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View Diary: How Airliners Work - Weight and Balance (160 comments)

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  •  Trim weights (15+ / 0-)

    When I first moved to Seattle to work for Boeing I discovered that my '84 Mustang convertible tended to fishtail all over the place with the perpetually damp Seattle roads. When I complained about it at work I got told to put a bunch of cat litter in the trunk to put some weight over the rear wheels, which worked except for the fact that enough cat litter to fix the problem ended up filling the trunk. After complaining once again at work one of the engineers took me to Boeing Surplus during lunch one day and had me pick up a pair of lead ingots - 60 lbs apiece - which solved both the handling and the trunk space problems neatly.

    When I asked why Boeing had lead ingots lying around the engineer told me they were 747 trim weights used to help refine the plane's balance before delivery. I never did find out how much lead it took to trim a typical 747.

    •  if memory serves (9+ / 0-)

      a 747 could often have up to 2,000 lbs of spacers and shims
      as the airframe came together.  

      so i wouldn't be surprised if they had all sorts of trim weights out there.

      the 777 was so well designed and the manufacturing was so tight, the first birds were coming together without any shims.

      Meanwhile, the 787  is coming together with so many challenges, it's overweight, there are a number of non-conforming aircraft, it's such a challenge

    •  We used to use bags of buckshot, same reason. n/t (3+ / 0-)
      Recommended by:
      mlharges, BlackSheep1, ER Doc

      Information is abundant, wisdom is scarce. ~The Druid.
      ~Ideals aren't goals, they're navigation aids.~

      by FarWestGirl on Tue May 07, 2013 at 05:24:07 PM PDT

      [ Parent ]

      •  living in Big Spring, which is Texas's (4+ / 0-)

        "Bullitt hill" from San Francisco, in the mid-80s, I had the one-and-only real issue I've ever had with a Dodge in the snow. Pickups with empty beds will create ... issues ... on icy hills. I'm a farm kid. My dad got a couple of old 2x4s and some baling wire, and we set the pressure-fit 2xs into the bed, one in front of the wheel well, one behind. Then we backed up to the Oliver, laid a pair of 2x6s down from the tailgate to the bracket, and slid the front tractor weight into the gap.

        Presto. Traction.

        LBJ, Lady Bird, Van Cliburn, Ike, Ann Richards, Barbara Jordan, Molly Ivins, Sully Sullenburger, Drew Brees: Texas is NO Bush League!

        by BlackSheep1 on Tue May 07, 2013 at 07:02:18 PM PDT

        [ Parent ]

        •  Oh, yeah, baaaad issues. Even a Dodge needs a (4+ / 0-)
          Recommended by:
          mlharges, KenBee, ER Doc, BlackSheep1

          little help in extremis. ;-) Necessity's a mother, all right, does anybody wonder why all us farm kids end up gadget people?

          Thank gawd for tractor weights. I still have a few near the main barn. Too damned old to move them without a good sized lever, but they're still around, just waiting for some need. :-)

          Information is abundant, wisdom is scarce. ~The Druid.
          ~Ideals aren't goals, they're navigation aids.~

          by FarWestGirl on Tue May 07, 2013 at 07:13:52 PM PDT

          [ Parent ]

          •  about the weight & complexity of a (1+ / 0-)
            Recommended by:
            FarWestGirl

            4x4 transmission, but the tractor weight cost about $20. Cut gas mileage about the same, too, but I figure not winding up in the barditch is worth it.

            LBJ, Lady Bird, Van Cliburn, Ike, Ann Richards, Barbara Jordan, Molly Ivins, Sully Sullenburger, Drew Brees: Texas is NO Bush League!

            by BlackSheep1 on Wed May 08, 2013 at 08:52:59 AM PDT

            [ Parent ]

    •  Gliders use them a lot. (4+ / 0-)
      Recommended by:
      mlharges, Simplify, KenBee, ER Doc

      A great many gliders have either sets of weights that screw in (to handle low-weight pilots) or we put weighted bags down under the pilot seats to keep c/g under control. We also use them on wingtips when parking gliders on the ground for a while.

      The bags are made specifically for this, usually being a bit over a foot square, with 25 pockets or so, each with a lead or steel weight sewn in it.

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