Description

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).

Gun Characteristics

Designation 30.5 cm/45 (12")
30.5 cm/45 (12") K10
Ship Class Used On
  • Austria-Hungary:
    • 30.5 cm/45 (12"): Radetzky
    • 30.5 cm/45 (12") K10: Viribus Unitis classes
  • Italy: Coastal Artillery
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
Chamber Volume N/A
Rate Of Fire 3 rounds in first minute with ready ammunition, 1 to 2 rounds per minute afterwards

Ammunition

Type Separate
Projectile Types and Weights
  • Austria-Hungary:
    • APC L3,4 2crh: 992 lbs. (450 kg)
    • APC L3,4 4crh: 992 lbs. (450 kg)
    • Common L4,0: 992 lbs. (450 kg)
  • Italy:
    • APC: 997 lbs. (452 kg)
Bursting Charge
  • Austria-Hungary:
    • APC: 8.8 lbs. (4.0 kg)
    • Common: 58.9 lbs. (26.7 kg)
  • Italy: N/A
Projectile Length
  • Austria-Hungary:
    • APC: about 40.8 in (103.7 cm)
    • Common: about 48.0 in (122 cm)
  • Italy: N/A
Propellant Charge 1
  • Austria-Hungary:
    • Non-K10: N/A
    • K10: 308.6 lbs. (140 kg) 25/660 mm M97 f.R.P.
  • Italy: 304 lbs. (138 kg)
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.

  • ^Propellant was in a single brass cartridge.
  • ^Outfit for the Radetsky class was 42 APC and 42 Common per gun.
  • ^Outfit for Viribus Unitis class was 38 APC and 38 Common per gun in magazines plus another six rounds per gun in the turret.

Range

Ranges with Austria-Hungary shells
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)

Armor Penetration

Range 992 lbs. (450 kg) APC 2crh Shell 992 lbs. (450 kg) APC 4crh Shell
KC Side Armor Deck Armor KC Side Armor Deck Armor
6,560 yards (6,000 m) 5.3 in (136 mm) --- 18.7 in (475 mm) ---
19,900 yards (18,200 m) 4.2 in (106 mm) --- --- ---
20,890 yards (19,100 m) --- --- 6.8 in (173 mm) ---

Mount/Turret Data

Designation Two-gun Turrets: Radetzky (2) 1a
Three-gun Turrets: Viribus Unitis (4)
Weight 620 tons (630 mt)
Elevation 2a 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.

Additional Pictures

Sources

Data from:

  • "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

External Sites

Page History

27 November 2007
Benchmark
18 July 2010
Updated with information supplied by Mihály Krámli
12 October 2013
Added pictures of Radetzky turret and cartridge being rammed
01 May 2014
Added additional gun, ammunition and mounting information, new range and armor penetration tables