Re: A3XX vs B747-600 (was: Airbus lawsuit coming?)

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         23 Aug 96 13:44:58 
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Jean-Francois Mezei <jfmezei@videotron.ca> wrote:
>... computer systems (FBW). Airbus already has experience in adapting its
>320 systems to its other planes (340 and the latest model of the 310).

True for the A340, but not the A310 -- even the newest A310 (and A300)
models still use yokes and conventional cable/hydraulic linkages to
the surfaces.  They do have a very modern, glass cockpit, but in terms
of implementation is more like the 747-400 or 757/767.

>And before I would beleive that Boeing can just extend the 747 without
>redesign costs etc, I would like to know more about what changes had to
>be done between the 747-100 and 200, 200 to 300 and 300 to 400. Are the
>landing gears the same ? Are all the doors the same design, even the
>ones on the second deck ? Are the wings identical ? Made of the same
>materials ? Are engines the same ? Obviously, the cockpit in the 400 was
>re-designed.

I believe the landing gear is essentially the same on almost all 747
models thru the -400, though probably with some reinforcement as
weights grew.  Nothing substantial in terms of major redesign.  The
only exception would be the special versions for the Japanese domestic
market, which had to be reinforced for the higher number of cycles.

Doors are the same except for the new upper deck door on the -300 and
-400.  (The -400 may be different from the -300.)  There are also some
options on upper deck doors for the short hump, as discussed recently,
but those date back to the -100.  The SP may also have a different
design for the #2 doors on the main deck.

Wings are the same basic design, again with structural reinforcement
over time as they learned where the weak spots were and wanted to
increase gross weights.  It was my impression that the -400 had some
significant changes beyond the winglets, but someone told me that a
747-400(D) has a wing that's identical to the -300 or a late -200.

The big exception in the wing area is the SP -- it has a totally
different flap design, though the basic structure and fixed part of
the airfoil is still the same.  It also has a different vertical and
horizontal tail.  (The -400's tail looks the same as the other full-
sized 747s but has substantial changes, including more composites and
optional fuel tanks in the horizontal stabilizers.)

Engines changes were gradual and don't clearly correlate to models in
most cases.  The -100s all had the early JT9D, which could also be had
on a -200 or SP.  (United's 747SPs and 747-100s had the same JT9D-7A
engines, for example.)  Later models offered GE or RR engines but you
could get similar engines from a given manufacturer on any of the
different types.  (QANTAS has -200s and SPs with similar RR engines.)
Later, heavier -200 models (and the -300s) have more substantial engine
changes, but it's not model-specific.  The biggest change was the -400,
which went from the JT9D to the PW4000 if you bought PW engines.  With
GE or RR engines, the change was much less and apparently late -300s
(and perhaps late, heavy -200s) have very similar engines and nacelles
to the -400.

Speaking of engines and nacelles, note that the 747-400 and late 767s
equipped with engines from the same manufacturer are designed to be
interchangeable with only minor adjustment.

Bottom line: Boeing has thus far grown the 747 without a tremendous
amount of redesign, the largest effort to date probably being the -400
because of the new cockpit.  The proposed -500X/600X models will be a
much larger effort than any previous 747 derivatives because of the
entirely new wing.  Still, they'll retain most of the fuselage from
the -400, much of the cockpit will be from either the -400 or the 777,
and I've heard the larger vertical tail will be derived from the SP's,
so it's going to be a lot cheaper than starting from scratch.

--
Karl Swartz	|Home	kls@chicago.com
		|Work	kls@netapp.com
		|WWW	http://www.chicago.com/~kls/
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills