I wouldn't see such a ship being a direct replacement for a LSD, or logistic support for army units ashore. More providing the logistics and equipment/vehicles for the embarked marines/shore landed sailors, enabling independent operations.
In most small interventions we would have access to port facillities (I think we had such for Sierra Leone, Lebanon, Bosnia?). Where we didn't have such access we could use the 4 dock capabible ships (LPD/LSD). Additionally the ships would have their two Merlins for logistics (assume no port facilities in Haiti?). I think adding 1000-1500 to a T45 design would enhance not compromise the design, enabling radars to be mounted higher.
The flexibility of a enhanced T45/Absalon combination would enable it to also act as a ASW/commerce command ship (high threat anti sub or even anti pirate patrols) , AWD or independent intevention. Unlike a Bay these ships don't require escorts and carry their own helicopters (athought I think the Bays can mock up a hanger?)
I think any logistic capability lost by selling a couple of Bays could be replace with more Points built at H & W,
Actually as I was thinking about this, as a principle if we say helicopter/long range radars are better suited to big hulls than small, prehaps there are more hybrid opportunites. Could a future LPD not be fitted for (if probably not fitted with due to cost!) a full Sampson/Area Missile fit, at c20-25,000t it must be able to mount a Radar far higher than even a T45, and it would remove the burden on the escorts (preventing a Galahad/Tristram)
Add 1000-1500 tonnes to a Type 45 design and it isnt a Type 45 design, its a new design with a completely different underwater shape to accomodate this logistics deck at the rear. Hence different speed, stability, and fuel economy. So be ready to commence a whole new ship design process.You could add a hull plug to a 45, similar to the 42 stretch, but this wouldnt allow any additional height to radar, it might allow a few more VLS cells, but I assume they have learnt from the lessons of Batch 1 Type 42 and gave the Type 45 good seakeeping charcteristics from the beginning.
As I understand it, the machinery fit of GT's on the Type 45 doesnt make it a particulrly good ASW ship, its not the role its designed for afterall, so the Type 26 is ASW ft will need the silent sub stalking ability of the Type 23, its a specialised task to isolate machinary noise, and to make a stealthy hull, I have read that from numerous people within the industry on these boards. A fat arsed flex deck slamming up and down in the waves would add noise.
I would like to see the Ebay add for the two Bays that you will flog, what reserve price will you place on them? You will lose capability and gain very little back, I doubt the fee for the pair of used LSD's would pay for third a Type 45 so what would be the point??
So fit 20-25000 tonne LPD for but not with PAAMS? What would be the point, do you actually think it would get fitted. On one hand you would flog off two extremetly versatile 18,000 tonne LSD, then replace them with something bigger? What happened to the build 12 Absalon type hybrids? If you are going to purchase more PAAMS/SAMPSON then surely add a couple of escorts that could guard CV or Amphibs?
The Type 45 is a complete system, a very stealthy hull with a small RCS with powerful sensors, the low RCS gives it an enhanced ability to survive, easier to soft kill a misile of you are a small target. The Sampson should have a Low Prob of Intercept in search mode, I imagine it will be quite hard to locate and attack a Type 45 in air defence mode, especially as it will be taking feeds from other ships and AEW assets. A big slab sided 25,000 tonne LPD flooded down seems a completely unsuitable and unstealthy ship in which to mount a £600m air defence system, unless you happen to be the USN, and even they dont seem to be doing something so costly?
I think Type 26 will look pretty traditional ship , weapons plus Camm that we currently use.
I dont think the RN should or will go to hybrids between civil designs, if it does, it may never get "proper warships" again, I think you are playing lego, plugging bits on, mixing and matching bits of ships to create a franken-fleet, I would suggest the RN knows what it is doing after several hard lessons, it will get warships, that look like and are warships, not something cobbled in foreign yards with the cheapest costs designed to appeal to Liberal politicians who like the disaster relief sections of the brochures rather than the section that refers to its ability to kill people.