Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Tue, 16 Sep 2003 20:58:41 -0400
Message-ID: <redirect-2582084@logan.com>
Reply-To: "Skip Slater" <skipslater@earthlink.net>
From: "Skip Slater" <skipslater@earthlink.net>
References: <list-2581580@logan.com>
Subject: Re: [LML] Re: Gross Weight & Balance of IV-P
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Brent,
   Thanks for once again so eloquently stating what most of us consider such
a patently obvious point.
    In airliners, we have two different weights to deal with, max takeoff
and max landing weight.  The max takeoff weight is considerably higher than
max landing (in the 737-800 I fly, it's about 30,000 pounds higher).  The
difference, of course, is to allow for the large quantity of fuel we carry
and will burn off prior to landing.  The planes were designed from scratch
to do this.  If we happen to have a takeoff emergency that necessitates an
overweight landing (the 737 does not have the ability to dump fuel as some
larger airliners do), the plane is taken out of service until an extensive
overweight landing inspection is completed.  The point here is that the
stresses put on an airframe by landing at a very heavy weight are
considerable and often the first point of failure will be the landing gear
itself.  Also, keep in mind that airliners can lose an engine and keep
flying; Lancairs cannot.
   When contemplating the arbitrary raising of your gross weight, consider
how you'll feel at your higher max gross weight takeoff when your engine
fails or you have some other problem that requires an emergency return to
the field and you don't happen to grease it back on the runway.  At some of
the weights I've heard being discussed on this list, something is likely to
break in the best case, and a flying fuel tank is going to rupture on impact
in the worst.  Picture where your full belly tank will be if your gear
collapses on an overweight landing.  Or picture yourself trying to stop in a
limited amount of remaining runway when your brakes are trying to stop a
plane that now weighs about a third more than the book says it should.
   When our planes were designed, the gear and brakes were meant to operate
at a given weight.  Granted, there's a fudge factor there, but the weights
now being discussed far exceed that in my view unless a new engineering
analysis is done and there is a resulting beefing up of both gear and
airframe to handle the higher weight.  In all the posts I've heard about
higher gross weights, I haven't seen one that addresses a structural
analysis of the implications of doing so.
   There are enough unknown dangers in flying.  I hate to see any of us
introduce new ones that should be obvious and can be avoided.
   Skip Slater