What I was meaning to say (and I hope came across).
Was,
1) That I would use a turret ! (lots of advantages if a bit more expensive, I'm not sure that the RN has the industrial/financial resources to have the best it may have to make do with a just ok weapon in sufficient numbers, so a mix of 4.5' in turrets and 4' in mounts ?)
2) But that I would not use that turret type you have drawn (from Navweps)
Intended to save costs, an unusual feature of this mounting was that only the gunhouse rotated, the ammunition supply hoists did not rotate and were part of the fixed structure. This design necessitated that the ammunition and powder hoists needed to come up at the center of rotation, which explains why the guns are so widely separated in this mounting. Since the hoists did not rotate with the mounting, large angles of train caused difficulties with transferring ammunition to the guns and thus slowed down the ROF. "Destroyer Weapons of World War 2" notes that a true turret mounting including a rotating stalk would have almost certainly been rejected by the Exchequer for cost reasons. However, given the actual cost growth experienced during design and construction, one must wonder if the final cost of such a true turret mounting would have been much if any different from the final design. It almost certainly would have meant a smaller gunhouse and lower mounting weight. The widely separated gun barrels meant that the guns had to be individually sleeved and thus dual elevation mechanisms were needed.
I would stump up the cost of designing a brand new turret (that may as well look like the post war 4.5).
Remember when the 5.25" were in short supply, the RN was happy to arm HMS Scylla with 8x4.5" in open mountings. All of the 'C' class conversions were 4", the only 'D' class conversion was with the US single 5"/38, the new US Atlantas had the 5"/38. Size of gun for the CLA's does not seem to be a problem. One point often overlooked, the UK 4.5"/45 outperformed the US 5"/38.
3) The RN didn't have much of a choice it was 4.5 or nothing when they got to HMS Scylla and they where mocked as the toothless terrors (and used I think mostly to chase blockaded runners ie. AMC at best).
4) The US Atlantas are CLAAs but the RN Didos where (supposed to be) CLs (they where supposed to do both AA and surface action well)
5) Yes I like and will use the 4.5 but not for many CLs (apart from AA CLAs).
crew fatigue
6) Yes that's why I don't like the 5.25 and will not both with it in this AU (and I want to cut down on types of gun !).
(I will add that the early WW2 4.5 used a fixed round that weighted a total of 91.75 lbs. (41.6 kg) but I will used the split one in my AU !)
To compare handling weights (all from Navweps),
- 4"/40 (10.2 cm) QF Mark XIX = 50.06 lbs. (22.71 kg)
- 4"/45 (10.2 cm) QF HA Marks XVI, XVII, XVIII and XXI = SAP - 66.75 lbs. (30.28 kg)
- 4.7"/45 (12 cm) QF Mark IX, XII = 50 lbs. (22.68 kg)
- 4.7"/50 (12 cm) QF Mark XI = 62 lbs. (28.12 kg)
- 4.5"/45 (11.4 cm) QF Marks I, III and IV SAP - 91.75 lbs. (41.6 kg)
- 5.25"/50 (13.4 cm) QF Mark I = 80 lbs. (36.3 kg)
I will in this AU develop the separate 4.5 early !
- 4.5"/45 (11.4 cm) QF Mark V = 55 lbs. (25 kg)
Compare to the USN,
- 5"/38 (12.7 cm) Mark 12 = 55.18 lbs. (25.0 kg)
So In this AU I need to develop a working 4.5 MK V early on (don't see any problems the fixed 4.5 was designed in 1935 apart from finding a bit of cash from HMT).
JSB