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A358 Vs A351x Numbers Don't Make Any Sense  
User currently offlineClickhappy From United States of America, joined Sep 2001, 9633 posts, RR: 68
Posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7667 times:
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Was just having a look at the link provide in another thread, where some numbers are provided for the A350XWB family.

Something does not make sense to me. But I am no engineer, so please feel free to set me straight.

The number supplied by Flight International show that the A350-800 has a range max range of 15,730km, with a max fuel capacity of 150,000 litres.

The numbers for the A350-1000 show it to have a range of 15,360km, with a max fuel capacity of 150,000 litres.

The A350-1000 is a much larger plane than the A358, 40 feet longer, with a capacity of 80 more pax than the A350-800. It also has much more powerful engines.

So, how is it that the A350-1000 range will be almost the same as the A350-800, yet it is a much bigger airframe?

53 replies: All unread, showing first 25:
 
User currently offlineN328KF From United States of America, joined May 2004, 6485 posts, RR: 3
Reply 1, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7637 times:

Quoting Clickhappy (Thread starter):

So, how is it that the A350-1000 range will be almost the same as the A350-800, yet it is a much bigger airframe?

Bigger belly == more belly tanks.



When they call the roll in the Senate, the Senators do not know whether to answer 'Present' or 'Not guilty.' T.Roosevelt
User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 2, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7637 times:

Quoting Clickhappy (Thread starter):
So, how is it that the A350-1000 range will be almost the same as the A350-800, yet it is a much bigger airframe?

A good reason would be that the -800 engines are derates from the -900 and -1000 versions, and therefore less efficient than the -900 and -1000 series engines. This would make for a lower decrease in range for a larger airframe as the higher thrust engines gain efficiency on the scale. Theres a reduction but not as big as it should be on an 'all things equal' scale because all things are not equal.

[Edited 2006-12-11 20:34:37]

User currently offlineClickhappy From United States of America, joined Sep 2001, 9633 posts, RR: 68
Reply 3, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7641 times:
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The numbers provided show the max fuel being the same for both models, 150,000 litres.

I would assume you mean that additional fuel can be carried in belly tanks?

Perhaps the specs are wrong?


User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 4, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7622 times:

Quoting N328KF (Reply 1):
Bigger belly == more belly tanks.

But Clickhappy quotes the two max fuel capacities as the same.


User currently offlineIkramerica From United States of America, joined May 2005, 21532 posts, RR: 60
Reply 5, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7622 times:

Or that the 358 is MTOW limited, not fuel limited.


Of all the things to worry about... the Wookie has no pants.
User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7621 times:

Quoting Clickhappy (Reply 3):
Perhaps the specs are wrong?

Thats the most obvious. We shall see over the next year or two when the specifications and numbers are refined.


User currently offlineClickhappy From United States of America, joined Sep 2001, 9633 posts, RR: 68
Reply 7, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7603 times:
AIRLINERS.NET CREW
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Thank you for the replys.

Here is the link if anyone wants to see the numbers.

http://www.flightglobal.com/Articles...s's+A350+vision+takes+shape+.html


User currently offlineBaron95 From United States of America, joined May 2006, 1335 posts, RR: 8
Reply 8, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7574 times:

Here is what I think the OP is referring to (from the same FI article above).

I think the key is that it is shown as "Design Range". To me that is a fuzzy term that can mean almost anything. My take is that they just adjust the payload down on the larger models to meet the similar ranges - or some other vodoo like that. I have serious doubt that they can get the -1000 off the groun (except maybe with 12,000feet+ runways) with just 95Klbs of thrust.

Big version: Width: 450 Height: 337 File size: 41kb
A350XWB Family Specifications



Killer Fleet: E190, 737-900ER, 777-300ER
User currently offlineIkramerica From United States of America, joined May 2005, 21532 posts, RR: 60
Reply 9, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7510 times:

Look, it's not as weird as it seams.

The fuel capacity of the 787-3 is the same as the 787-8, yet the 787-8 range is 5000nm greater. Just because a fuel tank can hold a certain amount doesn't mean it can lift all that fuel and a full payload at the same time.



Of all the things to worry about... the Wookie has no pants.
User currently offlineAstuteman From United Kingdom, joined Jan 2005, 10046 posts, RR: 96
Reply 10, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7506 times:
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Quoting Baron95 (Reply 8):
I have serious doubt that they can get the -1000 off the groun (except maybe with 12,000feet+ runways) with just 95Klbs of thrust.

Isn't 295t (or 650 000lb) remarkably similar to the 772ER, which has similar thrust?

Quoting Ikramerica (Reply 5):
Or that the 358 is MTOW limited, not fuel limited.

It may possibly be a typo, but it might also be possible that Ikramerica's comment may apply. In practice, the A358 may never actually carry 150k litres, except, maybe on ferry flights, whereas the -1000 might routinely carry 150k litres with high payloads.
(you'd still expect it to have a bigger capacity, though, wouldn't you? )

Regards


User currently offlineBaron95 From United States of America, joined May 2006, 1335 posts, RR: 8
Reply 11, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7427 times:

Quoting Astuteman (Reply 10):
Isn't 295t (or 650 000lb) remarkably similar to the 772ER, which has similar thrust?

True enough.

But I was referring to Airbus claims of a 3-class config of 350 passengers (like an 77W) and 8,300nm range (like an 77L). I don't believe that a plane with that capability (as many pssengers and greater range than a 77W) can weigh (MTOW) as only as much as 772ER. Therefore, I don't think it can take-off with the same thrust, except if the runway requirements are out of sight. Just my 2c - what do I know - they design and build airplanes for a living.



Killer Fleet: E190, 737-900ER, 777-300ER
User currently offlineHamlet69 From United States of America, joined Mar 2000, 2744 posts, RR: 58
Reply 12, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7412 times:

What I don't get is how the A350-800 is roughly 5 feet longer than the 787-9, but will carry 10 fewer LD-3's!!

Anyone?

Hamlet69  profile 



Honor the warriors, not the war.
User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 13, posted (7 years 9 months 2 weeks 3 days 10 hours ago) and read 7397 times:

Quoting Astuteman (Reply 10):
Isn't 295t (or 650 000lb) remarkably similar to the 772ER, which has similar thrust?

A350-1000 - 95,000lb thrust
777-200ER - 90,000 to 93,000lb thrust

A350-1000 - 295mt MTOW
777-200ER - 297mt MTOW

A350-1000 - 15,360km
777-200ER - 14,316km

Good spot there Astuteman, it would seem you are correct.
(data above taken from the chart above and http://www.boeing.com/commercial/777family/pf/pf_200product.html )


User currently onlineStitch From United States of America, joined Jul 2005, 31012 posts, RR: 86
Reply 14, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7372 times:
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Quoting Baron95 (Reply 11):
I don't believe that a plane with that capability (as many pssengers and greater range than a 77W) can weigh (MTOW) as only as much as 772ER.

Depends on how much weight-savings Airbus' construction materials provide.


User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Reply 15, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7345 times:

Hamlet, maybe there is less room in the hold due to crew rest area, lavs, etc?

User currently offlineWINGS From Portugal, joined May 2005, 2831 posts, RR: 68
Reply 16, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7338 times:

Quoting Hamlet69 (Reply 12):
What I don't get is how the A350-800 is roughly 5 feet longer than the 787-9, but will carry 10 fewer LD-3's!!

Anyone?

Could it be that the A350 will use underfloor galleys,toilets, crew rest compartment?

Regards,
Wings



Aviation Is A Passion.
User currently offlineBaron95 From United States of America, joined May 2006, 1335 posts, RR: 8
Reply 17, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7326 times:

Quoting RichardPrice (Reply 13):
A350-1000 - 95,000lb thrust
777-200ER - 90,000 to 93,000lb thrust

A350-1000 - 295mt MTOW
777-200ER - 297mt MTOW

A350-1000 - 15,360km
777-200ER - 14,316km

Lets add:
A350-1000 - 350 passengers 3-class config
777-200ER - 301 passengers 3-class config

So Airbus can add 49 passangers (20%), oven 1,000 KM of range (7.5%) and keep have a lower MTOW? I'm not saying it is impossible, but I have a hard time believing they'll get there.



Killer Fleet: E190, 737-900ER, 777-300ER
User currently offlineBeech19 From United States of America, joined Jul 2006, 936 posts, RR: 4
Reply 18, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7272 times:

Quoting Ikramerica (Reply 9):
Look, it's not as weird as it seams.

The fuel capacity of the 787-3 is the same as the 787-8, yet the 787-8 range is 5000nm greater. Just because a fuel tank can hold a certain amount doesn't mean it can lift all that fuel and a full payload at the same time.

You just compared two different situations though. True they ARE the same size but they -3 is designed to have a lower MTOW because it carries much less fuel (and less wing for that matter). The A358 and A3510 are 40ft difference in size and i would expect the -1000 to have a much higher MTOW, if not the range would be drastically lower based on the same fuel.

I'm thinking its either a limitation by weight or the spec was screwed up. We shall wait and see...



KPAE via KBVY
User currently offlineA342 From Germany, joined Jul 2005, 4682 posts, RR: 3
Reply 19, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7262 times:

Quoting Ikramerica (Reply 9):
Look, it's not as weird as it seams.

The fuel capacity of the 787-3 is the same as the 787-8, yet the 787-8 range is 5000nm greater. Just because a fuel tank can hold a certain amount doesn't mean it can lift all that fuel and a full payload at the same time.

Bingo ! It's the same thing with the A332 and A343. Both have about the same fuel capacity, yet the A332 is significantly smaller, lifts less payload and has a lower range.

A manufacturer might chose to give an aircraft excess fuel capacity so that just one version of the wing/tank has to be produced



Exceptions confirm the rule.
User currently offlineFuturecaptain From , joined Dec 1969, posts, RR:
Reply 20, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7094 times:

From the released design specs...

The A350-8 can fly 15,730 km on 150,000 L of fuel.
So, 9.53 L per Km

The 787-9 can fly 16,300 km on 138,700 L of fuel
So, 8.51 L per Km

At the paper specs for the airplanes the 787 comes out a full 10.7% more efficient than the A350.

Now I realize both I am comparing manufacurers numbers for both birds and neither are in service, but it seems Airbus better have some great technology in the A350 to make up for this.


User currently offlineRuscoe From Australia, joined Aug 1999, 1567 posts, RR: 2
Reply 21, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7082 times:

Quoting Baron95 (Reply 17):
Lets add:
A350-1000 - 350 passengers 3-class config
777-200ER - 301 passengers 3-class config

This is at 9 abreast for the 350 & 772ER, but the 777 can go 10 abreast and the 350 can't.
Airlines being what they are, and competition being what it is, I think the extra width of the 350, without allowing an extra row of seats, will be a disadvantage eventually.

Seems to me that Airbus have set the width to compete with 787 and weights to compete with 777. I can see problems ahead.

Also $15.5 billion should buy you more than CFRP coverd aluminium.

Ruscoe


User currently offlineBoomBoom From , joined Dec 1969, posts, RR:
Reply 22, posted (7 years 9 months 2 weeks 3 days 9 hours ago) and read 7070 times:

Quoting WINGS (Reply 16):
Could it be that the A350 will use underfloor galleys,toilets, crew rest compartment?

Won't that limit cargo? I thought the new fuselage cross section will allow for a crown area crew rest.

[Edited 2006-12-11 22:27:18]

User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 23, posted (7 years 9 months 2 weeks 3 days 8 hours ago) and read 7112 times:

Quoting Futurecaptain (Reply 23):

The A350-8 can fly 15,730 km on 150,000 L of fuel.
So, 9.53 L per Km

The 787-9 can fly 16,300 km on 138,700 L of fuel
So, 8.51 L per Km

At the paper specs for the airplanes the 787 comes out a full 10.7% more efficient than the A350.

Maximum fuel capacity does not equal 'wot will be used for maximum range' - as stated above, the aircraft may be MTOW limited (as is some of the A320 family aircraft due to using the same fuel tanks). Technically thats the capacity, but it wouldnt be usable.


User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 24, posted (7 years 9 months 2 weeks 3 days 8 hours ago) and read 7088 times:

Quoting BoomBoom (Reply 25):
Won't that limit cargo?

Thats already been pointed out.


25 Jonathan-l : The ranges you quote are for max pax. The fuel capacities you quote are the max fuel capacity. They do not occur simultaneously on the payload range.
26 EI321 : edit: double post ..........................[Edited 2006-12-11 22:19:19]
27 EI321 : Its important to take into account that the A350-1000 will weigh less per passenger than the 772ER, so despite having an (approx) 15% higher capacity
28 Post contains images Futurecaptain : Granted, we have to see how both planes perform in service before making sweping generalizations as I have. But it is still fun to think about.
29 Gigneil : The plane itself is significantly lighter and will consume some 15 to 20% less fuel. NS
30 Atmx2000 : I don't the A350 is tall enough to support an overhead crew rest, so they probably use under deck space. That will take up a fair amount of space.
31 Post contains links DEVILFISH : Here's the latest FI report on the Trent XWB engine with some details..... http://www.flightglobal.com/Articles...eleases+new+data+on+Trent+XWB.html Q
32 DIA : In reply #8, the table shows a note at the bottom stating that the A350-900R has an EIS of mid-2016. What is an A350-900R?
33 Clickhappy : The plane itself is significantly lighter and will consume some 15 to 20% less fuel. 30%, if you believe the hype.
34 Stitch : "R" is an Airbus designation for a long-range aircraft. Essentially the A350's answer to the 777-200LR and A340-500.
35 Beech19 : One of the many hypotheticals in the A350 project... supposedly a -900 super duper long freaking range. We'll see...
36 EI321 : Both airbus and boeing already have LR planes in service already, why cant it be done with future models?
37 Post contains images Astuteman : FWIW, I think there's a "virtuous" circle made possible by the improvements in engine SFC, and the improved structural weight combined, provided you
38 Prebennorholm : We are here assuming figurative and airline specific configurations. Configurations which may, or may not ever exist in reality. WINGS is likely to b
39 Atmx2000 : I have noted this before. If you reduce fuel burn significantly, you need far less fuel to carry the additional fuel required for long range travel.
40 Post contains images Revelation : Maybe the A358 was done in CATIA v3 and the A359 was done in CATIA v4?
41 Post contains images Beech19 : I didn't say it couldn't be done... i just said its a hypotetical. We shall see if the A350 ever meets the tarmac... i'm still not a beleiver.
42 Pygmalion : I still think that the preferred Boeing plan for the Y3 would be to target the Y3-8 at the 350 pax space, the Y3-9 at 400 and the Y3-10 at 450. The Y3
43 Atmx2000 : The 787-10 is the A359 competitor. Anyway, I think a Y3 will start closer to 370 seats than 350. The 787-10 will likely seat between 310-330 seats wi
44 Post contains images Pygmalion : I could be off on the A350-XXX... I am so confused by the A350 numbering system ... But I think we are pretty much on the same page. At least I can't
45 Post contains images Hamlet69 : While I certainly understand and agree with the point you are trying to make, I don't believe that was what the chart was showing. On any manufacture
46 Ap305 : It appears, from the figures, that the a350-800xwb pays the price of over engineering for a stretch(-1000). The 787-9 carries more passengers with a g
47 Post contains images SailorOrion : Just to shed some light into the darkness, I've been crunching some numbers. When using some first-order approximation, I get the following data: I've
48 EI321 : Its a bigger aircraft.
49 Ap305 : Yes but it weighs the same.
50 Zvezda : Back to the original question. The only reply which really answers the question is Baron95's. As he said, we don't know what "design range" means. Air
51 Ap305 : I think we are is trying find ghosts where there are none.Airbus very clearly states the number of passengers+bags each version of the xwb carries for
52 Zvezda : Are you suggesting that design range is ferry range? That doesn't add up. Ferry range for the A350 should be much greater.
53 Ap305 : No Iam not. "Design range" is probably the marketing range which means the range for the lightest possible configuration(i.e no ife,minimum galleys a
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