Škoda guns built at the Pilsen works. Fitted to Austria-Hungary's last pre-dreadnoughts and to her only completed dreadnoughts. Used a horizontal wedge breech and the propellant charge was in a brass case.
The Škoda Works of Pilsen produced a total of 65 guns (5 of them were spares) in this caliber. The first 13 were for the Radetzky-class, the second 52 were for the Tegetthoff-class. Only the second series, the guns for the Tegetthoff-class, were designated as K10. The K10 differed slightly from the earlier 30.5 (12") guns in that its chamber was 1.97 inches (5 cm) longer, so that it could handle a heavier propellant charge.
Erzherog Franz Ferdinand, Radetzky and Tegetthoff were ceded after World War I to Italy, where they were scrapped and their guns then used as coastal artillery.
Actual bore diameter was 30.50 cm (12.008 inches).
|Designation||30.5 cm/45 (12")
30.5 cm/45 (12") K10
|Ship Class Used On||
|Date Of Design||1908|
|Date In Service||1910|
|Gun Weight||116,070 lbs. (52,650 kg)
(54,250 kg) including BM
|Gun Length oa||541 in (13.750 m)|
|Bore Length||about 512 in (13.000 m)|
|Rifling Length||417.6 in (10.606 m)|
|Grooves||(92) 0.115 in deep x 0.271 in (2.92 mm x 6.9 mm)|
|Lands||0.138 in (3.5 mm)|
|Twist||RH 1 in 25|
|Rate Of Fire||3 rounds in first minute with ready ammunition, 1 to 2 rounds per minute afterwards|
|Projectile Types and Weights||
|Propellant Charge 1||
|Cartridge Empty Weight||153.4 lbs. (69.6 kg)|
|Muzzle Velocity for AP||Austria-Hungary: 2,625 fps (800 mps)
Italy: 2,510 fps (765 mps)
|Working Pressure||18.4 tons/in2 (2,900 kg/cm2)|
|Approximate Barrel Life||200 rounds|
|Ammunition stowage per gun||Radetzky: 84 rounds 2
Viribus Unitis: 82 rounds 3
The figures for Italian service are an assumption based upon notes in "Naval Weapons of World War Two" by John Campbell.
|Elevation||992 lbs. (450 kg) APC 2crh Shell||992 lbs. (450 kg) APC 4crh Shell|
|3.4 degrees||---||6,560 yards (6,000 m)|
|6.0 degrees||---||10,930 yards (10,000 m)|
|16.0 degrees||17,830 yards (16,300 m)||20,890 yards (19,100 m)|
|20 degrees||19,900 yards (18,200 m)||about 24,000 yards (22,000 m)|
|Designation||Two-gun Turrets: Radetzky (2) 1
Three-gun Turrets: Viribus Unitis (4)
|Weight||620 tons (630 mt)|
|Elevation 2||Radetzky: -4 / +20 degrees
Viribus Unitis: -4 / +20 degrees
|Elevation Rate||2.5 degrees per second|
|Train||+140 / -140 degrees|
|Train Rate||3 degrees per second|
|Gun recoil||33.5 inches (85 cm)|
|Loading Angle||+2 degrees|
These turrets were poorly protected with thin armor. There was an unprotected slot between the gunhouse and the barbette. The cupolas for the rangefinders on the turret roofs were overly large. A hit on one of these could have peeled back the thin turret roof armor.
Under battle conditions the gun houses could not be ventilated as they would have sucked in the propellant gasses. It was estimated that they had no more than 15 minutes of oxygen once the ventilation was shut down.
- ^On the Viribus Unitis class the heavy weight of the superimposed turrets caused hull distortions, requiring stiffening of the longitudinal frames.
- ^The Radetzky class and Tegetthoff could elevate all guns to 20 degrees either individually or when coupled together. The other ships in the Viribus Unitis class were able to elevate all guns individually to -4 / +20 degrees, but when the guns were coupled together, the elevation range for the center gun was -3 / +15.5 degees and the outer guns were limited to -4 / +16 degrees.
- "Naval Weapons of World War Two" by John Campbell
- "Naval Weapons of World War One" by Norman Friedman
- "The Big Gun: Battleship Main Armament 1860-1945" by Peter Hodges
- "The Viribus Unitis Class" article in "Warship Volume II" and "A's and A's" comments in "Warship Volume III" both by Friedrich Prasky
- "A Szent István Csatahajó" (The battleship Szent István) by Balogh Tamás and Csepregi Oszkár
Original research by Mihály Krámli
Special help from Daniel Papp