art
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Will The 748F Carry On After Y3?

Mon Jun 18, 2007 2:35 pm

When Boeing embark on Y3, will there be a freighter version with the sort of capability offered by the 747F and 748F? My naive guess is that the answer will be "no". Is there any reason why Boeing should not continue producing the 748F in parallel with Y3 for as long as the demand is there?
 
XT6Wagon
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 3:31 pm

Depends on what the Airlines want and the success of the BWB studies.

If the BWB is successful as a freight platform, then expect Y3 *IF* it persued to be optimized for passengers only.

If the BWB doesn't pay off at this time, then you can expect Y3 to be more of a "hybrid" like the 747. Boeing would likely try for a swingtail first then go to a nose door if that can't be done effectively in daily cargo ops. The failure for the BWB to be adopted in the near future (in industry time, IE decade or two) then its the most likely case that Y3 will exist.

That said at this time I expect the 787 to get a major MTOW growth version after the 737RS is done, Then for Y3/BWB to be decided on. A MTOW growth version of the 787 could haul near 744 volume and payload for a fraction of the cost of the other planes used today. The economies of scale would make a 787F completely ruin older freighters in overall cost. The A330F has been rumored to sell for $90M, but the 787F if done on a higher MTOW version could sell for not much more and haul 744 loads.. all while having higher margins. Of course the A350XWB freighter might be equaly impressive, but at this time its no more solid than my guesswork on possible future versions of the 787.
 
jonathan-l
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 4:07 pm

MTOW=range
MZFW=payload
 
zvezda
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 4:21 pm

Quoting Art (Thread starter):
When Boeing embark on Y3

IF Boeing embark on Y3. I think that's a very big IF. It appears the market is far too small to justify the development costs. I don't see Boeing repeating the WhaleJet mistake.
 
deltadc9
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 10:18 pm

Quoting Zvezda (Reply 3):
IF Boeing embark on Y3. I think that's a very big IF. It appears the market is far too small to justify the development costs. I don't see Boeing repeating the WhaleJet mistake.

Y3 is intended to replace the 777-300, 747, and possibly go bigger and compete with the 380.

The question is not will they build Y3, the question is only what size range will they design into it. They will not stay with the 748 and 773 forever, and the 787 will not be stretched to 773 size IMO. The comment about not making the same mistake as Airbus is very valid, I dont see them going with a base model anywhere near the size of the 380.

As for the thread topic, the 748F, as Boeing has said for a while, will be built for quite a while and along side Y3 possibly. Y3 will likely start with a passenger model and then a freighter when the market warrants. The 748F will most likely start to decline once the Y3 freighter is offered, which will be after they milk the 748 for all its worth.
Dont take life too seriously because you will never get out of it alive - Bugs Bunny
 
zvezda
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 10:22 pm

Quoting DeltaDC9 (Reply 4):
The question is not will they build Y3, the question is only what size range will they design into it. They will not stay with the 748 and 773 forever, and the 787 will not be stretched to 773 size IMO.

Building a 787-11 the size of the 777-300ER is a very real low-cost, low-risk, high-profit option for Boeing. The question is whether or not Boeing will ever build a Y3. I think not. In my opinion, the market is too small to justify the development costs.
 
EI321
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 10:27 pm

As has been asserted above, we should not automatically assume that there will ever be a Y3. The VLA market is sketchy at this point. Its assumed that Y3 will seat around 400-500 passengers. One of Randy Baslers favourite weapons was highlighting the apparent 200 seat gap in Airbus' product lineup. What Randy never cared to point out was the sales figures for aircraft in this segment. There has only been one airline order in the last 5 years.

The freighter market is different however, but with Boeing having a monopoly in the large freighter at this point in time, I cant see there being much pressure on them to spend $10b+ developing a new aircraft. I still see Boeing sticking with larger 787 versions for the forseeable future. The advent of the A350XWB may have altered their product strategy.
 
AirSpare
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 10:41 pm

I started this thread some time ago, there are some excellent points made regarding this subject.
Y3, Chaos At The Top Of B's Plans? (by AirSpare Sep 27 2006 in Civil Aviation)

I think that a "777RS" or Y3 is likely. The 777 is a popular product to the people that fly (pay the airlines bills). My gamble is that B will take the plunge, the R&D, manufacturing processes and engines (RR) are being worked on now, between the 787/737RS and the XWB.

If the 777 can hit 1000 frames, I think a replacement will also.


Hey Zvezda~Best regards
Get someone else for your hero worship fetish
 
zvezda
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RE: Will The 748F Carry On After Y3?

Mon Jun 18, 2007 10:49 pm

Quoting AirSpare (Reply 7):
If the 777 can hit 1000 frames, I think a replacement will also.

I agree that the 787, which is the 777 replacement, will achieve 1000 orders.
 
cloudy
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:01 am

Quoting XT6Wagon (Reply 1):
Depends on what the Airlines want and the success of the BWB studies.

If the BWB is successful as a freight platform, then expect Y3 *IF* it persued to be optimized for passengers only.

I think your right about the BWB being used for military or freight applications first.

The BWB may allow two versions of the same airframe to compete in both the military and civilian cargo markets - something we haven't seen since the first jetliners. Another possibility is a combination tanker/stand-off bomber/UAV platform with only the cockpit pressurized . The later seems more likely to me. Besides efficiency, a main advantage of the BWB is the ability to combine many roles in one platform. Unfortunately, it is weakest in its passenger carrying potential.

The BWB is a very versatile platform - but it has two main weaknesses. The first is that it would have to have a much stronger skin in order to have a pressurized interior. The other is that it would give the passengers a rough ride during turns in all but the center seats, and more space would have to be "wasted" on aisles to create a comfortable seating arrangement. The cabin could easily have the feel of a very tightly packed, cramped movie theatre. One could throw weight and money at these problems because of the BWB's far superior efficiency - but I don't see how anybody would risk it unless a freight model was proven first.

If I had to bet I would say we will see a widebody-sized multi-role BWB military plane in the next decade or two - whether Boeing or somebody else builds it. Civilian freight applications would soon follow. That would allow Boeing to optimize the Y3 for passengers. But consider that most of the foretasted market for Very Large Aircraft is for freighters. They would have to wait a long time for the market to grow enough for a passenger-only version viable. By that time, a passenger BWB could be a reasonable proposition.

Quoting Zvezda (Reply 5):
Building a 787-11 the size of the 777-300ER is a very real low-cost, low-risk, high-profit option for Boeing. The question is whether or not Boeing will ever build a Y3. I think not. In my opinion, the market is too small to justify the development costs.

"ever" is a very long time and I'm sure you don't mean it literally. When do you think a new design airframe with a base model larger than the 777-300ER would be viable? the 10-20 year time frame the thread starter mentioned? Not anytime in the reasonably foreseeable future? I'm not being sarcastic, I really respect your knowledge and would like to know what you think.
 
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Stitch
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:15 am

I expect Y3 will offer an eventual freighter version, but I would be surprised if it was a nose-loader. The 747-8F is available to meet that demand and someone may figure out how to put a nose-door on a passenger 747-400 which opens that fleet up.
 
deltadc9
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:25 am

Quoting Zvezda (Reply 5):
Building a 787-11 the size of the 777-300ER is a very real low-cost, low-risk, high-profit option for Boeing. The question is whether or not Boeing will ever build a Y3. I think not. In my opinion, the market is too small to justify the development costs.

It is not that I disagree completely, it is just that there is a compelling argument against the 787-11, and the need for something slightly larger than the 773 and maybe as big as a 748, which is only worth looking at with the large end of a Y3 family that inculdes smaller higher selling models such as a 773 sized plane and maybe one increment bigger. Its the smaller higher selling model that will make or break Y3 IMO.

One thing I do know is that the market has not solidified enough in this arena for Boeing to feel comfortable enought to decide on a strategy. I think they are simply in the analysis phase and will remain so for a while.

The 777 and 748I, in addition to EIS of the 350 give them plenty of cushion to do so. The dividing line between Y2 and Y3 has always been the most foggy element of Yellowstone and what it has spawned.
Dont take life too seriously because you will never get out of it alive - Bugs Bunny
 
EI321
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:32 am

Quoting Zvezda (Reply 8):
Quoting AirSpare (Reply 7):
If the 777 can hit 1000 frames, I think a replacement will also.

I agree that the 787, which is the 777 replacement, will achieve 1000 orders.

was it truely intended as a 777 replacement, is it the 767 replacement or is it both?
 
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Stitch
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:36 am

Quoting EI321 (Reply 12):
was it truely intended as a 777 replacement, is it the 767 replacement or is it both?

I believe both, at least with the 777-200 and 777-200ER. I don't believe Boeing expected to have to worry about the 77L, 77W and 77F within a decade, but they did have the foresight to plan for some significant MTOW growth, at least, with a stronger undercarriage and wing then what would have been needed just to compete with the 767, A330 and 777-200A.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 2:52 am

Quoting Cloudy (Reply 9):
When do you think a new design airframe with a base model larger than the 777-300ER would be viable? the 10-20 year time frame the thread starter mentioned? Not anytime in the reasonably foreseeable future? I'm not being sarcastic, I really respect your knowledge and would like to know what you think.

My suspicion (and I'm not convinced this is the case, but it seems likely to me) is that there will not be a sufficient market for a Y3 unless and until it is possible to build it with a CASM at least 15-25% lower than the 787-11/A350-1000. The problem is that, even in 20 years, it would then be possible to build replacements for the A350 and 787 with correspondingly lower CASM. Getting that far ahead of a moving target seems hopeless.

Quoting DeltaDC9 (Reply 11):
there is a compelling argument against the 787-11

Please share. I have not seen a compelling argument against the 787-11.

Quoting DeltaDC9 (Reply 11):
The dividing line between Y2 and Y3 has always been the most foggy element of Yellowstone and what it has spawned.

Here we are in complete agreement.  Smile

Quoting EI321 (Reply 12):
was it truely (sic) intended as a 777 replacement, is it the 767 replacement or is it both?

Corporations don't have intent; people have intent. I'm sure there were differing intentions among people at Boeing who backed the 7E7. Whatever they were, I don't think they matter as far as what the 787 is becoming. The 787-8 is larger than the 767-400. A 787-11, if built, would be very nearly the same size as the 777-300ER. I think we can all agree, whether we think the chances of a 787-11 are 10% or 70%, that they are higher than the chances of a 787-7. There is no overlap in size between the 767 and 787 families and almost certainly never will be. The 787 and 777 families (including the 787-10) do overlap. In terms of mission performance, the 787 is a rough match for the 777 and far exceeds the 767.
 
deltadc9
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 3:52 am

Quoting EI321 (Reply 12):
was it truely intended as a 777 replacement, is it the 767 replacement or is it both?

Y2 was intended to replace the 757-300, all 767s, and the 777-200. Going after the 777-300 is an afterthought that is possible, but shrinking is out of the question AFAIK.

Quoting Zvezda (Reply 14):
Please share. I have not seen a compelling argument against the 787-11.

I guess that is subjective.

There have been plenty of debates here on the subject, not that I agree with any of them, that suggest the 787-11 would not complete well enough against the comparable A-350 without new wings, landing gear....I guess the basis of the argument is that you basically end up with a different plane, so why not increase the cross section and make it Y3.

I am still not in the camp that thinks Y3 will be a blended wing, either...yet.

This will be one of Boeings most critical decisions of this century IMO.
Dont take life too seriously because you will never get out of it alive - Bugs Bunny
 
zvezda
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 4:09 am

Quoting DeltaDC9 (Reply 15):
There have been plenty of debates here on the subject, not that I agree with any of them, that suggest the 787-11 would not complete well enough against the comparable A-350 without new wings, landing gear.

Certainly a 787-11 would need revised landing gear, as would a 787-9ER, 787-10ER, and probably any 787F. The existing wing could be strengthened and the swept area could be increased without having to develop a wholly new wing. Even if a wholly new were needed, that would still be less of a difference than that between the A340-300 and the A340-500/600.

Quoting DeltaDC9 (Reply 15):
I guess the basis of the argument is that you basically end up with a different plane, so why not increase the cross section and make it Y3.

Ah, but one doesn't end up with such a different plane. The important thing is that all the systems could be retained. Even with a wholly new wing, the development cost would be about 20-25% that of a Y3.

Quoting DeltaDC9 (Reply 15):
I am still not in the camp that thinks Y3 will be a blended wing

A BWB would not be a Yellowstone family aircraft.

Quoting DeltaDC9 (Reply 15):
This will be one of Boeings most critical decisions of this century IMO.

Here again we agree.  Smile
 
Rheinbote
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 4:24 am

Quoting Zvezda (Reply 8):
I agree that the 787, which is the 777 replacement, will achieve 1000 orders.

Permanently re-iterating your idea of a prospective '787-11' and the 787 alledgedly being a 777 replacement doesn't make your assertions anymore credible. There's next to nothing in the baseline 787 design that makes a 787-11 plausible, apart from the equally often re-iterated contemplations of hypothetic fuselage lengths and floor areas.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 4:35 am

Quoting Rheinbote (Reply 17):
Permanently re-iterating your idea of a prospective '787-11' and the 787 alledgedly being a 777 replacement doesn't make your assertions anymore credible. There's next to nothing in the baseline 787 design that makes a 787-11 plausible, apart from the equally often re-iterated contemplations of hypothetic fuselage lengths and floor areas.

There is certainly a very good chance that there will never be a 787-11. Regardless, if the 787 ranges from the 787-3/8 to the 787-10, then it is much more of a 777 replacement than a 767 replacement. The smallest 787s are larger than the 767-400. At the upper end, the 787-10 will be larger than the 777-200(ER/LR).
 
A350
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 5:49 am

When the Y3 is rolled out, the 748 (both versions) will have done its job for Boeing anyway. Boeing must continue to fight pro-active for their market share, nor re-active, for its market share, and I don't see any reason not to built the Y3. The 773ER shows that there is a market for planes of that size, and it would be stupid from Boeing to stop the successfull Yellowstone project. Being A and B fan, I look forward for the y3!

Cheers

A350
 
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Stitch
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 6:58 am

Quoting Rheinbote (Reply 17):
There's next to nothing in the baseline 787 design that makes a 787-11 plausible, apart from the equally often re-iterated contemplations of hypothetic fuselage lengths and floor areas.

Would you be so kind as to enlighten me as to what in the baseline 787 design that makes a 787-11 implausible?

The 787 fuselage is wider then an A340's, so it would not suffer as much from bending stretches at 75m in length as the A340-600 does. Also, CFRP is stronger and lighter then Al, so a 75m 787-11 fuselage can more easily be reinforced to handle what bending stresses it will encounter more then the A340-600 was.

The 787 wing is designed for MTOWs approaching 640,000lbs, though it will need additional reinforcement. That is 100,000lbs above the MTOW of the 787-9. With extensions, the wing would probably be around 70m, similar to the span of the 747-8I so it should not impact gate operations since it will still offer 20m clearance wingtip to wingtip in the traditional 80m "box".

The undercarriage is "only" able to handle 560,000lbs, but Boeing has experience designing triple-axle undercarriages handling 750,000lbs so 640,000lb should prove no problem. And the 787-11 will have sufficient underfloor space to take a six-wheel bogie without killing fuel or cargo capacity.

Engine thrust will be in the 85,000lb range which is 10,000lbs beyond the current GEnx and Trent 1000 variants, but in and of itself should not be insurmountable. It might even be possible to fit a Trent XWB/"GEnx2" either with the existing 123" fan. If not, they may proceed with a new model with a slightly smaller fan (as GEnx does with the 748 variant).

Seems doable to me...
 
sv11
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:22 pm

Is there a big enough market for the Y3 in the near future? The 747-8 and A380 are not selling well right now. The 777-300ER appears to be mostly replacing 747-400s converted to cargo.

sv11
 
zvezda
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 1:53 pm

Quoting Stitch (Reply 20):
The 787 fuselage is wider then an A340's, so it would not suffer as much from bending stretches at 75m in length as the A340-600 does.

The essence of your point is correct, but it is fuselage height not width that matters because the vertical stresses are much greater than the horizontal stresses.

Quoting Stitch (Reply 20):
Also, CFRP is stronger and lighter then Al, so a 75m 787-11 fuselage can more easily be reinforced to handle what bending stresses it will encounter more then the A340-600 was.

Yes, exactly.

Quoting Stitch (Reply 20):
The 787 wing is designed for MTOWs approaching 640,000lbs, though it will need additional reinforcement. That is 100,000lbs above the MTOW of the 787-9. With extensions, the wing would probably be around 70m

If just changing wingtip extensions, Boeing would probably choose to keep wingspan within the 65m limit for E sized gates. If Boeing choose to develop a wholly new wing, then 70m is plausible. The two main reasons for considering a new wing are field performance and fuel capacity. Another benefit would be improved L/D due to both advances in aerodynamics and the availability of more computing resources for less money.

Quoting Stitch (Reply 20):
The undercarriage is "only" able to handle 560,000lbs, but Boeing has experience designing triple-axle undercarriages handling 750,000lbs so 640,000lb should prove no problem. And the 787-11 will have sufficient underfloor space to take a six-wheel bogie without killing fuel or cargo capacity.

Yes, exactly, though an electronics bay would have to be relocated. That requires significant wiring changes.

Quoting Stitch (Reply 20):
Engine thrust will be in the 85,000lb range which is 10,000lbs beyond the current GEnx and Trent 1000 variants, but in and of itself should not be insurmountable. It might even be possible to fit a Trent XWB/"GEnx2" either with the existing 123" fan. If not, they may proceed with a new model with a slightly smaller fan (as GEnx does with the 748 variant).

If the wing is retained and only the wingtip extensions are changed, then more thrust would be needed to achieve good field performance. Utilization of the 123" fan is not unlikely.
 
WingedMigrator
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 2:10 pm

Quoting DeltaDC9 (Reply 4):
The 748F will most likely start to decline once the Y3 freighter is offered, which will be after they milk the 748 for all its worth.

Here I must wonder if freighters are also subject to Zvezda's law: will freight operators always go for the lowest tonne-mile operating cost, in the smallest possible format?

The reason this might be important is that the A359F (EIS 2017) would burn roughly 10% less fuel per tonne-mile than even the 748F, based on an analysis of the specs announced at the XWB launch in Farnborough last year. (90 tonnes max payload @ 5000 nm range).

There is the sticky point of the nose door, but I believe that factor is blown out of proportion on a.net in comparison to basic operating costs.

Quoting Rheinbote (Reply 17):
There's next to nothing in the baseline 787 design that makes a 787-11 plausible, apart from the equally often re-iterated contemplations of hypothetic fuselage lengths and floor areas.

Quite the contrary, at least on a technical basis (as opposed to business case). By careful and educated guesswork one can reasonably extrapolate the performance of aircraft derivatives that haven't even been publicly discussed by the OEMs. The Breguet range equation is very powerful for this sort of analysis, as are the trends of technical metrics (SFC, L/D, OEW) across aircraft families and over time. A 787-11 with the modifications outlined by Stitch would likely be very competitive (by my estimate, nearly 20% lower fuel burn than the 773ER, and on a par with the A350-1000)
 
zvezda
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 2:20 pm

Quoting WingedMigrator (Reply 23):
Here I must wonder if freighters are also subject to Zvezda's law: will freight operators always go for the lowest tonne-mile operating cost, in the smallest possible format?

With the constraint from Zvezda's Law that range is sufficient and the additional constraint that the pallets/containers/cargo actually fit in the smaller aircraft, I would say Yes. There is a lot of opportunity to increase frequencies on freight routes. Increased frequency means higher revenue/tonne.

Quoting WingedMigrator (Reply 23):
By careful and educated guesswork one can reasonably extrapolate the performance of aircraft derivatives that haven't even been publicly discussed by the OEMs. The Breguet range equation is very powerful for this sort of analysis, as are the trends of technical metrics (SFC, L/D, OEW) across aircraft families and over time. A 787-11 with the modifications outlined by Stitch would likely be very competitive (by my estimate, nearly 20% lower fuel burn than the 773ER, and on a par with the A350-1000)

 checkmark  Looked at another way, a 787-11 with the same payload/range performance of a 777-300ER would have an OEW 80-85,000 lbs lower. It would also have a much lower manufacturing cost. If Boeing can sell 777-300ERs (and as of this year they still can) then there is certainly demand for an aircraft with the same performance at dramatically lower purchase and operating cost.
 
lehpron
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 4:22 pm

Quoting Sv11 (Reply 21):
Is there a big enough market for the Y3 in the near future? The 747-8 and A380 are not selling well right now. The 777-300ER appears to be mostly replacing 747-400s converted to cargo.

Of course not. Whatever becomes of Y3 is NOT near-term. Boeing initially meant a Y3 to replace 777/747 with a overall family pax range of 300-600. If it's true that Boeing is thinking of a stand-alone 777 replacement, then maybe the largest derivative will slightly overlap the 747. Y3 might now have become the 777RS (if the idea implied in this thread that the lower end of 777 can be dealt with a 787, leaving the upper end plus 747 for a completely new airplane). I do not think a BWB will find its way into Boeing's pax fleet in near-term.  Wink

Quoting Zvezda (Reply 16):
Quoting DeltaDC9 (Reply 15):
I am still not in the camp that thinks Y3 will be a blended wing

A BWB would not be a Yellowstone family aircraft.

How much of this certainty is preference? I don't get the impression that your logic will be limited to a "787-11", what about the idea of a 787-12 (747RS?), all things considered? We don't know the future, I don't see how you can be so sure of things, unless it was your opin, but then you shouldn't act so confident.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
XT6Wagon
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 4:40 pm

787-12 can't exist... While a typical stretch would make a 787-11 75m long, I would expect Boeing if they do one to poll the customers hard, then likely deliver one a few frames longer than 75m. Possibly just short of 80m long to maximize the utility of the Airframe

While others are expressing concern for bending stiffness of the airframe, I would note that in addition to the natural stiffness benefit of the larger cross section than the A346, The larger cross section provides more room for a taller keel and/or backbone to aid stiffness without intruding on revenue space. Doesn't help the lateral bending much if at all, but for vertical stiffness if you have room to make your keel/backbone taller instead of thicker you add very little weight for the benefit.
 
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Stitch
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RE: Will The 748F Carry On After Y3?

Tue Jun 19, 2007 9:44 pm

Quoting XT6Wagon (Reply 26):
787-12 can't exist...

Technically it could, in that a 5m stretch would take it right to 80m. I'd only see it happen if Airbus makes an 80m A350-1100.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 2:48 am

Quoting Lehpron (Reply 25):
How much of this certainty is preference?

The Yellowstone family is a tube-and-wings concept family. A BWB would be something else.

Quoting Lehpron (Reply 25):
I don't get the impression that your logic will be limited to a "787-11"

Huh?

Quoting Lehpron (Reply 25):
what about the idea of a 787-12 (747RS?)

Some cabin floor areas for comparison:

B787-11X 324.6
B777-300 330.4
B787-12X 352.6 (80 meter)
B747-400 372.0
B747-8I 426.2
 
Rheinbote
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 3:52 am

Quoting Stitch (Reply 20):
Would you be so kind as to enlighten me as to what in the baseline 787 design that makes a 787-11 implausible?

Sure. Amongst others you need to take things like buffet margins, approach speeds, and field performance into account.

You can't stretch the 787-10 much more, because the resulting low tail clearance angle would limit alpha, which in turn would limit lift. To maintain lift, you can go faster. Stretching the 787-9 by 12 frames requires an increas in Vapp (approach speed) by about 10 knots. What's the limit...155...160 kts? In that respect, the 787-10 already is at the limit, unless you resort to a tip-toe gear a la 773ER, restoring tail clearance.

The current landing gear design is limiting the 787 to a ramp-weight of ~570.000lbs or thereabouts. Depends on how much you fudge the pavement loading definitions (777 cheats already included). You can either spread the footprint of the four wheel truck, which is limited by the current wheel bay constraints. Or you can go for a six-wheel truck, but that would entail a complete redesign of the wheel-bay and all the surrounding structure and systems. There was a previous thread elaborating this nicely. Forget the body-gear, that's another Anet myth, doesn't work, there's a keel-beam at the centerline and the bay is too short to begin with.

The wing...there seems to be some growth potential regarding cruise buffet margin, but there's not much growth potential towards higher gross weights in the low speed regime. Acceptable take-off performance, say slightly above 10.000ft FL, could be maintained with current engines to about ~570.000 lbs (co-incidence?). Obvously, more T/O thrust would help to sustain higher gross weights. But max landing weight would again be limited by Vapp. For a 10% increase in MLW, you'd need at least a 10% increase in wing area plus whatever is needed to compensate for lower alpha resulting from fuselage stretch. You can't do this with a simple tip extension, less so as it has already been done with the -9. Either needs a new, larger wing or new, more efficient high-lift devices.

So even if the 787 wing would be 'good for 640.000 lbs with some structural strengthening' (hard to believe, where did you get that?), you couldn't make much use of it due to the above limitations (and some others that are too much to type)

For me the baseline 787 design looks to be sized around something like ~570.000lbs MTOW and about the length of the current 787-10. IMO there's not much growth potential left unless some extensive and expensive re-design would be done.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 4:13 am

Quoting Rheinbote (Reply 29):
In that respect, the 787-10 already is at the limit, unless you resort to a tip-toe gear a la 773ER, restoring tail clearance.

If Boeing produce a six-wheel bogey for heavier 787s, there is no reason why it shouldn't have the tip-toe feature developed for the 777.

Quoting Rheinbote (Reply 29):
So even if the 787 wing would be 'good for 640.000 lbs with some structural strengthening' (hard to believe, where did you get that?)

That number was first posted on A.net by Widebodyphotog. I confirmed it with a source at Boeing.

Quoting Rheinbote (Reply 29):
IMO there's not much growth potential left unless some extensive and expensive re-design would be done.

Clearly, increasing the MTOW of the 787 beyond about 560,000 lbs would involve extensive redesign of some significant systems. Expensive? Relative to what? Relative to my salary, very expensive. Relative to the cost of developing a Y3, very inexpensive.
 
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 6:16 am

Quoting Zvezda (Reply 30):
I confirmed it with a source at Boeing.

Last time you confirmed something with a source at Boeing your source was wrong. Even if the wing would be good for 640K, how would you get any 787 longer than a -10 on and off a runway at corresponding MTOW and MLW? The 787 has comparably shorter legs than a 777, so even tip-toe gears wouldn't get you very far.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 7:42 am

Quoting Rheinbote (Reply 31):
Last time you confirmed something with a source at Boeing your source was wrong.

It can happen. I also consider Widebodyphotog to be a reliable source, but I wouldn't bet a finger on him always being right.

Quoting Rheinbote (Reply 31):
how would you get any 787 longer than a -10 on and off a runway at corresponding MTOW and MLW?

I've written before that, without a new wing, 787s much heavier than 540,000 lbs will have field performance issues.

Quoting Rheinbote (Reply 31):
The 787 has comparably shorter legs than a 777, so even tip-toe gears wouldn't get you very far.

I've always presumed that if Boeing were to develop new maingear with six-wheel bogeys for the 787 that they would increase ground clearance relative to the current maingear. Except perhaps with a freighter, one wouldn't want the six-wheel bogeys on any 787-8. A 787-9ER would probably be the smallest 787 to warrant upgraded landing gear. With a size range from 787-9ER to 787-11, lengthening the maingear makes sense if new maingear must be developed anyway.
 
XT6Wagon
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 8:54 am

Quoting Stitch (Reply 27):
Technically it could, in that a 5m stretch would take it right to 80m. I'd only see it happen if Airbus makes an 80m A350-1100.

yah, a 5m stretch would be nearly worthless. possible, but I think just jumping straight to 80m or just under makes more sense.

If Boeing does a new wing... that more or less means a new wing box. I've long thought that one of the things that would be possible is find a place in the wing box and the barrel above where no components other than straight runs of wiring/hydraulics run through it and stuff in some of the stretch for the higher MTOW versions there. This makes the wing pick up area. Might be able to devote the new space to the front of the landing gear bay for the extra wheels on the MLG without moving anything. Not familiar with how the 787 is arranged in that section so...

Also how much room is left for say.. making the landing gear TALLER. If Boeing can pick up the height needed to simply steal the XWB engines or whatever is out at the time, and use the extra height to allow more rotation... Nose gear might be a real pain in the ass to extend though.

also someone was saying that the tip-toe feature might not be as good as the 777... its very possible to design it to be better depending on how complex and/or heavy they want to go. A longer beam or moving the pivot point as far forward as possible would give the tiptoe more reach.
 
zvezda
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 10:25 am

Quoting XT6Wagon (Reply 33):
I think just jumping straight to 80m or just under makes more sense.

There are other reasons not to go to 80m. There are taxiing issues with turning radii at many airports and many airports don't have taxiways spaced far enough from the gates to accommodate 80m long aircraft parked at the gates. Many airports were built before the 80x80m box was agreed upon.

Quoting XT6Wagon (Reply 33):
Nose gear might be a real pain in the ass to extend though.

Extending the nose gear is not necessary.
 
lehpron
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 2:21 pm

Quoting Zvezda (Reply 28):
Quoting Lehpron (Reply 25):
I don't get the impression that your logic will be limited to a "787-11"

Huh?

If I used your logic with 787, I could keep stretching it and somehow it would be justified on a cost per unit payload basis. My proof is that the hypothetical "787-12" was even considered as part of this thread's discussion instead of rubbed under the carpet as if I bought up the idea a supersonic will replace 787 in the future.  Smile

Quoting Zvezda (Reply 28):
B787-11X 324.6
B777-300 330.4
B787-12X 352.6 (80 meter)
B747-400 372.0
B747-8I 426.2

There you go, a 787-13 (at 380.6) would cut right into 744's backyard. But seeing how mot many have sold in recent years, why should it be stretched as far? Boeing isn't interested in the niche A380 has made, presumably a super stretch of A350-1000 and beyond would be nichesque -- why pursue?

Quoting Zvezda (Reply 32):
I've always presumed that if Boeing were to develop new maingear with six-wheel bogeys for the 787 that they would increase ground clearance relative to the current maingear.



Quoting XT6Wagon (Reply 33):
Also how much room is left for say.. making the landing gear TALLER.

Lift is a function of more than just angle of attack. Could the takeoff velocity be made faster, to make up the neccesary lift for increased MTOW?
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zvezda
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 2:42 pm

Quoting Lehpron (Reply 35):
Lift is a function of more than just angle of attack. Could the takeoff velocity be made faster, to make up the neccesary lift for increased MTOW?

An increase in takeoff velocity requires a more than proportional increase in thrust (given the same wing).
 
XT6Wagon
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 3:19 pm

Quoting Zvezda (Reply 34):
Extending the nose gear is not necessary.

Well, I'm sure the 787F would be built on a high MTOW variant and would need the strongest landing gear regardless due to the need to have as high a MLW as possible. So leveling the plane is a good idea to start with, or you end up with some redneck fiberglass work on your aircraft like the A332F.

Quoting Lehpron (Reply 35):
Lift is a function of more than just angle of attack. Could the takeoff velocity be made faster, to make up the neccesary lift for increased MTOW?

While this is true, and I am shaky on the exact mechanics of takeoff/landing its clear that being able to have a higher angle at takeoff and landing is a good idea... If for no other reason than it keeps the bills down from pilots smacking the fuselage into the runway. Yes they get paid the big bucks to not do that, but I bet you would find that the shallower the max angle at liftoff, the higher % of takeoffs and landings see some tail dragging.

And yes, throwing big engines on does wonders for field performance. Ask 757 pilots.
 
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Stitch
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 9:27 pm

Quoting Lehpron (Reply 35):
There you go, a 787-13 (at 380.6) would cut right into 744's backyard. But seeing how mot many have sold in recent years, why should it be stretched as far?

A 787-13 would exceed 80m in length and as such would probably not be compatible with most facilities whose name did not end with the words "Air Force Base"...  Wink
 
deltadc9
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RE: Will The 748F Carry On After Y3?

Wed Jun 20, 2007 9:55 pm

Quoting Sv11 (Reply 21):
The 777-300ER appears to be mostly replacing 747-400s converted to cargo.

Which makes me wonder if that is because there was no 748 and the 777 was a better choice than a 744.

Quoting WingedMigrator (Reply 23):
Here I must wonder if freighters are also subject to Zvezda's law: will freight operators always go for the lowest tonne-mile operating cost, in the smallest possible format?

I dont think so, the 250 747 freighters in service (accounting for more than 50% of the tonnage) seem to require a variant law for freighters. Also, the fact that planes that no longer compete in the passenger market are coveted by freight operators makes me think the law does not apply.
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