46 cm/45 Type 94
A Type 94 Naval Gun being calibrated on Yamato during construction
Type	Naval gun
Place of origin	Japan
Service history
In service	1940–1945
Used by	Imperial Japanese Navy
Wars	World War II
Production history
Designer	C. Hada [1]
Manufacturer	Kure Naval Arsenal [1]
No. built	~27
Specifications
Mass	147.3 tonnes
Barrel length	21.13 m (69 ft 4 in), 46 calibers
Diameter	46 cm (18.1 in)
Shell	AP Type 91: 1,460 kg (3,218.7 lb) HE Type 0: 1,360 kg (2,998.3 lb) AA Type 0: 1,360 kg (2,998.3 lb)
Calibre	46 cm (18.1 in)
Breech	Welin breech block
Recoil	Hydraulic recoil mechanism
Carriage	Yamato-class battleship
Elevation	+45/-5 degrees. 10°/s
Traverse	300°, 2°/s
Rate of fire	1.5 - 2 rounds/min
Muzzle velocity	780 m/s (2,600 ft/s)
Effective firing range	25 km (16 mi)
Maximum firing range	42 km (26 mi) at 45° elevation

The Japanese "40 cm/45 Type 94 naval gun" (四五口径九四式四〇糎砲, Yonjūgo-kōkei kyūyon-shiki yonjussenchi-hō) was the biggest naval gun used by battleships in World War II. They were actually 46 cm (18.1 in) guns, but were designated 40 cm (15.7 in) in an effort to hide their true size.

Description[edit]

The 46 cm (18.1 in) 40 cm/45 Type 94 naval gun was a wire-wound gun. Nine, mounted in three triple turrets, served as the main armament of the Yamato-class battleships that were in service with the Imperial Japanese Navy during World War II. When the turrets and the guns were mounted, each weighed 2,510 tons, which is about the same tonnage as an average sized destroyer of the era.

The Japanese guns were of a slightly larger bore than the three British 18 inch naval guns built during World War I, although the shells were not as heavy. Britain had later designed the N3-class battleship with 18-inch guns but none were built, leaving no Allied naval guns to compare with the Type 94. Unlike most of the very large guns of other navies, they could fire special anti-aircraft shells (Sanshiki) referred to as "beehive".

Construction[edit]

Some 27 guns were built for the three ships of the Yamato class. Two thirds of the guns were lost with the sinking of Yamato and Musashi. As built, the design of the barrels was complex. A tube was built then auto-frettaged in three stages. A half length tube was fitted over the first tube and shrunk onto it. The assembly was then wire wound and two additional tubes shrunk over the entire length of the gun tubes. A final inner tube was then inserted down the gun and expanded into place. This inner tube was then rifled to finish the gun. As designed, this gun could not cost effectively be relined but instead had to have the entire gun tube replaced due to wear.^[2]

Unlike previous designs the turrets were found to have nothing in common with previous British Vickers designs used in other Japanese battleships when examined by a US naval technical team. Each gun was independently sleeved allowing for separate elevation. The shell hoists and powder rams were found to be ingenious though unduly heavy designs that allowed a relatively rapid rate of reload.^[2] 180 shells (60 rounds per gun) were stored in the turret's rotating structure. The shells were stored vertically and an innovative system of geared mechanical conveyors was employed to move the extremely large and heavy shells from the shell rooms. The mechanical advantage required to move the heavy shells meant these conveyors operated extremely slowly but the 180 shells stored in each turret were considered sufficient for a surface engagement. ^[3]

Range and flight time[edit]

With Type 91 AP shell

Impact angle and velocity[edit]

With Type 91 AP shell

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  A Type 1 armour-piercing shell at the Yasukuni Shrine in Tokyo.
  

  
  

  
  


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  Drawing showing internal structure of Type 91 armour-piercing shell.
  

  
  

  
  


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  High-explosive Type 0 shell.
  

  
  

  
  


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  Yamato's 46 cm/45 Type 94 naval gun shells.
  

  
  

  
  

See also[edit]

• BL 18 inch Mk I naval gun


• 18"/48 caliber Mark 1 gun


• 16"/50 caliber Mark 7 gun


• List of naval guns


• List of the largest cannons by caliber

References[edit]

• Scottish History - Mons Meg reportedly mounted at sea


• 
  18.1"/45 caliber, Nihon Kaigun


• 
  Japan 46cm/45 (15.9") Type 94 - Actual Size 46cm (18.1"), Navweaps.com


• 
  PIECES LOURDES : 240 et plus, le.fantasque.free.fr


• 
  Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
  

External links[edit]

Media related to 40 cm/45 Type 94 naval gun at Wikimedia Commons