Does anyone know if the ANZAC frigates can still accommodate a second 8 cell VLS ?
The answer is a bit of maybe yes and no...
The RAN found that there was not enough of a top weight margin in the
ANZAC-class FFH once the Harpoon AShM and mini-Typhoon mountings were fitted, and the existing Mk-41 VLS loaded with quad-packed ESSM, for a 2nd Mk-41 VLS to be included (or at least be included and loaded with anything...)
The RNZN situation is slightly different, because no Harpoons or Typhoons are fitted, but a Mk 15 Mod 1b Phalanx is. Another major difference is that the RNZN is replacing the RIM-7 Sea Sparrows with Sea Ceptor, which is a smaller, lighter missile which has an active radar seeker, vs. the semi-active radar seeker of the Sea Sparrow/ESSM missile family. This means that the RNZN frigates will not need to have an illuminator which can further reduce the topweight. Something else significant is that each quad-packed ESSM cannister weighs ~ the same as 11 Sea Ceptor missiles. The real issue though is that a 2nd VLS weighs ~12,000 kg (assuming the self-defence length)
Based off the weight of a VLS, it would seem that the RNZN also could not afford to add a 2nd Mk-41 VLS, at least not without removing the Mk-15 Phalanx.
Now the RNZN could opt to remove the Mk-41 VLS and add in the Sea Ceptor launcher which I believe is smaller/lighter, but I am uncertain what the exact impact would be in terms of weight reduction, as well as max missile loadout.
-Cheers