GENERAL EXPLANATION OF DC-8 VARIANTS
DC-8, DC-8B, DC-8C, SUPER DC-8
What do all these designations mean?
In general, the original or "Standard" DC-8 was applied to the DC-8 Series 10 through 55 & the "Super " DC-8 was applied to the DC-8-61 through 73. However, shortly after the introduction of the DC-8 a few airlines decided to designate their standard DC-8’s with different letters to imply a more advanced model. Eastern started this out by calling their DC-8-21 the "DC-8B" and Northwest & Japan Air Lines called their DC-8-32 the "DC-8C" to cite a couple of examples. Some of the airlines operating earlier versions of the DC-8 (mainly Delta & United Air Lines) claimed that these designations were inaccurate & appealed to stop their use to the U.S. Civil Aeronautics Board (CAB) which then governed the airlines on fares, routes and other matters such as these. The CAB ruled in United’s favor and thus Eastern & Northwest had to drop the "B" & "C" designations. However, the CAB had no control over how other countries airlines chose to designate their DC-8s so Japan Air Lines continued with the DC-8C designation.
When Canadian Pacific & Alitalia took delivery of their DC-8-40’s, with the more advanced Rolls Royce "Low Bypass Ratio" Fan Jet engines, they chose to call their DC-8s "Super" DC-8s. However, this "Super" DC-8 designation was dropped relatively quickly because of two factors. First, Pratt & Whitney developed the JT3D-3B Fan Jet Engine which had a "Higher Bypass Ratio" than the earlier Rolls Royce engines. In general the higher the bypass ratio an engine has > the the more air will bypass (or be diverted around) the engine’s compressors & then join the extremely hot air from the compressors at the rear end of the engine. This increased the engine’s power & at the same time, decreased the noise & fuel consumption. These new Fan Jet engines were quickly utilized by Douglas & Boeing on all of their new aircraft from that time on. In addition, some airlines chose to re-engine their "pure or straight" jet engines with the new Fan Jets. The second factor which caused the "Super" designation to be dropped was that Douglas announced the development of the DC-8 "Super 60s" Series which were dramatically different from the earlier DC-8s & thus Canadian Pacific could no longer justify the use of "Super DC-8" on the older DC-8-40 Series.
Later, in the 1980s, a further increased high bypass ratio engine was developed to re-engine the DC-8 Super 61, 62 & 63 and thus extend their useful lives, especially for freight hauling. When they were re-engined with the new General Electric/Snecma CFM56 Engines, along with some other optional modifications*, the aircraft were re-designated as the DC-8 Super 71, 72 & 73 respectively.
Optional modifications for the Super 70s DC-8s included a newer, more efficient
pressurization & air conditioning system; addition of an Auxiliary Power
Unit on board to provide both electrical power and air supply for engine starting
(while all earlier DC-8 Versions require Ground Power & Air Supply Equipment);
Updated Avionics in the cockpit (to state-of-the-art "Glass Cockpits") and an Updated Cabin Cabin Interior.
jet engine technology (including further increased bypass ratios) has reached
the point where just One Boeing 777 GE90-115B Engine Generates
More Thrust Than Six DC-8 JT3B-7 Engines.
It’s amazing how far our technology has progressed in such a short time!