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JustSomeDood wrote:Secondly, for some reason, every single-deck aircraft places the window line near half-way down the fuselage, leaving the main floor quite low in the fuselage, in a window-less design, would it be possible to move up the main deck in such a way that the aircraft can fit 2 decks of passengers in the same height of fuselage? (Think 777/787/A350 fuselages, obviously, cargo is disregarded).
Detailed answers/discussion to both questions would be helpful, thanks.
JustSomeDood wrote:Hi, first post here so I hope this is the right section to post this:
Say, hypothetically, if A/B can make a window-less version of any model of their aircraft lineup (e.g Windowless A350/787), while re-optimizing the aircraft's structure for window-less design (i.e taking out reinforcements, less wing etc), what's the sort of weight savings that can be made (assuming identical capabilities)?
Secondly, for some reason, every single-deck aircraft places the window line near half-way down the fuselage, leaving the main floor quite low in the fuselage, in a window-less design, would it be possible to move up the main deck in such a way that the aircraft can fit 2 decks of passengers in the same height of fuselage? (Think 777/787/A350 fuselages, obviously, cargo is disregarded).
Detailed answers/discussion to both questions would be helpful, thanks.
CowAnon wrote:JustSomeDood wrote:Hi, first post here so I hope this is the right section to post this:
Say, hypothetically, if A/B can make a window-less version of any model of their aircraft lineup (e.g Windowless A350/787), while re-optimizing the aircraft's structure for window-less design (i.e taking out reinforcements, less wing etc), what's the sort of weight savings that can be made (assuming identical capabilities)?
Secondly, for some reason, every single-deck aircraft places the window line near half-way down the fuselage, leaving the main floor quite low in the fuselage, in a window-less design, would it be possible to move up the main deck in such a way that the aircraft can fit 2 decks of passengers in the same height of fuselage? (Think 777/787/A350 fuselages, obviously, cargo is disregarded).
Detailed answers/discussion to both questions would be helpful, thanks.
Can't answer anything, but I've been wondering about the possibility of double-decking existing widebodies as well. Theoretically a 787 has space for a 3-3 configuration on an upper deck and either a 2-3-2 or a tight 2-4-2 on the lower deck, if you vertically stagger the outer seat groups upward (for example, the flooring for the outer aisle seat being 7" higher than the aisle floor, and then flooring for the adjacent window seat being an additional 7" higher, similar to what is shown in the patent link's images). That would probably require eliminating overhead stowage bins above the outer seats, but the bins above the inner seat group would have enough room, or you could even use the floor space next to the upper deck's window seats (which is large but unusable for seating because of the fuselage curvature) for bin stowage. You'd then have to add room for a staircase and put the cargo at the back of the fuselage (like the Mitsubishi regional jet does), but combined with the 13-to-14 seats abreast (+above/below) for the double deck configuration, the amount of wetted area per seat would still be much less than with a typical 8-9 abreast 787 single decker setup.
Had the 787 program not been fouled up for so long, maybe Boeing could've considered a double-deck 787 program (using the existing 787-8/9/10 fuselage lengths) with new wings to replace the larger-capacity 777 classic, rather than doing the 777-X. Or maybe Airbus could've double-decked the 350-900 fuselage for additional seating instead of doing a 350-1000 stretch, which goes beyond the upper optimum fineness ratio of 12. I'm also wondering how short you could make a double-deck 787 if you wanted it to be the NMA/MOM. A double-deck 787 with 18 rows at 30" seat pitch would hold 234 passengers in the [3-3]/[2-3-2] configuration or 252 passengers in the [3-3]/[2-4-2] configuration, only take up 45' of fuselage length, and allow quick embarking and disembarking. According to the Hamburg Open Online University (HOOU) aircraft design course's chapter on fuselage design, (http://www.fzt.haw-hamburg.de/pers/Scho ... selage.pdf), planes with a fineness ratio of 5 have been tried. For the 787, that would mean an aircraft length of 95'. Would you be able to fit a 45' seating area, lavatories, galleys, cargo, cockpit, empennage, and wings onto such a short, stubby plane? Although the cross section is twice that of a narrowbody plane, the amount of fuselage wetted area would be slightly less than the A321, and isn't skin friction the most important factor in drag?
gloom wrote:We're talking probably 30-40 % higher OEW here.
Two: Once you have the structure, you'll land probably 60-70% more passenger. Assuming standard 300 widebody, you raise it with 200 persons. Another 40.000 lbs.
Armadillo1 wrote:facepalm
its not about fitting 789 as dd's with old wing.
its about placing 777 load in 767|787 size fuselage
CowAnon wrote:Can't answer anything, but I've been wondering about the possibility of double-decking existing widebodies as well.
RJMAZ wrote:CowAnon wrote:Can't answer anything, but I've been wondering about the possibility of double-decking existing widebodies as well.
I was actually thinking about this for the 777.
Adding a 747 style hump forward of the wing for a first class cabin. Then add a 3m stretch behind the wing for weight distribution bringing the length to 80m. The wing seems big enough and it would make a great twin engine lightweight 747. Range would be reduced unless they up the maximum takeoff weight significantly
Starlionblue wrote:Boeing tried the "adding a hump" concept with with the 767-X
RJMAZ wrote:Starlionblue wrote:Boeing tried the "adding a hump" concept with with the 767-X
I'm thinking something like this.
A new nose and a very subtle hump. High commonality with the 777-9.
Wings, wingbox, engines, tail, landing gear, rear fuselage and cockpit all shared with the 777X.
zeke wrote:If your going windowless, why stick with a tube with wings ?
JustSomeDood wrote:Actually, how feasible would it be to "hollow out" much of the crown space above the main deck to be used as flat beds for premium class? from this picture of an A350, the crew rest areas only take up a small amount of a widebody's fuselage length, have J/F passengers sit on much smaller footprint W-ish seats during take-off/landing before they head up for the majority of the flight, it certainly doesn't seem to be a huge engineering endeavour (relatively speaking) to relocate the crew rest areas into cargo hold areas for more premium seats/long haul configurations where cargo holds are mostly empty anyways.
Starlionblue wrote:RJMAZ wrote:CowAnon wrote:Can't answer anything, but I've been wondering about the possibility of double-decking existing widebodies as well.
I was actually thinking about this for the 777.
Adding a 747 style hump forward of the wing for a first class cabin. Then add a 3m stretch behind the wing for weight distribution bringing the length to 80m. The wing seems big enough and it would make a great twin engine lightweight 747. Range would be reduced unless they up the maximum takeoff weight significantly
Boeing tried the "adding a hump" concept with with the 767-X, but then they came to their senses and designed the 777 from scratch. And then everyone agreed never to speak of what became known as "The Hunchback of Mukilteo" ever again. Ever...
Starlionblue wrote:
Using crown space is certainly feasible, but there's not as much space up there as one might think. The 777 or 350 crew bunks are not for the claustrophobic. And to my knowledge cargo holds are not mostly empty on long haul.
CplKlinger wrote:Not having the mechanics perspective on this, but isn't there a fair amount of stuff running above the ceiling in the crown space, like cabling, ductwork, SATNAV/WiFi Receivers? That stuff is going to have to go somewhere, and as others have said, you may not get the amount of space you think you'll get. Why try reinventing the wheel?
Starlionblue wrote:and with a 747 style hump there is some "dead" area along the walls which would come off the 60 square meters.
JustSomeDood wrote:Actually, how feasible would it be to "hollow out" much of the crown space above the main deck to be used as flat beds for premium class?
Armadillo1 wrote:i think 6+9 +ld3/45 can be put in fuselage 6.5-6.7m diameter
cargo cant be totaly disregarded.
gloom wrote:Armadillo1 wrote:its not about fitting 789 as dd's with old wing.
its about placing 777 load in 767|787 size fuselage
Both are quite the same.
I'm not considering geometrical shape here, just weights.
I can think of two scenarios:
NB expanded to 250-300 places (from current standard 180-200).
WB expanded to 450-500 places (from current standard of ~300).
Both by probably a factor of 50-60%. Main deck lowered (and probably shape more ovoidal cross-section to accomodate cargo on the belly as usually, but that's just remark, nothing really difficult here), new one above.
So basically, what we have here is:
1. extra weight (structural): new floor, more seats, lavatories, galleys etc.
2. extra weight (pax): 1 ton for each 10 pax extra. That will be up to 10 tons extra for NB, with around 90t MTOW for A321 nowadays - you realize that? WBs are easier, since one can dump fuel and make it medium range plane, but it's also 15-20t extra - especially for landing.
3. That weight is both on wings AND landing gear. Effecting PCN and many more (infrastructure).
4. Costs might be reduced a bit on fuel, but fees and crew will cost the same to the comparable onedecker (comparable = similar seat number).
I'll keep my case as still effective. While possible technically, and maybe also economically CASM will go by a small factor, but other problems make it just a concept, not to be seen in real aviation. Small plane with large wings and large gear to keep weight to lift right, will not work better than longer hull with one deck. And complexity increase over current concept will cost extra.
I just don't see it coming. And certainly not in you weight class (777x load in 781 weight? c'mon).
Cheers,
Adam