Unlike the 727, which was designed for high performance in the 1960s, the 7N7 was aimed specifically at the economy minded short-haul routes where speed was less vital. Boeing calculated that climb consumed 60 percent of the fuel that the 7N7 would use on a 500-nautical-mile trip. It was therefore expected to spend almost as much time climbing and descending as cruising. As a result, the wing was optimized for a Mach 0.8 cruise, substantially less than the 727's Mach 0.9 top speed (147)
|Quoting Blackbird (Reply 3):|
So if there was a plane that could do Mach 0.85 with the desired fuel efficiency, it would have been accepted by the airlines?
|Quoting Zeke (Reply 4):|
The Convair 990 entered service in 1961, it cruised at M0.91, sadly it used too much fuel.
|Quoting Blackbird (Reply 6):|
So, the airlines would have accepted a Mach .85 plane if it was just as efficient as the 757/767/A-320?
|Quoting Blackbird (Reply 8):|
They didn't know HOW to build a mach 0.85 airliner that could meet the fuel-burn requirements back then. I don't know if extensive wing/body blending, supercritical foils, and a 30-degree sweep even would have done the trick.
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