Re: A3XX vs B747-600

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         18 Sep 96 13:50:34 
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>OK. Here are some of the things being talked about the 747 "derivative."

The 747 derivatives we've been discussing are the -500X and -600X, the
two which many people expected to be launched at Farnborough.  Note
the subject of this thread mentions the 747-600, not any subsequent
derivatives (nor the -500(X)).  You yourself focused on these two
variants in your last post when you wrote "Boeing 747-500/600/(700,
800, whatever)."

The most recent AW&ST which included substantial data on the 747-500X
and -600X was the July 1, 1996 issue (pp. 20-21).  There's a little
bit in the Sep. 2, 1996 issue (pp. 50-52), but for the hard core specs
it refers back to the July 1 article.  An article in the Sep. 9, 1996
issue (pp. 25-26) notes increased ranges for the 747-500X/600X but
otherwise has nothing new on those models.  It does talk about the
possible future 747-700X, the first serious mention I recall in AW&ST.

>It will weigh about 300,000 to 600,000 lb more than the current
>versions of the aircraft.

Referring to the above-cited AW&ST articles, the MGTOW for the -500X
will be 1.116 million lbs, and the -600X will be 1.126 million lbs.
The 747-400 currently has a MGTOW of at least 875,000 lbs, with work
in progress to bring that up to 890,000 lbs.  I think the 747-400F
can go up to 920,000 lbs.  Even comparing the lower 875,000 lbs value
to the 747-600X, the difference is only 251,000 lbs.  This isn't that
much greater than the 175,000 lbs difference between the current
747-400 and the original 747-100.

>It will have a new engine

Not entirely correct -- Rolls-Royce will offer a variant of their
current Trent, which is available for both the 747-400 and the 777.
GE has to have a new engine because the CF6-80 has no growth room
left and the GE90 is much too big.  I don't see why P&W doesn't offer
a PW4000 midway between the PW4060 (767-300, and, derated to 56,000
lbs thrust, 747-400) and the "PW4077" (777-200; really a de-rated
PW4084).  Boeing says a PW4000 wouldn't meet their noise and fuel
burn targets, but the PW4000 isn't that much worse than the Trent.

In any case, even if a new engine were used, that doesn't make it a
new type, unless you'd also claim that the 737-300 isn't a 737.

>new wing

True.  So what?  The 737-600/700/800 has a new wing but Boeing still
calls them 737s.  Later DC-9s have substantial wing changes from the
original DC-9-10, if not an entirely new design, but they're still
DC-9s.

>new technology "derived" from the 777 experience

The 747-400 has a lot of new technology derived from the 757/767,
and improved from there.  The A300-600 has a lot of new technology
derived from the A310.

>new undercarriage

Ditto for the 737-600/700/800, yet they're still 737s.

>wider fuselage

Not true, at least not for the 747-500X/600X.  You're taking this out
of context from the paragraph in AW&ST on the 747-700X, while I'll
quote in full, with some emphasis added to key points:

    The developing family of 747s also *could* *eventually* include
    the 747-700X, Woodard said, a growth derivative that could carry
    up to 650 passengers about the saem range of the -400 -- 7,300
    naut. mi.  This larger derivative would have a wider fuselage
    than the -600X but retain its wing, systems, engines, struts and
    landing gear.  "We're designing-in the capability for the future
    derivative growth model, the 747-700X, even though *we don't see
    a market for that airplane today*," Woodard said.

The 747-500X/600X simply have a stretched 747-400 fuselage, with four
plugs added, totaling 538" (44'10") for the -600X and 318" (26'6") for
the -500X.

>and will be limited in overall size by the airports that can handle it.

Any aircraft is "limited in overall size by the airports that can
handle it."  The 777 started off as a DC-10/L-1011 replacement (in
part) and was therefore limited in size by the airports (the gates,
mainly) that could handle those aircraft.  That's why Boeing came up
with the still-born folding wingtips.

For United's recent A319 order, Boeing was competing the 737-300.
Not the 737-700 -- United needed a plane that would fit its gates at
Denver, and the longer wings on the 737-700 wouldn't fit.  (Why they
designed such tight gates at a brand-new airport is beyond me, but
that's a different issue.)

>Please do not call it a new aircraft.

Right.  It's not.

>All of the above information has appeared in the Aviation Week and Space
>Technolgy magazine.  You are welcome to check it out.

I already had, except I made sure I got the facts straight, applied
them to the right airplanes, and didn't take quotes out of context.

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