Third year type 20 cm/50 caliber guns (五十口径三年式二〇糎砲, gojūkōkei sannenshiki ni-maru centi-hō) formed the main battery of Japan's World War IIheavy cruisers. These guns were also mounted on two early aircraft carriers.[2] The typical installation was ten 20 cm/50 guns; although Tone-class cruisers carried eight while Furutaka and Aoba-class cruisers carried six. After modernization, Akagi carried only six.
20 cm/50 3rd Year Type naval gun
Tone-class cruiser Chikuma mounted all 4 turrets forward of the bridge.
These were built-up guns with an inner A tube, encased by a second tube, encased by a full length jacket. Early guns were partially wire-wound, but later guns dispensed with the wire winding. The guns were breech loaded with two cloth bags of smokeless powder.[2] Third year type refers to the Welin breech block on this gun. Breech block design began in 1914 AD, the third year of the Taishō period. This breech block design was also used on Japanese 41 cm (16.1 inch), 15.5 cm (6 inch), 14 cm (5.5 inch), 12.7 cm (5 inch), and 12 cm (4.7 inch) naval guns.[3]
The first model of this gun used a 32.63 kg (71.9 lb) powder charge to fire 20 cm (7.9 in) projectiles weighing 110 kg (242.5 lb) at a velocity of 870 m/s (2,854 ft/s).[4] Useful life was 300 effective full charges (EFC) per gun. These guns were initially installed in type A low-angle (25°) single mounts aboard Furutaka-class cruisers, in type C (40°) twin turrets in the Aoba class, and in type D (40°) twin turrets in the Myōkō class. Mark I guns can be visually distinguished from Mark II guns by an abrupt step in the chase diameter which was absent on the latter guns.[2]
2 GÔ (Mark II) guns
Second model guns used a 33.8 kg (74.5 lb) powder charge to fire 8 in (203.2 mm) projectiles weighing 125.85 kg (277.5 lb) at a velocity of 835 m/s (2,740 ft/s).[5] These guns had a useful life expectancy of 320 to 400 EFC (Effective/Equivalent Full Charge). Rate of fire varied from four rounds per minute firing at low angles diminishing to two or three rounds per minute firing at maximum elevation.[2] These guns and the type E twin turret with 70-degree elevation installed on Takao-class cruisers were influenced by Royal NavyCounty-class cruisers.[1] Type E turrets were promptly redesigned to limit elevation to 55 degrees when 70-degree elevation proved impractical. Modified type E turrets were installed as original equipment aboard Maya and the Tone-class cruisers, and replaced the original turrets aboard Furutaka and Mogami-class cruisers. Mark II guns replaced the original Mark I guns in type C and D turrets so all Japanese heavy cruisers carried Mark II guns in twin turrets by December 1941.
Aircraft carrier installations
Starboard quarter of Kaga with three casemate guns visible.
Mark I guns were installed in casemates with a maximum elevation of 25 degrees limiting maximum range to 22 kilometers (14 mi). Aircraft carriers originally had four guns mounted in two type B twin turrets with a maximum elevation of 70 degrees. These were transferred to casemates in Kaga in 1934 and simply removed from Akagi in 1936.
Ammunition
Shell weights and muzzle velocities for high explosive or San Shiki incendiary shrapnel are specified for each of the Marks above. Infobox muzzle velocity applies to type 91 armor-piercing (AP) shells with trajectory information below. Illuminating shells were fired with a reduced charge at a muzzle velocity of 710 meters per second (2330 ft/sec).[2]
Only Mark I guns were installed in type A mounts. Maximum elevation was 25° in the six single mounts installed aboard Furutaka-class cruisers in 1926, in the six casemate mountings installed on aircraft carriers Akagi in 1927 and Kaga in 1930, and in the four casemate mountings added to Kaga in 1934.
Type B
Only Mark I guns were installed in type B mounts. Maximum elevation was 70° in the two twin turrets installed aboard Akagi in 1927 and Kaga in 1930. These turrets were removed from Kaga in 1934 and from Akagi in 1936. Guns removed in 1934 were transferred to additional casemates aboard Kaga, but those removed in 1936 were not replaced.
Type C
Three twin turrets with maximum elevation of 40° were installed only aboard Aoba-class cruisers. The Mark I guns installed in 1927 were replaced by Mark II guns in 1937 and 1938.
Type D
Five twin turrets with maximum elevation of 40° were installed only aboard Myōkō-class cruisers. The Mark I guns installed in 1928 and 1929 were replaced by Mark II guns between 1931 and 1934.
Type E
Only Mark II guns were installed in type E twin turrets. Maximum elevation was 70° in the five turrets installed aboard Atago, Takao, and Chōkai in 1932. Early recognition of the impracticality of using these guns for anti-aircraft fire caused reduction of maximum elevation to 55° in all subsequent installations. Maya received five 55° turrets as original equipment in 1932. Three new turrets with Mark I guns from Myōkō-class cruisers re-bored to Mark II replaced the original type A mounts aboard Furutaka-class cruisers in 1936 and 1937. Tone-class cruisers were completed with four type E turrets in 1937 and 1938. Five new turrets replaced the original triple 6-inch turrets aboard Mogami class cruisers between 1939 and 1941.
Wartime installations of 3 Nendo Shiki 20 cm/50 caliber guns
^ abDiGiulian, Tony. "20 cm/50 (7.9") 3rd Year Type". NavWeaps. Retrieved 4 September 2017.
References
Brown, David (1977). Aircraft Carriers. Arco Publishing Company. ISBN0-668-04164-1.
Campbell, John (1985). Naval Weapons of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN0-87021-459-4.
Whitley, M.J. (1995). Cruisers of World War Two. Brockhampton Press. ISBN1-86019-874-0.
Lacroix, Eric; Wells, Linton (1997). Japanese Cruisers of the Pacific War. Naval Institute Press. ISBN0-87021-311-3.
External links
Wikimedia Commons has media related to 20 cm/50 3rd Year Type naval gun.
Tony DiGiulian, Japanese 20 cm/50 (7.9") 3rd Year Type No. 1
Tony DiGiulian, Japanese 20 cm/50 (8") 3rd Year Type No. 2
March 05, 2023
year, type, naval, third, year, type, caliber, guns, 五十口径三年式二, 糎砲, gojūkōkei, sannenshiki, maru, centi, formed, main, battery, japan, world, heavy, cruisers, these, guns, were, also, mounted, early, aircraft, carriers, typical, installation, guns, although, to. Third year type 20 cm 50 caliber guns 五十口径三年式二 糎砲 gojukōkei sannenshiki ni maru centi hō formed the main battery of Japan s World War II heavy cruisers These guns were also mounted on two early aircraft carriers 2 The typical installation was ten 20 cm 50 guns although Tone class cruisers carried eight while Furutaka and Aoba class cruisers carried six After modernization Akagi carried only six 20 cm 50 3rd Year Type naval gunTone class cruiser Chikuma mounted all 4 turrets forward of the bridge TypeNaval gunPlace of originJapanService historyIn service1926 1945 1 Used byImperial Japanese NavyWarsSecond World WarProduction historyManufacturerKure Naval ArsenalMuroran Ironworks 2 Produced1 GO Mark 1 1923 2 GO Mark 2 1932No built 300 2 SpecificationsMass1 GO Mark 1 17 6 tonnes 2 2 GO Mark 2 18 7 tonnesLength1 GO Mark 1 10 metres 33 ft 2 GO Mark 2 10 31 metres 33 8 ft Barrel length1 GO Mark 1 9 144 metres 30 00 ft 2 GO Mark 2 10 metres 33 ft 2 Shell1 GO Mark 1 110 kilograms 240 lb 2 GO Mark 2 126 kilograms 278 lb Calibre1 GO Mark 1 20 centimetre 7 874 in 2 GO Mark 2 8 inch 203 2 mm 2 Muzzle velocity835 m s 2740 ft sec 2 Maximum firing range29 kilometres 18 mi 2 These were built up guns with an inner A tube encased by a second tube encased by a full length jacket Early guns were partially wire wound but later guns dispensed with the wire winding The guns were breech loaded with two cloth bags of smokeless powder 2 Third year type refers to the Welin breech block on this gun Breech block design began in 1914 AD the third year of the Taishō period This breech block design was also used on Japanese 41 cm 16 1 inch 15 5 cm 6 inch 14 cm 5 5 inch 12 7 cm 5 inch and 12 cm 4 7 inch naval guns 3 Contents 1 1 GO Mark I guns 2 2 GO Mark II guns 3 Aircraft carrier installations 4 Ammunition 5 Type 91 AP shell trajectory 6 Gun mounts 6 1 Type A 6 2 Type B 6 3 Type C 6 4 Type D 6 5 Type E 7 Wartime installations of 3 Nendo Shiki 20 cm 50 caliber guns 8 See also 8 1 Weapons of comparable role performance and era 9 Notes 10 References 11 External links1 GO Mark I guns EditThe first model of this gun used a 32 63 kg 71 9 lb powder charge to fire 20 cm 7 9 in projectiles weighing 110 kg 242 5 lb at a velocity of 870 m s 2 854 ft s 4 Useful life was 300 effective full charges EFC per gun These guns were initially installed in type A low angle 25 single mounts aboard Furutaka class cruisers in type C 40 twin turrets in the Aoba class and in type D 40 twin turrets in the Myōkō class Mark I guns can be visually distinguished from Mark II guns by an abrupt step in the chase diameter which was absent on the latter guns 2 2 GO Mark II guns EditSecond model guns used a 33 8 kg 74 5 lb powder charge to fire 8 in 203 2 mm projectiles weighing 125 85 kg 277 5 lb at a velocity of 835 m s 2 740 ft s 5 These guns had a useful life expectancy of 320 to 400 EFC Effective Equivalent Full Charge Rate of fire varied from four rounds per minute firing at low angles diminishing to two or three rounds per minute firing at maximum elevation 2 These guns and the type E twin turret with 70 degree elevation installed on Takao class cruisers were influenced by Royal Navy County class cruisers 1 Type E turrets were promptly redesigned to limit elevation to 55 degrees when 70 degree elevation proved impractical Modified type E turrets were installed as original equipment aboard Maya and the Tone class cruisers and replaced the original turrets aboard Furutaka and Mogami class cruisers Mark II guns replaced the original Mark I guns in type C and D turrets so all Japanese heavy cruisers carried Mark II guns in twin turrets by December 1941 Aircraft carrier installations Edit Starboard quarter of Kaga with three casemate guns visible Mark I guns were installed in casemates with a maximum elevation of 25 degrees limiting maximum range to 22 kilometers 14 mi Aircraft carriers originally had four guns mounted in two type B twin turrets with a maximum elevation of 70 degrees These were transferred to casemates in Kaga in 1934 and simply removed from Akagi in 1936 Ammunition EditShell weights and muzzle velocities for high explosive or San Shiki incendiary shrapnel are specified for each of the Marks above Infobox muzzle velocity applies to type 91 armor piercing AP shells with trajectory information below Illuminating shells were fired with a reduced charge at a muzzle velocity of 710 meters per second 2330 ft sec 2 Type 91 AP shell trajectory EditRange 2 Elevation Descent Impact velocity5 km 3 miles 2 24 3 2133 ft s 650 m s 10 km 6 miles 5 18 7 30 1634 ft s 498 m s 15 km 9 miles 10 30 15 48 1299 ft s 396 m s 20 km 12 miles 18 29 1194 ft s 364 m s 25 km 15 miles 30 47 1247 ft s 380 m s Gun mounts EditType A Edit Only Mark I guns were installed in type A mounts Maximum elevation was 25 in the six single mounts installed aboard Furutaka class cruisers in 1926 in the six casemate mountings installed on aircraft carriers Akagi in 1927 and Kaga in 1930 and in the four casemate mountings added to Kaga in 1934 Type B Edit Only Mark I guns were installed in type B mounts Maximum elevation was 70 in the two twin turrets installed aboard Akagi in 1927 and Kaga in 1930 These turrets were removed from Kaga in 1934 and from Akagi in 1936 Guns removed in 1934 were transferred to additional casemates aboard Kaga but those removed in 1936 were not replaced Type C Edit Three twin turrets with maximum elevation of 40 were installed only aboard Aoba class cruisers The Mark I guns installed in 1927 were replaced by Mark II guns in 1937 and 1938 Type D Edit Five twin turrets with maximum elevation of 40 were installed only aboard Myōkō class cruisers The Mark I guns installed in 1928 and 1929 were replaced by Mark II guns between 1931 and 1934 Type E Edit Only Mark II guns were installed in type E twin turrets Maximum elevation was 70 in the five turrets installed aboard Atago Takao and Chōkai in 1932 Early recognition of the impracticality of using these guns for anti aircraft fire caused reduction of maximum elevation to 55 in all subsequent installations Maya received five 55 turrets as original equipment in 1932 Three new turrets with Mark I guns from Myōkō class cruisers re bored to Mark II replaced the original type A mounts aboard Furutaka class cruisers in 1936 and 1937 Tone class cruisers were completed with four type E turrets in 1937 and 1938 Five new turrets replaced the original triple 6 inch turrets aboard Mogami class cruisers between 1939 and 1941 Wartime installations of 3 Nendo Shiki 20 cm 50 caliber guns EditShip Gun Installation 2 Akagi 6 Mark I guns in type A casemates with 25 elevation 6 Aoba 3 type C twin turrets with 40 elevation 7 Ashigara 5 type D twin turrets with 40 elevation 8 Atago 5 type E twin turrets with 70 elevation 9 Chikuma 4 type E twin turrets with 55 elevation 10 Chōkai 5 type E twin turrets with 70 elevation 9 Furutaka 3 type E twin turrets with 55 elevation 7 Haguro 5 type D twin turrets with 40 elevation 8 Kaga 10 Mark I guns in type A casemates with 25 elevation 11 Kako 3 type E twin turrets with 55 elevation 7 Kinugasa 3 type C twin turrets with 40 elevation 7 Kumano 5 type E twin turrets with 55 elevation 12 Maya 5 type E twin turrets with 55 elevation 9 Mikuma 5 type E twin turrets with 55 elevation 12 Mogami 5 type E twin turrets with 55 elevation 12 Myōkō 5 type D twin turrets with 40 elevation 8 Nachi 5 type D twin turrets with 40 elevation 8 Sri Ayudhya 2 type D twin turrets with 40 elevation 13 Suzuya 5 type E twin turrets with 55 elevation 12 Takao 5 type E twin turrets with 70 elevation 9 Thonburi 2 type D twin turrets with 40 elevation 13 Tone 4 type E twin turrets with 55 elevation 10 Furutaka class heavy cruisers Furutaka Kako till 1937 6 7 9 inch type A 25 from 1937 3 twin 8 0 inch type E 55 Aoba class heavy cruisers Aoba Kinugasa till 1938 3 twin 7 9 inch type C 40 from 1938 3 twin 8 0 inch type C 40 Myoko class heavy cruisers Myoko Nachi Ashigara Haguro till 1934 5 twin 7 9 inch type D 40 from 1934 5 twin 8 0 inch type D 40 Takao class heavy cruisers Takao Atago Chokai 5 twin 8 0 inch type E 70 Maya 5 twin 8 0 inch type E 55 Mogami class heavy cruisers Mogami Mikuma Kumano Suzuya till 1939 5 triple 6 1 inch 55 classified as light cruiser from 1939 5 twin 8 0 inch type E 55 Tone class heavy cruisers Tone Chikuma 4 twin 8 0 inch type E 55 See also EditWeapons of comparable role performance and era Edit 203mm 50 Modele 1924 gun French equivalent 20 3 cm SK C 34 Naval gun German equivalent 203 mm 53 Italian naval gun Italian equivalent BL 8 inch Mk VIII naval gun UK equivalent 8 55 caliber gun US equivalentNotes Edit a b Whitley 1995 pp 177 a b c d e f g h i j k l m n Campbell 1985 pp 185 187 Campbell 1985 pp 173 amp 183 Lacroix Japanese Cruisers p 61 Lacroix Japanese Cruisers p 97 Brown 1995 pp 15 a b c d Whitley 1995 pp 170 a b c d Whitley 1995 pp 174 a b c d Whitley 1995 pp 178 a b Whitley 1995 pp 185 Brown 1995 pp 16 a b c d Whitley 1995 pp 182 a b DiGiulian Tony 20 cm 50 7 9 3rd Year Type NavWeaps Retrieved 4 September 2017 References EditBrown David 1977 Aircraft Carriers Arco Publishing Company ISBN 0 668 04164 1 Campbell John 1985 Naval Weapons of World War Two Annapolis Maryland Naval Institute Press ISBN 0 87021 459 4 Whitley M J 1995 Cruisers of World War Two Brockhampton Press ISBN 1 86019 874 0 Lacroix Eric Wells Linton 1997 Japanese Cruisers of the Pacific War Naval Institute Press ISBN 0 87021 311 3 External links Edit Wikimedia Commons has media related to 20 cm 50 3rd Year Type naval gun Tony DiGiulian Japanese 20 cm 50 7 9 3rd Year Type No 1 Tony DiGiulian Japanese 20 cm 50 8 3rd Year Type No 2 Retrieved from https en wikipedia org w index php title 20 cm 50 3rd Year Type naval gun amp oldid 1092263517, wikipedia, wiki, book, books, library,
