Gun turret
Overview
 
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 and at the same time lets the weapon be aimed and fired in many directions.

The turret is also a rotating weapon platform. This platform can be mounted on a fortified
Fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

 building
Building
In architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...

 or structure
Structure
Structure is a fundamental, tangible or intangible notion referring to the recognition, observation, nature, and permanence of patterns and relationships of entities. This notion may itself be an object, such as a built structure, or an attribute, such as the structure of society...

 such as an anti-naval land battery
Land battery
A land battery is a special type of gun emplacement or anti-shipping naval interdiction fortification used in coastal defense to protect areas such as anchorages, harbors, and rivers...

, or on an combat vehicle
Combat vehicle
A combat vehicle, also known as a ground combat vehicle, is a self-propelled, weaponized military vehicle used for combat operations. Combat vehicles can be wheeled or tracked.- Automation :...

, a naval ship
Naval ship
A naval ship is a ship used for combat purposes, commonly by a navy. Naval ships are differentiated from civilian ships by construction and purpose...

, or a military aircraft
Military aviation
Military aviation is the use of aircraft and other flying machines for the purposes of conducting or enabling warfare, including national airlift capacity to provide logistical supply to forces stationed in a theater or along a front. Air power includes the national means of conducting such...

.

Turrets may be armed with one or more machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

s, automatic cannons
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

, large-calibre
Caliber
In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....

 guns, or missile launcher
Multiple rocket launcher
A multiple rocket launcher is a type of unguided rocket artillery system. Like other rocket artillery, multiple rocket launchers are less accurate and have a much lower rate of fire than batteries of traditional artillery guns...

s.
Encyclopedia
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 and at the same time lets the weapon be aimed and fired in many directions.

The turret is also a rotating weapon platform. This platform can be mounted on a fortified
Fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

 building
Building
In architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...

 or structure
Structure
Structure is a fundamental, tangible or intangible notion referring to the recognition, observation, nature, and permanence of patterns and relationships of entities. This notion may itself be an object, such as a built structure, or an attribute, such as the structure of society...

 such as an anti-naval land battery
Land battery
A land battery is a special type of gun emplacement or anti-shipping naval interdiction fortification used in coastal defense to protect areas such as anchorages, harbors, and rivers...

, or on an combat vehicle
Combat vehicle
A combat vehicle, also known as a ground combat vehicle, is a self-propelled, weaponized military vehicle used for combat operations. Combat vehicles can be wheeled or tracked.- Automation :...

, a naval ship
Naval ship
A naval ship is a ship used for combat purposes, commonly by a navy. Naval ships are differentiated from civilian ships by construction and purpose...

, or a military aircraft
Military aviation
Military aviation is the use of aircraft and other flying machines for the purposes of conducting or enabling warfare, including national airlift capacity to provide logistical supply to forces stationed in a theater or along a front. Air power includes the national means of conducting such...

.

Turrets may be armed with one or more machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

s, automatic cannons
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

, large-calibre
Caliber
In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....

 guns, or missile launcher
Multiple rocket launcher
A multiple rocket launcher is a type of unguided rocket artillery system. Like other rocket artillery, multiple rocket launchers are less accurate and have a much lower rate of fire than batteries of traditional artillery guns...

s. It may be manned or remotely controlled
Remote Weapon Station
A remote weapon station, also known as a remote weapon system, is a weaponized system for light and medium caliber weapons which can be installed on ground combat vehicle or sea and air-based combat platforms. Such equipment is used on modern military vehicles, as it allows a gunner to remain in...

, and is often armoured
Vehicle armour
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships....

. A small turret, or sub-turret on a larger one, is called a cupola. The term cupola also describes rotating turrets that carry no weapons but instead sighting devices, as in the case of tank
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 commanders. A finial
Finial
The finial is an architectural device, typically carved in stone and employed decoratively to emphasize the apex of a gable or any of various distinctive ornaments at the top, end, or corner of a building or structure. Smaller finials can be used as a decorative ornament on the ends of curtain rods...

 is an extremely small sub-turret or sub-sub-turret mounted on a cupola turret.

The protection provided by the turret may be against battle damage, or against the weather conditions and general environment in which the weapon or its crew will be operating.

The term comes from the pre-existing noun turret—a self-contained protective position which is situated on top of a fortification or defensive wall, as opposed to rising directly from the ground, when it constitutes a tower
Tower
A tower is a tall structure, usually taller than it is wide, often by a significant margin. Towers are distinguished from masts by their lack of guy-wires....

.

History

Before the development of large-calibre, long-range guns in the mid-19th century, the classic battleship
Battleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

 design used rows of port-mounted guns on each side of the ship, often mounted in casemate
Casemate
A casemate, sometimes rendered casement, is a fortified gun emplacement or armored structure from which guns are fired. originally a vaulted chamber in a fortress.-Origin of the term:...

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 provided armoured protection to the gun crew.

The first naval vessel to be fitted with a turret was HMS Trusty
HMS Trusty
Four ships of the Royal Navy have borne the name HMS Trusty: was an Aetna class ironclad floating battery launched in 1855 and broken up in 1864. It was the first turret ship. was a tug launched in 1866, renamed in 1917 as HMS Trustful and broken up in 1920. was an S-class destroyer launched in...

 of 1860, which was fitted with the prototype Coles
Cowper Phipps Coles
Captain Cowper Phipps Coles, C.B., R.N. , the son of the Reverend John Coles and his wife Mary Ann Goodhew Rogers, was an English naval Captain and inventor. Coles died when HMS Captain, an experimental warship built to his designs, sank with him onboard.-Naval career:He entered the Royal Navy at...

 turret. The first operational use was by USS Monitor
USS Monitor
USS Monitor was the first ironclad warship commissioned by the United States Navy during the American Civil War. She is most famous for her participation in the Battle of Hampton Roads on March 9, 1862, the first-ever battle fought between two ironclads...

 of 1862, which mounted two muzzle loading cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...

s in a fully rotating armoured drum. An alternative at the time used a static drum, the barbette
Barbette
A barbette is a protective circular armour feature around a cannon or heavy artillery gun. The name comes from the French phrase en barbette referring to the practice of firing a field gun over a parapet rather than through an opening . The former gives better angles of fire but less protection...

, 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".

Early ships like Monitor and the converted HMS Royal Sovereign
HMS Royal Sovereign (1857)
HMS Royal Sovereign was originally laid down as a 120-gun first-rate ship of the line of the Royal Navy. She would have mounted sixteen cannon, 114 guns, and a pivot gun. With the rise of steam and screw propulsion, she was ordered to be converted on the stocks to a 131-gun screw ship, with...

 had little sea-keeping qualities being limited to coastal waters. HMS Captain
HMS Captain (1869)
HMS Captain was an unsuccessful warship built for the Royal Navy due to public pressure. She was a masted turret ship, designed and built by a private contractor against the wishes of the Controller's department...

 of 1869 was one of the first sea-going turreted sailing ships. Poor design led to a top-heavy, low freeboard vessel and it was lost in a gale.

With the advent of the South Carolina class battleship
South Carolina class battleship
The United States Navy's South Carolina class consisted of two battleships: and , both of which were launched in 1908. These were among the first warships built with armament organized on the "all-big gun" and the first American battleships of the type...

s in 1908, main battery turrets were designed so as to superfire
Superfire
The idea of superfire is to locate two turrets in a row, one behind the other, but with the second turret located above the one in front so that the second turret could fire over the first...

, 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
HMS Dreadnought (1906)
HMS Dreadnought was a battleship of the British Royal Navy that revolutionised naval power. Her entry into service in 1906 represented such a marked advance in naval technology that her name came to be associated with an entire generation of battleships, the "dreadnoughts", as well as the class of...

 which, while revolutionary in many other ways, still retained wing turrets. The superfiring or superimposed arrangement had not been proven until after South Carolina
USS South Carolina (BB-26)
USS South Carolina , the lead ship of her class of dreadnought battleships, was the fourth ship of the United States Navy to be named in honor of the eighth state, and was the first American dreadnought or all-big gun battleship....

went to sea, and it was initially feared that the weakness of the previous Virginia class
Virginia class battleship
The Virginia class battleship was designed to be the first truly seagoing U.S. battleships. Five ships were commissioned between 1906 and 1907. The ships participated in the round-the-world cruise of the Great White Fleet. For the second and last time, the U.S...

 ship's stacked turrets would repeat itself.

Another major advancement was in the Kongō class battlecruiser
Kongo class battlecruiser
The were a class of ships of the Imperial Japanese Navy constructed immediately before World War I. Designed by British naval architect George Thurston, the lead ship of the class was the last Japanese capital ship constructed outside of Japan. Displacing upon completion, the vessels of this...

s and Queen Elizabeth class battleship
Queen Elizabeth class battleship
The Queen Elizabeth-class battleships were a class of five super-dreadnoughts of the Royal Navy. The lead ship was named after Elizabeth I of England...

s, which dispensed with the "Q" turret amidships in favour of heavier guns in fewer mountings.

While World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 ships commonly had a twin-turret configuration, ships by World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 were commonly using triple and even quadruple turrets, which reduced the total number of mountings altogether and improved armour protection, though quad mount 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 30 cm (12 in) up to 46 cm (18.1 in). The turrets carrying the 460 mm guns of Yamato
Japanese battleship Yamato
, named after the ancient Japanese Yamato Province, was the lead ship of the Yamato class of battleships that served with the Imperial Japanese Navy during World War II. She and her sister ship, Musashi, were the heaviest and most powerfully armed battleships ever constructed, displacing...

each weighed around 2,500 tonnes. The secondary armament of battleships (or the primary armament of cruiser
Cruiser
A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

s) was typically between 127 and 152 mm (5–6 in). Smaller ships typically mounted guns from 76 mm (3 in) upwards, although these rarely required a turret mounting.

Layout

In naval terms, turret traditionally and specifically refers to a gun mounting where the entire mass rotates as one, and has a trunk that pierces the deck
Deck (ship)
A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...

. The rotating part of a turret seen above deck is the gunhouse, which protects the mechanism and crew, and is 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
Capsize
Capsizing is an act of tipping over a boat or ship to disable it. The act of reversing a capsized vessel is called righting.If a capsized vessel has sufficient flotation to prevent sinking, it may recover on its own if the stability is such that it is not stable inverted...

, 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
Shell (projectile)
A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

 and propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

 hoists that bring ammunition up from the magazines
Magazine (artillery)
Magazine is the name for an item or place within which ammunition is stored. It is taken from the Arabic word "makahazin" meaning "warehouse".-Ammunition storage areas:...

 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
Vehicle armour
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships....

 barbette
Barbette
A barbette is a protective circular armour feature around a cannon or heavy artillery gun. The name comes from the French phrase en barbette referring to the practice of firing a field gun over a parapet rather than through an opening . The former gives better angles of fire but less protection...

. 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
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

, the hoists have to be powerful and rapid; a 15 inch turret of the type in the animation was expected to perform a complete loading and firing cycle in a minute

The loading system is fitted with a series of mechanical interlocks
Interlock (engineering)
Interlocking is a method of preventing undesired states in a state machine, which in a general sense can include any electrical, electronic, or mechanical device or system....

 that 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
Breech-loading weapon
A breech-loading weapon is a firearm in which the cartridge or shell is inserted or loaded into a chamber integral to the rear portion of a barrel....

.

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

A wing turret is a gun turret mounted along the side, or the wings, of a warship
Warship
A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

, off of the centerline.

The positioning of a wing turret limits its arc of fire, so that it generally can contribute to only the broadside
Broadside
A broadside is the side of a ship; the battery of cannon on one side of a warship; or their simultaneous fire in naval warfare.-Age of Sail:...

 weight of fire on one side of the ship. This is the major weakness of wing turrets as broadsides were the most prevalent type of gunnery duels. Depending on the configurations of ships, such as HMS Dreadnought
HMS Dreadnought (1906)
HMS Dreadnought was a battleship of the British Royal Navy that revolutionised naval power. Her entry into service in 1906 represented such a marked advance in naval technology that her name came to be associated with an entire generation of battleships, the "dreadnoughts", as well as the class of...

 but not SMS Blücher
SMS Blücher
SMS Blücher was the last armored cruiser to be built by the German Imperial Navy . She was designed to match what German intelligence incorrectly believed to be the specifications of the British s...

, the wing turrets could fire fore and aft, so this somewhat reduced the danger of crossing the T
Crossing the T
Crossing the T or Capping the T is a classic naval warfare tactic attempted from the late 19th to mid 20th century, in which a line of warships crossed in front of a line of enemy ships, allowing the crossing line to bring all their guns to bear while receiving fire from only the forward guns of...

 and the turrets could fire at enemies to the rear.

Attempts were made to mount wing turrets en echelon so that they could fire on either beam, such as the Invincible
Invincible class battlecruiser
The three Invincible class battlecruisers were built for the Royal Navy and entered service in 1908 as the world's first battlecruisers. They were the brainchild of Admiral Sir John Fisher, the man who had sponsored the construction of the world's first "all big gun" warship,...

 and SMS Von der Tann
SMS Von der Tann
SMS Von der Tann"SMS" stands for "Seiner Majestät Schiff", or "His Majesty's Ship" in German. was the first battlecruiser built for the German Kaiserliche Marine, as well as Germany's first major turbine-powered warship. At the time of her construction, Von der Tann was the fastest dreadnought-type...

 battlecruisers, but this tended to cause great damage to the ships' deck from the muzzle blast.

Wing turrets were commonplace on capital ship
Capital ship
The capital ships of a navy are its most important warships; they generally possess the heaviest firepower and armor and are traditionally much larger than other naval vessels...

s and cruiser
Cruiser
A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

s during the late 19th century up until the early 1910s. In pre-dreadnought
Pre-dreadnought
Pre-dreadnought battleship is the general term for all of the types of sea-going battleships built between the mid-1890s and 1905. Pre-dreadnoughts replaced the ironclad warships of the 1870s and 1880s...

 battleships, the wing turret contributed to the secondary battery
Battleship secondary armament
The secondary armament of a capital ship are smaller, faster-firing weapons that are typically effective at a shorter range than the main weapons...

 of sub-calibre weapons. In large armoured cruisers, wing turrets contributed to the main battery, although the casemate
Casemate
A casemate, sometimes rendered casement, is a fortified gun emplacement or armored structure from which guns are fired. originally a vaulted chamber in a fortress.-Origin of the term:...

 mounting was more common. At the time, large numbers of smaller calibre guns contributing to the broadside were thought to be of great value in demolishing a ship's upperworks and secondary armaments, as distances of battle were limited by fire control and weapon performance.

In the early 1900s, weapon performance, armour quality
Vehicle armour
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships....

 and vessel speeds generally increased along with the distances of engagement; the utility of large secondary batteries reducing as a consequence. Therefore, the early dreadnought battleships featured "all big gun" armaments of 11 or 12 inches calibre, some of which were mounted in wing turrets. This arrangement was not satisfactory, however, as the wing turrets not only had a reduced fire arc for broadsides, but also because the weight of the guns put great strain on the hull and it was increasingly difficult to properly armour them.

Larger and later dreadnought battleships carried superimposed or superfiring turrets (i.e. one turret mounted higher than and firing over those in front of and below it). This allowed all turrets to train on either beam, and increased the weight of fire forward and aft.
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
Virginia class battleship
The Virginia class battleship was designed to be the first truly seagoing U.S. battleships. Five ships were commissioned between 1906 and 1907. The ships participated in the round-the-world cruise of the Great White Fleet. For the second and last time, the U.S...

 ship's stacked turrets would repeat itself. Larger and later guns (such as the US Navy's ultimate big gun design, the 16"/50 Mark 7) also could not be shipped in wing turrets, as the strain on the hull would have been too great.

Modern turrets

Many modern surface warships have mountings for large calibre guns, although the calibres are now generally between 3 and 5 inches (76–127 mm). The gunhouses are often just weatherproof covers for the gun mounting equipment and are made of light un-armoured materials such as glass-reinforced plastic
Glass-reinforced plastic
Fiberglass , is a fiber reinforced polymer made of a plastic matrix reinforced by fine fibers of glass. It is also known as GFK ....

. Modern turrets are often automatic in their operation, with no humans working inside them and only a small team passing fixed ammunition into the feed system. Smaller calibre weapons often operate on the autocannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

 principle, and indeed may not even be turrets at all, they may just be bolted directly to the deck.

Naming

On board warships, each turret is given an identification. In the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, these would be letters: "A" and "B" were for the turrets from the front of the ship backwards in front of the bridge, and letters near the end of the alphabet (i.e., "X," "Y," etc.) for turrets behind the bridge ship—"Y" being the rearmost. Mountings in the middle of the ship would be "P," "Q," "R," etc. Confusingly, the Dido class
Dido class cruiser
The Dido class was a class of sixteen light cruisers built for the Royal Navy. The design was influenced by the Arethusa class light cruisers. The first group of three ships was commissioned in 1940, the second group and third group were commissioned in 1941–1942...

 cruisers had a "Q" and the Nelson class
Nelson class battleship
The Nelson class was a class of two battleships of the British Royal Navy, built shortly after, and under the terms of, the Washington Naval Treaty of 1922...

 battleships had an "X" turret in what would logically be "C" position; the latter being mounted at the main deck level in front of the bridge and behind the "B" turret, thus having restricted training fore and aft.

Secondary turrets were named "P" and "S" (port and starboard) and numbered from fore to aft, e.g. P1 being the forward port turret.

Exceptions were of course made; the battleship HMS Agincourt
HMS Agincourt (1913)
HMS Agincourt was a dreadnought built in the early 1910s. The ship was originally ordered by Brazil, but the collapse of the rubber boom plus a lessening of the rivalry with Argentina led to her resale while still under construction to the Ottoman Empire who renamed her as Sultan Osman I...

 had the uniquely large number of seven turrets. These were numbered "1" to "7" but were unofficially nicknamed "Monday", "Tuesday", etc. through to "Sunday".

In German use, turrets were generally "A," "B," "C," "D," "E" going backwards from bow to stern. Usually the radio alphabet was used on naming the turrets, e.g. "Anton", "Bruno" or "Berta", "Caesar," "Dora" as on the German battleship Bismarck
German battleship Bismarck
Bismarck was the first of two s built for the German Kriegsmarine during World War II. Named after Chancellor Otto von Bismarck, the primary force behind the German unification in 1871, the ship was laid down at the Blohm & Voss shipyard in Hamburg in July 1936 and launched nearly three years later...

.

In the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

, turrets are numbered fore
Bow (ship)
The bow is a nautical term that refers to the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway. Both of the adjectives fore and forward mean towards the bow...

 to aft
Aft
Aft, in naval terminology, is an adjective or adverb meaning, towards the stern of the ship, when the frame of reference is within the ship. Example: "Able Seaman Smith; lay aft!". Or; "What's happening aft?"...

.

Land fortifications

Gun turrets have been placed in static, land fortifications such as the Maginot Line
Maginot Line
The Maginot Line , named after the French Minister of War André Maginot, was a line of concrete fortifications, tank obstacles, artillery casemates, machine gun posts, and other defences, which France constructed along its borders with Germany and Italy, in light of its experience in World War I,...

 forts in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and particularly in coastal artillery
Coastal artillery
Coastal artillery is the branch of armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications....

 defences such as Fort Drum
Fort Drum (El Fraile Island)
Fort Drum , also known as the “concrete battleship,” is a heavily fortified island fortress situated at the mouth of Manila Bay in the Philippines, due south of Corregidor Island. It was occupied by the Japanese in World War II, and was recaptured by the U.S...

, the "concrete battleship", near Corregidor
Corregidor
Corregidor Island, locally called Isla ng Corregidor, is a lofty island located at the entrance of Manila Bay in southwestern part of Luzon Island in the Philippines. Due to this location, Corregidor was fortified with several coastal artillery and ammunition magazines to defend the entrance of...

, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

. Some nations, from Albania
Albania
Albania , officially known as the Republic of Albania , is a country in Southeastern Europe, in the Balkans region. It is bordered by Montenegro to the northwest, Kosovo to the northeast, the Republic of Macedonia to the east and Greece to the south and southeast. It has a coast on the Adriatic Sea...

 to Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 and Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

, have embedded the turrets of obsolete tanks in concrete fortifications (usually to secure choke points such as mountain passes).

Aircraft

At first, guns on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 were either fixed in orientation or mounted on pedestals or simple swivel mounts. The latter evolved into the Scarff ring
Scarff ring
The Scarff ring was a type of machine gun mounting developed during the First World War by Warrant Officer F. W. Scarff of the Admiralty Air Department for use on two-seater aircraft...

, a rotating ring mount which allowed the gun to be turned to any direction with the gunner remaining directly behind it. As aircraft flew higher and faster, the need for protection from the elements led to the enclosure or shielding of the gun positions, as in the "lobsterback" rear seat of the Hawker Demon fighter.

The first bomber in the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 to carry an enclosed power operated turret was the Boulton Paul Overstrand
Boulton Paul Overstrand
-See also:-References:NotesBibliography* Brew, Alec. Boulton Paul Aircraft since 1915. London: Putnam, 1993. ISBN 0-85177-860-7.* Halley, James J. Royal Air Force Aircraft: K1000 to K9999. Tonbridge, Kent, UK: Air-Britain Ltd., 1976. ISBN 0-851330-048-0.* Lewis, Peter. The British Bomber since...

 which first flew in 1933. The Overstrand had a single turret, which was at the front of the bomber fitted with one machine gun. Movement of the gun on its mount actuated motors that rotated the turret.

In time the number of turrets carried and the number of guns mounted increased. RAF heavy bombers of World War II typically had three powered turrets, with the rear one—the tail gunner
Tail gunner
A tail gunner or rear gunner is a crewman on a military aircraft who functions as a gunner defending against enemy fighter attacks from the rear, or "tail", of the plane. The tail gunner operates a flexible machine gun emplacement on either the top or tail end of the aircraft with a generally...

 or "Tail End Charlie" position—mounting the heaviest armament of four 0.303 inch Browning machine guns
M1919 Browning machine gun
The M1919 Browning is a .30 caliber medium machine gun that was widely used during the 20th century. It was used as a light infantry, coaxial, mounted, aircraft, and anti-aircraft machine gun by the U.S. and many other countries, especially during World War II, the Korean War, and the Vietnam War...

 or, late in the war, two 0.5 inch machine guns.
During the World War II era, British turrets were largely self contained units, manufactured by Boulton Paul Aircraft
Boulton Paul Aircraft
Boulton Paul Aircraft Ltd was a British aircraft manufacturer that was created in 1934, although its origins lay in 1914, and lasted until 1961...

 and Nash & Thomson
Nash & Thomson
Nash & Thompson was a British engineering firm that specialised in the production of hydraulically-operated gun turrets for aircraft. The company was also an important manufacturer of hydraulic powered radar scanners, used on radar systems such as H2S and AI Mark VIII.- History :Nash & Thompson was...

. The same model of turret might be fitted to several different aircraft types.
Some models included gun-laying radar that could lead
Deflection (military)
Deflection is a technique used for effectively firing a ranged weapon at a moving target, that describes "leading the target"; that is, shooting ahead of a moving target so that the target and projectile will collide...

 the target and compensate for bullet drop.

The Martin B-10
Martin B-10
The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934...

 introduced turret-mounted defensive armament within the United States Army Air Corps
United States Army Air Corps
The United States Army Air Corps was a forerunner of the United States Air Force. Renamed from the Air Service on 2 July 1926, it was part of the United States Army and the predecessor of the United States Army Air Forces , established in 1941...

, nearly a year after the Overstrand, with a power-operated nose turret.

The UK introduced the concept of the "turret fighter", with aeroplanes such as the Boulton Paul Defiant
Boulton Paul Defiant
The Boulton Paul Defiant was a British interceptor aircraft that served with the Royal Air Force early in the Second World War. The Defiant was designed and built by Boulton Paul Aircraft as a "turret fighter", without any forward-firing guns. It was a contemporary of the Royal Navy's Blackburn Roc...

 where the armament (4 x 0.303 in (7.7 mm) machineguns) was in a turret mounted behind the pilot rather than in fixed positions in the wings. The concept came at a time when the standard armament of a fighter was only two machine guns. In the face of heavily armed bombers operating in formation it was felt that a group of turret fighters would be able to concentrate their fire flexibly on the bombers; making beam, astern and from below attacks practicable.

Although the idea had some merits in attacking bombers, it was found to be impractical when dealing with other fighters; the weight and drag of the turret impaired the airplane's speed and maneuverability relative to a conventional fighter which the flexibility of the turret armament could not compensate for. At the same time conventional fighter designs were flying with 8 or more machine guns. Attempts to put heavier armament (multiple 20 mm cannon)in low profile aerodymanic turrets were explored by the British
Boulton Paul P.92
-See also:-External links:* * * *...

 but not successful.

The placing of some of the armament in a turret was taken up by other countries. The large purpose-built Northrop P-61 Black Widow nightfighter was produced with a dorsal turret that had a wide range of fire though in practice it was generally fired directly forward under control of the pilot. Some German heavy fighters had barbettes that fired to the rear.

Not all turret designs put the gunner in the turret along with the armament. Both the Americans and Germans produced aircraft with remote controlled turrets. In the US B-17 Flying Fortress a 2-gun chin turret was added to later models to give more forward defence. Specifically designed to be compact and not obstruct the bombardier, it was operated by a hand-controller and aimed by a reflector sight mounted in the windscreen. The German He-177 Greif
Heinkel He 177
The Heinkel He 177 Greif was the only operational long-range bomber to be operated by the Luftwaffe. Starting its existence as Germany's first purpose-built heavy bomber just before the war, and built in large numbers during World War II, it was also mistakenly tasked, right from its beginnings,...

 had a turret on the top of the fuselage which was operated from an "astrodome" in the cockpit. The US B-29 Superfortress had four remote controlled turrets operated from the pressurised sections in the nose and middle of the aircraft with one gunner directing the others.

The defensive turret on bombers fell from favour with the realization that bombers could not attempt heavily defended targets without escort regardless of their defensive armament unless very high loss rates were acceptable, and the performance penalty from the weight and drag of turrets reduced speed, range and payload and increased the number of crew required. The British de Havilland Mosquito
De Havilland Mosquito
The de Havilland DH.98 Mosquito was a British multi-role combat aircraft that served during the Second World War and the postwar era. It was known affectionately as the "Mossie" to its crews and was also nicknamed "The Wooden Wonder"...

 light bomber was designed without any defensive armament and used its speed to avoid engagement with fighters.

A small number of aircraft continued to use turrets however—in particular maritime patrol aircraft such as the Avro Shackleton
Avro Shackleton
The Avro Shackleton was a British long-range maritime patrol aircraft for use by the Royal Air Force. It was developed by Avro from the Avro Lincoln bomber with a new fuselage...

 used one as an offensive weapon against small unarmoured surface targets. The Boeing B-52 jet bomber and many of its contemporaries (particularly Russian) featured a tail-mounted barbette
Barbette
A barbette is a protective circular armour feature around a cannon or heavy artillery gun. The name comes from the French phrase en barbette referring to the practice of firing a field gun over a parapet rather than through an opening . The former gives better angles of fire but less protection...

, or "remote turret" —an unmanned turret but often with more limited field of fire.

Aircraft carry their turrets in various locations:
  • "dorsal" – on top of the fuselage
    Fuselage
    The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

    , sometimes referred to as a mid-upper turret.
  • "ventral" – underneath the fuselage.
  • "rear" or "tail" – at the very end of the fuselage.
  • "nose" – at the front of the fuselage.
  • "chin" – below the nose of the aircraft as on later versions of the Boeing B-17.
  • "wing" – a handful of very large aircraft, such as the Messerschmitt Me 323
    Messerschmitt Me 323
    The Messerschmitt Me 323 Gigant was a German military transport aircraft of World War II. It was a powered variant of the Me 321 military glider and was the largest land-based transport aircraft of the war...

     and the Blohm & Voss BV 222, had manned turrets in the wings
  • "beam" – mounted on the sides of the fuselage such as on the Consolidated Privateer.


Combat vehicles

Although considered for use from the start, turrets for combat vehicle
Combat vehicle
A combat vehicle, also known as a ground combat vehicle, is a self-propelled, weaponized military vehicle used for combat operations. Combat vehicles can be wheeled or tracked.- Automation :...

s were not introduced until late in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 by the French Renault FT-17
Renault FT-17
The Renault FT, frequently referred to in post-WWI literature as the "FT-17" or "FT17" , was a French light tank; it is among the most revolutionary and influential tank designs in history...

 light tank—a single, fully rotating turret carried the vehicle's main armament. This continues to be the standard of almost every modern main battle tank
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 and many self-propelled gun
Self-propelled gun
A self-propelled gun is form of self-propelled artillery, and in modern use is usually used to refer to artillery pieces such as howitzers....

s.

In the 1930s, several nations produced multi-turreted tanks—probably influenced by the British Vickers A1E1 Independent
Vickers A1E1 Independent
The Independent A1E1 is a multi-turreted tank that was designed by the British armaments manufacturer Vickers during the interwar period. Although it only ever reached the prototype stage it influenced many other tank designs....

 of 1926. Those that saw combat during the early part of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 performed poorly and the concept was soon dropped. Combat vehicles without turrets, with the main armament mounted in the hull, or more often in an integral armored casemate
Casemate
A casemate, sometimes rendered casement, is a fortified gun emplacement or armored structure from which guns are fired. originally a vaulted chamber in a fortress.-Origin of the term:...

 as part of the main hull, saw extensive use by German and Russian forces during World War II as Tank destroyer
Tank destroyer
A tank destroyer is a type of armored fighting vehicle armed with a gun or missile launcher, and is designed specifically to engage enemy armored vehicles...

s and assault gun
Assault gun
An assault gun is a gun or howitzer mounted on a motor vehicle or armored chassis, designed for use in the direct fire role in support of infantry when attacking other infantry or fortified positions....

s. However, post-war, the concept fell out of favour due to its limitations, with the Swedish Stridsvagn 103
Stridsvagn 103
The Stridsvagn 103 , or S-Tank , was a Swedish post-war main battle tank. It was known for its unconventional turret-less design, with a fixed gun traversed by engaging the tracks and elevated by adjusting the hull suspension...

 'S-Tank' and the German Kanonenjagdpanzer
Kanonenjagdpanzer
The Kanonenjagdpanzer 4 - 5 was a German Cold War tank destroyer equipped with a 90mm anti-tank gun, which remained from the outphased M47 Patton tanks...

 being exceptions.

In modern tanks, the turret is armoured for crew protection and rotates a full 360 degrees carrying a single large-calibre tank gun
Tank gun
A tank gun is the main armament of a tank. Modern tank guns are large-caliber high-velocity guns, capable of firing kinetic energy penetrators, high explosive anti-tank rounds, and in some cases guided missiles. Anti-aircraft guns can also be mounted to tanks.-Overview:Tank guns are a specific...

, typically in the range of 105 mm to 125 mm calibre. Machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

s may be mounted inside the turret. On modern tanks, the turret houses all the crew except the driver—two or more crewmen, typically a tank commander, gunner, and often a gun loader.

For other combat vehicles, the turrets are equipped with other weapons dependent on role. An infantry fighting vehicle
Infantry fighting vehicle
An infantry fighting vehicle , also known as a mechanized infantry combat vehicle , is a type of armoured fighting vehicle used to carry infantry into battle and provide fire support for them...

 may carry a smaller calibre gun or an autocannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

, or an anti-tank missile launcher, or a combination of weapons. A modern self-propelled gun mounts a large artillery gun but less armour. Lighter vehicles may carry a one-man turret with a single machine gun.

The size of the turret is a factor in combat vehicle design. One dimension mentioned in terms of turret design is "turret ring diameter" which is the size of the aperture in the top of the chassis.

External links

  • Air Gunnery November 1943 Popular Science
    Popular Science
    Popular Science is an American monthly magazine founded in 1872 carrying articles for the general reader on science and technology subjects. Popular Science has won over 58 awards, including the ASME awards for its journalistic excellence in both 2003 and 2004...

    article on aircraft turrets
  • Flight article on aircraft gun turrets amongst others
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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