PM,
I quite agree that a slower turboprop will outperform the best jet (edit: or quasi-jet-speed aircraft) in MPG, and that's partly because it does weigh less, so both your observations are correct. To take a simple, comparable example, a Bombardier Q400 turboprop - with not much more advanced tech than the Belfast - is more effiicient than the same company's similarly sized CRJ.
However, the Belslow is just that, which has a special meaning in military airlift where the figure of merit is tons/aircraft/day. If the aircraft is half as fast then you need twice as many to deliver X amount of kit in Y hours.
As for the converted civvy freighter: an idea that Boeing tried to pursue on many occasions, including a 747 derivative with a long nose ramp and a kneeling front gear that looked like a giant puking dog.
The problem here is utility. The Civvy freighter can't be unloaded without large specialized pieces of equipment (scissor lifts). It's confined to large airports with major taxiways and 10,000 foot concrete runways. Absent those things its utility declines to zero.
Last edited by LowObservable; 30th Aug 2007 at 16:52.