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777X Vs 787XL  
User currently offlinemorrisond From Canada, joined Jan 2010, 234 posts, RR: 0
Posted (2 years 1 month 3 weeks 3 days 5 hours ago) and read 6996 times:

Wouldn't it be easier just to base the 773 successor off the 787? Just like Boeing did with the 767 and 777?

What is more work - Rewinging the 777 and redoing all the systems to bring them up to spec which probably includes needing to lengthen the Nose gear and you will need longer MLG as well to get good enough rotation angle due to the longer length.

Or take all the work you just did on 787 and systems/structure, XL the fuselage (out of Carbon) and Upsize the wing/engines? An 11W (3-5-3 the max you can go with 2 aisles) Slightly Ovalized Cross Section should be more efficient than an 777 Cross section that you would have to reengineer anyways to get additional width.

What takes all the engineering time these days? Systems or Structure? It seems like all the 787 woes were systems, and that work is finished now.

By 2018/19 they should have figured out how to efficiently build carbon aircraft due to experience with the 787.

A 787XL may not take any longer than the 777X as envisioned, and I would assume may be a little easier as I assume it was designed on a lot more modern software.

From an MX standpoint wouldn't a 787(9W) and 787XL(11W) with same systems architecture be a lot nicer from a fleet standpoint?

What would be easier? If there the same why not build an 11W 787?

[Edited 2012-02-23 10:30:10]

18 replies: All unread, jump to last
 
User currently offlineLAXDESI From United States of America, joined May 2005, 5086 posts, RR: 48
Reply 1, posted (2 years 1 month 3 weeks 3 days 4 hours ago) and read 6945 times:

I have not done any calculations to support my claim, but an 11-abreast platform will have to be near 475 seats(3-class marketing) to be more efficient than a ten abreast platform(which btw is more efficient than 9-abreast platform beyond 370-380 seats).

The Y3 project is more likely to be 10-abreast than 11-abreast.


User currently offlinemogandoCI From , joined Dec 1969, posts, RR:
Reply 2, posted (2 years 1 month 3 weeks 3 days 4 hours ago) and read 6885 times:

Quoting LAXDESI (Reply 1):
I have not done any calculations to support my claim, but an 11-abreast platform will have to be near 475 seats(3-class marketing) to be more efficient than a ten abreast platform(which btw is more efficient than 9-abreast platform beyond 370-380 seats).

The Y3 project is more likely to be 10-abreast than 11-abreast.

3-5-3 would have a *lot* of unpopular middle seats (45% of Y ... compare that to only 25% of A330)

If they really want tons of seats without going double decker, i'd think even 3-3-3-3 would be way more popular (how catering is handled is a different story)


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9375 posts, RR: 52
Reply 3, posted (2 years 1 month 3 weeks 3 days 4 hours ago) and read 6831 times:

Quoting morrisond (Thread starter):

What is more work - Rewinging the 777 and redoing all the systems to bring them up to spec which probably includes needing to lengthen the Nose gear and you will need longer MLG as well to get good enough rotation angle due to the longer length.

There are ways to get around rotation angle without lengthening the gear. Tail skids, rotation protection, semi-levered gear, etc.

Quoting morrisond (Thread starter):

What takes all the engineering time these days? Systems or Structure? It seems like all the 787 woes were systems, and that work is finished now.

That's an open ended question. Systems engineering is larger than structures. It's about 2 to 1, however structures engineering is all designed up front while systems engineering continues through flight test and entry into service. Systems are harder to get right and usually where major delays are caused (with the exception of the 787 wing to body join). Also don't forget payloads/interiors. That's a pretty big group which has a lot of customization work to do for each airplane. For mature production lines, the most work is in interiors.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinemorrisond From Canada, joined Jan 2010, 234 posts, RR: 0
Reply 4, posted (2 years 1 month 3 weeks 3 days 3 hours ago) and read 6728 times:

Quoting LAXDESI (Reply 1):
I have not done any calculations to support my claim, but an 11-abreast platform will have to be near 475 seats(3-class marketing) to be more efficient than a ten abreast platform(which btw is more efficient than 9-abreast platform beyond 370-380 seats).

The Y3 project is more likely to be 10-abreast than 11-abreast.

Well then that leads to what about an 370 Seat 9W 787 with bigger wing/wingbox and existing 787 Cross Section, nose, tail and systems? 250-260' Feet in length (20-30' more than a 787-10).

Would that be more efficient than the proposed 777X and a whole bunch simpler?

How much lighter would this option be with similar capabilities to the 777X?

[Edited 2012-02-23 10:41:17]

[Edited 2012-02-23 10:42:16]

User currently offlinepnwtraveler From Canada, joined Jun 2007, 2199 posts, RR: 12
Reply 5, posted (2 years 1 month 3 weeks 3 days 3 hours ago) and read 6681 times:

I thought there was a maximum size that the 787-10 could be before such massive structural changes happened that a whole new design was necessary anyways. Something to do with how the carbon fiber is engineered and the 8,9 and 10 were in the sweet spot for that design. Larger would have to be totally re-engineered which basically becomes a new aircraft. or the 777 followon.

User currently offlineLAXDESI From United States of America, joined May 2005, 5086 posts, RR: 48
Reply 6, posted (2 years 1 month 3 weeks 3 days 3 hours ago) and read 6601 times:

Quoting morrisond (Reply 4):
Well then that leads to what about an 370 Seat 9W 787 with bigger wing/wingbox and existing 787 Cross Section, nose, tail and systems? 250-260' Feet in length (20-30' more than a 787-10).

To answer your question, I will use A350 platform as a proxy. A350-1100(375 seats) at 260 feet should be about 20,000 lbs. lighter than the current B77W.

Based on my model, A350-11(375 seats) with above specs. should have about 10% lower fuel burn per seat than B777-9X(388 seats) on a 6,300 nm mission. A350-1100(375 seats) should have about 7% lower fuel burn per seat than stretched B777-9X(405 seats).


User currently offlineEPA001 From Netherlands, joined Sep 2006, 4593 posts, RR: 38
Reply 7, posted (2 years 1 month 3 weeks 3 days 2 hours ago) and read 6477 times:
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Quoting LAXDESI (Reply 6):
Based on my model, A350-11(375 seats) with above specs. should have about 10% lower fuel burn per seat than B777-9X(388 seats) on a 6,300 nm mission. A350-1100(375 seats) should have about 7% lower fuel burn per seat than stretched B777-9X(405 seats).

Interesting numbers, but we will only know (if ever) by the late 2010's or early 2020's if these numbers turned out to be true. They look credible to me, but that is just my opinion.  .


User currently offlinemorrisond From Canada, joined Jan 2010, 234 posts, RR: 0
Reply 8, posted (2 years 1 month 3 weeks 3 days ago) and read 6249 times:

Quoting LAXDESI (Reply 6):
To answer your question, I will use A350 platform as a proxy. A350-1100(375 seats) at 260 feet should be about 20,000 lbs. lighter than the current B77W.

Based on my model, A350-11(375 seats) with above specs. should have about 10% lower fuel burn per seat than B777-9X(388 seats) on a 6,300 nm mission. A350-1100(375 seats) should have about 7% lower fuel burn per seat than stretched B777-9X(405 seats).

So how much lighter is an 8,000nm+ 370 Seat 9W 787 than an A350?

I would assume same wing and engine weight - but maybe the 787 is a bit lighter as it's basically 5 years newer, but does the Electric Systems architecture and Composite Fuselage, save you some weight and gain some efficiency?


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 9, posted (2 years 1 month 3 weeks 2 days 23 hours ago) and read 6081 times:

Quoting morrisond (Thread starter):
Rewinging the 777 and redoing all the systems to bring them up to spec which probably includes needing to lengthen the Nose gear

Why would you lengthen the nose gear? The 777X engines are smaller, not larger. Plus, if you're re-winging, you'd just include it in the loft/pylon design rather than screw with the gear.

Quoting morrisond (Thread starter):
you will need longer MLG as well to get good enough rotation angle due to the longer length.

If you're re-winging anyway, you can make this issue go away completely.

Quoting morrisond (Thread starter):

Or take all the work you just did on 787 and systems/structure, XL the fuselage (out of Carbon) and Upsize the wing/engines?

That's far more work.

Quoting morrisond (Thread starter):
Slightly Ovalized Cross Section

This means all new tooling...the 777 fuselage tooling is still good. That's a huge capital expense.

Quoting morrisond (Thread starter):
What takes all the engineering time these days? Systems or Structure?

Yes.

Quoting morrisond (Thread starter):
I would assume may be a little easier as I assume it was designed on a lot more modern software.

777 is on CATIA V4, 787 is on CATIA V5. V5 is more capable but not particularly easier or harder.

Quoting morrisond (Thread starter):
From an MX standpoint wouldn't a 787(9W) and 787XL(11W) with same systems architecture be a lot nicer from a fleet standpoint?

If it's bigger enough to be a viable 777 competitor, most of the maintenance-intensive systems (bleed, electrical, hydraulics, ECS) won't be common anyway. Common architecture doesn't do much for maintenance, it's common parts that pay off.

Quoting morrisond (Thread starter):
What would be easier?

777X.

Tom.


User currently offlinetravelhound From Australia, joined May 2008, 824 posts, RR: 12
Reply 10, posted (2 years 1 month 3 weeks 2 days 14 hours ago) and read 5665 times:

Quoting morrisond (Thread starter):

Sounds nice in theory but you still have to industrialise the project. The 777 infrastructure and people are all in place. It is a lot easier to evolve a manufacturing base than to revolutionise it.

I think the 777 will be here a little longer yet.


User currently offlinerheinwaldner From Switzerland, joined Jan 2008, 2197 posts, RR: 5
Reply 11, posted (2 years 1 month 3 weeks 2 days 10 hours ago) and read 5436 times:

Quoting morrisond (Thread starter):

The idea is good. Your assesment about the 77X is correct as well.

I just don't think that the new 787 version would have to go as far as you propose.

IMO Boeing only needs to stretch it, rewing it and spend it the A350 engines. Finished!

As 9 abreast, 80m long aircraft there will not be the slightest wish for more capacity. This 787 would be an upgrade as fresh and as competitive as a new design from scratch.

And I can't think why it would cost more to develop it than the 77X.

Important are large wings that support an efficient cruise with higher weights than those of the today 787 (beside supporting the quite higher MTOW).

I once said the A350 will always be "more" airplane with a higher capability than the 787. If I think about such a real 787 stretch I am not so sure anymore whether the two would not be very close.

The problems of a 787 based 777 replacement are more factors like this one:

- Overstretched supply situation. Satisfying demand for all sizes can be a burden on just one family. E.g. a large backlog for 767 replacements prevents timely delivery slots for A340 replacements.

- 8.5 abreast might make it the second choice for airlines who put a special focus on customer comfort (e.g. like CX).

- Maybe the heritage as 1. generation cfrp design will pay some tribute (lost opportunities in comparison with a fresh design that would consider the initial lessons learnt).

But IMO eventually the 787 will grow into every role Boeing want to cover above 250 seats. Including anything where today 777's prove to be useful.

When looking far into the future I would say, that the only thing that ever will endanger the 787 will be BWB's. But until then I don't see any technology or solution that will threaten it. That will be a time when the 777 will long be gone. In about 15 - 25 years the 787 will be reengined with GTF's but this will happen in parallel with the competition. Of course for many years there will be a duopoly with the A350. These are just rough estimations about the long term evolution of the 777, 787 and A350.


User currently offlineBurkhard From Germany, joined Nov 2006, 4360 posts, RR: 2
Reply 12, posted (2 years 1 month 3 weeks 2 days 9 hours ago) and read 5330 times:

Quoting morrisond (Thread starter):
What takes all the engineering time these days? Systems or Structure?

Both are peenuts. Certification takes most of the time.
How many new parts have to be done for an enhanced 777. As many as on the 737MAX?
How many parts of the 787 can be reused on the far bigger 777 without going through new certification?


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12060 posts, RR: 52
Reply 13, posted (2 years 1 month 3 weeks 2 days 8 hours ago) and read 4831 times:

Quoting morrisond (Reply 8):
So how much lighter is an 8,000nm+ 370 Seat 9W 787 than an A350?

Since both are hypoteical airplanes right now, that is difficult to determine.

But here are the numbers comparing the B-789 to the A-359.

Max range; B-789 = 8,500 nm, A-359 = 8,100 nm
Empty Weight; B-789 OEW^ = 242,000 lbs, A-359 MEW^^ = 255,075 lbs
Max # LD3 Payload; B-789 = 36, A-359 = 36
Max Pax (3 class); B-789 = 280, A-359 = 314
MTOW; B-789 = 502,500 lbs, A-359 = 571,000 lbs
MLW*; B-789 = 380,000 lbs, A-359 = 425,000 lbs
Max Fuel Capacity; B-789 = 36,641 US Gallons, A-359 = 36,500 US Gallons
Lenght**; B-789 = 206', A-359 = 219' 6"
Wingspan**, B-789 = 197' A-359 = 213'

^ Operating empty weight
^^ Manufacture's empty weight
* Airports use max landing weight to compute landing fees
** Airports use the total square footage (L X WS = total sq ft) to compute parking fees

Now, I am not sure Boeing can build a B-7811 based on the exsisting B-787 airframe, it may be just to long. But I do think the B-777 can be streched one or two more times, depending on how much longer airlines want it to be. I think the max Boeing can strech the B-777 is about 30', or 10 m over the current B-773/W lenght. It will need a new wing, wingbox, pushed further aft along the fuselarge, and taller landing gear and/or new rotation schedule.


User currently onlineRevelation From United States of America, joined Feb 2005, 11918 posts, RR: 25
Reply 14, posted (2 years 1 month 3 weeks 2 days 8 hours ago) and read 4526 times:

Quoting travelhound (Reply 10):
Sounds nice in theory but you still have to industrialise the project. The 777 infrastructure and people are all in place. It is a lot easier to evolve a manufacturing base than to revolutionise it.

And you have to have the stomach for an all-new plane, and I have to wonder if Boeing has it at this point in time. We have still yet to see 787-8 production stabilized, 787-9 in production and 787-10 introduced. 787 is still cash negative at this point in time (meaning cost to produce frames is less than price paid) and it will stay so for several years to come.

Quoting travelhound (Reply 10):
I think the 777 will be here a little longer yet.

Boeing execs are now talking of 787-10, 777-8X and 777-9X all being 15% apart in pax capacity.

Chances are good that we'll see that before we see a 787-11X or a Y3.

But just like NSA vs 737MAX, we'll have a few years of gossip and potentially some backtracking before any decision comes out, because as the saying goes, talk is cheap.



Inspiration, move me brightly!
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12060 posts, RR: 52
Reply 15, posted (2 years 1 month 3 weeks 2 days 7 hours ago) and read 4193 times:

Quoting Revelation (Reply 14):
Boeing execs are now talking of 787-10, 777-8X and 777-9X all being 15% apart in pax capacity.

Chances are good that we'll see that before we see a 787-11X or a Y3.

I agree, there will be no B-7811. The B-7810 and B-777NGs will be considered next, I think the B-777NGs will begine flying in airline service by the end of this decade, the B-7810 should be flying by 2017.

Quoting KC135TopBoom (Reply 13):
I am not sure Boeing can build a B-7811 based on the exsisting B-787 airframe, it may be just to long. But I do think the B-777 can be streched one or two more times, depending on how much longer airlines want it to be.


User currently offlineStickShaker From Australia, joined Sep 2004, 722 posts, RR: 5
Reply 16, posted (2 years 1 month 3 weeks 1 day 18 hours ago) and read 2720 times:

Quoting Revelation (Reply 14):
And you have to have the stomach for an all-new plane, and I have to wonder if Boeing has it at this point in time. We have still yet to see 787-8 production stabilized, 787-9 in production and 787-10 introduced. 787 is still cash negative at this point in time

  

I don't see any all new program from Boeing until the middle of the next decade (aka 2025) or later - being the 797.
Boeing have to dig themselves out of a big hole before getting so ambitious again.

Regards,
StickShaker


User currently offlineferpe From France, joined Nov 2010, 2792 posts, RR: 59
Reply 17, posted (2 years 1 month 3 weeks 3 hours ago) and read 2188 times:

I think the OPs view is a very valid one, right now B is communicating the obvious changes going forward, doing a minimum chage 787-10 for the 320 seat market and 777 variants beyond for 350 and 400 seats but they also say they are looking at a Y3 scenario. Why is not that hard to understand, see blow:


STRATEGY A
787 for 320 and 350 seat, 748 for 400 seats until Y3 covers 400-500 seats:
The 787 architecture needs a new larger wing to cover the market 320 and 350 seats ULH (ie the ubiquitous 8000nm all trick pony). MTOW would be from 265-310t which requires an upgraded MLG and a lager wing + engines in the TXWB class. It would compete head on with the A350 and be as efficient, perhaps the odd % more efficient on ULH due to the non bleed architecture, maintenance cost would also be competitive. The 777 will only get a + upgrade, B then makes a 3Y long term to cover 400-500 seats (which will be a large future market when the mega-cities triple in number)

SUMMARY: B would take at least 50% market share in 320 and 350 seats and more then 50% below 270 seats (more efficient frame then the 350-800). 400 seats covered by 748-8 which takes most of that market for lack of competition until Y3 arrives. With Y3 B is top notch 230 to 500 seats.



STRATEGY B
787 320 seat and 777X 350 and 400 seat, no Y3 for long time

SUMMARY: Covers the market less efficiently as the 320 787-10 does not cover ULH, the 777-8X does not beat the A350 main models (-900, -1000). The only positive would be the 400 seat 777-9X (this relegates the 748 to freighters) but A could do a 350-1100 to cover that using the 9X engines and a mildly stretched wing. A rules at 320ULH, 350 and over 450 seats, B rules 230-270 and 400 seats (until 350-1100 arrives).



NOT THAT CLEAR A CHOICE
As can be seen it is not that straight forward, the short term obvious is the medium to long term negative  Wow! .



Non French in France
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4773 posts, RR: 9
Reply 18, posted (2 years 1 month 3 weeks 2 hours ago) and read 2110 times:

The 777 can be stretched... remember any stretch would involve only half the plugs aft of the main gear, the other plugs would be forward ie half the stretch would not be influencing the rotation angle. 2 metres aft (or so) will not have a big influence on this and as others have said protection can be put in place. Also Boeing could simply carve out a little of the underside of the tail section a little more. The nose gear will not need to be lengthened at all as the new engines are planned to be smaller diameter than the current ones (due to larger wings producing more lift and the increased length reducing the side on drag normally associated with single engine out performance, and improved power from small diameter).


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