Re: Are Two Engine 757 & 767 Jets Dangerous?

Date:         05 Dec 96 02:27:19 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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Stefano Pagiola <spagiola@worldbank.org> wrote:
>First, should the 4-engine A340 have been built at all? ie, are you
>correct in supposing that it would not have been had 777-class engines
>been available at the time?  If one judges by the continuing demand for
>the A340 even now that the 777 is available, including by airlines that
>have 777s on order (eg Cathay), it would seem that not all agree with you.

Ordering both A340 and 777 seems rather bizarre.  One has to wonder
if it is motivated not by business needs but by politics.  Malaysia
Airlines has both A330 (not A340) and 777 on order, but they're also
the carrier that has 747s with all four engine choices -- JT9D,
PW4000, CF6-80C2, and RB.211.

In Cathay Pacific's case, the A330s seem to be L-1011 replacements for
shorter routes, while the A340s and 777-200s (I'm not sure about the
-300s) are intended for longer flights.  None of the 777-200s are IGW
versions, so their range is much less than that of the A340s, but that
just leaves the question of why no IGWs instead of A340s.  ETOPS may
have been a key factor in wanting a non-twin.

>Lufthansa explicitly preferred the 4-engine A340 for its long routes.

I thought they preferred the A340 over the A330, period.  There have
been discussions about this in sci.aeronautics.airliners in the past
(see http://www.chicago.com/airliners/archives.html).

>Second, given that Airbus wanted to proceed with a 4-engine aircraft, is
>the fact that stretched versions will need a new class of engines "poor
>planning"?
...
>By the time the A340 came around with the perfect engine, there would
>have been little market left (especially with Boeing squeezing from
>the other end).

The next step up from the CFM56 (and IAE V2500) was either the PW2000
or the RB.211-535, both of which had more thrust than Airbus needed
and, more significantly, weighed about twice as much.

The perfect engine, then, would have been one *starting* at around
30,000-35,000 lbs of thrust, with some growth room left (the CFM56
is being pushed pretty far from it's original 18,000-20,000 lbs
thrust), but without a big weight increase.  That would have meant
a new engine, an unlikely proposition even if they had waited until
the MD-11 was already in service.

--
Karl Swartz	|Home	kls@chicago.com
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