Shipbucket

I think the really big saving is to go with both old 15inch guns and turrets.

In real life that would never have been accepted as only new would be worth it for the 20+years service life against potentially newer foreign battleships (not to mention the prestige involved ).

But knowing time and cash is short (and that you only need it for about 6ish years) why not. The old 15 guns will work against everything but maybe Yamato and refitting the turrets is much cheaper (and takes less time and has fewer bottlenecks than building new ones). So with hindsight I think using 4 old 15inch turrets makes sense.

8 guns (2x4) will not fit on 35kt in a balanced 30Kn design but we know that the treaty's are dead so we don't need to stay under 35k.

I would also modify the design,

- To fit better AA, I have gone with more 4.5 (2x12) and more 40mm (8x6 although I might swap in more Bofors as well before we go to war !).
- Better underwater protection, especially the shafts and ruder (might fit 2)
- I would have a big transom (and maybe a bulbous bow) and forget the fuel costs.(the RN has plenty of bases so range isn't everything)

JSB

how old was those guns on Vanguard.

Well all of the 15 inch British service are the same basic gun designed in 1912 and fired at sea in 1915.
Not sure how old the actual guns used where (and the relined from a common pool so swapped them around) but they stopped making them pre WNT.

A total of 186 guns, including two prototypes, and 58 turrets were manufactured between 1912 and 1918

http://www.navweaps.com/Weapons/WNBR_15-42_mk1.htm

JSB

The 9 gun 15" proposals were for both 30 and 27 knots respectively.

15A as follows:

Armament as follows:

-9x 15" (3*3)
-20x 4.5" (10*2) in BD mounts
-Four aircraft and one catapult

30kts on 112,000SHP
-12.5" belt abreast magazines
-12.5" belt abreast machinery
-5.25" deck over magazines
-4.25" deck over machinery
-10" bulkheads
-12" barbettes (maximum)
-9",11",16" turret armouring
-1.5" torpedo bulkheads

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AU Projects: | Banbha et al. | New England: The Divided States
Blood and Fire

If you carry that 15A & B forward, then you would also delete the 5.25" from the inventory. That would give the Dido an armament of 10x4.5" which I figure could have been mounted in L/M twin turrets which with the 4.5" having an 80+ degree elevation would have been a decent mounting. (Would also be interesting as enclosed mounts for the Falkand Islands AU). One of the problems with the Didos was the amount of topweight. The 4.7 mounting was 58k lbs per mounting while the 5.25 mounting on the Didos was 95k lbs per mounting. The 4.5" fired 21k yards the 5.25 23.5k yards. So you are not losing a lot.

Krakatoa,
1) I would not use that turret,
I thing that's a 4.7 one with wide guns (it saved having a full turret, just have a stork in the centre that rotates, It was a nice idea but ended up much heavier than having a full rotating turret with closer guns. A good way not to save money long term that I would not be doing ! I would go for something like the post war 4.5 twin one and develop a single as well.)

2) Its not just the weight of the gun, The 5.25 has a 80 lbs. (36.3 kg) shell v the 4.5 with a 55 lbs. (25 kg) this is not a small difference if you are going to make it the main gun for surface action on a CL. (I don't think a 4.5 CL can hope to fight a CA with any tinclad belt).

The Didos where not supposed to be just AA but to do both AA and surface fire (not that the 5.25 really managed both better than a mix of 6'and 4' guns).

JSB

My fleet plan (open to change ) POD is 1 JAN 1930.(as I cant think of anything batter may change)

BBs
- 4/5 KVG/Vangard class
- rebuild Hood
- N&R
- R&R
- QE (less rebuilds)
- R(not used for parts)

CVs
- Courageous x 3
- Argus
- Hermes
- Eagle
- new CV class x 6+
- CVEs x lots

CA/CLs
- County x 13
- York x 2
- Emerald x 2 (ocean searching mainly)
- C (upto 28) + D (8) 2ndary duties and conversion to AA ships)
- Hawkins x 4 (hum ? rebuild as CVLs ? or not )
- Leander x 1

Then what 6 inch to build,
- Leander (or even smaller Arethusa class ships) or just build to the limits with Town (or maybe Crown Colony + extra AA fit).
- not going for Dido class.

DDs/etc.

- Super DD escorts (4.5')
- Cheap DDs (4')
- convoy escorts (4')

Subs/auxiliaries etc.

What do you think ?

JSB

JSB:
I would use it every time - and using your crystal balls - I would cure the major problem the turret had. Which was hydraulic training and elevation. Replace that with electric systems and the mount is better.
Have a read of Navweaps on the turret. Remembering that i'm replacing the 60 degree elevation 4.7" with the 80 degree 4.5".

http://www.navweaps.com/Weapons/WNBR_47-50_mk11.htm

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.

Last point with shell sizes - crew fatigue - shuffling round an 80lb shell wore out the crews and gun performance dropped quickly when compared with a gun crew loading 55lb shells. Both guns had manual loading.

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) I would stump up the cost of designing a brand new turret (that may as well look like the post war 4.5).
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).
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

Totally agree - the best turret for the 4.5" is the one trialled on HMS Savage in 1943, and used as the main turrets on the Battle class. Using your crystal ball to make that one available would be great. I only use the earlier turret because of its position in the timeline. It had the capability to be good but too many cooks spoilt the turret.

Splitting the fixed 4.5" ammunition is a no-brainer. I would never have the fixed ammunition unless all my crews were built like Schwarzeneger and Van Damme.

It is a wonder that the RN didn't learn from its earlier mistake with fixed ammunition for the 4.7"AA on the Nelson class which no one liked.

I'll see if I can find a Battle class turret and see what that looks like on a Dido.

Edit: Updated alternate Dido with Savage 4.5" twins.