Re: Boeing considering ultra-long range 747-200X

Date:         15 Nov 97 16:24:42 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>The Flight International Article quotes the MGTOW as 397,000 Kg, which
>is 875,000 pounds. This is the standard for  passenger and Combi
>-400's. Aviation Week's 1997 Aerospace Source book quotes the MGTOW on
>the 747-400F as 811,000 pounds however

While generally a good reference, I've found a number of errors in
AvLeak's Aerospace Source Book.  811,000 lbs MGTOW for the 747-400F
is certainly one example.  (The 875,000 lbs figure I cited came from
Boeing's web site.)

>but MLW on the 400F is 660,000 pounds versus 630,000 pounds on the
>standard -400.

This is interesting if you want to trade fuel (hence range) for
greater payload.  Quite useful for freighters, but of no value for
a longer-range passenger aircraft.

>The 400F has an empty weight advtange over a passenger -400 of about
>35,000 pounds.

Most of which is due to the lack of seats, galleys, lavatories, and
windows, plus the shorter upper deck.  (The reinforced floor and cargo
handling equipment adds a bit back.)  A more meaningful estimate of
the -200X empty weight can be had by comparing the 747-200B and -300.
Going back to the Source Book, the empty weight differential of these
two aircraft is only 8,900 lbs.  Add in some structural reinforcements
from the 747-400F and any empty weight advantage the 747-200X might
have over the passenger -400 is minimal.

>I am compelled to point that early examples of aircraft almost never
>meet performance guarantees. There are enough differences in how the
>loads and ranges are calculated that it hard to be sure if the
>747-200X really has shorter range than the A340-500.

Quite true.  Also, the "maximum range" figures are "best case" and in
practice the useful range which an airline can plan on routinely using
is significantly less.

>It may well be academic, because I can't think of any routes that are
>longer than 14,800km and shorter than 15,400km.

JFK-SIN (15,362 km), which is frequently cited as an interesting route
for a very long range transport.  However, it's not entirely clear that
the market on this route is large enough for a plane as large as the
747-200X or A340-500.  The slightly smaller 777-200X might be a better
choice for the route.

--
Karl Swartz	|Home	kls@chicago.com
		|Work	kls@netapp.com
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