8"/55 caliber gun

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8"/55 caliber naval gun
Damages New Orleans Tassafaronga.jpg
No. 2 turret of USS New Orleans (CA-32) following a Japanese torpedo-initiated explosion of the forward magazine during the Battle of Tassafaronga on 30 November 1942.
Type Naval gun
Service history
In service 1925–1975
Used by United States
Wars World War II
Korean War
Vietnam War
Production history
Variants Mk 9, Mk 12, Mk 14, Mk 15, Mk 16
Specifications
Barrel length 440 inches (11 m) bore (55 calibers)

Shell

335 pounds (152 kg)[1]A.P.

260 pounds (118 kg)[2] H.E.
Caliber 8 inches (20 cm)
Muzzle velocity 2,500 feet per second (760 m/s)[1]
Maximum firing range 30,050 yards (27,480 m)[1]

The 8"/55 caliber gun (spoken "eight-inch-fifty-five-caliber") formed the main battery of United States Navy heavy cruisers and two early aircraft carriers. United States naval gun terminology indicates the gun fired a projectile 8 inches (203 mm) in diameter, and the barrel was 55 calibers long (barrel length is 8 inch × 55 = 440 inches or 11 meters).[3]

Compare the rounded roofs of early Mark 9 twin and triple turrets of USS Salt Lake City (CA-25) and USS Pensacola (CA-24) with the later turrets of USS New Orleans (CA-32) on the right.

Mark 9[edit]

These built-up guns weighed about 30 tons including a liner, tube, jacket, and five hoops. A down-swing Welin breech block was closed by compressed air from the gas ejector system. Loading with two silk bags each containing 45-pounds (20 kg) of smokeless powder gave a 260-pound (120 kg) projectile a velocity of 2800 feet per second (850 m/s).[1] Range was 31,860 yd (29,130 m) at the maximum elevation of 41 degrees.[1][4]

Mark 12[edit]

These simplified built-up guns eliminated hoops to reduce weight to 17 tons. The breech mechanism was similar and loading two silk bags each containing 43-pounds (20 kg) of smokeless powder gave a 335-pound (152 kg) projectile a velocity of 2500 feet per second (760 m/s).[1] Each gun could fire about four rounds per minute. Maximum range was 30,050 yd (27,480 m) at the maximum elevation of 41 degrees.[5]

Mark 14[edit]

These guns were similar to Mark 9, with the same shell weight and maximum range,[4] with a smaller chamber and rifling twist increased from 1 in 35 to 1 in 25 in a chromium-plated bore.

Mark 15[edit]

These guns were similar to Mark 12, with the same shell weight and maximum range, with the smaller chamber of the Mark 14 gun.[5] Useful life expectancy was 715 effective full charges (EFC) per liner.

Mark 16[edit]

These self-loading guns with lined monobloc construction and vertical sliding breech blocks weighed about 20 tons. Semi-fixed ammunition (projectile and powder case handled separately) with 78 pounds (35 kg) of smokeless powder gave a 335-pound (152 kg) projectile a velocity of 2500 feet per second (760 m/s).[1] Each gun could fire about ten rounds per minute. Useful life expectancy was 780 EFC per liner. Range was 17 miles (27 kilometers) at the maximum elevation of 41 degrees.[1][6] This gun was modified for the experimental Major Caliber Lightweight Gun.

Ships mounting 8"/55 caliber guns[edit]

The heavy cruiser USS Helena (CA-75) fires her 8"/55 caliber Mark 15 guns at enemy forces ashore on the Korean Peninsula in August 1950 during the Korean War.
The after turret of the heavy cruiser USS Toledo (CA-133) fires its 8"/55 caliber Mark 15 guns at enemy targets ashore around Incheon, South Korea, on 13 or 14 September 1950 during the bombardment preceding the invasion of Incheon during the Korean War.
The heavy cruiser USS Saint Paul (CA-73) fires her 8"/55 caliber Mark 15 guns at Chinese troops threatening the evacuation of United Nations troops from Hungnam, North Korea, in December 1950 during the Korean War.
The heavy cruiser USS Saint Paul (CA-73)'s forward 8"/55-caliber guns fire at enemy targets ashore in North Vietnam in October 1966 during the Vietnam War.
Ship Gun Installation[1]
USS Lexington (CV-2) Mk 9 guns in four 190-ton twin turrets
USS Saratoga (CV-3) Mk 9 guns in four 190-ton twin turrets
USS Pensacola (CA-24) Mk 9 (later Mk 14) guns in two 190-ton twin turrets
and two 250-ton triple turrets
USS Salt Lake City (CA-25) Mk 9 (later Mk 14) guns in two 190-ton twin turrets
and two 250-ton triple turrets
USS Northampton (CA-26) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS Chester (CA-27) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS Louisville (CA-28) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS Chicago (CA-29) Mk 9 guns in three 250-ton triple turrets
USS Houston (CA-30) Mk 9 guns in three 250-ton triple turrets
USS Augusta (CA-31) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS New Orleans (CA-32) Mk 9 (later Mk 14) guns in three 294-ton triple turrets
USS Portland (CA-33) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS Astoria (CA-34) Mk 9 guns in three 294-ton triple turrets
USS Indianapolis (CA-35) Mk 9 (later Mk 14) guns in three 250-ton triple turrets
USS Minneapolis (CA-36) Mk 9 (later Mk 15) guns in three 294-ton triple turrets
USS Tuscaloosa (CA-37) Mk 12 guns in three 250-ton triple turrets
USS San Francisco (CA-38) Mk 12 guns in three 250-ton triple turrets
USS Quincy (CA-39) Mk 12 guns in three 250-ton triple turrets
USS Vincennes (CA-44) Mk 12 guns in three 250-ton triple turrets
USS Wichita (CA-45) Mk 12 guns in three 314-ton triple turrets
USS Baltimore (CA-68) Mk 12 guns in three 300-ton triple turrets
USS Boston (CA-69) Mk 15 guns in three 300-ton triple turrets
USS Canberra (CA-70) Mk 15 guns in three 300-ton triple turrets
USS Quincy (CA-71) Mk 15 guns in three 300-ton triple turrets
USS Pittsburgh (CA-72) Mk 15 guns in three 300-ton triple turrets
USS Saint Paul (CA-73) Mk 15 guns in three 300-ton triple turrets
USS Columbus (CA-74) Mk 15 guns in three 300-ton triple turrets
USS Helena (CA-75) Mk 15 guns in three 300-ton triple turrets
USS Oregon City (CA-122) Mk 15 guns in three 300-ton triple turrets
USS Albany (CA-123) Mk 15 guns in three 300-ton triple turrets
USS Rochester (CA-124) Mk 15 guns in three 300-ton triple turrets
USS Bremerton (CA-130) Mk 15 guns in three 300-ton triple turrets
USS Fall River (CA-131) Mk 15 guns in three 300-ton triple turrets
USS Macon (CA-132) Mk 15 guns in three 300-ton triple turrets
USS Toledo (CA-133) Mk 15 guns in three 300-ton triple turrets
USS Des Moines (CA-134) Mk 16 guns in three 450-ton triple turrets
USS Los Angeles (CA-135) Mk 15 guns in three 300-ton triple turrets
USS Chicago (CA-136) Mk 15 guns in three 300-ton triple turrets
USS Salem (CA-139) Mk 16 guns in three 450-ton triple turrets
USS Newport News (CA-148) Mk 16 guns in three 450-ton triple turrets
USS Hull (DD-945) Mk 16 gun in one 86-ton single automatic turret
(8"/55 caliber Mark 71 gun installation)

See also[edit]

Weapons of comparable role, performance and era[edit]

References[edit]

  1. ^ a b c d e f g h i Campbell 1985 pp.127-131
  2. ^ http://www.hnsa.org/doc/ordnance/pg056.htm
  3. ^ Fairfield 1921 p.156
  4. ^ a b DiGiulian, Tony (27 April 2011). "United States of America 8"/55 (20.3 cm) Marks 9, 10, 11, 13 and 14". Navweaps.com. Archived from the original on 30 June 2011. Retrieved 2011-07-21. 
  5. ^ a b DiGiulian, Tony (7 February 2008). "United States of America 8"/55 (20.3 cm) Marks 12 and 15". Navweaps.com. Archived from the original on 30 June 2011. Retrieved 2011-07-21. 
  6. ^ "New Cruiser Packs 8 inch Automatics" , May 1949, Popular Science detailed illustrations of Mark 16
  • Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4. 
  • Fairfield, A.P. (1921). Naval Ordnance. The Lord Baltimore Press. 

External links[edit]