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A gun turret is a device that protects the crew or mechanism of a projectile firing weapon and at the same time lets the weapon be aimed and fired in many directions. A turret is usually a rotating weapon platform. This can be mounted on a Fortified Building or Structure such as an anti-naval Land Battery , or on an Armoured Fighting Vehicle , a Naval Ship , or a Military Aircraft . Turrets may be armed with one or more Machine Gun s, Automatic Cannon , large- Calibre guns, or Missile Launcher s. It may be manned or Remotely Controlled , and is often Armoured . A small turret, or sub-turret on a larger one is called a Cupola . Cupola is also used for rotating turrets that carry no weapons but instead sighting devices as in the case of tank commanders. The protection provided by the turret may be against battle damage or against the weather, conditions and environment in which the weapon or its crew operate. The term comes from Turret - a protective position on a fortification situated on top of a building or wall, as opposed to rising directly from the ground which is a Tower . WARSHIPS History , compare the layout and nomenclature with the American design below.]] gun turret.]] Before the development of large calibre, long range guns in the middle 1800s, the classic battleship design used rows of port mounted guns on each side of the ship, often mounted in Casemate s. Firepower was provided by a large number of guns which could only be aimed in a limited arc from one side of the ship. Due to instability, fewer larger and heavier guns can be carried on a ship. Also, the casemates often sat near the waterline, which made them vulnerable to flooding and restricted their use to calm seas. Turrets allowed the smaller number of guns to be aimed and fired on both sides of the ship and at the same time provide armoured protection to the gun crew. One of the earliest Turret Gun Ships was the USS ''Monitor'' , which mounted two Muzzle Loading Cannon s in a fully rotating armoured drum. An alternative at the time used a static drum, the Barbette , inside which the gun mount rotated - the gun barrel projecting over the edge of the drum. In latter designs this was developed to have an armoured portion that sat over the gun and the edge of the barbette leading to the term "hooded barbette". With the advent of the South Carolina Class Battleship s, 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. This is a stark contrast to the contemporary HMS Dreadnought which, while revolutionary in many other ways, still retained Wing Turret s. The superfiring or superimposed arrangement had not been proven until after ''South Carolina'' went to sea, and it was initially feared that the weakness of the previous Virginia class ship's stacked turrets would repeat itself. Another major advancement was in the Kongō Class Battlecruiser s and Queen Elizabeth Class Battleship s, which dispensed with the "Q" turret amidships in favour of heavier guns in fewer mountings. While World War I ships commonly had a twin-turret configuration, ships by WWII were commonly using triple and even quadruple turrets, which reduced the total number of mountings altogether and improved armour protection, though quad mount turrets turned out to be too cramped. The largest warship turrets were in World War II Battleship where a heavily armoured enclosure protected the large gun crew during battle. The calibre of the main armament on large battleships was typically 12 in (30 cm) up to 18 in (45 cm). The turrets carrying the 18-inch guns of '' Yamato '' each weighted around 2,500 tons. The secondary armament of battleships (or the primary armament of cruisers) was typically between 5 and 6 in (127 - 152 mm). Smaller ships typically mounted guns from 3 in (76 mm) upwards, although these rarely require a turret mounting. Layout In naval terms, a turret traditionally and specifically refers to a gun mounting where the entire mass rotates as one, and has a trunk that pierces the deck. The rotating part of a turret seen above deck is the gunhouse, which protects the mechanism and crew, and where the guns are loaded. The gunhouse is supported on a bed of rotating rollers, and is not physically attached to the ship; were the ship to Capsize , the turret would fall out. Below the gunhouse there may be a working chamber, where ammunition is handled, and the main trunk, which accommodates the Shell and Propellant hoists that bring ammunition up from the Magazines below. There may be a combined hoist (''cf'' the animated British turret) or separate hoists (''cf'' the American turret cutaway). The working chamber and trunk rotate with the gunhouse, and sit inside a protective Armoured Barbette . The barbette extends down to the main armoured deck (red in the animation). At the base of the turret sit handing rooms, where shell and propelling charges are passed from the shell room and magazine to the hoists. The handling equipment and hoists are complex arrangements of machinery that transport the shells and charges from the magazine into the base of the turret. Bearing in mind that shells can weigh around a Ton , the hoists have to be powerful and rapid; a 15 inch turret of the type in the animation was expected perform a complete loading and firing cycle in a minuteCapt. S. W. Roskill, RN, ''HMS Warspite'', Classics of Naval Literature, Naval Institute Press, 1997 ISBN 1-55750-719-8 The loading system is fitted with a series of Mechanical Interlocks that (in theory) ensure that there is never an open path from the gunhouse to the magazine down which an Explosive Flash might pass. Flash-tight doors and scuttles open and close to allow the passage between areas of the turret. Generally, with large-calibre guns, powered or assisted ramming is required to force the heavy shell and charge into the Breech . As the hoist and breech must be aligned for ramming to occur, there is generally a restricted range of elevations at which the guns can be loaded; the guns return to the loading elevation, are loaded, then return to the target elevation. The animation illustrates a turret where the rammer is fixed to the cradle that carries the guns, allowing loading to occur across a wider range of elevations. Earlier turrets differed significantly in their operating principles. It was not until the last of the "rotating drum" designs described in the previous section were phased out that the "hooded barbette" arrangement above became the defining turret. Wing turrets , with 9.2 inch secondary guns shipped in wing turrets.]] |
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