Iberian PDN Upgrade Project

[Guinness]

I don't think the barbettes are necessary for twin 150mms. As far as deskspace, my answer is "probably just enough space". The flush deck will help here. You'll probably only have ~35% of waterline length to fit them, which is somewhere around 43 meters. You'll need 5 or 5.5 meters working circle per mount minimuim, with a total rotational circle of something just a little bit bigger than 5.5 meters. I'm not sure how long your guns are. So if you mounted them all in line (worse case) and wanted each to be able to traverse the full 180 degrees, I'd say you are looking at something around 22 - 25 meters per side to fit them, which ought to have them out of the blast of the main battery. Cramming the 40mm, smaller mgs, and boats in will be a challenge though.

I think these ships have a enough freeboard though that you could still get away with mounting 4 or six guns per side in hull casemates, and then mount maybe 3 deck mounts on deck, to relieve main deck congestion a bit.

[miketr]

A rough sketch of the ship I am not really happy with the 280mm turret size; they are L40's.  The 150mm are L55's or perhaps L60's I will see what I end up researching.  I think that the 150mm turrets compared to the 280's look oversized.  So I am trying to think of what changes to make to get things to look better.

[The Rock Doctor]

Setting aside the propulsion issue - the hulls are old but reasonably well armored, so I'm not sure whether it's worth the effort or not.

Have you contemplated modifying the Alfonsos to have six twin 250mm in a hexagonal pattern, rather than keeping the 280mm and a 150mm secondary?

[miketr]

Yes the problem is it gets me two slow 250mm armored cruisers from four PDN's.  I could do something like trying to fit a triple 250mm in place of the twin 280mm.  I would rather keep the 280mm guns but I will think it over.

Michael 

[The Rock Doctor]

It gets you two slow armored cruisers plus whatever you do with the Pelayos.  I think the uniform battery of 8x250mm will deter a raider somewhat more than 4x280mm, myself.

As for the Pelayos, the 280mm + 150mm route may be the way to go - the casemated 250mm won't be of a lot of value.

[Guinness]

How long are those 250mm guns? A modern 9.2" armed ship might be able to use superior speed operate outside their effective range and pummel ships armed that way...

[The Rock Doctor]

Well, yeah, perhaps.  But the ship could still accomodate a newer set of 250mm/45 or 50 cal twins.

Hey, here's an alternative - design a single 280mm and replace the 250mm twins in the Alfonso.  That'll give you 2x2 and 2x1 on the broadside.

[miketr]

If I replace the main guns and engines and add armor, then we have ask why I am not building a new ship?  The objective here is to attempt to get a useful escort with a cost of 3 to 5 BP per ship.

As to what the guns are.  Looking at the gunnery chart the I had assumed 280mm L40's (1895 tech level) which would put the 250mm secondaries as L45's.

Looking at navweapons.

http://navweaps.com/Weapons/WNGER_11-40_skc04.htm

It looks like the 280mm could shoot at from 20,000 yards to 28,000 yards depending on date, both assume 30 degree elevation of the weapon.  Looking around I have scene all sorts of ranges for 24cm/25cm weapons with a low end of 13,000 yards for a RN weapon @13.5 degrees but same weapon in japanese service with 30 degee elevation shot out to 27,000 yards.  Lots of German weapons able to shoot out to about 20,000 yards.  So its I think a question of powder charge and elevation with a L45 but shooting out to 30,000 yards with a L50 or L55 isn't going to get to many hits.

Michael

[miketr]

Looking things over I can fit a triple 250mm in place of the twin 280mm.  The question is what would the cost be?  Doing two end turret to match the wing turrets in armor would weigh 243 tons.  I ignore the weapon cost as I am reusing the 250 casement mounts form the other ships.  So I would pay 0.243 BP and $0.486 for the weapon reuse?

Resulting in this design, which has about the same broadside as the old design.

Alfonso IV (refit 2), Iberia Battleship laid down 1899 (Engine 1922)

Displacement:
   12,938 t light; 13,661 t standard; 14,386 t normal; 14,966 t full load

Dimensions: Length overall / water x beam x draught
   403.87 ft / 403.54 ft x 91.86 ft x 22.64 ft (normal load)
   123.10 m / 123.00 m x 28.00 m  x 6.90 m

Armament:
      6 - 9.84" / 250 mm guns (2x3 guns), 476.75lbs / 216.25kg shells, 1899 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
      8 - 9.84" / 250 mm guns (4x2 guns), 476.75lbs / 216.25kg shells, 1899 Model
     Breech loading guns in turrets (on barbettes)
     on side, all amidships
      16 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1899 Model
     Breech loading guns in casemate mounts
     on side, evenly spread
     16 guns in hull casemates - Limited use in all but light seas
      4 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1899 Model
     Breech loading guns in deck mounts
     on side, evenly spread, all raised mounts
      4 - 1.57" / 40.0 mm guns in single mounts, 1.95lbs / 0.88kg shells, 1899 Model
     Quick firing guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 7,299 lbs / 3,311 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   11.0" / 280 mm   264.80 ft / 80.71 m   11.52 ft / 3.51 m
   Ends:   5.91" / 150 mm   138.71 ft / 42.28 m   11.52 ft / 3.51 m
   Upper:   4.72" / 120 mm   264.80 ft / 80.71 m   8.01 ft / 2.44 m
     Main Belt covers 101 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   9.84" / 250 mm   4.72" / 120 mm      9.06" / 230 mm
   2nd:   9.84" / 250 mm   4.72" / 120 mm      9.06" / 230 mm
   3rd:   3.94" / 100 mm         -               -
   4th:   0.98" / 25 mm         -               -

   - Armour deck: 2.95" / 75 mm, Conning tower: 10.24" / 260 mm

Machinery:
   Diesel Internal combustion motors,
   Geared drive, 2 shafts, 22,002 shp / 16,413 Kw = 20.00 kts
   Range 10,000nm at 10.00 kts
   Bunker at max displacement = 1,305 tons

Complement:
   656 - 853

Cost:
   £1.324 million / $5.295 million

Distribution of weights at normal displacement:
   Armament: 912 tons, 6.3 %
   Armour: 5,613 tons, 39.0 %
      - Belts: 2,337 tons, 16.2 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1,665 tons, 11.6 %
      - Armour Deck: 1,481 tons, 10.3 %
      - Conning Tower: 130 tons, 0.9 %
   Machinery: 746 tons, 5.2 %
   Hull, fittings & equipment: 5,375 tons, 37.4 %
   Fuel, ammunition & stores: 1,448 tons, 10.1 %
   Miscellaneous weights: 291 tons, 2.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     21,231 lbs / 9,630 Kg = 44.5 x 9.8 " / 250 mm shells or 3.4 torpedoes
   Stability (Unstable if below 1.00): 1.19
   Metacentric height 6.1 ft / 1.9 m
   Roll period: 15.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 51 %
         - Recoil effect (Restricted arc if above 1.00): 0.30
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.600
   Length to Beam Ratio: 4.39 : 1
   'Natural speed' for length: 20.09 kts
   Power going to wave formation at top speed: 55 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 1.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      18.70 ft / 5.70 m
      - Forecastle (20 %):   16.40 ft / 5.00 m
      - Mid (50 %):      15.58 ft / 4.75 m
      - Quarterdeck (15 %):   13.94 ft / 4.25 m
      - Stern:      13.94 ft / 4.25 m
      - Average freeboard:   15.52 ft / 4.73 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 67.2 %
      - Above water (accommodation/working, high = better): 120.7 %
   Waterplane Area: 27,113 Square feet or 2,519 Square metres
   Displacement factor (Displacement / loading): 98 %
   Structure weight / hull surface area: 156 lbs/sq ft or 759 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.91
      - Longitudinal: 2.18
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent

Long Range Radio 25 tons,
Fire Control 250 tons
16 tons construction reserve.

[miketr]

Any thoughts on the drawing?  This assumes 280mm in the main turrets and 150mm in the wing turrets.

[miketr]

Oh I want to work on a version of the the drawing with the 250mm weapons.  Any idea what size I should make the barbettes?  I had the 280mm's as a 25' barbette and the 150mm's as 18' (I could have made these smaller I suspect maybe 16').  I looked over the Knowledge Base and didn't see any info on turret sizes for a 10" weapon.

Michael 

[Guinness]

I think the 150mm turrets are too long. Something like 35' barrel to back end of turret should be enough. Sitting on barbettes they can be shorter too.

As far as barbettes: 17.5 feet internal diameter is perfectly reasonable for twin 150mm. So armored outside diam. or 18 feet is gine. For 250mm: Looking at an internal arrangement drawing of the Tennessee class ACs in Friedman, it seems that the barbettes for their 10" guns were 23 feet in diameter. This seems a reasonable starting point for your 250mm guns. Maybe 22 or 22.5 feet inside rolling diameter?

For your 280mm, 25 feet seems about right.

[miketr]

OK current drawings.

First is the PDN Pre-reuild (280mm 2x2 and 250mm 4x2) and the second a rebuild is with a 280mm and 150mm battery.

I think the best rebuild would be to turn the Alfonso IV class into a semi DN with 280mm 2x2 and 4x1.  I could steal the 280's from the Pelayo's and build new turrets.  The problem with that choice is I then have no useable battery on the Pelayo's.

Second is to rebuild the Alfonso into a AC by taking the 250mm casement guns from Pelayo then build new triple turrets and drop them in place of the 280's.  Resulting in a battery of 250mm 2x3 and 4x2.  Then rebuild Pelayo into the mixed 280 and 150 bettery above.  Putting the extra 11.1" guns into a coast defense battery some place.

Or I could rebuild all four ships to the 250mm / 150mm design and put the 250's into coast defense battery. 

Thoughts?

[The Rock Doctor]

Mulling this over...

Take Pelayo's 280s and use them to give Alfonso 8x280.

You're taking out Alfonso's 250 twins to do this - why not swap two turrets into each Pelayo for 10x250mm? 

You've then got four extra turrets for coastal defences, monitors, or something.

[miketr]

Alfonso's have 4x2 for eight 250mm's, with a total sixteen 250's.
Pelayo's have 6x1 for six 250mm's, with a total of twelve 250's.

So are you suggesting converting the 280mm turret locations on the Pelayo's into a triple 250's with a twin super firing over them or as wing mounts?  Let me fool around with the drawing.