True the 757 is smaller than the 767, and if we try to point out the increased payload of the 767, the A330 will trump that argument.
As for the differences between the USAF
and Italian KC
-767s, There really won't be too much of a difference. They will both be 767-200 airframes with side cargo door and centerline boom and hosereel pods. Any other differences would be in engines (USAF
is taking P&W 400 series, is Italy taking CF-6?), avionics, defense systems.. paintjob?
Looking specifically as to why the 757 (KC-32?) or A330 wouldn't be an appropriate choice:
desire to go from narrowbody (KC-135) to widebody transport
2) Increased payload
3) Airframe still in production
4) Commonality with already orcered E-10 (767-400) fleet
5) Commonality with already purchased/certified medevac interior (used on CRAF
767-200 fleet of USAir)
6) Demonstrated ability to integrate systems into tanker fleet (EADS failure to get working wing pods on L-1011 tankers is a big issue)
7) Existing tanker and cargo conversions
8) Existing industrial base (EADS proposing to build A330s in America would require a huge amount of infastructure and investment)
9) Inability to provide enough booms on station. USAF
aircraft refuel one at a time. When you have to refuell a whole strike package of, say 10 aircraft, being able to throw up 3 tankers instead of 2 (due to groundspace concerns) is much more important than how much gas each one of those tankers can individually carry.