Re: Delta Flt 1288

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         04 Aug 96 16:44:51 
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> >They the same engine types, at least as delivered from the factory.
>
> The MD11 tail engine is slightly different in performance than the wings.

Sure, but it's still the same type -- a PW4460 (or PW4462 on the new
ER versions) or a CF6-80xx (I don't know the exact model offhand).

> For example, the inlet air has to flow through a much longer path, and has
> to undergo a rather severe acceleration-deceleration before entering the
> fan.

I know it's worse than on the DC-10-10, because they retained the same
the banjo frames and thus diameter for the main part of the duct, with
the flared bell on the front to address the higher airflow requirement.
(The DC-10-40 also has this, though I think they're different versions
of the same basic idea.  The -30 and -15 don't seem to need it.)

Do you know how much of a performance hit the #2 on the -10-10 took,
if any?

> Also, the thrust reverser cascade arrays are significantly different between
> the wing and tail.

Makes sense, though some would argue that the thrust reverser isn't
really part of the engine, since usually it is designed for a given
airframe by the *airframe* manufacturer, not by the engine supplier.

> The engine and nacelle hardware are basically the same, but configured
> differently for the two positions.

That was my main point.  It's a lot easier to fiddle with some bits
on the outside, even big bits like thrust reversers, than it is to
have two significantly different engine types on the same airframe.

--
Karl Swartz	|Home	kls@chicago.com
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