody FIS facilities and they have no problem supporting 747's. I think you might want to re-think your BS assertion because clearly you have no idea what you are talking about.
Come back to us when you realise that outside the insular USA where the non standard aircraft design groups (ADG) are used, the rest of the 190 odd countries in the world use ICAO standards, and the A350 is ICAO E.
As for supporting 747s, even at LAX a 772 need to shut its engines down and be towed to gate, it is a non standard poorly planned airport.
Have you ever flown a wide body into a US airport or overseas ?
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 17, posted (5 years 4 days 3 hours ago) and read 7394 times:
Quoting Zeke (Reply 16): Come back to us when you realise that outside the insular USA where the non standard aircraft design groups (ADG) are used, the rest of the 190 odd countries in the world use ICAO standards, and the A350 is ICAO E.
ADG-V and ICAO E are the same gate spacing standard smart guy.
Group I - < 49' (15m)
Group II - 49' (15m) - <79' (24m)
Group III - 79' (24m) - <118' (36m)
Group IV - 118' (36m) - <171' (52m) Group V - 171' (52m) - <214' (65m)
Group VI - 214' (65m) - <262' (80m)
ICAO Annex 14 - Aerodrome Reference Code Element 2, Table 1-1
(Aeroplane Wingspan; Outer Main Gear Wheel Span)
Quoting Zeke (Reply 16): As for supporting 747s, even at LAX a 772 need to shut its engines down and be towed to gate, it is a non standard poorly planned airport.
That's an airfield and terminal layout issue, not a gate wingspan spacing issue. An issue LAX is working with given the constraints of existing infrastructure reaching the end of its 50 year useful life making reconstruction and layout improvements a going concern. Then again, most airports abroad are built with public funds with no tie to airport financial accountability, the bond market, or sensitivity to an airline cost competitive operating environment.
Quoting Zeke (Reply 16): Have you ever flown a wide body into a US airport or overseas ?
Have you ever designed an airport and do you know anything about Airport Design Characteristics? Clearly you are guessing.
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 18, posted (5 years 3 days 19 hours ago) and read 7352 times:
Quoting Boeing7E7 (Reply 17): ADG-V and ICAO E are the same gate spacing standard smart guy.
No they are not, one is a FAA standard, one in an international standard (ICAO), comparing Table 1-1 out of a 200+ page standard is being somewhat dishonest.
Quoting Boeing7E7 (Reply 17): That's an airfield and terminal layout issue, not a gate wingspan spacing issue. An issue LAX is working with given the constraints of existing infrastructure reaching the end of its 50 year useful life making reconstruction and layout improvements a going concern. Then again, most airports abroad are built with public funds with no tie to airport financial accountability, the bond market, or sensitivity to an airline cost competitive operating environment.
More excuses, American airports are crap, LAX is a good example of how crap they are, that is the first thing a lot of people see when they get to the states, some run down clapped out airport and terminal.
Quoting Boeing7E7 (Reply 17): Have you ever designed an airport and do you know anything about Airport Design Characteristics? Clearly you are guessing.
"do you know anything about Airport Design" yes I do, I have formally studied the topic at post graduate level, I have my own personal copy of Annex 14, plus I have the operational experience to back it up.
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 19, posted (5 years 3 days 17 hours ago) and read 7317 times:
Quoting Zeke (Reply 18): No they are not, one is a FAA standard, one in an international standard (ICAO), comparing Table 1-1 out of a 200+ page standard is being somewhat dishonest.
The FAA ADG-V gate dimensional standard is the same as the ICAO E gate dimensional standard. LAX's problem is not the gate-span issue as I have stated previously, its a taxiway/taxilane/FMO deficiency that impacts airfield mobility, this is not a function of the gate dimensions.
Quoting Zeke (Reply 18): More excuses, American airports are crap, LAX is a good example of how crap they are, that is the first thing a lot of people see when they get to the states, some run down clapped out airport and terminal.
Something LAX is poised to spend billions on.
Quoting Zeke (Reply 18): "do you know anything about Airport Design" yes I do, I have formally studied the topic at post graduate level, I have my own personal copy of Annex 14, plus I have the operational experience to back it up.
Regardless your experience or level of education, you are confusing an airport mobility issue with a gate dimensional issue. As someone who deals with FAA and ICAO design standards on a daily basis, I can tell you that you are unequivocally wrong in your assertions concerning this issue.
It started here when you showed your apparent lack of understanding that ADG-V and ICAO E are the same dimensional standards. An ADG-V is for a 744, or aircraft with wingspans up to 65-meter. The same as ICAO Index E which supports wingspans up to 65-meter:
Quoting Zeke (Reply 14): It is a fallacy to say "Most long haul international gates will be ADG-V", it maybe the case in the USA, but in the real world international airports don't have problems fitting in ICAO cat E aircraft such as the 744 at gates.
In fact, in terms of gate wingtip separation, the ICAO standard is 7.5-meter where the US standard is 7.6-meter. Thus, any ADG-V gate in the US will be able to support the A350 as I stated.
Stitch From United States of America, joined Jul 2005, 23618 posts, RR: 80 Reply 20, posted (5 years 3 days 16 hours ago) and read 7305 times:
Quoting Zeke (Reply 18): No they are not, one is a FAA standard, one in an international standard (ICAO), comparing Table 1-1 out of a 200+ page standard is being somewhat dishonest.
Yet if both standards map to each other, does it matter? A plane with a wingspan between 52m and 65m should fit into a gate designated ADG-V or ICAO Code E, correct?
Quoting Zeke (Reply 18): American airports are crap, LAX is a good example of how crap they are, that is the first thing a lot of people see when they get to the states, some run down clapped out airport and terminal.
And this applies to a plane fitting into a gate how?
Kappel From Suriname, joined Jul 2005, 3533 posts, RR: 21 Reply 22, posted (5 years 2 days 22 hours ago) and read 7234 times:
Getting back to the topic at hand...
Quoting Astuteman (Reply 10): As far as I can calculate, the extra span will give the A350XWB-800 some 3% less cruise drag than the 787-9 at MTOW (c.7% better lift drag, offset by higher wetted area drag and slightly larger engines).
I am having trouble finding the wing area of the 787 (-8 and -9 share the same wing right?). Do you know what the 787 wing area is? I'm assuming in the 777 ballpark?
Quoting Astuteman (Reply 10): If RR are correct, and the Trent XWB is 2% more efficient than the 787's engines, then the A358 will burn 5% less fuel than the 787-9.
I'm actually surprised by this. How do RR achieve the 2%? Bigger fan or other improvements (or both)?
If your calculations are correct, it's no wonder that some airlines are holding out on the final specs of the a350 before ordering. It's looking like a very attractive aircraft. If only Airbus wasn't "caught napping" (as Leahy acknowledged) they might have stolen many orders from Boeing, especially the 787-9 orders.
Boeing7E7 From , joined Dec 1969, posts, RR: Reply 23, posted (5 years 2 days 19 hours ago) and read 7213 times:
Quoting Boeing7E7 (Reply 21): I am having trouble finding the wing area of the 787 (-8 and -9 share the same wing right?).
The -8 has a 197' 3" wingspan, the -9 has a 203' 8" span. Not sure how that translates in terms of area. Ones a smidge bigger than the 777, one larger. Both smaller than the 777-200LR/777-300ER which is at 212' 7".
Astuteman From United Kingdom, joined Jan 2005, 8612 posts, RR: 96 Reply 24, posted (5 years 2 days 18 hours ago) and read 7205 times:
Quoting Kappel (Reply 22): I am having trouble finding the wing area of the 787 (-8 and -9 share the same wing right?). Do you know what the 787 wing area is?
For the purposes of "calculation", I simply assumed that the 787-9's wing is (62/64)^2 as a proportion of the A350XWB's wing area, and used the proportions of the fuselage to determine the proportion of fuselage wetted area vs the A350XWB.
Fag-packet stuff
Quoting WingedMigrator (Thread starter): Leaving aside for the moment the many slightly different ways of measuring wing area
. Calculating the "true" wetted area of the wing is a work of art, beyond my craft...
Quoting Kappel (Reply 22): I'm actually surprised by this. How do RR achieve the 2%? Bigger fan or other improvements (or both)?
I would have expected 2% just from the scale-up to 118" from 112".
In truth, RR will be incorporating tech developments beyond the Trent 1000 (inevitably so, given the 5 year time gap).
My suspicion is that RR will beat 2% better
Quoting Kappel (Reply 22): It's looking like a very attractive aircraft
It certainly won't be a dog. As per the dialogue above, the biggest trick will be keeping (for example), the OEW of the A358 within 2-3t of the 787-9.
If my drag and SFC figures are anywhere near, the A358 has a 4% - 5% fuel burn advantage over the 787-9, for a very similar (near-identical) range/payload capability.
Even if the A358 OEW ends up, say 3t overweight, then a 5t hike in MTOW (to 250t) should restore the range/payload capability.
In doing this, a 2% penalty in lift drag is realised, but of course wetted area and appendage drag are fixed.
Therefore fuel burn most likely goes up by about 1% at most.
(and in all probability RR will get this back by beating the SFC figure, as I said above)
Still a very capable aeroplane........
Regards
25 OldAeroGuy: The back of the envelope method you are using appears to be playing you false. The basic flaw in your assumption appears to be that the 789 wing area
26 Stitch: According to Widebodyphotog's 787 family chart: 787-3: 302.2 meters squared 787-8: 346.9 meters squared 787-9: 359.2 meters squared
27 OldAeroGuy: Pretty close agreement (within 9 sq. m.) Makes for a better A3510 ( and additional stretches) and doesn't hurt the A358 too much since the A350's are
28 WingedMigrator: Thanks for your insight. To first order, there is something that still doesn't make sense for me... comparing the A358 to the 789, if you assume: (a)
29 Astuteman: Many thanks for your response, OAG. I'm always conscious that a little knowledge is a dangerous thing when I play with these analyses. My first comme
30 Baroque: At one stage RR had a page of waffle about what wonderful things they would do beyond the T1000 for the T1700. This page then disappeared, alas befor
31 XT6Wagon: Where then does the A358 get its nearly identical seating capacity to the 789 then if it is substantially shorter? Also you might note that Boeing ad
32 Astuteman: IIRC it doesn't. 9-abreast, the A350-XWB-800 seats 270 (according to Airbus) 8 abreast, the 787-900 seats 250 (according to Boeing) 9 abreast, the 78
33 Astuteman: Further thoughts (musings). On the basis that an A350-XWB sized wing (effectively) gives the 360t ish 77W's just fine field performance, why does the
34 AutoThrust: Very interesting read Astuteman and OldAereoGuy. Not that i do understand everything but why does Airbus tend to make Wing larger then Boeing which le
35 OldAeroGuy: The Breguet Range equation is just fine for this type of analysis. The problem may lie in the L/D assumption. Airbus is planning to put a cruise vari
36 WingedMigrator: I used 8250 nmi for 263 pax. This may have been a tad on the high side... 8160 nmi is more like it according to your figures above. Plugging that in
37 Stitch: No offense, chief, but .3" does not a "genuine" product make in my mind... Per Airbus' own presentation slide decks, an A350 in 3-3-3 will have 17.5"
38 TristarSteve: Fascinating reading guys, just wished I understood more. Anyway just a small question. A lot of posts at the front of this thread about Cat E gates. I
39 Astuteman: Find this one difficult - the A358 is 6% shorter but only about 1.5% wider in one dimension (methinks..) However, I've no probs with this, particular
40 OldAeroGuy: Oh for the lack of a good set of three views. According to the first reference below, the A350XWB is 60.5m long while the 789 is 63m. Since these dis
41 WingedMigrator: I'm not sure it's a fair comparison to use the same payload, since a smaller airplane will always benefit from such a comparison, provided that it is
42 OldAeroGuy: I'd agree if there were a significant size difference between the A358 and the 789. In this case though, they are virtually the same size with very s
43 Astuteman: That's another possible source for conflict rooted out. I understood the A358 XWB to be 59m long, not 60.5m, hence 6.7% difference in length........
44 Stitch: Airbus' Flash site shows 60.5m, I believe. Not sure where I got it, but I do show 60.5m for her length.
45 Astuteman: I'm happy to believe it. In which case my "optimistic" assessment of the A358's efficiency was driven by primarily underestimating the wetted areas o
46 Boeing7E7: Pre A380 the depth standard was 240'. Most new gates, even at airports that won't support 747's or A380's the standard is 250'. For those expecting t
47 WingedMigrator: the million (billion!) dollar question. Something isn't quite right and I can't wait to see if we'll get more detail for our "fag packet" spreadsheet
Sponsor Message: 
From United States of America, joined Oct 2005, 1944 posts, 
From Hong Kong, joined Dec 2006, 6800 posts, 
From France, joined May 2007, 126 posts, 
From United Kingdom, joined Jan 2005, 8612 posts, 
)
From Suriname, joined Jul 2005, 3533 posts, 
. Calculating the "true" wetted area of the wing is a work of art, beyond my craft... 
Sponsor Message: 
Printer friendly format
