WesWorld

Italian Anti-Aircraft Weapons of the 1930s and 40s

One of the main drivers of warship design during the 1930s was the increasing need to provide effective air defence. The ever increasing performance of aircraft was complemented by examples of their effectiveness; the SAE's attack on Rio de Janeiro becoming a oft-studied example from the period. Whilst the performance of aircraft increased, the need to defend against them increased also, which presented a wide range of problems for the warship constructors of the period that is still felt today. The increased mass of anti-aircraft weapons and sensors was accompanied by a need to mount them in places with good arcs of fire - leading to their installation high up in the ship. It was this effect on stability which lead to spiralling ship size.

The major navies of the 1930s and 40s all developed specific anti-aircraft weaponry. For most navies, light AA weapons settled onto autocannon of around 20mm and 40mm calibre. In Italy, Breda developed the 37/54 which was built in a variety of mountings, the most common being the quadruple mounting. Accomodating a weatherproof and stabilised mounting of this size and mass presented significant design challenges given that at 18t it weighed considered more than the 100/47 duple AA mounting common throughout the 1920s.

A similar increase in size and mass was common with the new dual-purpose large calibre weapons that emerged during the 1930s. The majority of countries settled on somewhere between 120-130mm as providing the necessary balance between striking power and rate of fire. Noticeably apart from this grouping where Italy and Canada with 152mm and 140mm weapons respectively. Italy's dual-purpose weapon grew out of the 152/53 cruiser weapon which in the late 1920s had been modified to achieve a rate of fire of 8rpm, which compared favourably with smaller weapons of that period. With the first mountings being on cruisers, high angle elevation and increased training rates were accomodated, but only at the expense of a considerable growth in mass. The mass of the weapon lead to it not being used on smaller vessels. Experience through the 1930s lead to it being regarded as a good weapon, but the hoped for performance against aircraft targets was not achieved. This lead to a new design of dual-purpose weapon.

Throughout the 1930s, OTO had been developing a new medium anti-aircraft weapon, with particular study in the programme being placed on increasing the rate of fire by automatic loading. The first weapons were the 65/64 prototype guns which had mixed results on trials. The next guns had the calibre increased and manual loading version of the resulting 76/62 went to sea in 1938. Whilst work was ongoing on the automatic firing version, the deficiencies of the 152/53 for anti-aircraft fire were becoming apparent. The need for a new medium-calibre dual-purpose gun was apparent. This lead to the 127/64 weapon. The 127mm calibre had emerged as the most popular choice elsewhere in the world and was found to give a good compromise of shell size and mass. The 127/64 adopted by Italy was noted for the long barrel length and high velocity, which increased it's effectiveness in the anti-aircraft role, following firing trials with the 152/53 and 76/62 weapons. The resulting weapon went to sea in 1943 on the Serie III "Town" class destroyers.

Serie III Town Class Destroyer

The more outward-looking Italian Navy of the 1930s had started the design of a new ship that was a blend of light cruiser and destroyer that eventually emerged as the so-called Town class vessels. The first four vessels were built in 1938 and followed by another four in 1939. These ships were large, powerful and seaworthy vessel, well suited to extended operations.

These initial vessels were followed by another quartet, the Serie II which were similar in capabilities but with revised superstructure and above decks arrangement.

The next vessels to be built were the Serie III which were more specialised Air Defence vessels. These traded in the anti-surface capabilities inherent of the 152/53 and mounted the new 127/64 in four twin mounts, distinctive from the sighting hoods on the left hand side of the mountings. Alongside the new medium-calibre mountings were increased light anti-aircraft guns and new fire control directors.

The experience gained with the previous ships lead to another revision of the upperdeck arrangement in order to improve seakeeping and firing arcs for the anti-aircraft weapons. The underwater hullform and machinery arrangement was kept the same as the previous vessels. The increase in topweight caused by the addition of new sensors and additional light anti-aircraft weapons resulted in the removal of the torpedo armament - a loss that was not particularly felt. The resulting two ships were well-regarded in service, the much larger superstructure resulting in much larger accomodation spaces than usual in the Navy at that time.


Serie III Town Class Destroyer, laid down 1942 (Engine 1938)

Displacement:
4,134 t light; 4,496 t standard; 5,210 t normal; 5,782 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(512.64 ft / 492.13 ft) x 49.21 ft x (16.73 / 17.98 ft)
(156.25 m / 150.00 m) x 15.00 m x (5.10 / 5.48 m)

Armament:
8 - 5.00" / 127 mm 64.0 cal guns - 67.24lbs / 30.50kg shells, 500 per gun
Dual purpose guns in deck and hoist mounts, 1938 Model
4 x Twin mounts on centreline ends, evenly spread
2 raised mounts - superfiring
24 - 1.46" / 37.0 mm 54.0 cal guns - 1.66lbs / 0.75kg shells, 4,000 per gun
Anti-air guns in deck mounts, 1938 Model
5 x Quad mounts on sides, evenly spread
4 raised mounts
1 x Quad mount on centreline, forward deck centre
1 double raised mount
16 - 0.98" / 25.0 mm 77.0 cal guns - 0.54lbs / 0.24kg shells, 4,000 per gun
Anti-air guns in deck mounts, 1938 Model
14 x Single mounts on sides, evenly spread
2 x Single mounts on sides aft
2 double raised mounts
Weight of broadside 586 lbs / 266 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.42" / 36 mm 344.49 ft / 105.00 m 9.84 ft / 3.00 m
Ends: Unarmoured
Main Belt covers 108 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.42" / 36 mm 1.42" / 36 mm 1.42" / 36 mm
2nd: 0.79" / 20 mm 0.79" / 20 mm -
3rd: 0.39" / 10 mm - -

- Armoured deck - multiple decks: 0.79" / 20 mm For and Aft decks

- Conning towers: Forward 2.76" / 70 mm, Aft 0.00" / 0 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 58,000 shp / 43,268 Kw = 33.04 kts
Range 3,000nm at 24.00 kts
Bunker at max displacement = 1,286 tons

Complement:
306 - 398

Cost:
£2.517 million / $10.067 million

Distribution of weights at normal displacement:
Armament: 195 tons, 3.7 %
Armour: 481 tons, 9.2 %
- Belts: 195 tons, 3.7 %
- Armament: 76 tons, 1.5 %
- Armour Deck: 192 tons, 3.7 %
- Conning Tower: 18 tons, 0.3 %
Machinery: 1,588 tons, 30.5 %
Hull, fittings & equipment: 1,706 tons, 32.7 %
Fuel, ammunition & stores: 1,076 tons, 20.7 %
Miscellaneous weights: 165 tons, 3.2 %
- Hull below water: 10 tons
- Hull above water: 10 tons
- On freeboard deck: 25 tons
- Above deck: 120 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
4,200 lbs / 1,905 Kg = 67.2 x 5.0 " / 127 mm shells or 0.9 torpedoes
Stability (Unstable if below 1.00): 1.15
Metacentric height 2.2 ft / 0.7 m
Roll period: 13.8 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.39
Seaboat quality (Average = 1.00): 1.41

Hull form characteristics:
Hull has a flush deck,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.450 / 0.465
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 25.47 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 29.86 ft / 9.10 m, 20.01 ft / 6.10 m
- Forward deck: 20.00 %, 20.01 ft / 6.10 m, 20.01 ft / 6.10 m
- Aft deck: 45.00 %, 20.01 ft / 6.10 m, 20.01 ft / 6.10 m
- Quarter deck: 15.00 %, 20.01 ft / 6.10 m, 20.01 ft / 6.10 m
- Average freeboard: 20.80 ft / 6.34 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 117.4 %
- Above water (accommodation/working, high = better): 199.9 %
Waterplane Area: 16,047 Square feet or 1,491 Square metres
Displacement factor (Displacement / loading): 114 %
Structure weight / hull surface area: 60 lbs/sq ft or 295 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.67
- Longitudinal: 2.07
- Overall: 0.75
Caution: Hull subject to strain in open-sea
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily

10t = D3 sonar
10t = Scaricabombe
14t = 8 x DC Throwers + 50 W100 charges
10t = Diesel Emergency Generator
30t = AIRONE-2 Air Search Radar
10t = GUFO-4 Surface Search Radar
5t = Radio Beacon
20t = 2 x GDR.101
66t = 6 x Quadruple 37/54 mountings (18t ea - 1.75t per gun)

Think we can safely call this one a light cruiser rather than a destroyer...

How does it look in SS2? As far as I recall, we've still not voted to accept SS3 as a legitimate way to sim warships...

Quoted

Originally posted by Brockpaine
Think we can safely call this one a light cruiser rather than a destroyer...

How does it look in SS2? As far as I recall, we've still not voted to accept SS3 as a legitimate way to sim warships...

I think I have these ships listed as "heavy destroyers" but I quite like the Italian term of Esploratori or Scout. They're sort of in between.

It shouldn't look too different in SS2, and as my critique pointed out, SS3b2 is a better tool to use.

Quoted

Originally posted by Red Admiral
It shouldn't look too different in SS2, and as my critique pointed out, SS3b2 is a better tool to use.

It may be a better tool to use, but we've never voted to adopt it, and the mods have been asking people for quite some time to re-sim SS3 designs which have slipped through back to SS2. Unless and until we all vote to accept SS3 as legit, that's going to be the case. That rule is open for debate, but until it's changed, it will be enforced.

No one opposed my arguments in favour of SS3b2 hence I see little reason not to adopt it.

Quoted

Originally posted by Red Admiral
No one opposed my arguments in favour of SS3b2 hence I see little reason not to adopt it.

Lack of opposition does not equate to official adoption. If you want it to be officially adopted, request an official vote.

Quoted

Originally posted by Red Admiral
No one opposed my arguments in favour of SS3b2 hence I see little reason not to adopt it.

Silence is not acceptance. Commenting on the technical merits of one sim program or another is far different from voting to adopt one sim program over another.

Among others, I was specifically requested by the Administrator to resim a design from SS3 to SS2 - a request that I complied with; other have done likewise where appropriate. I for one do not wish to see SS3b2, or any other SS3 variant, adopted.

Thanks for the comments. It's a bit smaller than a Dido-Class. I think the main differences would be that it's not a true cruiser and isn't set up for extended indiviual operations like a cruiser, though still rather better than a normal destroyer.

I imagine the duple 127/64 mountings are a good 60 tons or so which is pretty close to what SS actually gives as the output. It tends to way underestimate light AA which is why there is additional misc. weight accounted for (SS says 7t for a quad mount but the historical quads weighed 18t)

It's maybe not clear from the drawing, but I was intending for a limited open bridge around the forward FC director on top of the enclosed bridge. In bad weather, more likely to use the enclosed bridge. Firings arcs for the forward 37/54 mountings aren't as great as could be hoped for, but I was trying to get away with the minimum of changes from the previous version of this ship which had three 3 duple mountings.

With regards to armour; it's really only against splinters and near-misses. It's difficult to armour against anything more. I don't feel that 50mm really buys you anything. You'd really want 100mm or so for protection against 152mm shells, and even then, there are very large unarmoured portions of the ship vulnerable to HE fire. My philosophy for cruisers is generally large amounts of light armour to protect buoyancy.