Also, what was the point of the tanks if the ac perf was so restricted?
The RE tanks were only available when the MR1 was in Service. The MR1 ZFW was a lot less than the MR2, which meant that the jet had the capability to carry more weight in the fuselage. The designers believed this to be a valuable option so they came up with the RE tanks. As far as I know, they were never used because it was simpler to flag somewhere en route and, besides, once the tanks were fitted the bomb doors could not be opened in flight. Therefore, you would get to your destination and before you could go out and play at ASW you had to remove wet and noxious tanks from the bomb bay. Sadly, the aircraft manufacturer does not always have the full picture of how we operate.
The MR2 basic weight is much greater, so with full normal tanks we cannot carry extra RE fuel due to the max AUW, anyway. So, with that factor in mind, the tanks were scrapped.
We are now left with a cavernous bay that is not in anyway sealable to create a leak proof void to contain a fire that we could smother with inerting gas, foam or powder. As I mentioned before, the bomb bay heating system pumps hundreds of litres of warm air into the bay every minute, supplemented by 2 ram air valves (tumble drier hose size) at 350 kts TAS. The incoming air mix is not exhausted in any special way; it simply flows out around the edges of the doors and the bay does not pressurize. Therefore, if an extinguishant is to be effective (and sustained for approx 30 secs) it has to be supplied directly to the root of the fire (which will require a very smart detection and distribution system) or it has be enormous and space hungry in an already bulked out fuselage. If a system can be found to do this: great, I'm in, but I'm not convinced.