Re: 747-100 vs. -200

Date:         09 Jan 98 00:50:48 
From:         Chuanga@cris.com (H Andrew Chuang)
Organization: Concentric Internet Services
References:   1 2
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In article <airliners.1998.2@ohare.Chicago.COM>,
Karl Swartz <kls@ohare.Chicago.COM> wrote:
>>... All 747SPs
>>eventually had a modified pylon, where the trailing edge was a generous
>>curve, staying low before ascending to the wing.  Additionally, where
>>the outboard pylon meets the wing was extensively modified with a
>>fairing that goes over the wing leading edge and is almost vertical on
>>the inboard side and curved on the outboard side.
>
>>... Earlier -100/-200s seem to have both pylons.  My guess is that the
>>-100s are the ones with the earlier pylons, while -200s have the later
>>pylons.  Can anyone confirm this?
>
>Funny, I was just sitting in the Red Carpet Club at ORD this afternoon,
>looking at a parked at gate C16 and noticing the different pylons on the
>#1 and #2 engines.  I couldn't see the trailing edge of the pylon and
>hadn't seen your message yet, but I did notice that the outboard (#1)
>pylon had the fairing you describe where it meets the leading edge of
>the wing, unlike the #2 pylon, just as you describe.
>
>This aircraft was an early 747-123 (N156UA, ln 77), so the presence of
>the fairing does not distinguish a 747-200 from a -100.  The trailing
>edge still might.

I don't think the curved trailing-edge pylon can be used to distinguish
a 747-200 from a -100.  My recollection is the newer pylon started to
appear on the B747-200 in the late 70s.  I believe the pylon modification
was to accommodate higher thrust versions of the JT9D engine.  The first
time I noticed the modified pylon was on a JT9D-7Q-powered B747-200,
which, I believe, went in service around 1978 or 1979 (but it could have
been introduced earlier).  I think pylons on all the JT9D-7A-powered
B747-100 and -200 are of the same design.