100 mm/47 O.T.O. Mod. 1928 (100 mm)

Triple-turret battery of the 100 mm/47 O.T.O. Mod. 1928 on RN Eugenio di Savoia

Description

The 100 mm/47 O.T.O. Mod. 1928 is an Italian naval gun. It serves as a secondary multi-purpose gun in open twin-gun turrets on a number of Italian cruisers. Being a relatively old design, it struggles with rate of fire and the damage inflicted by an individual shell. But overall it offers an important component of the anti-air defence for the cruisers, being able to engage bombers even a few kilometres up when controlled by the AI gunners.

Vehicles equipped with this weapon

• RN Bartolomeo Colleoni
• RN Duca degli Abruzzi
• RN Eugenio di Savoia
• RN Pola
• RN Raimondo Montecuccoli
• RN Trento
• RN Zara

General info

Available ammunition

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		100 m	1,000 m	2,000 m	3,000 m	4,000 m	5,000 m
HE Dirompente	HE	17	17	17	17	17	17
HE-TF Contro-aerea	HE-TF*	17	17	17	17	17	17
APHE Perforante	APHE	150	129	109	93	78	67

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile mass (kg)	Fuse delay (s)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (g)	Ricochet
							0%	50%	100%
HE Dirompente	HE	850	13.2	0	0.1	1,300	79°	80°	81°
HE-TF Contro-aerea	HE-TF*	850	13.2	0	0.1	1,300	79°	80°	81°
APHE Perforante	APHE	850	13.8	0.01	6	820	47°	60°	65°

Comparison with analogues

Comparing to the foreign equivalents of a similar calibre the 100 mm/47 O.T.O. Mod. 1928 is rather underwhelming weapon, showing its age when matched against more modern counterparts. For starters, it lacks HE-VT shells that its British and Soviet equivalents have access to, and thus it offers a much lower anti-air potential with its plain HE-TF shell. The filler in the high-explosive shells is also one of the lowest, thus being limited in the amount of damage done. This is made worse by a very low rate of fire (owning it to a fully manual operation of the gun by the crew), low targetting speed and a low muzzle velocity. In fact, the gun suffers from having a low reload rate even compared to the variant of the same gun found on the Soviet ships, designated Minizini.

There are two upsides however: unusually for the calibre (and owning it to the dated design), the gun comes with a dedicated APHE shell that can penetrate the hulls of most destroyers and even a number of cruisers, though a low number of guns and the inaccuracy of the AI gunners against bluewater ships make it an unlikely mean of sinking enemy warships. The other saving grace of these guns is their long range, similar to the foreign equivalents, which allows them to harass enemy bombers long before they get ready to drop their bombs, thus discouraging enemy from attempting engagement.

HE

Cannon		Ammo	Calibre (mm)	Muzzle Velocity (m/s)	Sustained rate of fire (rounds/min)	Targeting speed (°/s)		TNT Equivalent (kg)	Penetration @ 0° Angle of Attack (mm)
						Horizontal	Vertical		1,000 m	5,000 m
	100 mm/47 O.T.O. Mod. 1928	HE	100	850	9.6	11	6	1.3	17	17
	Minizini (100 mm)	HE	100	800	12	11	6	1.24	45	26
	100 mm/70 SM-5-1	HE	100	1,000	15	14	14	1.94	24	24
	100 mm/56 B-34	HE	100	900	15	21	17	1.95	24	24
	4 inch/45 Mark XVI	HE	102	811	10	20	6	8.5	20	20
	10.5 cm SK C/32	HE	105	875	15	6.8	6.8	1.55	20	20
	100/65 mm Type 98 mod A	HE	100	950	15	12	16	0.95	13	13

AP and SAP

Cannon		Ammo	Calibre (mm)	Muzzle Velocity (m/s)	Sustained rate of fire (rounds/min)	Targeting speed (°/s)		TNT Equivalent (kg)	Penetration @ 0° Angle of Attack (mm)		Penetration @ 60° Angle of Attack (mm)
						Horizontal	Vertical		1,000 m	5,000 m	1,000 m	5,000 m
	100 mm/47 O.T.O. Mod. 1928	APHE	100	850	9.6	11	6	0.82	129	67	52	29
	4 inch/45 Mark XVI	SAP	102	811	10	20	6	0.6	102	64	43	27

Usage in battles

These guns are used exclusively as secondaries and unlike a number of other secondary guns on cruisers - they are best left for the AI to control at all times, as the guns simply lack both punching power and/or rate of fire to be worth being manually-controlled, maybe with exception of the Zara-class where three-turret broadside is just-about enough to save the day in specific circumstances. These guns should be primarily thought of as a psychological warfare against enemy airplanes: they offer just enough fire to look discouraging, while also being able to score a random hit every now and then. They are by no means reliable, but still better than having no long-range protection (an issue Japanese warships struggle with throughout the research tree).

Pros and cons

Pros:

• Good APHE shell for the calibre
• Long engagement range

Cons:

• Poor damage potential (small explosive fillers in HE shells, low rate of fire, poor muzzle velocity)
• Lack of HE-VT shells
• Low targeting speed

History

The Austro-Hungarian Empire began to lay down plans for a much expanded naval force in the early 1900s. No longer content with a coastal defense force, they wanted to have control over the Adriatic Sea. The change was influenced by the politics of Marinekommandant (Chief of the Navy) Rudolf Montecuccoli and crown prince Archduke Franz Ferdinand who viewed Italy as a threat, along with the new railway linking their ports at Trieste (present-day Italy) and the Dalmatian coastline (present-day Croatia) to the rest of the Empire. The new fleet expansion program led to orders for a new cannon to arm their destroyers and scout cruisers leading to the Škoda K 10 first developed in 1907 and adopted in 1910. After World War I ended, the Austro-Hungarian Empire was dismantled by the Allied Powers. This dismantling included the navy with Italy getting the K 10 guns on the Brindisi and Venezia which were ships ceded from the Austro-Hungarian Navy as war reparations.

The Italians were so enamoured with the design, they began to produce the design locally through OTO which resulted in a variety of different variants of the design. The O.T.O. Mod.1928 was a dual-mount anti-aircraft variant with electrically powered adjustable trunnions, rope rammers and mechanized spring, and a loose liner. Despite being intended for anti-aircraft use, the gun was too slow for this role, particularly if a ship was rolling and it was instead more suited for barrage fire. The RN Balzano, Condottieri-class, RN San Giorgio, and Zara-class cruisers all used these guns. They were also used on the Conte di Cavour-class dreadnoughts. The Soviet Navy also used this gun as the Minizini named for the developer of the duel mount Italian Commandante Minizini.

Media

Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

• Minizini (100 mm) - Soviet variant.
• 100 mm/47 O.T.O. Mod. 1937 (100 mm) - later single-mount variant.

External links

• [Wikipedia] Škoda 10 cm K10
• [NavWeaps] Italy 100 mm/47 (3.9") Models 1924, 1927 and 1928

USSR naval cannons
20 mm	ShVAK
25 mm	2M-3
30 mm	AK-230 · 30 mm/54 AK-630 · 30 mm/54 AK-630M · BP "Plamya"
37 mm	37 mm/67 70-K · V-11
45 mm	45 mm/46 21-K · 45 mm/68 21-KM · 45 mm/89 SM-20-ZIF · 45 mm/89 SM-21-ZIF
57 mm	AK-725
75 mm	75 mm/50 Canet patt.1892
76 mm	34-K · 39-K · 76 mm/60 AK-176M · AK-726 · D-56TS · F-34 · Lender AA gun, pattern 1914/15
85 mm	85 mm/52 92-K · 85 mm/54.6 ZIS-C-53 · 90-K
100 mm	100 mm/56 B-34 · 100 mm/70 SM-5-1 · Minizini
102 mm	Pattern 1911
120 mm	120 mm/50 pattern 1905
130 mm	130 mm/55 pattern 1913 · 130 mm/58 SM-2-1 · B-13
152 mm	152 mm/57 B-38
180 mm	180 mm/57 B-1-P · 180 mm/60 B-1-K
305 mm	12-inch/52 pattern 1907 · 305 mm/54 B-50
356 mm	14-inch/52 pattern 1913 (356 mm)
	Foreign:
40 mm	2pdr QF Mk.IIc (Britain) · Skoda (Czechoslovakia)
47 mm	3 pdr QF Hotchkiss (Britain)
76 mm	76 mm/40 Ansaldo mod.1917 (Italy)
88 mm	SK C/30 (Germany)
120 mm	120 mm/50 Mk.4 Bofors M1924 (Sweden) · 120 mm/50 O.T.O. Mod.1933 (Italy)
152 mm	152/53 mm O.T.O. Mod.1929 (Italy)
320 mm	320 mm/44 Ansaldo model 1934 (Italy)