The Supers were all identified as '70 series' aircraft all from -61's or -63's so they are -71 or -73 depending on who the original operator was and the size, number, and location of fuel tanks in the wings. There are 8 tanks, and 10 tank models out there to this day making their operators money. With the various tank arrangements to be a DC-8 F.E. you almost had to have apprenticed as an Engineer on a BALDWIN steam locomotive to move fuel around for burn and balance. Find a picture of an 8's F.E. panel and look @ the levers and switches involved in pushing gas around, that would be most of the bottom half of the facing panel for the F.E. 8 dial , 8 tanks, 10 dials, 10 tanks. The 8 tankers actually have more fuel capacity and range, the 10 tanks were for weight and balance considerations on shorter fuselages or customer unique requirements UAL operated 61's to Hawai`i for max body count and medium range out of SEA or SFO (see below). Due to transfer plumbing configuration, fuel is loaded in reverse of how it will be burned, and fuel is always moved to the outboard tanks then the engines for balance and to prevent 'wing flapping'. (kinda like a really big CESSNA 310)
Some 8's were built with very thick fuselage skins so that later, if the operator wanted to, they could cut out and install a standard Douglas MCD which came as a kit from MDC. DELTA learned to be a bit more careful when chosing candidates to turn into box haulers, they started converting one only to discover after cutting into it, that it was a standard 'thin skin' pax only model and it became too distorted to salvage or save. at least the rotables bins got fuller @ DELTA. The 61/71 & 63/73 freighters require mandatory straight taxi to the gate of around 200 feet so the fuselage will 'unwind' otherwise you can get the MCD open, but maybe not get it shut. Several years ago, an EMERY 55 series freighter out of PDX took off with the MCD unlocked, it flew around the Portland area for about 45 minutes with the door flapping up and down, made a cautionary landing back @ PDX. the door was given a visual inspection, a functional test open, shut, latch, open, shut latch. determined to good to go and the aircraft was redispatched on it's trip, ther's news footage video of it probably on youtube (that's Y'ALLTUBE for our friends in the South)
DAC did build a very very few -62's for UAL and JAL for really long but thin routes (Chicago to Tokyo over the pole). These were standard length 50 series fuselages mated to 10 tank wings from the 61 series. Of the few of these one or two became SUPER 72's but the market didn't develop because the stretch 8 could carry 16 cans over the same distances. (a stretch 8 is about 11 feet longer than a DC-10) The extra tanks on a 10 tanker were actually the inboardmost leading edges between the fuselage and engines 2 or 3, bolted to the front spars these 'slipper' tanks held around 10K pounds of fuel each and couldn't be distinguished from a standard leading edge because all the transfer plumbing was inside the wings.
And keep this fact in mind, there are only three mass produced, commercial jet airframes that intentionally were taken through Mach 1, the CONCORDE, the TU-144, and a TRANS CANADA DC-8 50 with R/R CONWAYS, and it was verified by a USAF F-104 chase plane on a test flight to EAFB from Santa Monica.
_________________ Don't make me go get my flying monkeys-
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