Turret

Corbelled corner turrets at Newark Castle, Port Glasgow.

In architecture, a turret (from Italian: torretta, little tower; Latin: turris, tower) is a small tower that projects from the wall of a building such as a medieval castle. Turrets were used to provide a projecting defensive position allowing covering fire to the adjacent wall in the days of military fortification. As their military use faded turrets were adopted for decorative purposes, as in the Scottish baronial style.

In current military terminlogy, 'turret' usually refers to 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.

Contents

1 Turrets in architecture
2 Gun turrets

2.1 Aircraft
2.2 Armoured fighting vehicles
2.3 Warships

2.3.1 Naming

3 See also

Turrets in architecture

Turret (highlighted) attached to a tower on a baronial building in Scotland.

A building may have both towers and turrets; turrets might be smaller or higher but the difference is generally considered to be that a turret projects from the edge of the building, rather than continuing to the ground. The size of a turret is therefore limited by technology, since it puts additional stresses on the structure of the building. It would traditionally be supported by a corbel.

A turret might have a flat top with crenellations as in the picture, a pointed roof, or any other kind of top. It might contain a staircase if it projects higher than the building. However, a turret might not be any higher than the rest of the building; in this case it is part of a room, that can be simply walked into – see the turret of Chateau de Chaumont on this [collection of turrets], which also illustrates a turret on a modern skyscraper.

Gun turrets

A turret may be armed with one or more machine guns, automatic cannon, large-calibre guns, or missile launchers. 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.

Aircraft

At first, guns on aircraft were either fixed in orientation or mounted on simple swivel mounts. The latter evolved into the Scarff ring, 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. The first bomber in the Royal Air Force to cary a power operated turret was the Boulton Paul Overstrand which first flew in 1933. The Overstrand had a single turret which was at the front of the bomber fitted with one machine gun. In time the number of turrets carried and the number of guns mounted increased. RAF heavy bombers of the Second World War typically had 3 powered turrets, with the rear one - the "Tail End Charlie" position - mounting four 0.303 inch machine guns.

The UK tried the concept of the "turret fighter" in planes such as the Boulton Paul Defiant where the sole armament was in a turret mounted behind the pilot rather than in fixed positions in the wings. Though the idea had some merits in attacking bombers, it was found to be impractical when dealing with other fighters as the weight and drag slowed the aeroplane. The defensive turret on bombers fell from favour with the advent of the jet age, though the Boeing B-52 jet bomber and many of its contemporaries featured a tail mounted barbette - a form of turret but with more limited field of fire.

Aircraft carry their turrets in various locations:

"dorsal" - on top of the fuselage
"ventral" - underneath the fuselage
"rear" - at the very end of the fuselage
"nose" - at the front of the fuselage
"chin" - below the nose of the aircraft

Armoured fighting vehicles

In modern tanks the turret (which is armoured for crew protection) rotates a full 360 degrees and carries a single large-caliber tank gun, typically in the range of 105 mm to 125 mm caliber and one or more machine guns. The turret houses two or more crewmen, typically a tank commander, gunner, and often a gun loader. For other armoured fighting vehicles, the turrets are equipped with other weapons dependent on role. An infantry fighting vehicle may carry a smaller caliber gun or an autocannon, or a 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.

Warships

Model of quadruple 380 mm turret, the main armament of the French battleships Richelieu and Jean Bart.

The parts of a battleship turret.

One of the earliest turret gun ships was the USS Monitor, which mounted two cannons 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".

The rotating part of a battleship turret is the "gunhouse" where the guns are loaded. Below the gunhouse are the loading hoists that bring ammunition up from the magazines to the gunhouse. The handling equipment and hoists can be complex arrangements of machinery. They have to take the shells and propelling charges from their magazines into the base of the turret. There they have to be lined up with the hoists which are fixed in orientation to the guns. The hoists then lift the ammuniton up to the gunhouse where the shells and the appropriate charge are mechanically loaded into each gun breech. It was not until the last of the rotating drum designs was phased out that the hooded barbette arrangement - which is the style associated with modern warships - took the name "turret". The barbette is armoured down to where it reaches the main armoured deck of the warship. The gunhouse is not attached to the ship in any way, but rides on rollers; if the ship were to capsize, the gunhouses would fall out.

Some modern warships still have turrets with guns, though these are less important to ships with modern missile systems. These turrets are often just covers for the gun mounting equipment, and are made of light unarmoured materials such as fibreglass

Naming

On board warships, each turret is given an identification. In British use, these would be letters: "A," "B," "C," etc. for the turrets from the front of the ship backwards, and letters near the end of the alphabet (i.e., "X," "Y," etc.) for turrets in the rear of the ship. Mounts in the middle of the ship would be "Q," "R," etc. In one instance (HMS Agincourt), the battleship's turrets were named "Monday," "Tuesday," etc. up to "Sunday." In German use, turrets were generally "A," "B," "C," "D," "E" going backwards from stem to stern. Usually the phonetic alphabet was used on naming the turrets, e.g. "Anton", "Bruno", "Caesar," "Dora" as on the German battleship Bismarck.