Re: A330/340 vs. B777

Date:         27 Dec 96 19:09:39 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>>... to get to the next thrust level
>>(65K-68K), it will mean Boeing will also need to redesign the engine
>>installation because the 65K-68K engine is larger than the 62K engine.

>As for the range, two questions. Firstly, how fixed is the design. If
>Delta were to push hard for the bigger engine, could it still end up on
>the plane?

Anything is *possible*.  Looking at the 737-100/200, one might have
thought it impossible to use the much larger CFM56 without switching
to taller landing gear, but that's exactly what Boeing did with the
737-300.  Ground clearance may not be an issue for the 767-400ERX
since it will have new or modified landing gear anyway, but a new
pylon and localized wing reinforcements might be needed, which could
start to get both expensive and time-consuming.  Delta already seems
to be concerned about delivery times, and if it gets too expensive as
well, they might as well just buy 777s.

Another alternative might be to get Pratt (and GE) to push the thrust
of the 62K engine up a bit, without going to the larger fan of the
A330's 65K-68K engines.  Physically, this is essentially the same
engine as the 56K version used on the 747-400, and maybe also the 52K
version used on the A310, so 62k is probably already close to the
limits.

Upsizing the 62K engine's fan just a little -- enough to get a bit
more thrust without resorting to the potentially substantial air-
frame mods needed to accomodate A330-class engines -- probably is
not an economically viable option for the engine manufacturers.

>... I would have thought that the wing was just about pushed
>it its limit. In short, is the wing going to be able to lift the
>weight necessary to get the full A330-200 range even if the aircraft
>has bigger engines?

I doubt the wing is much of an issue.  Remember, Boeing never broke
the 767's wing -- they were well past its design limits when the
fuselage finally broke just aft of the wing root.  There was an
incredible amount of growth room in the original wing.  (This is not
necessarily a good thing, as it means the original 767 carried more
structural weight in the wing than needed to do the job.  My father
made this error with a toy boat when he was a kid -- it was strong,
but placed in water it sunk like a rock. :-) )

--
Karl Swartz	|Home	kls@chicago.com
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Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills