The Flight III sports the AMDR which is essentially AN/SPY-1 +15dB so a tremendous gain in terms of quality and area coverage when compared to the current AEGIS without significant increase in radar size. This effectively means half the warhead RCS being detected at twice the distance of the current AEGIS ships. This is obviously fueled by better digital processors (plus element level digitizations) and much higher power, higher efficiency GaN T/R modules compared to the decades old SPY-1.
But beyond, as they move to the larger cells that enable larger diameter, longer ranged missiles they would need even larger radars. With some low risk VLS modifications and Navy's changes in regulations allowing for SM3 Block IIB these sensors would very much come into play. Same with the larger 30 foot radars. We are then reaching into ICBM defense territory or carrying larger diameter, heavier KKVs and MOKVs. This is where the BMD mission begins to demand a larger platform hence this concept.
But the DDG 51 has to do a lot more than BMD and the Navy would be happy with a larger vessel since they have a global strike mission on top of other missions.
Singha wrote:I am not so hot on the railgun and laser potential for BMD...not for a large area bubble .. seems more suited to point defence ? a railgun shell is just a hypersonic unguided KE weapon?
The Hypervelocity Projectile and DEW are for organic defense against all types of incoming targets. You can use them for extending reach of your close in systems, anti-cruise missile defense mission, and even taking on incoming warheads in lower atmosphere when they are slower. These technologies are still a good decade away but the idea is to share the burden of these missions with the VLS allowing the VLS to gain flexibility and focus on area defense. Given that ESSM Block II is entering the SRBM defense mission you are taking out a cell that is available for area defense every time you put an ESSM in there so the idea is for these technologies to share this burden so that you trade off some ESSM's for SM6 and 3s.
It's not much of a concern for this particular vessel proposal however since the Navy won't need that many VLSs so there will be plenty of room for future growth. 280+ MK41 are a $hit load of cells.