The Fuze Keeping Clock (FKC) was a simplified version of the Royal Navy's High Angle Control System analogue fire control computer. It first appeared as the FKC MkII in destroyers of the 1938 ,''Tribal Class Destroyers'', Hodges, p. 27 while later variants were used on

sloops A sloop is a sailboat with a single mast typically having only one headsail in front of the mast and one mainsail aft of (behind) the mast. Such an arrangement is called a fore-and-aft rig, and can be rigged as a Bermuda rig with triangular ...

, frigates, destroyers, aircraft carriers and several cruisers. The FKC MkII was a non- tachymetric anti-aircraft fire control computer. It could accurately engage targets with a maximum speed of .

Operation

The FKC received vertical reference information from a ''Gyro Level Corrector'' and aircraft altitude, range, direction, and speed input information from the ''Rangefinder-Director'', and output to the guns the elevation and deflection data needed to hit the target, along with the correct fuze timing information, so that the shells fired would explode in the vicinity of the target aircraft. Most guns controlled by the FKC had ''Fuze Setting Pedestals'' or ''Fuze Setting Trays'' where the correct fuze timing was set on a clockwork mechanism within the AA shell warhead. Radar and Electronic Warfare 1939-1945 A28824

Radar and Electronic Warfare 1939-1945 A28824

Development

Type 285 radar The Type 285 radar was a British naval anti-aircraft gunnery radar developed during the Second World War. The prototype was tested at sea aboard the escort destroyer in August 1940.Campbell, p. 16 Notes Bibliography * * *{{cite book, last ...

was an early addition to the FKC system, being fitted on new destroyers from mid-1941 onward, and retrofitted to existing destroyers as time and opportunity permitted. Later variants increased the maximum target speed to , and were combined with Gyro Rate Units (GRU) which gave tachometric capabilities to the system, and

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

which greatly improved ranging and rate keeping accuracy.Naval Weapons of WW2, Campbell

Wartime use

The FKC saw extensive use during the war on

British Commonwealth The Commonwealth of Nations, simply referred to as the Commonwealth, is a political association of 56 member states, the vast majority of which are former territories of the British Empire. The chief institutions of the organisation are the C ...

naval ships, typically on destroyers and sloops. Prior to the widespread use of radar, optical detection and ranging on high altitude aerial targets was a daunting task, as shown by 's Report of Proceedings, for 3 September 1940: Occasionally conditions would conspire to favour the surface ships during an aerial attack, as again revealed by HMAS ''Parramatta''s Report of Proceedings, for 20 September 1940: The FKC was used throughout the war and its effectiveness was increased by the use of radar for gunnery and to provide warning against surprise attack, as demonstrated by this account of bringing down a Japanese

A6M Zero The Mitsubishi A6M "Zero" is a long-range carrier-based fighter aircraft formerly manufactured by Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and was operated by the Imperial Japanese Navy from 1940 to 1945. The A6M wa ...

fighter aircraft (a "HAMP"), in 1944:

Notes

External links

''The Gunnery Pocket Book'', B.R. 224/45, 1945
* {{webarchive , url=https://web.archive.org/web/20110810225047/http://sydney.edu.au/engineering/it/research/tr/tr223.pdf , title= British Mechanical Gunnery Computers of World War II
Illustration of the FKC Mk II
Anti-aircraft artillery Military computers Naval artillery Artillery operation Equipment of the Royal Navy Fire-control computers of World War II Military equipment introduced in the 1930s