RJ Ops
Key to RJ operations is maximum time on orbit. Cold War ops was 450kts TAS cruise to the operations area, orbit at around 360kts TAS, based on weight, and return. This was with the old TF33s. The F108s provide a bigger capability to take-off with higher weights and burn less fuel in both cruise and orbit.
Our un-refueled missions were built around eight to nine hours with the TF33, flying with start takeoff weights around 285-288,000 lbs on longer runways (Kadena, not Mildenhall). In-flight gross weight was 299,000, which did not fill all the tanks. I believe the F108s will give you about three-four hours above that.
The longer you need to drive to the ops area the more you need an a/r top-off prior to arrival there. Remember, the reason for the mission is max time on the collection orbit.
With both the Sentry and Airseeker with receptacles maybe it is time for the UK to look at leasing dual-capable tankers. Of course, the RAF can always book production slots now for wholly-owned KC-46s.