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WW II Gun Turret Tech Advance

12 May 2022

Geoff Wong is an avid aviation researcher and had moment to observe the stark advances in gun turret technology of heavy aircraft during World War II. Recently he was in the RAAFA Aviation Heritage Museum in Bull Creek Australia (near Perth) and took closer looks at the standard-of-the-day bow turret of a Short Brothers Sunderland and a remarkably dissimilar gun turret of a Boeing B-29 Superfortress—the differences in their technology are astounding and occurred over just a handful of years.

The Sunderland’s bow turret was hydraulically operated and mounted a pair of Vickers Browning .303 machine guns. Unusually, this turret was retractable—being pulled into the fuselage to expose a line handling position for a crewman to stand within for mooring the aircraft at a buoy or dock. A gunner was required to sit within the FN-13 turret, manufactured by Nash & Thompson, relying on eyesight, as well as crew communication, to defend the aircraft from attacking aircraft.

Short Bros. Sunderland Nash & Thompson FN-13 bow gun turret—Geoff Wong ©2022
Rear view of the Short Bros. Sunderland FN-13 bow gun turret showing the clear space required to retract the turret for mooring operations—Geoff Wong ©2022
Interior view of the Short Sunderland Nash & Thompson bow gun turret looking into the gunner’s position—Geoff Wong ©2022
Port side view of the Short Bros. Sunderland bow gun turret as well as its pair of Vickers Browning .303 machine guns—Geoff Wong ©2022

The Avro Lincoln’s (an evolution of the Avro Lancaster) nose turret was remotely controlled but only just. This was the Boulton-Paul F turret and it was placed directly over the bombardier’s position where its controls extended downward to the bombardier. This allowed for a bit of weight saving (by eliminating required space for an additional gunner) as well as streamlining. It was maneuvered by a hybrid electro-hydraulic system and loaded with just 275 rounds for each weapon. Fire control was still the basic Mark I eyeball. The RAF had, at least, improved defensive firepower by using .50 caliber machine guns over the formerly ubiquitous .303 caliber machine guns. The Lincoln’s other turrets each also had two .50 caliber machine guns mounted but were each manned by a gunner with no remote control capability.

Boulton-Paul F remotely controlled gun turret from an Avro Lincoln—Geoff Wong ©2022
Rear aspect of this Boulton-Paul F remotely controlled gun turret from an Avro Lincoln—Geoff Wong ©2022
The RAAFA Air Heritage Museum innovatively employs a clear plastic panel to better observe the interior of the Boulton-Paul F remotely controlled gun turret from an Avro Lincoln—Geoff Wong ©2022

On the other hand, the B-29 gun turrets were unmanned, electrically driven and were armed with two Browning .50 caliber machine guns each as well as being entirely remote from the gunner positions. This design had many inherent advantages as the weight of each turret was reduced which eased in mechanically traversing them. Aiming was vastly improved with the use of analog computers developed by General Electric—which accounted for barometric pressure, altitude, relative velocity and parallax error—that doubled the effective range of the Superfortress’s machine guns. This same system also had redundancy which allowed for one gunner to control multiple turrets or another turret of a wounded, or killed, fellow gunner. Quite a difference from other heavy bombers of the war as attacking fighters could now get the full, computer assisted, attention of at least four .50 caliber machine guns in two of the B-29’s five gun positions—all with a greater effective range than the opposing fighter’s own machine guns.  

Our thanks to Geoff Wong for these images and insights 🙂



This post was revised from the original post as an error was made in originally identifying the Boulton-Paul F turret, from an Avro Lincoln, as one from a B-29 turret.

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