It turns out that a huge amount of the ASWE thinking around SIGS (guidance, surveillance, illumination etc.) survives. It seems that the need to fit the system in a 3,000 ton ship was the primary driver and that the required space, weight and power characteristics from the surveillance radar to achieve this came from DGS, as such the basic requirements were:
Maximum aerial weight of 3 tons
Diameter of swept volume of 12 ft
Aerial to be mounted 70 ft above the waterline
Power consumption, from the ships mains system and including data-handling, of under 80 kw.
ASWE proposed a single rotating aerial that featured a small electronic scan in azimuth as well as electronic scanning in the vertical plane, it would have operated in C-band. The aerial was was 8 ft 6" wide and 8 ft 6" high and consisted of a stack of linear arrays fed by phase shifters, it would have rotated at 40rpm. There would have been 3 transmitters at 2.5 mw peak power each. There was technology, though not components and it is a different configuration, from the NSR for NIGS in this concept. The staff requirement called for a 50% probability of 'painting' a 1 sq.m. target at 200nm. ASWE thought they could get close to this (180nm) with their basic proposal but to reliably meet it they would either have to successfully develop a maser receiver or step up the aerial size and radiated power with a corresponding impact on ship size.
The Dutch radar offered marginally superior performance but at twice the space and weight allowance, at the time it's aerial was to be 16ft 6". ASWE considered their own S-band radar scaled to the size, weight and power of the Dutch set and thought it would result in superior performance to the latter but there was no way that either would fit on a 3,000 ton ship (it would have had a 12 ton aerial weight). The selection of the Type 988 over the smaller ASWE proposal was probably one of the first big drivers in the size growth of the Type 82.
As a result of the above I have had a rethink of
these drawings. In the report they are from they are used to illustrate arrangements for missile handling systems for a combined stand-off ASW and CF.299 fit in a 3,000 ton ship, I had assumed the depicted ship to be generic but had always wondered about the surveillance radar and the presence of illuminators. At first glance its dimensions and location appear to match those outlined above, being mounted as high as possible and about 12 ft wide. Additionally, as Ikara equipped ships would not have MATCH, CF.299 was conceived as a 4.5" Mk.6/MRS.3 replacement and these ships were originally seen as direct follow-ons to the Leander class the lack of a main gun may be an intended armament fit rather than the product of a simplified drawing. Therefore, those drawings, especially the ones with the Ikara and CF.299 specific launchers, may be much closer to what the RN then (1961/62) had in mind than I had previously understood, e.g. they are a planned 3,000 ton hull/propulsion combination with outline SIGS and Ikara systems meeting the size, weight and power requirements as they existed at the time.
With regard to the growth in the size of the T82, I don't believe for a second that a 40 Sea Dart, 20 Ikara armament fit with the above mentioned surveillance radar could have been achieved on 3,000 tons. The Type 42 proves that, 3,500 tons for a
planned 26 missile Sea Dart outfit and MATCH with Lynx, and it was still too small. But there are clear drivers in the T82's size, the Type 988 seems the most significant (when CVA01 was cancelled it had a 9 ton aerial weight with an additional 3 tons for the radome), the added weight and complexity associated with the RN Ikara launcher another, once the switch was made to a propulsion plant based on that of the County class all bets were off. With the ASWE C-band surveillance radar proposal, 40 Sea Darts with two illuminators and a 20 x Ikara outfit (especially with an installation closer to the Australian one) without a main gun seems viable on 4-5,000 tons.
