Further, if weight is an issue (and hence potentially leading to consideration to instead procure the BAE 5-inch gun), it entails a different fire control radar than the NA-30S Mk2 as I am not aware of the NA-30S Mk2 ever having been used with a BAE 5-inch gun.
I have read that both Saab CEROS 200 and Mk 160 Gun Computing System (GCS) (where Mk160 is paired with the AN/SPQ-9B radar) are known to have been interfaced to the BAE 5-inch gun.
Following up on the speculative possibility that the Leonardo 127mm gun might be replaced with a much lighter BAE 5-inch gun (so to reduce the weight forward), I tried to dive into looking at what Fire Control radar might be chosen for the River Class destroyer as the Leonardo NA-30S may no longer be suitable for use with a BAE gun. As I noted, one possibility is the Saab CEROS 200 where I believe it has been used with a BAE gun in the following cases:
- New Zealand ANZAC class - Saab CEROS 200 with CMS-330 and a BAE-5-inch Mk-45 Mod 2 gun
- Canadian Halifax class - Saab CEROS 200 with CMS-330 and a Bofors (now BAE Systems AB) 57mm Mk-3 gun
- Thailand Naresuan-class - Saab CEROS 200 with Saab CMS-9LV Mk4 and a BAE 5-inch Mk-45 Mod2 gun.
- Australia ANZAC class - Saab CEROS 200 with Saab Systems CMS-9LV453 Mk3E (acting as AAW/Fire Control core) and a BAE 5-inch Mk-45 Mod 2 gun
- Sweden Visby - Saab CEROS 200 with a Saab 9LV CMS and a Bofors (now BAE Systems AB) 57mm Mk-3 gun
- Finland Hamina - Saab CEROS 200 with a Saab 9LV CMS and a Bofors (now BAE Systems AB) 40mm Mk4 gun
I may have that above information inexact - as it is difficult (when relying on unclassified sources) to be totally exact.
Now the Canadian River Class destroyer is not the only Type-26 class of warship that needs to be aware of
potential topside weight issues forward on the warship - where with placement of a VLS forward brings up such need to be careful with weight distribution.
I speculate, that to reduce weight, the UK and Australia, for their Type-26 class of frigates (possibly with the intent to contribute to reduction of topside issues) are going with the Sea Eagle FCEO (optical only and not the Sea Eagle FCR) and for use with the BAE-5-inch gun those warships are obtaining the 'radar' information from different radars, and feeding such through a CMS to the gun. Obviously radar information can be needed when weather conditions (rain/fog) cause electro-optical + laser to be inadequate.
In the UK case the Type-997 Artisan radar (UK) with the BAE Systems CMS-1 and with the Australian case the CEFAR2 to Aegis/9LV to BAE Gun there is likely a major non-recurring engineering (ie major expensive development) effort going on here to use radar from those systems for Fire Control for the BAE gun.
By adopting such an approach (of not having a dedicated Fire Control Radar), the UK and Australia are planning to remove most the topside weight of a Fire Control radar, but they are, IMHO, in turn possibly having major non-recurring engineering (ie additional) costs with the potential serious technical issues of information latency to address (associated with track quality and update rates) to solve in the timely transfer of radar based Fire Control data to the gun.
It will be interesting to monitor and see how this develops.
So Saab CEROS-200 is likely lighter, but , ... one speculation I have (where speculation is the operative word) is using a Saab CEROS 200 may forfeit the ability to use the BAE 5-inch gun's HVP (hypervelocity projectile) potential functionality for high-end missile defense - but the Mk160 GCS + AN/SQP-9B may provide such capability.
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In regards to the USN HVP (hypervelocity projectile), as far as i can determine, an export licence has not been granted to ANY country. Hence this is likely not thus a consideration factor.
