Re: B737-400 range

Date:         31 Dec 99 17:11:12 
From:         james matthew weber <jmweber@goodnet.com>
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Petrus Lundqvist wrote:
> I've read in several places that the Boeing 737-400 has a range
> of about 2050 nm, or 3800 km. What does that mean exactly? The
> range circle drawn on the Boeing website for the 737-400 centers
> on Boston but doesn't reach the west coast of the USA. This should
> correctly be about 2050 nm but does this mean 2050 nm after take
> off, and then cruising at 35000 feet and running out of fuel after
> 2050 miles, or does it mean 2050 miles including takeoff, approach,
> landing.. Does it include reserves and if so, then how much?

The answer is such a range quotation doesn't mean much. Most aircraft
are capable of carrying far more fuel than they are likely to ever be
able to actually put on board due to weight limitations.  This is
further complicated by the fact that the manufacturer may offer
differing maximum takeoff weight, which increases the possible fuel
carriage. For instance Boeing offers a high weight 737-400 option that
increases the range to almost 2400nm, and still others may fit
additional tanks in the belly for even more range with reduced payload.
I have been on a 737-400IGW that spent almost  5 hours airborne, flying
from Phoenix, AZ. to Philadelphia, and then took a 1 hour weather delay
at PHL and was still legal.

Generally the range is quoted at optimum conditions in still air, and
often involves serious payload penalties. How serious a payload penalty
you are prepared to pay in no small part determines the range. For
instance if you would like to fly a 777-200ER with a 656,000 pound MGTOW
and only carry a crew , you can get more than 20,000km as Boeing did
several years ago.  With a realistic load, the limit in such an aircraft
is more like 12000 km.

The best way to look at realistic range is to look at the spread between
Maximum Gross Takeoff Weight and Maximum landing weight. Divide by
average fuel consumption per hour, multiply by typical cruise speed and
you have still air range at maximum payload. If you do this on a 747-400
you end up with about 5500 statute miles. You can obviously fly much
further if you can carry the fuel, and are prepared to exchange fuel for
payload. For instance the QF 747-400's that fly LAX-SYD (which is about
7500 statute miles), typically can only carry about 3500kg of freight.
This is much much less than Boeing quotes, and it happens because the
roughly 2500 miles worth fuel had to come out of payload.

Boeing quotes the 747-400 as having a 8400nm range. at economy cruise
that is about 17 hours. If you work backward from the fuel required,
such an activity will take 135,000 pounds or so out of the lift
capacity. That means you would probably have a hard time doing it in an
empty airplane if it had a passenger interior fitted!.

--
James Matthew Weber   (623) 587 7514 .  Fax  (623) 434 7598