The Royal Navy during the Second World War A3651

"Pom-Pom" director was a

director Director may refer to: Literature * ''Director'' (magazine), a British magazine * ''The Director'' (novel), a 1971 novel by Henry Denker * ''The Director'' (play), a 2000 play by Nancy Hasty Music * Director (band), an Irish rock band * ''Di ...

for British anti-aircraft guns on British warships of the 1930s into the Second World War.

Development

The Vickers 40 mm QF 2 pounder "Pom-Pom" gun anti-aircraft mounting was introduced to the Royal Navy in the early 1930s. The multi-barrel mounting was capable of a tremendous volume of fire but the crew had great difficulty in aiming the mounting due to the smoke and vibration created by the guns. It was, therefore, essential to aim the mount from a remote location, using a

that had a clear view, free from smoke and vibration. The director crew would aim at the target aircraft and, in the early versions of the director, cause the layer (altitude) and trainer (

azimuth An azimuth (; from ar, اَلسُّمُوت, as-sumūt, the directions) is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north. Mathematicall ...

) pointers to rotate on the gun mount. The gun crew would then move the mount to match the pointers rather than having to try and aim at the target aircraft.

Mark I - III directors

Directors I to III controlled the gun mounting through "follow the pointer" control and aimed at aircraft using eye shooting techniques through a simple ring sight. These directors began to appear on Royal Navy cruisers, battleships and aircraft carriers in 1930. They were universally fitted, one per pom-pom gun mounting, by the late 1930s. Most destroyers and smaller ships that carried 2-pounder guns continued to rely on aiming the guns with the on-mount gunsights due to the lack of space on these ships to site a director.

Director Mark IV

The Mk IV director was a considerable improvement and used

gyroscopes A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotat ...

in a gyro rate unit coupled to an optical

rangefinder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, such as photography an ...

and

Type 282 radar Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

to determine the range, speed and direction of enemy aircraft and then used an on-director computer to produce an accurate fire control solution to hit the target. Later versions of the Mk IV director introduced remote power control (RPC) and could control the gun mounting by remote control from the director. The Mk IV director was fully

tachymetric A tachymetric anti-aircraft fire control system generates target position, speed, direction, and rate of target range change, by computing these parameters directly from measured data. The target's range, height and observed bearing data are fed i ...

, but performance suffered as the director was not stabilized against the movement of the ship. It consequently required a carefully trained crew (a total of eight including the radar operator in the radar office) to achieve good results. Even so, the Mk IV director was highly advanced and placed the Royal Navy in the forefront of naval anti-aircraft fire control when it was introduced to the Royal Navy on in 1940. Later versions were upgraded with

and RPC beginning in 1941, with HMS ''Prince of Wales'' being one of the first ships to receive the radar upgrade, which she first used in action during

Operation Halberd Operation Halberd was a British naval operation that took place on 27 September 1941, during the Second World War. The British were attempting to deliver a convoy from Gibraltar to Malta. The convoy was escorted by several battleships and an air ...

.Tarrant, ''King George V class Battleships'', p88

Notes and references

External links

{{Commonscat-inline, QF 2 pounder pom-pom
The Pom-Pom Director, Mark IV
in ''The Gunnery Pocket Book'', B.R. 224/45, 1945 placed online courtesy of Historic Naval Ships Association
Illustration of the Pom-Pom Director, Mark IV in ''The Gunnery Pocket Book'', B.R. 224/45, 1945
placed online courtesy of Historic Naval Ships Association Artillery operation Naval guns of the United Kingdom Military computers Fire-control computers of World War II de:Ordnance QF 2-Pfünder-Marinegeschütz it:2 libbre navale ja:ポンポン砲 pl:Armata przeciwlotnicza 40 mm Mark VIII

Development

Mark I - III directors

Director Mark IV

See also

Notes and references

External links