As for comments about useless fuel tanks in the hold on the K1 and KC!, there are a lot of fast jet folks out there who during all the conflicts we have been involved in over the last 20 years who have been very pleased that we had the capacity!! The useless fuel tanks funny old thing did the job they were designed for, provided lots of fuel in the air!!!
Have they upped the MTOW and Max Airborne weight for the old girl then?
The K1 and KC1 had an MTOW of 245 Tonnes and an empty weight of approx 117 Tonnes when I flew them. The max I ever uplifted on a tanking sortie was 128 tonnes of gas to take off at MTOW we had plenty of unusable tank space onboard. They had tank space for 144 Tonnes of gas onboard, so unless things have changed significantly or the laws of Physics have changed there most definitely IS useless tank space on the RAF TriStar tankers.
The RAF would be better served with the rear hold returned to a traditional hold, particularly on the K1. This would provide them with a far more flexible asset. Comments about giving away gas you cannot carry are a little pointless. In general ops the TriStar hardly ever gets airborne at max weight with no freight of any kind using the tank space it can for fuel.
The gold plated solution would be modular system allowing the extra tanks to be fitted in the holds when a pure tanking mission was required and allowing it to be used as hold space the rest of the time. I doubt the AAR lobby would allow that, but if that cannot be done at least get the tanks out of the rear hold