ocy9
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B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:11 am

The 787-9 has a longer fuselage compared to the -8. Are all -9s built from the ground up with the longer fuselage, or have some -9s been produced by converting or modifying a -8 via fuselage lengthening?

In other words, are there any examples of Dreamliners that were converted from -8 to -9 by fuselage lengthening modifications?
 
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ikolkyo
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:12 am

No. The original -8 actually lacks a bit of commonality with the -9 and -10.
 
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:26 am

ikolkyo wrote:
No. The original -8 actually lacks a bit of commonality with the -9 and -10.


Not really. Give some examples please.
 
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OA940
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:31 am

BoeingGuy wrote:
ikolkyo wrote:
No. The original -8 actually lacks a bit of commonality with the -9 and -10.


Not really. Give some examples please.


Actually it does lack commonality. Don't picture anything major, like differences that would need a seperate certification for the -8, but there are some minor design differences (I'm not exactly aware of them but I think they have to do with the wings and tail)
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GoSharks
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:34 am

BoeingGuy wrote:
ikolkyo wrote:
No. The original -8 actually lacks a bit of commonality with the -9 and -10.


Not really. Give some examples please.

This is fairly common knowledge around here...
https://leehamnews.com/2018/04/17/boein ... mmonality/
 
ocy9
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:41 am

Yes, I know that the -8 and -9 have commonality and that Boeing made changes to their production to ensure this.

So what does that mean in the context of the original question? Are you saying that there are examples of -9s that were converted from -8s?
 
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ikolkyo
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 7:57 am

ocy9 wrote:
Yes, I know that the -8 and -9 have commonality and that Boeing made changes to their production to ensure this.

So what does that mean in the context of the original question? Are you saying that there are examples of -9s that were converted from -8s?


No such thing has ever occurred. All 787s were built outright as their respective variant from the get go. There are no such conversions you speak of.
 
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 3:21 pm

The difference between the lengths of the -8 and -9 lie in the lengths of the 41 and 46 fuselage sections. These are the body sections before and after the wing box. Each of these section skin is fabricated in one continuous fiber placed barrel with no slices. So to convert from one to the other you will need to replace one barrel with the other.

Airlines can convert from one to the other during the buying process. But at some point when the parts gets built the only way to convert is to swap your frame with some one else.

There may also be differences in the wing due to optimization, that I am not sure.

bt
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VSMUT
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 3:45 pm

The only conversions as extensive as that I know of, are the Tu-204s that were cut into shorter variants for Air Koryo, and the 747-200s that received the stretched upper deck. And the C-141B.
 
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Channex757
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 3:50 pm

bikerthai wrote:
The difference between the lengths of the -8 and -9 lie in the lengths of the 41 and 46 fuselage sections. These are the body sections before and after the wing box. Each of these section skin is fabricated in one continuous fiber placed barrel with no slices. So to convert from one to the other you will need to replace one barrel with the other.

Airlines can convert from one to the other during the buying process. But at some point when the parts gets built the only way to convert is to swap your frame with some one else.

There may also be differences in the wing due to optimization, that I am not sure.

bt

It's more complicated than that, which would preclude a lengthening exercise.

The A350 construction gives a major clue. When the shorter A350-800 was being designed, the crown panels built by Spirit had to be subtly different in their ability to carry load. This meant differences in the thickness and layup of the carbon fibre. Boeing designed the same thing into the barrels of the 788 and 789, so it's not as simple as slotting an extended section onto the jig. Load paths have to be preserved and no unintended weak points created, so the simplest way of dealing with this is to ensure parts only get fitted with others specifically designed for that aircraft.

Working in composites does mean healthy weight savings but also requires different thinking in design.
 
ocy9
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 8:37 pm

Interesting. Learning something new every day.

So with all that said, I'm guessing it's safe to say that 1) no 787 has ever been lengthened or shortened after the airframe had been built and 2) such an exercise would be impractical and more complicated than just simply slotting in an extension. Right?
 
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 9:07 pm

Channex757 wrote:
The A350 construction gives a major clue. When the shorter A350-800 was being designed, the crown panels built by Spirit had to be subtly different in their ability to carry load. This meant differences in the thickness and layup of the carbon fibre. Boeing designed the same thing into the barrels of the 788 and 789, so it's not as simple as slotting an extended section onto the jig.


That is the difference between the A350 and 787. The 350 barrel is constructed from panels and assembled in jigs. The 787 barrel sections are fiber placed on one continuous mandrel and cured in one shot. The variation in skin thickness is controlled by the fiber placed lay-up machine. You can see these machine work on YouTube.

https://www.google.com/url?sa=t&source= ... OD4xbU2nov

While there is complexity in the various systems, load path and structure optimization, in the simplest terms, the difference between in lengths between the -8 & -9 is the two body sections.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
ocy9
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 9:32 pm

bikerthai wrote:
Channex757 wrote:
The A350 construction gives a major clue. When the shorter A350-800 was being designed, the crown panels built by Spirit had to be subtly different in their ability to carry load. This meant differences in the thickness and layup of the carbon fibre. Boeing designed the same thing into the barrels of the 788 and 789, so it's not as simple as slotting an extended section onto the jig.


That is the difference between the A350 and 787. The 350 barrel is constructed from panels and assembled in jigs. The 787 barrel sections are fiber placed on one continuous mandrel and cured in one shot. The variation in skin thickness is controlled by the fiber placed lay-up machine. You can see these machine work on YouTube.

https://www.google.com/url?sa=t&source= ... OD4xbU2nov

While there is complexity in the various systems, load path and structure optimization, in the simplest terms, the difference between in lengths between the -8 & -9 is the two body sections.

bt


Are you saying that converting between a -8 and -9 is not impractical and can be accomplished?
 
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 9:49 pm

ocy9 wrote:
bikerthai wrote:
Channex757 wrote:
The A350 construction gives a major clue. When the shorter A350-800 was being designed, the crown panels built by Spirit had to be subtly different in their ability to carry load. This meant differences in the thickness and layup of the carbon fibre. Boeing designed the same thing into the barrels of the 788 and 789, so it's not as simple as slotting an extended section onto the jig.


That is the difference between the A350 and 787. The 350 barrel is constructed from panels and assembled in jigs. The 787 barrel sections are fiber placed on one continuous mandrel and cured in one shot. The variation in skin thickness is controlled by the fiber placed lay-up machine. You can see these machine work on YouTube.

https://www.google.com/url?sa=t&source= ... OD4xbU2nov

While there is complexity in the various systems, load path and structure optimization, in the simplest terms, the difference between in lengths between the -8 & -9 is the two body sections.

bt


Are you saying that converting between a -8 and -9 is not impractical and can be accomplished?


You'd have to cut a completed plane into three sections, including all the associated wiring and anything else running the length of the fuselage. I guess it's not literally impossible, but given that it would be an entirely bespoke process I can't imagine it would be any cheaper than building an entirely new -9.

I don't understand why everyone keeps consistently telling you that it's massively impractical and you keep fighting it. People have given you links showing that the commonality between -8 and -9 is a lot less than it typically is between stretches/shrinks of most commercial planes. Ask yourself this: if it were practical to convert shorter planes to longer ones of aluminum planes - which would be much easier to do this with than a composite - why has nobody done it?
 
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77west
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 9:57 pm

ocy9 wrote:
Interesting. Learning something new every day.

So with all that said, I'm guessing it's safe to say that 1) no 787 has ever been lengthened or shortened after the airframe had been built and 2) such an exercise would be impractical and more complicated than just simply slotting in an extension. Right?


Not just no 787, no commercial airliner EVER. Apart from the TU204 that were made shorter and the 747 stretched upper deck retrofit, there has never been such a major modification.

I won't include things like the LCF 747 as that is not a commercial frame.
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 10:03 pm

The FAA would never allow it. Each version is certified as built with the sections 41, 46 and tail for that version, and cutting, splicing and whatever to change one int another would throw all of the load calculations into a cocked hat, to say nothing of accepted assembly procedures, which are part of the certification. So even if it were feasible (which it isn’t) it would be illegal.
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 10:04 pm

77west wrote:
ocy9 wrote:
Interesting. Learning something new every day.

So with all that said, I'm guessing it's safe to say that 1) no 787 has ever been lengthened or shortened after the airframe had been built and 2) such an exercise would be impractical and more complicated than just simply slotting in an extension. Right?


Not just no 787, no commercial airliner EVER. Apart from the TU204 that were made shorter and the 747 stretched upper deck retrofit, there has never been such a major modification.

I won't include things like the LCF 747 as that is not a commercial frame.


How about the Prinair Heron's, they were heavily modified like this.
 
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alex0easy
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sat Feb 23, 2019 11:27 pm

I think the first CRJ700 was converted into the first CRJ900 then converted into the first CRJ1000.
https://www.planespotters.net/airframe/ ... r/Dn7gtNMP
But again, that frame was never delivered to anyone for commercial operations.
 
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Channex757
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 12:24 am

Lockheed is also famous for doing just that on military aircraft. The C-130 and C-141 Starlifter both had plugs to increase the length of certain variants, but those were heavy-duty military aircraft with less emphasis on economy.
 
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 1:14 am

ocy9 wrote:
bikerthai wrote:
Channex757 wrote:
The A350 construction gives a major clue. When the shorter A350-800 was being designed, the crown panels built by Spirit had to be subtly different in their ability to carry load. This meant differences in the thickness and layup of the carbon fibre. Boeing designed the same thing into the barrels of the 788 and 789, so it's not as simple as slotting an extended section onto the jig.


That is the difference between the A350 and 787. The 350 barrel is constructed from panels and assembled in jigs. The 787 barrel sections are fiber placed on one continuous mandrel and cured in one shot. The variation in skin thickness is controlled by the fiber placed lay-up machine. You can see these machine work on YouTube.

https://www.google.com/url?sa=t&source= ... OD4xbU2nov

While there is complexity in the various systems, load path and structure optimization, in the simplest terms, the difference between in lengths between the -8 & -9 is the two body sections.

bt


Are you saying that converting between a -8 and -9 is not impractical and can be accomplished?


Cannot be accomplished. The -8 has a different kind of nose section and tailplane from any other variant, let alone center wing box, landing gear, etc.
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nz2
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 4:04 am

To ocy9 -you cannot be serious can you? every plane (basically) when starts construction is intended to be a specific type, you cant change your mind halfway through, the customer can of course change and if they desire a different model type then another aircraft of that type has to be sourced, built or swapped in, you cannot just decide to shorten or lengthen a plane on the assembly line. Think or a car, a short/standard wheel base cant be changed to a long wheel base because it requires a different (lengthened) chassis
 
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 4:28 am

Spacepope wrote:
The -8 has a different kind of nose section and tailplane from any other variant, let alone center wing box, landing gear, etc.


Actually, I believe the nose (section 41) and tail (section 48) are common across all 787 models. Boeing does this to increase commonality and reduce cost.

As for stretching a -8 to a -9 after production, it is more of a certification issue more than a technical issue. During fabrication, these section may come with electrical disconnect at these section joints. This allow Boeing to pre-install many systems before they fastened the barrels together. So, in theory, you can disconnect these systems, remove the splice joint fasteners and re-assemble a new barrel in the place of the barrel.

Re-building an airplane has been done before. I believe the whole bottom of a 747 was rebuilt in India by an AOG team.

With metal fuselage, when you perform these repairs, you end up using oversized fasteners which reduce the strength or fatigue life of the joint. I'm not, sure how it is with composite fuselage and titanum fittings used.

bt
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 4:35 am

SEPilot wrote:
The FAA would never allow it. Each version is certified as built with the sections 41, 46 and tail for that version, and cutting, splicing and whatever to change one int another would throw all of the load calculations into a cocked hat, to say nothing of accepted assembly procedures, which are part of the certification. So even if it were feasible (which it isn’t) it would be illegal.


You can not say that the FAA will never allow it. The regulation say that as long as you can show through analysis or testing that what ever you did to the airplane will still make it airworthy per the regulations, then you can get it certified. It would just be too expensive to do so. . . if it gets too complicated.

bt
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 4:43 am

bikerthai wrote:
Spacepope wrote:
The -8 has a different kind of nose section and tailplane from any other variant, let alone center wing box, landing gear, etc.


Actually, I believe the nose (section 41) and tail (section 48) are common across all 787 models. Boeing does this to increase commonality and reduce cost.

As for stretching a -8 to a -9 after production, it is more of a certification issue more than a technical issue. During fabrication, these section may come with electrical disconnect at these section joints. This allow Boeing to pre-install many systems before they fastened the barrels together. So, in theory, you can disconnect these systems, remove the splice joint fasteners and re-assemble a new barrel in the place of the barrel.

Re-building an airplane has been done before. I believe the whole bottom of a 747 was rebuilt in India by an AOG team.

With metal fuselage, when you perform these repairs, you end up using oversized fasteners which reduce the strength or fatigue life of the joint. I'm not, sure how it is with composite fuselage and titanum fittings used.

bt


Except it’s not. 788 has 30% commonality with the 9/10, including vastly different sections for the fuselage. 9 and 10 are 95% common. https://leehamnews.com/2018/04/17/boein ... mmonality/
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Channex757
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 7:50 am

bikerthai wrote:
Spacepope wrote:
The -8 has a different kind of nose section and tailplane from any other variant, let alone center wing box, landing gear, etc.


Actually, I believe the nose (section 41) and tail (section 48) are common across all 787 models. Boeing does this to increase commonality and reduce cost.
(snipped for brevity)

bt

The tail on the 787-8 is actually different, for the -9 Boeing introduced a laminar flow treatment to the section in order to minimise drag. This was then made standard on the -8 from roughly about now in the production cycle, but early -8 models do not have this tail.

It would be impractical and hugely expensive to offer this in retrofit but it's certainly worth the extra design and test work Boeing did on it. Same thinking as Airbus and their occasional changes like increased height sabre wingtips. Improving your product never stops and this is now standard across the 787 range.
 
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 5:52 pm

What you guys are saying is true. During the life of the production design can change that can not be retrofit back to previous aircrafts.
However, the philosophy at Boeing at any point in time is the 41 an 47 section should be as similar as possible for the same model to facilitate commonality and reduce fabrication cost.

From a structure stand point, most of the differences are not impossible to address during a retrofit. But I do not dispute that it might not be practical or cost effective.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 6:06 pm

Spacepope wrote:
Except it’s not. 788 has 30% commonality with the 9/10, including vastly different sections for the fuselage. 9 and 10 are 95% common.


Which does not contradict with the statement that the 41 and 48 section are more or less common (%30). Channex757 said as much with the aft section. One thing that the 9 & 10 may have in common is the wing and body section.

So you can try to retrofit an 8 to a 9 by changing the fuselage. But your wing would not able to carry the extra capacity. You can retrofit a 9 to an 8, but you'll be carrying a heavier wing.

So to summarize, you can do it. It is not impossible structurally an it can be certified. It would just not be practical.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
WIederling
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 6:30 pm

bikerthai wrote:
So to summarize, you can do it. It is not impossible structurally an it can be certified. It would just not be practical.


you can create a Frankentanker from any types model range. :-)))))))))

on the Starlifter front the thing that is really noteworthy is that
all of the in service fleet C-141A ( 270 frames )
were stretched to the C-141B Model spec
~~as a kind of "after market conversion".
https://en.wikipedia.org/wiki/Lockheed_ ... ter#C-141B
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zanl188
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 6:53 pm

[quote="ocy9”]

Not just no 787, no commercial airliner EVER. Apart from the TU204 that were made shorter and the 747 stretched upper deck retrofit, there has never been such a major modification.

I won't include things like the LCF 747 as that is not a commercial frame.[/quote]

Ok, I think that means it’s time to start a list of commercial airliners that have been stretched...

747SUD
L-100
DC-3
CV-580
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JayinKitsap
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Sun Feb 24, 2019 9:36 pm

It is doable with enough money, but why spend the value of 5 787's to get one. Several Billion is certification costs that Boeing has no time or desire to do. Actually Boeing would buy back the starting 787 for like 60% of value (to be sold to another airline) and sell at list price the new model. Cheaper for both customer and Boeing.

I suppose someone could convert a Stingray into a Chevy Tahoe but why?
 
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bikerthai
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Thu Feb 28, 2019 5:25 pm

Think stretch limo's. But that's because they don't build stretch limo's on a production line.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
strfyr51
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Re: B787-9 Dreamliner, built from the ground up or converted into?

Fri Apr 19, 2019 4:20 am

ocy9 wrote:
Yes, I know that the -8 and -9 have commonality and that Boeing made changes to their production to ensure this.

So what does that mean in the context of the original question? Are you saying that there are examples of -9s that were converted from -8s?

Having seen the winding machine? I would seriously doubt that the 9 was converted from the 8. though I do think the -10 is A -9 with an added fuselage Barrel

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