Originally Posted by
ConnieLover
I remember being told long ago that DC-4s were not pressurized. Is that true? If not, how could they have had what Wikipedia claims is a service ceiling of 22,300 feet without everyone on board needing oxygen? And -- if DC-4s were, indeed, pressurized, how did their aft toilet flush without depressurizing the airplane?
That is correct. Do not confuse service ceiling, which is an aeroengineering aspect of the aircraft design, with whether crew and/or passengers require oxygen (where 12,000 feet is a common upper limit). A WW2 Spitfire, unpressurised, had a service ceiling up to 34,000 feet, with the pilot obviously on oxygen.
The DC4 thus thundered across the Atlantic at about 10,000 feet. The DC6, pressurised, more powerful, a bit longer, higher fuel capacity and take-off weight, etc, flew at about double that. A DC4 from New York to Dhahran must have been quite a story to tell about.
Basic identification differences include that the DC4 has round cabin windows, where the DC6 has square ones. Both had three-bladed props, where the DC7, a further advance, has four-bladed ones. Beyond that you need to be a bit of an aficionado to spot the Douglas differences, and the various submodels identified by a letter suffix.
Aramco never had the DC7 so we needn't cover here that if a Douglas is coming in with one prop feathered and engine oil-strewn, it's most likely a DC7 ...