Re: 707 engine nacels

From:         jim@specialix.com (Jim Maurer)
Organization: Specialix Inc.
Date:         04 May 93 11:22:53 PDT
References:   1
Followups:    1
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"John (J.F.) Hawkins" <jhawkins@bnr.ca> writes:

>I've gotta question about the venerable 707 jet. I've taken a liking
>to the old bird, and have started collecting pictures, postcards, whatever
>I can get ahold of containing images of the noble jetliner. In these images
>I notice something peculiar about the outboard engine nacels (sp?) namely,
>they are different from one another (No. 1 nacel != No. 4 nacel).

...

>The number one engine (on captain`s side?) seems to have a shorter nacel
>which tappers off into the engine cowling itself in a smooth fashion about
>mid-way between intake and exhaust.  The  number four engine (co-pilots 
>side?) terminates in a large bulge above the engine intake in what appears 
>to be another, though smaller intake. Is this some sort of auxiliary 
>powerframe for when the jet is sitting around on the ground?

The bumps on engines 2, 3, and 4 are turbo compressors for cabin
pressurization.  The number 1 engine doesn't have the bump.  I
guess they only needed 3 of them.  The 720 only had 2 engines
(numbers 2 & 3?) with turbo compressors.  That was the main
spotting feature to tell the difference.  Another clue (but it
didn't always work) was that the 707s have a "spike" antenna
coming out the top of the vertical stablizer for high frequency
communications, most 720s didn't have that.

Ah, I miss the good old days watching 707s, 720s, DC-8s, and
the occasional DC-7 and Constellation at SFO!