From: David Lednicer <dave@amiwest.com>
Newsgroups: rec.aviation.military
Subject: Re: KC-135R
Date: Mon, 08 Nov 1999 10:22:35 +0000

> >Here's a question many will be able to answer :-) What are the principal
> >airframe differences between the -135/717 and the 720, and the -135/717
> >and the 707 ?

Please, someone put this into the FAQ!

Yes, as Ron said, the fuselage cross-sections of 367-80 (the series
prototype), the KC-135 and 707/720 are all different:

1) 367-80 has an upper lobe width of 132 inches and a fuselage
cross-sectional height of 164 inches.

2) The 717/KC-135 upper lobe is 144 inches wide and the height is 168
inches.

3) The 707 upper lobe is 148 inches wide and the height is 170.5 inches.

Additionally:

1) The KC-135 fuselage is the same length as 367-80's.  The 707-138 and
720 are 20 inches longer, the 707-120 is 120 inches longer and the
707-320 and -420 are 200 inches longer.

2) The 707-120 has essentially the same wing as the KC-135 (and
367-80).  The 720 has a glove over the root area of the inboard wing,
which increases the max cruise Mach number of the aircraft.  The
707-320/-420 doesn't have this glove, but it has a root plug extending
the span and a different planform to the inboard wing area.
Additionally, it has a different tip planform and some of the wing
airfoils has been modified.

3) The type of Aluminum used in the construction of the KC-135 is
different than the 707 series.  Sorry, I don't remember the alloy
numbers off the top of my head.

4) KC-135s first had J57s (JT3Cs) without thrust reversers.  Some were
reengined with TF33s (JT3Ds) with thrust reversers (taken off of
scrapped 707s), while others got F108s (CFM56s), without thrust
reversers.  367-80 and all early 707s and 720s were powered by JT3Cs,
with thrust reversers.  Most were reengined with JT3Ds, with thrust
reversers.  707-320s were powered by JT3Ds, while -420s were powered by
RR Conways, both with thrust reversers.  There was one 707-700 built
with CFM56s (with thrust reversers), but this was later reengined with
JT3Ds and sold as a -320.  Some military 707s (RAF and French E-3s, USN
E-6s and one E-8C) were built with F108s (CFM56s).  I am not certain if
these latter aircraft have thrust reversers.

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