Gun turret
A gun turret is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in some degree of azimuth and elevation.
Description
Rotating gun turrets protect the weapon and its crew as they rotate. When this meaning of the word "turret" started being used at the beginning of the 1860s, turrets were normally cylindrical. Barbettes were an alternative to turrets; with a barbette the protection was fixed, and the weapon and crew were on a rotating platform inside the barbette. In the 1890s, armoured hoods were added to barbettes; these rotated with the platform. By the early 20th century, these hoods were known as turrets. Modern warships have gun-mountings described as turrets, though the "protection" on them is limited to protection from the weather.Rotating turrets can be mounted on a fortified building or structure such as a coastal blockhouse, be part of a land battery, be mounted on a combat vehicle, a naval ship, or a military aircraft, they may be armed with one or more machine guns, automatic cannons, large-calibre guns, or missile launchers. They may be manned or remotely controlled and are most often protected to some degree, if not actually armoured.
The protection provided by the turret may be against battle damage, the weather conditions, general environment in which the weapon or its crew will be operating. The name derives from the pre-existing noun turret, from the French "touret", diminutive of the word "tower", meaning a self-contained protective position which is situated on top of a fortification or defensive wall as opposed to rising directly from the ground, in which case it constitutes a tower.
Cupolas
A small turret, or sub-turret set on top of a larger one, is called a cupola. The term cupola is also used for a rotating turret that carries a sighting device rather than weaponry, such as that used by a tank commander.Warships
Before the development of large-calibre, long-range guns in the mid-19th century, the classic battleship design used rows of gunport-mounted guns on each side of the ship, often mounted in casemates. Firepower was provided by a large number of guns, each of which could traverse only in a limited arc. Due to stability issues, fewer large guns can be carried high on a ship, but as this set casemates low and thus near the waterline they were vulnerable to flooding, effectively restricted their use to calm seas. Additionally casemate mounts had to be recessed into the side of a vessel to afford a wide arc of fire, and such recesses presented shot traps, compromising the integrity of armour plating.Rotating turrets were weapon mounts designed to protect the crew and mechanism of the artillery piece and with the capability of being aimed and fired over a broad arc, typically between a three-quarter circle up to a full 360 degrees. These presented the opportunity to concentrate firepower in fewer, better-sited positions by eliminating redundancy, in other words combining the firepower of those guns unable to engage an enemy because they sited on the wrong beam into a more powerful, and more versatile unified battery.
History
Designs for a rotating gun turret date back to the late 18th century. In the mid-19th century, during the Crimean War, Captain Cowper Phipps Coles constructed a raft with guns protected by a 'cupola' and used the raft, named the Lady Nancy, to shell the Russian town of Taganrog in the Black Sea during the Siege of Taganrog. The Lady Nancy "proved a great success" and Coles patented his rotating turret design after the war.United Kingdom: Early designs
The British Admiralty ordered a prototype of Coles's patented design in 1859, which was installed in the ironclad floating battery, HMS Trusty, for trials in 1861, becoming the first warship to be fitted with a revolving gun turret. Coles's aim was to create a ship with the greatest possible all round arc of fire, as low in the water as possible to minimise the target.The Admiralty accepted the principle of the turret gun as a useful innovation, and incorporated it into other new designs. Coles submitted a design for a ship having ten domed turrets each housing two large guns.
The design was rejected as impractical, although the Admiralty remained interested in turret ships and instructed its own designers to create better designs. Coles enlisted the support of Prince Albert, who wrote to the first Lord of the Admiralty, the Duke of Somerset, supporting the construction of a turret ship. In January 1862, the Admiralty agreed to construct a ship, HMS Prince Albert which had four turrets and a low freeboard, intended only for coastal defence.
File:HMS Prince Albert.jpg|thumb|HMS Prince Albert, a pioneering turret ship, whose turrets were designed by Cowper Phipps Coles
While Coles designed the turrets, the ship was the responsibility of Chief Constructor Isaac Watts. Another ship using Coles' turret designs,, was completed in August 1864. Its existing broadside guns were replaced with four turrets on a flat deck and the ship was fitted with of armour in a belt around the waterline.
Early ships like the Royal Sovereign had little sea-keeping qualities being limited to coastal waters.
Sir Edward James Reed, went on to design and build HMS Monarch, the first seagoing warship to carry her guns in turrets. Laid down in 1866 and completed in June 1869, it carried two turrets, although the inclusion of a forecastle and poop prevented the turret guns firing fore and aft.
United States: USS ''Monitor''
The gun turret was independently invented in the United States by the Swedish inventor John Ericsson, although his design was technologically inferior to Coles's version. Ericsson designed in 1861, its most prominent feature being a large, cylindrical gun turret mounted amidships above the low-freeboard upper hull, also referred to as the "raft". This extended well past the sides of the lower, more traditionally shaped hull.A small, armoured pilot house was fitted on the upper deck towards the bow; however, its position prevented Monitor from firing her guns straight forward. Like Coles's, one of Ericsson's goals in designing the ship was to present the smallest possible target to enemy gunfire. The turret's rounded shape helped to deflect cannon shot. A pair of donkey engines rotated the turret through a set of gears; a full rotation was made in 22.5 seconds during testing on 9 February 1862. However, fine control of the turret proved to be difficult, as it would have to be reversed if it overshot its mark. In lieu of reversing the turret, a full rotation would have to be made to train the guns where desired.
Including the guns, the turret weighed approximately ; the entire weight rested on an iron spindle that had to be jacked up using a wedge before the turret was free to rotate. The spindle was in diameter which gave it ten times the strength needed in preventing the turret from sliding sideways.
When not in use, the turret rested on a brass ring on the deck that was intended to form a watertight seal. However, in service, the interface between the turret and deck ring heavily leaked, despite caulking by the crew.
The gap between the turret and the deck proved to be another kind of problem for several s, which used the same turret design, as debris and shell fragments entered the gap and jammed the turrets during the First Battle of Charleston Harbor in April 1863. Direct hits at the turret with heavy shot also had the potential to bend the spindle, which could also jam the turret.
Monitor was originally intended to mount a pair of smoothbore Dahlgren guns, but they were not ready in time and guns were substituted, each gun weighing approximately.
Monitors guns used the standard propellant charge of specified by the 1860 ordnance instructions for targets "distant", "near", and "ordinary", established by the gun's designer Dahlgren himself. They could fire a round shot or shell up to a range of at an elevation of +15°.
Later designs
represented the culmination of this pioneering work. An ironclad turret ship designed by Edward James Reed, she was equipped with revolving turrets that used pioneering hydraulic turret machinery to manoeuvre the guns. She was also the world's first mastless battleship, built with a central superstructure layout, and became the prototype for all subsequent warships. With her sister of 1871 she was another pivotal design, and led directly to the modern battleship.The US Navy tried to save weight and deck space, and allow the much faster firing 8-inch to shoot during the long reload time necessary for 12-inch guns by superposing secondary gun turrets directly on top of the primary turrets, but the idea proved to be practically unworkable and was soon abandoned.
With the advent of the s in 1908, the main battery turrets were designed so as to superfire, to improve fire arcs on centerline mounted weapons. This was necessitated by a need to move all main battery turrets to the vessel's centerline for improved structural support. The 1906, while revolutionary in many other ways, had retained wing turrets due to concerns about muzzle blast affecting the sighting mechanisms of a turret below. A similar advancement was in the s and s, which dispensed with the "Q" turret amidships in favour of heavier guns in fewer mountings.
Like pre-dreadnoughts, the first dreadnoughts had two guns in each turret; however, later ships began to be fitted with triple turrets. The first ship to be built with triple turrets was the Italian, although the first to be actually commissioned was the Austro-Hungarian of the. By the beginning of World War II, most battleships used triple or, occasionally, quadruple turrets, which reduced the total number of mountings and improved armour protection. However, quadruple turrets proved to be extremely complex to arrange, making them unwieldy in practice.
The largest warship turrets were in World War II battleships where a heavily armoured enclosure protected the large gun crew during battle. The calibre of the main armament on large battleships was typically. The turrets carrying three guns of each weighed around. The secondary armament of battleships was typically between. Smaller ships typically mounted guns of and larger, although these rarely required a turret mounting, except for large destroyers, like the American and the German Narvik classes.