Re: P3/Electra (was Questions about the DH Comet)

Date:         28 Sep 97 00:53:40 
From:         Steve Lacker <look@the.sig>
Organization: Applied Research Laboratories - The University of Texas at Austin
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Malcolm Weir apparently actually DID write:  ;-)

> >As for the other differences, I thought that they were really quite
> >minor (military rating and certification standards) and that it was
> >quite accurate to say that the P3 and Electra were more closely related
> >than, say, the KC-135 and 707.
> I guess the question is how to "score" differences!  For example, if the
> fuselage of a 707 has a larger diameter than that of a KC-135, but otherwise
> is constructed similarly (i.e. same frame arrangement), how does that rate
> on the difference scale?

Well, they aren't constructed as similarly as many people think... the
KC-135 is made of a different aluminum alloy than the 707. The KC-135
also had stiffening ribs added to the *exterior* of the fuselage aft of
the wing, because the intense noise from the J-57's was actually
fatiguing the skin, presumably because of the difference in alloy- 707's
didn't need these ribs even with the civilian J-57 (JT3?) engines.

> But otherwise, the 707/KC-135 and P3/Electra comparisons are extremely
> valid: the engine differences are approximately equivalent, etc.  The
> principal distinction is that the 707 and KC-135 were roughly contemporary,
> one could almost say siblings,

Siblings in that they both descended from the 367-80, but rather
fundamentally different. More like cousins. In one account I read, the
KC-135 is actually referred to as the "717" which as many have noted is
"missing" in the Boeing 7x7 scheme of things.

>while the relationship between the P3 and the
> Electra was rather more parent/child.

Ahh. A good analogy in that case. I would say that the 707 and the E3
AWACS compare in much the same way as an Electra and P3. The AWACS is a
707 airframe (not a KC-135 airframe), but it has substantial structural
mods. In fact, one book I have indicates that the prototypes for the E3
(called the EC-137 at the time) were civilian 707-320's pulled from the
production line.

Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
PO Box 8029, Austin TX 78713-8029
512-835-3286 (Remove the extra 'x' to mail me)