16-inch/45-caliber Mark 6 gun

May 2024 16"/45-caliber gun USS South Dakota (BB-57) at Scapa Flow, 1943.jpg 300px Battleship armament: 16"/45-caliber guns aboard the battleship South Dakota BB-57. United States Naval gun "yes" 1941–1956 US Navy World War II 1936 Mod 0–2 192310 lb kg on 61 ft 4 in m on 60 ft m on bore (45 calibers) AP, HC AP:2700 lb kg 0HC:1900 lb kg 0 16 inch (40.6 cm) 2 rpm AP: 2300 ft/s m/s 0HC: 2635 ft/s m/s 0 33741 m mi on with AP (on Battleship mount) 48 in cm on -2° to +45° -150° to 150° The 16"/45-caliber Mark 6 gun is a naval gun designed in 1936 by the United States Navy for their Treaty battleships. It was introduced in 1941 aboard their North Carolina battleships, replacing the originally intended 14"/50-caliber Mark B guns and was also used for the follow-up South Dakota class. These battleships carried nine guns in three three-gun turrets. The gun was an improvement to the 16"/45-caliber Mark 5 guns used aboard the Colorado battleship 4, and the predecessor to the 16"/50-caliber Mark 7 gun used aboard the Iowa battleship 4. Description The U.S. Navy had the 16"/50-caliber Mark 2 guns left over from the canceled Lexington battlecruiser 1s and South Dakota battleship (1920) 0 battleships of the early 1920s. However, it was already apparent that the Mark 2 was too heavy to arm the North Carolina and new South Dakota (1939) battleship classes, which had to adhere to the 35,000 long ton standard displacement set by the Second London Naval Treaty. Indeed, the Mark 6 45 caliber "three-gun" turret weighed some 400 LT t less than the Mark 2 50-caliber did; also thanks to a decreased barbette size in the Mark 6 the total weight savings over the Mark 2 would be 2000 LT t, The Mark 6 16 in/45 guns were improved versions of the Mark 1 guns (upgraded to Marks 5 and 8 in the late 1930s) mounted on the Colorado battleship 1s. The Mark 6 had a limit of a 2240 lb kg on shell with a maximum 35000 yd m on range and their turret limit of 30-degree elevation. DiGiulian Tony United States of America 16"/45 (40.6 cm) Mark 5 and Mark 8 http://www.navweaps.com/Weapons/WNUS_16-45_mk5.php Navweaps.com 11 July 2016 14 June 2017 A considerable upgrade over its predecessor was the Mark 6's ability to fire a new 2700 lb kg on armor-piercing (AP) shell developed by the Bureau of Ordnance. At full charge with a brand-new gun, the heavy shell would be expelled at a muzzle velocity of 2,300 feet per second (700 m/s); at a reduced charge, the same shell would be fired at 1,800 f/s (550 m/s). Barrel life—the approximate number of rounds a gun could fire before needing to be relined or replaced—was 395 shells when using AP, increasing to 2,860 for practice rounds. By comparison, the 12"/50-caliber Mark 8 gun of the Alaska cruiser 0 large cruisers had a barrel life of 344 shots, while the 16"/50-caliber Mark 7 gun fitted in the Iowa battleships had a barrel life of 290 rounds.DiGiulian, Tony. "United States of America 16"/50 (40.6 cm) Mark 7". Navweaps.com. 11 June 2017. Web. 14 June 2017. Turning at 4 degrees a second, each turret could train to 150 degrees on either side of the ship. The guns could be elevated to a maximum elevation of 45 degrees; turrets one and three could depress to −2 degrees, but due to its superfiring position, the guns on turret two could only depress to 0 degrees.DiGiulian, Tony. "United States of America 16"/45 (40.6 cm) Mark 6". Navweaps.com. 11 July 2016. Web. 15 June 2017. Each gun barrel was 61 ft 4 in m long overall, which is 45 bore diameters, hence the 16"/45-caliber; its bore length was 60 ft m and rifling length was 51.5 ft m. Maximum range was obtained at an elevation of 45 degrees. With the heavy AP shell the maximum range was 36900 yd mi km 3, and with the lighter 1900 lb kg on high capacity (HC) shell, 40180 yd mi km 3. The guns weighed 192,310 lb (87,230 kg; 86 long tons) not including the breech; the turrets weighed slightly over 3,100,000 lb (1,410,000 kg; 1400 long tons). When firing the same shell, the 16 in/45 Mark 6 had a slight advantage over the 16 in/50 Mark 7 when hitting deck armor—a shell from a 45 cal gun would be slower, meaning that it would have a steeper trajectory as it descended. At 35000 yd mi km, a shell from a 45 cal would strike a ship at an angle of 45.2 degrees, as opposed to 36 degrees with the 50 cal. 320px|right|thumb|A cut-away diagram of the 16-inch turrets on board the North Carolina class|alt=The turret held three guns; below the gun deck were the turret floor, the machinery floor, and two levels of magazines for the shells and propellant charges. Two centrally located ammunition hoists carried the ordnance from the magazines to the gun deck. Shell The Mark 6 and 7 guns were originally intended to fire the relatively light 2240 lb on (1.00 long ton) Mark 5 armor-piercing shell. However, the shell-handling system for these guns was redesigned to use the "super-heavy" 2700 lb on APCBC (armor-piercing, capped, ballistic capped) Mark 8 shell before any of the Iowa battleships were laid down. The large-caliber guns were designed to fire two different 16-inch (406 mm) shells: an armor-piercing round for anti-ship and anti-structure work, and a high-explosive round designed for use against unarmored targets and shore bombardment. The Mark 8 shells gave the North Carolina, South Dakota, and Iowa classes the second heaviest broadside of all battleship classes, despite the fact that the North Carolina and South Dakota ships were treaty battleships. Only the Yamato battleship 0 could throw more weight. The Mark 6's disadvantage relative to other contemporary battleship classes was its comparatively shorter range."Battleship comparison". Combinedfleet.com. Web. 7 August 2012. The propellant consists of small cylindrical grains of smokeless powder with an extremely high burning rate. A maximum charge consists of six silk bags, each filled with 110 pounds (50 kg) of propellant.Trainor, Bernard E. "Iowa Blast Inquiry: Long Search Ahead". The New York Times, 23 April 1989. Accessed 12 July 2009. Service history The Mark 6 16-inch gun holds several distinctions relating to the United States' World War II combat history. In the first instance, the battleship Massachusetts BB-59 employed these 16"/45-caliber guns as her primary armament, and she is believed to have fired the United States' first and last 16-inch shells of World War II; Massachusetts V (BB-59) https://www.history.navy.mil/research/histories/ship-histories/danfs/m/massachusetts-v.html Dictionary of American Naval Fighting Ships United States Navy 6 August 2015 14 June 2017 the first use occurring on 8 November 1942 during the Naval Battle of Casablanca (shortly before the Naval battle of Guadalcanal),Garzke Dulin 1980 103–107 the last on 9 August 1945 off the coast of Hamamatsu, Japan. Furthermore, their use at Casablanca was the only time that a fast battleship of the US Navy fired its guns in anger in the European theater, which was also one of the two engagements in World War II where the US Navy's fast battleship dueled an enemy battleship. Massachusetts heavy 16-inch AP shells caused significant damage to the incomplete battleship French battleship Jean Bart 1940 2 although few of the shells actually exploded because they had been fitted with fuzes manufactured in 1918. One of Massachusetts hits penetrated both of Jean Bart's armor decks and exploded in the empty magazines for the missing 152 mm guns, had this magazine been full of propellant charges the resulting explosion could have destroyed the vessel, while Massachusetts fifth salvo jammed the rotating mechanism of Jean Bart's sole operational main battery turret.Atkinson (2002), p. 131 In the second instance, as the primary armament of Washington BB-56 these guns were employed against the Imperial Japanese Navy's Japanese battleship Kirishima 2 (a much older and less powerful ship, armed with 8 × 14-inch guns and originally built as a battlecruiser during World War I) during the Naval battle of Guadalcanal; this has been cited by historians as the only instance in World War II in which one American battleship actually sank an enemy battleship.Battle 360° 1 5 https://www.youtube.com/watch?v=bCjPnpP31nE&NR=1 USS Enterprise – "Enterprise versus Japan" The History Channel 2007-04-23. (While there was a battleship-versus-battleship engagement at Leyte Gulf, torpedoes rather than gunfire were largely regarded as being responsible for sinking the enemy battleships.) The Washington had the aid of a naval fire control computer—in this case the Ford Instrument Company Mark 8 Range Keeper analog computer used to direct the fire from the battleship's guns, taking into account several factors such as the speed of the targeted ship, the time it takes for a projectile to travel, and air resistance to the shells fired at a target. This gave the US Navy a major advantage in the Pacific War, as the Japanese did not develop radar or automated fire control to a comparable level (although they did have complex mechanical ballistics computers, which had been in use since World War I). Washington was able to track and fire at targets at a greater range and with increased accuracy, as was demonstrated in November 1942, when she engaged Kirishima at a range of 8400 yd at night. Using her nine 16"/45-caliber Mark 6 guns, Washington fired 75 rounds of 16-inch AP shells and scored an incredible twenty heavy-caliber hits that critically damaged the Kirishima, which eventually sank. Mindell David Between Human and Machine https://archive.org/details/betweenhumanmach00mind limited Johns Hopkins 2002 Baltimore 262–263 0-8018-8057-2 Clymer, A. Ben The Mechanical Analog Computers of Hannibal Ford and William Newell Massachusetts Institute of Technology IEEE Annals of the History of Computing 15 2 1993 http://web.mit.edu/STS.035/www/PDFs/Newell.pdf 2006-08-26 https://web.archive.org/web/20060909064108/http://web.mit.edu/STS.035/www/PDFs/Newell.pdf 9 September 2006 Kirishima Damage Analysis by Robert Lundgren During the same battle, South Dakota also fired off several salvos from her 16"/45 guns before she had to withdraw for repairs due to a faulty circuit breaker. Successor The next US Navy battleship class, the Iowa battleship 4, did not fall under Treaty weight restrictions and allowed for additional displacement. However, in their original design, the General Board was incredulous that a tonnage increase of 10000 LT t would only allow the addition of 6 knots over the South Dakotas. Rather than retaining the 16"/45-caliber Mark 6 gun used in the South Dakotas, they ordered that future studies would have to include the more powerful (but heavier) 16"/50-caliber Mark 2 guns left over from the canceled Lexington battlecruiser 1s and South Dakota battleship (1920) 0 battleships of the early 1920s. It also allowed the draft of the ships to be increased, meaning that the ships could be shortened (lowering weight) and the power reduced (since a narrower beam reduces drag).Friedman, pp. 310–311. The Mark 2 50-caliber gun turret weighed some 400 LT t more than the Mark 6 45 caliber did; the barbette size also had to be increased so the total weight gain was about 2000 LT t, putting the ship at a total of 46551 LT t—well over the 45,000 long ton limit. An apparent savior appeared in a Bureau of Ordnance preliminary design for a turret that could carry the 50-caliber guns in a smaller barbette. This breakthrough was shown to the General Board as part of a series of designs on 2 June 1938.Friedman, p. 311. Nonetheless, the Mark 7 gun still weighed about 239,000 pounds (108 000 kg) without the breech, or 267,900 pounds with the breech, considerably heavier than the Mark 6, which weighed 192,310 pounds (87,230 kg). The Mark 7 had a greater maximum range over the Mark 6: 23.64 mi vs 22.829 mi. When firing the same conventional shell, the 16"/45-caliber Mark 6 gun used by the treaty battleships of the North Carolina battleship 5 and South Dakota battleship (1939) 4es had a slight advantage over the 16"/50-caliber Mark 7 gun on the Iowa battleship 4, when hitting deck armor—a shell from a 45 cal gun would be slower, meaning that it would have a steeper trajectory as it descended. At 35000 yd mi km, a shell from a 45 cal would strike a ship at an angle of 45.2 degrees, as opposed to 36 degrees with the 50 cal. Barrel life—the approximate number of rounds a gun could fire before needing to be relined or replaced—was 395 shells when using AP, increasing to 2,860 for practice rounds. By comparison, the 12"/50-caliber Mark 8 gun of the Alaska cruiser 0 large cruisers had a barrel life of 344 shots, while the 16"/50-caliber Mark 7 gun fitted in the Iowa battleships had a barrel life of 290 rounds. Most World War II large scale naval battles involving the US Navy were fought by carrier-based aircraft in the Pacific, and so the chief use of the US Navy's battleship guns was shore bombardment. Nonetheless, the Mark 6 guns saw ship-to-ship combat in the Pacific and European theaters. This was attributed to the fact that ships mounting the Mark 7 batteries, the Iowa battleship 4, were commissioned later than the Mark 6-equipped North Carolina battleship 5 and South Dakota battleship (1939) 4es, so they missed the Naval Battles of Casablanca and Guadalcanal, two of the few instances where the US Navy's battleships were deployed to fight other battleships. Operation Hailstone was the only instance when the Mark 7 guns were fired purely at surface ships, against two light cruisers and three destroyers, in a somewhat controversial surface action as US Navy carrier aircraft were available and could have achieved similar results.USA 16"/45 (40.6 cm) Mark 6 – NavWeaps See also 40.6 cm SK C/34 gun – German equivalent BL 16 inch Mk I naval gun – British equivalent 41 cm/45 3rd Year Type naval gun – Japanese equivalent References Bibliography https://www.history.navy.mil/research/histories/ship-histories/danfs/m/massachusetts-v.html Garzke William H. Dulin Robert O. Battleships: Allied Battleships in World War II Annapolis, Maryland Naval Institute Press 1980 0-87021-100-5 6355577 USS Massachusetts (BB-59) Turner Publishing Company 1997 1-56311-263-9 38874740 https://books.google.com/books?id=RYiqCYTd4BIC CITEREFTurner1997 14 August 2009 External links NavWeaps, 16"/45 (40.6 cm) Mark 6, navweaps.com, retrieved 21 Aug 16. Category:Naval guns of the United States Category:World War II naval weapons Category:400 mm artillery Category:Weapons and ammunition introduced in 1941