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Thread: 777 W & B

  1. #1
    Senior Member 3WE's Avatar
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    Default 777 W & B

    I recently lost my 777 virginity. It was a really big plane and was flown amazingly smoothly. However, I was impressed that forward of the wing was a very long section of the super luxurious walled-off seats, placed 4-across on the plane, versus the back of the plane being 9-across.

    That strikes me as making the plane quite tail heavy versus more traditional seating arrangements. In a 757/737 you have your 8 to 12 rows with four across vs. 6 across for the vast majority of the rows. At most, the front 25% of the plane with 33% fewer buttocks. (An MD-80 would be somewhat similar, with 20% fewer buttocks on only a few rows up front)

    Here you had ~40% of the plane with 56% fewer buttocks. I am sure that there are other planes configured with 'normal' seating all the way to the front.

    Can anyone provide insider information as to how this works? Is there ballast involved? Is there enough flexibility where you can 'overload' the front cargo area to compensate for the 'overloaded' back? Something you can do with fuel tanks?

    Or is the plane simply that flexible in weight and balance, or was it designed to need to be loaded back-heavy, or am I misunderstanding that 56% fewer humans is not that much of a weight effect.

    I look forward to replies (and hopefully there will be more than just ATLCrew's obligatory

    Quote Originally Posted by (actually, in the future to be posted by) ATLCrew
    Yes.
    )

    Thanks in advance.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  2. #2
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    I recently lost my 777 virginity. It was a really big plane and was flown amazingly smoothly. However, I was impressed that forward of the wing was a very long section of the super luxurious walled-off seats, placed 4-across on the plane, versus the back of the plane being 9-across.

    That strikes me as making the plane quite tail heavy versus more traditional seating arrangements. In a 757/737 you have your 8 to 12 rows with four across vs. 6 across for the vast majority of the rows. At most, the front 25% of the plane with 33% fewer buttocks. (An MD-80 would be somewhat similar, with 20% fewer buttocks on only a few rows up front)

    Here you had ~40% of the plane with 56% fewer buttocks. I am sure that there are other planes configured with 'normal' seating all the way to the front.

    Can anyone provide insider information as to how this works? Is there ballast involved? Is there enough flexibility where you can 'overload' the front cargo area to compensate for the 'overloaded' back? Something you can do with fuel tanks?

    Or is the plane simply that flexible in weight and balance, or was it designed to need to be loaded back-heavy, or am I misunderstanding that 56% fewer humans is not that much of a weight effect.

    I look forward to replies (and hopefully there will be more than just ATLCrew's obligatory

    )

    Thanks in advance.
    It is worse than that. You are counting only across, but there is a very different density along too (seat pitch). And you were lucky that coach was 9 across. There are 777 cofigs with 10 across. The pax density of business is about 1/3 the one at coach (this is a rule of thumb).

    That said, the pax weight (including carry-on) makes for about 10% of the airplane's EMPTY weight, which will even a smaller fraction that the plane's real landing weight (the lightest weight of the plane during any given flight), and it's not that this 10% mass will be concentrated in the radome or the APU tailpipe. It just will be somhowish more forwardish or backwardish in one configuration or another. And that will be about half of the payload. The other half will be checked baggage + cargo, where you have more freedom to distribute as you wish. And then you will take much more (and I mean not % more but times more) weight in fuel than in payload.

    Bottom line.... I think they can manage it without resourcing to a ballast.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  3. #3
    Senior Member Evan's Avatar
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    Quote Originally Posted by 3WE View Post

    Thanks in advance.
    Yes, there are fewer walled-off people but they are typically very well-fed and have heavier shoes, watches, jewelry wallets and egos. And more coins. And all the silverware, along with most of the food, drink and amenities are hidden up there. And most of the flight attendents. All that adds up. They also get to check more bags, which are kept up front in a velvet-lined compartment and guarded by a fierce clutch of large, finely groomed hounds.

    On the other hand, the optional aux fuel tank is installed back behind the wing, under your section. I thnk, if they are using that tank, they install a champagne tank up front to balance it off.

  4. #4
    Senior Member 3WE's Avatar
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    Thanks for two insightful replies...Gabe kept it below a half page too!
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Gabe kept it below a half page too!
    I learn write short.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

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    Be alert! America needs more lerts.

    Eric Law

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    Senior Member 3WE's Avatar
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    I sense an influx of foreign thought and humour...

    PS, the trip home included one hell of a greaser landing!
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    You're just looking at passengers, you're not taking into account cargo going into the pits underneath. Load planning will often put more cargo up front to counter the butts in back...
    The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.

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