Douglas seemed to have a tradition of advancing the aerodynamic configuration of their wings as they went along, almost as if their design office didn't have the best tools for development. Did I read once that Boeing's directors in the 1950s paid out for their own full wind tunnel but Donald Douglas didn't think it was necessary and just bought minimal time elsewhere ?
The DC8 did exactly the same advancement, the original DC8-11 had no leading edge devices and was re-engineered as early as the DC8-12 using slots, which all the original ones were converted to. They also found the original wingtips were high drag, and these were redone. Later on they found that it was more efficient to cruise with 1 degree of flaps set. These aspects should really have come out in the initial design analysis.
It is not correct to say that any airliners from the 1920s-30s were in service after 1945, the whole lot had been replaced by immediate post-war designs, or wartime military ones converted. Even the postwar DC3 fleets were generally from the last couple of years production 1944-45. Then there were multiple rollovers of fleets during the 1950s, few of the DC4s or L049s from 1945-50 were still with first line operators by 1960. The later piston aircraft of the late 1950s, the Lockheed L-1649Starliner or the DC7, had especially short lives before being scrapped - American Airlines scrapped pretty much their entire large DC7 fleet after no more than about 5 years service as the jets came along - American didn't want them any more, nor did anybody else.
Last edited by WHBM; 6th Oct 2013 at 18:59.