Remarks from the head of US Transportation command which are relevant for the KC-X programme - and equally for the RAF/Airtaker fleet and it's lack of of own AAR capability....
Danger For Strategic Airlift in Central Asia
.........McNabb also noted big savings from adjusting C-17 use in moving supplies to Afghanistan and predicted huge savings would be generated if a replacement tanker were available.
Because of the need to refuel C-17s during longer trips to Afghanistan, Transcom logisticians discovered it is 45% more efficient to use the new airlifters for only the last leg of the trip. Savings are pegged at $110 million to $116 million per month through a reduction in aerial refuelings, he says.
The savings from modifying in-flight refueling to make them more efficient could be further increased by introduction of a new tanker.
“We pass more fuel than we carry cargo,” McNabb says. Tankers constitute the majority of Transcom’s 900 daily sorties. But because most KC-135s cannot receive fuel in flight, they have to carry that fuel and weight back to their base. The average amount of fuel returned to base is 35,000-40,000 lb. per aircraft.
“They are carrying that all the time,” McNabb says. “We’re talking about 5 million lbs. a day. If you can leave that fuel in the fight, you only carry it one time. [Saving] 20 to 25 percent of the fuel bill is a lot.”
However, the new tanker designs would allow the remaining fuel to be transferred to other tankers remaining in refueling orbits. The savings in fuel are calculated in the millions of gallons.