This cruiser proposal dates back to 1943/44 to an imperial defence plan for Australia:“MP1049/5 2026/3/516 Cruiser and Destroyer Building Program”.The file begins in mid 1943, discussing the advisability of building cruisers and destroyers in Australia to replace war losses and the ageing remaining ships, and the file ends with the dispatch of the RA Eng and Director ordinance from the Naval Boards Melbourne office being ordered to London from June-Aug 1944 to consider current vessels under construction in Britain.Prior to this mission, the ACNB set out what it thought were the war lessons.A - Air Power – neither side seeks surface action in daylight without air support, so there are more night actions than day, and all ships require maximum AA fire power and ability to stand up to bomb and aerial torpedo damage.B - The destructive power of the modern torpedo.C - The ever increasing efficiency of radar.D - The devastating effect of high volume of fire at night ranges from medium calibre guns. and then the desirable features of an RAN future cruiser given the war lessons.
A - Main armament dual purpose guns. The 5.25in gun appears to be the most satisfactory calibre for HA/LA (with “at present” added in pencil)B - Secondary armament guns more numerous than in present design 40mm guns are required in addition to 20mm.C - Side armour and deck armour.D - Improved under water protection. Large compartments should be partitioned by water tight bulkheads,E - Maximum speed 30-32 knots. Higher speeds are not considered necessary.F - Large endurance.The paper then considers a number of British designs, improved Southampton, Fiji, Dido.It selects the Dido as the most suitable based on its HA/LA armament, but with these weaknesses.A - Endurance much too small. (stated at 7500miles econ, 1,700 miles full speed)B - Too vulnerable to under water attack.C - Insufficient HA firepower abaft the beam.D - Insufficient medium and short range AA armament.E - Inability to engage more than two AA targets in primary control with main armament. They then outline a cruiser the authors think would be perfect for the RAN post war.Speed – 30 knotsEndurance – 10-12,000 miles at economical speed.Gun armament – 12-15 5.25 HA/LA, 12 or more 40mm bofors, 12 or more 20mm.Protection – Side and deck armour, improved watertight subdivision.Displacement – 8-9000 tonsLength 550-570ft Beam 60-65ft No aircraft. The author proposes no torpedoes, but the paper is edited by someone who finds them essential, and points out that doctrine is to “fix by gunfire, and sink by torpedo”.They propose the main slipway at Cockatoo Island built up from its present 450ft to 600ft. All designs, plans, skilled technical personnel etc to be sourced from GB.Imports would include: 80% of all steel (the right grades were not made in Australia – this was cited by the minister in the 1930’s as a reason not to order an Australian Leander).All armour plate. All armament, All fire control. 80% of auxiliary machinery. Forgings for main turbines. 60% of electrical cable. 80% of electrical equipment. Anchor cables. To be laid down in 1944 for completion in 1948, and to be followed by another 5 similar ships from 1944-1953, replacing entirely the wartime losses and pre war ships.
The design the following characteristics:
Dimensions: 167,64 (wl) 173,74 (oa) x 19,8m
Displacement: 9.000tons (standard)
Armour: 51mm Deck, 89mm Belt
Engines: 4 shafts, Parson Steam Turbines, Unknown shp probably around 80.000shp
Speed: 56km/h (30knots)
Range: not sure but probably 22.000km (12.000nm)
4x3 5,25"/50 (133mm) Mark IV Guns
6x2 40mm/56 Bofors Mk X AA Guns or 5-6x4 40mm/39 Pom-Pom Mark VIII AA guns,
8x2 20mm/70 Oerlikon AA Guns
2x4 533mm Torpedo Tubes
I've based my drawing on the Crown Colony class light cruiser and the N2 design light cruiser.i.imgur.com/5C7wGMk.jpg