Ok, so, as a sales rep of the Bath Iron Works division of General Dynamics, is that I think we need to be looking at two different ship classes here.
On the one hand, there's a non-CVBG mostly-ASW frigate, so it doesn't need to be looking at 33+ knots, but does need
- About 5000ish tons displacement
- Something like 3000kW of diesels and about 60,000 shp of turbines for ~28kts and 9000nm range
- 2x helo of some LAMPS / navalised Blackhawk flavour.
- 8-module Mk 57 (32 cells) VLS - ESSM, ASROC, probably a few SSM - either Harpoon or that Norwegian NSM would be fine.
- 76mm Oto Melara or a 5" if it will fit.
- Maybe a Phalanx - is Phalanx capable against BrahMos etc? Not sure it's still a valid defence against current-generation missiles.
- 2xBushmaster 25mm to keep Boghammars honest
- a towed-array sonar
- The usual festoonery of radars, ESM, ECM, radar decoys, sonar decoys, Prairie/Masker, etc.
- Yes, a low RCS is nice, but as important is the ability to run quiet
Call it a
Knox II rather than a
Perry II, but it's not a million miles off a US-flavored reimagining of a Type 23. It's a non-littoral escort, because there are places that the USN wants to be (and here I mean "the Pacific") that it doesn't necessarily want to put a carrier group.
And on the other hand, there's an actual littoral combat ship, which only needs 1 helo, and does without the towed array, and is smaller - ANZAC sized, would be my guess. For playing in the Persian Gulf or the Straits of Malacca. For that RCS is more important than noise, what with the generally-degraded performance of sonar in cluttered shallow waters.
USN doctrine should include area AAW cover from a
Burke for both of these, and probably shove a
Knox II in with a division of LCSs for the odd thermocline in the deeper bits of the Gulf or off the Korean peninsula while the LCSs do the main business of sea control. And rely on Air Navy to make sure that no bad guys' planes manage to spoil the day of these folks, because with the best will in the world they are barely capable of self-defence against a moderate air attack.