Originally Posted by
Just This Once...
The 707 and KC-135 are different aircraft designs that happen to share the same family tree. The 707 and the military derivatives such as the E-3 have a lower lobe that is inside the pressure hull.
The apparent similarities between the 707 and KC-135 do cause confusion (see the RJ thread for example). You could say they were almost identical apart from the nose, forward fuselage, fuselage barrel, wings, primary structure, fin, rudder system, tail, overall dimensions et al.
Errrr ------
https://www.globalsecurity.org/milit...craft/b707.htm
The Dash 80 outgrowth was privately financed by Boeing with a view toward commercial passenger use and military tanker use, both of which were achieved. The 132 inches (3,350 mm) fuselage of the Dash 80 was only wide enough to fit 2+2 seating (in the manner of the Stratocruiser). Boeing soon realized that this would not provide a sufficient payload, so the fuselage was widened to 144 in (3,660 mm), the same as the KC-135 Stratotanker, which would allow six-abreast seating and the shared use of the KC-135's tooling. But Douglas launched the DC-8, with a fuselage width of 147 in (3,730 mm). The airlines [and passengers] liked the extra space, and Boeing was obliged to increase the 707's cabin width again, to 148 in (3,760 mm). This meant that little of the tooling for the Dash 80 was usable for the 707.
Now about claimed differences 707-kc135 ... Boeing leased some parts of 707 tooling FROM the airforce.for several years
And the early models of KC used water injection for takeoff especially from the relatively short renton airfield... about 5000 feet useable and they were loud loud loud !!