The USAF needs to study “future-based” tanker options. MCRS-16 only looked at current air tanking inventories based on current scenarios. Notwithstanding the gap in 2 out of 3 scenarios with current inventories (474+79), its not that big a gap. It does not factor potential allied support, the 179 KC-46 which has bigger fuel loads than KC-135, potential UAV tanker, V-22 tanking capabilities or, I’m guessing, even the future increased combat radius of the F-35.
A significant chunk of tanking is taken up by B-52s. Once B-21 kicks in, B1/2 retired and only 76 re-engined B-52Hs, heavy bomber won’t need as much tanking, most of it in safe locations way out of reach of potential aggressors.
At the tactical level, the F-35A will have 800+nm combat radius once F-135 option 3 kicks in. That’s not even taking into account external fuel tanks. Rather than a gas station concept, it would be interesting to see how the MQ-25 tanker works out for the navy.
The last was that the AMC was looking at KC-Y comp for buy of 15 a year from 2024-36 and KC-Z at 9 a year from 2036-48, where the flying wing is being considered (108 units).
The B-21 airframe has some advantages, compared to the MQ-25. It will be significantly larger and can carry a lot more fuel. B-2 carried 167,000 lbs of fuel, not including payload, which is way much closer to a KC-46 than the MQ-25 is. However, the difference between using a bomber airframe vs a dedicated airframe is a lot of wasted/unnecessary space. Hence a redesign would be needed which would probably be as costly as a new design.
Thought the models in recent article below does seem to address the issue a bit more.
http://www.thedrive.com/the-war-zone/21 ... conference