Originally Posted by
tubby linton
A passenger A330 can uplift 113t of fuel in the normal fuel structure without modification and leaving all of the holds and upper deck space empty.
Impressive capability. By comparison, KC-46 can only "uplift" 106 tons of fuel. The thing is, USAF does not care a wit how much gas a tanker can "uplift". It cares how much gas a tanker can offload over a range of distances and/or a range of on-station times. KC-46 meets or exceeds all of USAF's fuel offload requirements. Taking off with 7 extra tons of fuel is nice and all, but a larger, heavier tanker requires more powerful engines that consume more fuel. If the larger heavier tanker consumes 7 tons more fuel to perform its mission, that extra 7 tons is pointless. That's the very reason GEnX engines weren't put on the KC-46. They're more efficient but heavier and in the end, resulted in less fuel offload, which is what really matters.
In addition, if USAF is to be believed, KC-46 can "join the fight" and deliver that fuel in a much less benign airspace than legacy tankers. And can deliver that fuel to the entire range of US stealth aircraft. And after delivering fuel to fighters in the theater, KC-46 can perform an aeromedical evacuation of wounded personnel out of theater. KC-46 can also be used to carry "outsize" cargo, including vehicles, into and out of theater and move it around within the theater. It also has some in-theater electronic support capabilities I can't get into. Bottom line, for USAF it's the full military capability package that matters, not "fuel uplift".
One more time, USAF did
not want a tanker that could only pass gas and only do it in a benign airliner environment. It wanted a tanker that could pass gas in a much more hostile environment than airliners operate in and wanted a tanker that could be used for military taskings other than just passing gas. Some customers other than USAF may want such capabilities, in which case they'll want to buy KC-46. Other customers may not want those capabilities, in which case they'll buy A330MRTT.