411A,
You're right, of course - I was looking at figures for the 120B and 320 (and mixing statute and nautical miles
).
Boeing's own figures show that 3500-3750 NM are correct for the 120B and 320 (JT4A-11 engines), but the 320B (Advanced Passenger) does indeed have a range (with typical 141 passenger load) of 5000NM at max. take-off weight. It would have had a takeoff runway length requirement of about 2 miles at sea level, Standard day, or a further 1/4 mile +15C!
I admit that I'm rather confused, as all the 320s had the enlarged wings and increased tank capacity (over prior models), but it seems that until the 320B introduced different engines (JT3D-3B) as well as a stretched fuselage, and the "Advanced" introduced leading-edge flaps, the range was still under 4000NM
The Max. take-off weight increased from 316,000 (320) to 333,000 lbs (320B AP), does that 17,000lbs equate to 1250 NM?
I found the
Boeing 707 Performance Charts on the Boeing website.
The figures are for P&W engines, I assume that RR Conways would be reasonably similar - isn't that what BOAC used on their -400's?
SD