Re: An-124 and wing dihedral

Date:         06 Jun 98 15:38:56 
From:         niels@nospam.demon.co.uk (Niels Sampath)
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In article <airliners.1998.805@ohare.Chicago.COM>
           wolpjame@cwis.isu.edu "Jim Wolper" writes:

>I imagine that the 747 wings are stiffer than the 777
>wings because of the extra bending moment from the outboard
>engines.

	I am open to correction  but I thought that one advantage
of the L1011 over the DC-10 was that its engines were further outboard
(caveat: because the tail engine on the DC-10 was off the centreline viz.
one engine out scenario) resulting in:    a lighter TriStar wing (less
stiff?) ...despite their extra bending moment  outboard engines dampen the
flexing...need less inherant stiffness (weight) in the wing...
i.e. twins theoretically need(ed) a stronger wing than 4x wing-engined a/c
which in the past has meant a stiffer/heavier twin wing.
But, to pre-empt Mr. Faure <g>, Boeing obviously markets the 777 wing as great
because its both strong and light etc etc.....i.e. new wing technologies with
regards to wing strength/weight  have probably reduced twin disadvantages as
much as engine thrust + reliabilty advances.  A new light + flexible (but no
loss in strength) 777 wing may now simply reflect this change.
So I guess it depends on the comparative ages of the designs you are
looking at.

Relatedly I am pretty sure the `clean wing' VC-10 needed a stiffer/heavier
wing than the 4-engine 707  for the same sort(s) of reason(s) back in the `60s.

--
-Niels