Gun Turret - Aircraft

Aircraft

At first, guns on aircraft were either fixed in orientation or mounted on pedestals or 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, as in the "lobsterback" rear seat of the Hawker Demon fighter.

The first bomber in the Royal Air Force to carry an enclosed 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. Movement of the gun on its mount actuated motors that rotated the turret.

The American Martin B-10 all-metal monocoque monoplane bomber introduced turret-mounted defensive armament within the United States Army Air Corps, almost simultaneously with the RAF's Overstrand biplane bomber design. The Martin XB-10 prototype aircraft first featured the nose turret in June 1932, and was first produced as the YB-10 service test version by November 1933. The production B-10B version started service with the USAAC in July 1935.

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 or "Tail End Charlie" position—mounting the heaviest armament of four 0.303 inch Browning machine guns or, late in the war, two AN/M2 light-barrel versions of the American Browning M2 machine gun.

During the World War II era, British turrets were largely self-contained units, manufactured by Boulton Paul Aircraft and Nash & Thomson. The same model of turret might be fitted to several different aircraft types. Some models included gun-laying radar that could lead the target and compensate for bullet drop.

The UK introduced the concept of the "turret fighter", with aeroplanes such as the Boulton Paul Defiant 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 aerodynamic turrets were explored by the British but not successful.

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, the large, purpose-built Northrop P-61 Black Widow night fighter was produced with a remotely-operated dorsal turret that had a wide range of fire though in practice it was generally fired directly forward under control of the pilot. For the last production blocks of the B-17F, and for all versions of the B-17G Flying Fortress a twin-gun remotely operated "chin" turret, designed by Bendix and first used on the experimental YB-40 "gunship" version of the Fortress, was added 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 intended replacement for the German Bf 110 heavy fighter, the Messerschmitt Me 210, possessed twin half-teardrop-shaped, remotely-operated Ferngerichtete Drehringseitenlafette FDSL 131/1B turrets, one on each side "flank" of the rear fuselage to defend the rear of the aircraft, controlled from the rear area of the cockpit. By 1942, the German He 177A Greif heavy bomber would feature a Fernbedienbare Drehlafette FDL 131Z remotely operated forward dorsal turret, armed with twin 13mm MG 131 machine guns on the top of the fuselage, which was operated from a rotating "astrodome" just behind the cockpit glazing — a second, manned dorsal turret, further aft on the fuselage was also used on most examples. 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 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 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 (a term from British English), 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, sometimes referred to as a mid-upper turret.
"ventral" – underneath the fuselage, often on American WW II heavy bombers, a Sperry-designed ball turret .
"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 and the Blohm & Voss BV 222, had manned turrets in the wings
"beam" (British English) or "waist" (American English) – mounted on the sides of the fuselage such as on the Consolidated Privateer.

Consolidated B-24 Liberator nose turret
The Bendix-designed B-17 chin turret
A preserved North American B-25 Mitchell, showing the dorsal turret
B-29 remote controlled ventral turret
Wing turrets of an Me 323
Avro Lancaster tail turret