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54-556: 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 , while later variants were used on sloops , 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

108-421: A 100 kilograms (220 lb) bomb. The aircraft passed down the port side at an estimated speed of 340 knots (630 km/h). As this speed exceeded the limits of the fuze keeping clock, aim off was allowed in the director and the bursts, which were at first astern of the aircraft as the range opened, were then close ahead of the target. The port Oerlikons opened fire at the same time as the main armament and, when

162-493: A document dated as "revised Aug 1940": Morotai Island The island in the Halmahera group of eastern Indonesia 's Maluku Islands (Moluccas); it is one of Indonesia's northernmost islands. Morotai is a rugged, forested island lying to the north of Halmahera. It has an area of some 2,336.6 km (902.2 sq mi), including Rao Island which lies to the west of Morotai and forms an administrative district within

216-488: A maximum speed of 250 knots (460 km/h; 290 mph). 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

270-409: A paved road linking those on the east coast starts from Daruba and will eventually reach Bere-Bere , the principal town on Morotai's east coast, 68 kilometres (42 mi) from Daruba. Daruba, the main settlement and the seat of the regency has a tropical rainforest climate (Af) with moderate rainfall from August to October and heavy rainfall in the remaining months. At the 2010 census, the regency

324-477: A range of 2,000 yards (1,800 m). RN destroyers were hampered by the lack of good dual-purpose weapons suitable for ships of destroyer size; for much of the war 40° was the maximum elevation of the 4.7-inch (119 mm) guns equipping such ships, which were consequently unable to engage directly attacking dive bombers , although they could provide "barrage" and "predicted fire" to protect other ships from such attacks. Destroyers did not use HACS, but rather

378-563: A technique known as " lobe switching " but only crude estimates of altitude. It could not, therefore, "lock on" to aerial targets and was unable to provide true blindfire capabilities, which no other navy was able to do until the USN developed advanced radars in 1944 using technology transfers from the UK. This situation was not remedied until the introduction of the HACS Mark VI director in 1944 that

432-465: Is the apparent target motion along the line of sight. This was also printed on a paper plot so that a range rate officer could assess its accuracy. This calculated range rate was fed back to the UD4 where it powered a motor to move prisms within the UD4. If all the measurements were correct, this movement would track the target, making it appear motionless in the sights. If the target had apparent movement,

486-649: The Battle of Morotai , and used as a staging point for the Allied invasion of the Philippines in early 1945, and of Borneo in May and June of that year. In the latter part of 1944, 61,000 personnel landed on Morotai. Two thirds of them were engineers, who rapidly established facilities including harbors and two airstrips plus extensive fuel stores. Imperial Japanese forces on Morotai held out until 1945 but failed to expel

540-448: The CIA . AUREV aircraft attacked Morotai on April 21 and again early on April 26. The second air raid was immediately followed by an amphibious Permesta landing force that quickly captured the island. Within hours, a Douglas C-47 Skytrain transport aircraft landed on the now captured airstrip, carrying senior Permesta representative and two Americans. One was a USAF officer who inspected

594-519: The Fuze Keeping Clock (FKC), a simplified version of HACS. Starting in 1938 all new RN destroyers, from the Tribal class onwards, were fitted with a FKC and continuous prediction fuse setting trays for each main armament gun. WWII experience from all navies showed that dive bombers could not be engaged successfully by any remote computer-predictive AA system using mechanical fuzes due to

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648-605: The North Halmahera Regency . After assessing three potential spaceport sites in 2012, the national space agency LAPAN announced Morotai Island as a future spaceport site. Planning started in December 2012. The launch site's completion is expected in 2025. In 2013, LAPAN planned to launch an RX-550 experimental satellite launcher from a location in Morotai to be decided. This island was selected according to

702-464: The QF 2 pdr (40mm) "pom pom" mounts , and a long range Type 281 radar Warning Air (WA) radar which also had precision ranging panels for aerial and surface targets. This placed HMS Prince of Wales in the forefront of naval HA AA fire control systems at that time. In August and September 1941, HMS Prince of Wales demonstrated excellent long range radar directed AA fire during Operation Halberd . Although

756-629: The Allied troops. The formal surrender of the Second Japanese Army took place at Morotai on 9 September 1945. The last confirmed Japanese holdout from the war, Private Teruo Nakamura ( Amis : Attun Palalin), was discovered by the Indonesian Air Force on Morotai, and surrendered to a search patrol on December 18, 1974. The Dutch Empire withdrew in the Indonesian National Revolution in

810-646: The Christian population of the island moved to Malayu , on Ternate, where they could be more easily controlled. The Ternate Sultanate was a vassal of the Dutch East India Company by the end of the 17th century. The island was captured by the Japanese in early 1942 as part of its Dutch East Indies Campaign . Morotai's southern plain was taken by American forces in September 1944 during

864-458: The Convoy at approximately 14,000 ft and gave H.M.S "Auckland" and myself an unrivalled opportunity for steady firing for some minutes. Two of the aircraft appeared to drop out of formation, one going into a spin. It has been subsequently ascertained that not one of the five aircraft reached home, in fact we had a one hundred per cent success. The FKC was used throughout the war and its effectiveness

918-441: The Convoy, but they released early, and the entire outfit fell around "Parramatta". The ship, then nearly stopped getting in the mine-sweeps, was not struck, although there were several near misses. Although splinters flew over us there were no casualties, and the minesweeping party aft calmly continued to get in the sweeps with the after gun firing over their heads and bombs dropping close around them. The Italian planes continued over

972-632: The HACP, which transmits direction and fuse timing orders to the guns. The HACP transmits the computer generated range rate and generated bearing back to the HADT, creating a feedback loop between the HADT and HACP, so that the fire control solution generated by the computer becomes more accurate over time if the target maintains a straight line course. The HADT also observes the accuracy of the resulting shell bursts and uses these bursts to correct target speed and direction estimates, creating another feed back loop from

1026-477: The HACS into a tachymetric system. Also in 1940, radar ranging was added to the HACS. The GRU and its associated computer, the "Gyro Rate Unit Box" (GRUB) no longer assumed straight and level flying on the part of the target. GRU/GRUB could generate target speed and position data at angular rates of up to 6 degrees per second, which was sufficient to track a 360- knot (670 km/h; 410 mph) crossing target at

1080-849: The Luftwaffe with stabilised HACS IV systems with GRU/GRUB and Type 279 radar with the Precision Ranging Panel, which gave +/- 25 yd accuracy out to 14,000 yds. HMS Fiji was sunk in the Battle of Crete after running out of AA ammunition but her HACS IV directed 4-inch AA gun battery fended off Luftwaffe attacks for many hours. Demonstrating the RN's rapid strides in naval AA gunnery, in May 1941, HMS Prince of Wales went to sea with HACS IVGB, with full radar ranging systems, and nine AA associated fire control radars: four Type 285 radar , one on each High Angle Director Tower (HADT) and four Type 282 radar , one on each Mk IV director for

1134-513: The UD4 operator would adjust the range and height, and in so doing would update the generated range rate, thereby creating a feedback loop which could establish an estimate of the target's true speed and direction. The HACS also displayed the predicted bearing and elevation of the target on indicators in the Director tower, or on later variants, the HACS could move the entire Director through Remote Power Control so that it could continue to track

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1188-425: The aircraft was bearing approximately Red 140, bursts from the after port Oerlikon were seen to enter the target. The "HAMP" was seen to crash approximately one mile west of Dodola Island. This was confirmed later by an American Army Officer serving on Dodola Island and also by a tidal observation party from "WARREGO" , camped on Kokova Island. High Angle Control System High Angle Control System ( HACS )

1242-409: The direction of Bandera Hill... In the next few minutes three aircraft were picked up by radar on the starboard side. Two of these had closed to 9,000 yards when a "HAMP" appeared at Red 75 at a height of about 1,000 feet apparently making a bombing run on the ship. Fire was opened in director barrage firing and the first broadside burst immediately ahead of the aircraft forcing it to bank and to jettison

1296-607: The director. The HACS was a control system and was made possible by an effective data transmission network between an external gun director, a below decks fire control computer, and the ship's medium calibre anti-aircraft (AA) guns. The bearing and altitude of the target was measured directly on the UD4 Height Finder/Range Finder , a coincidence rangefinder located in the High Angle Director Tower (HADT). The direction of travel

1350-731: The extreme heat and humidity in Malayan waters and her 2-pdr ammunition had deteriorated badly as well. The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 28 March 1941: :Certain kills: 234, Probable kills: 116, Damage claims: 134 The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 31 Dec 1942: HACS used various director towers that were generally equipped with Type 285 as it became available. This metric wavelength system employed six yagi antennas that could take ranges of targets, and take accurate readings of bearing using

1404-461: The following criteria: Morotai is a rugged, forested island lying to the north of Halmahera . It has an area of some 2,336.6 square kilometres (902.2 sq mi), including Rao Island off the west coast of Morotai. It stretches 80 kilometres (50 mi) north-south and no more than 42 kilometres (26 mi) wide. The regency's largest town is Daruba , on the island's south coast. Almost all of Morotai's numerous villages are coastal settlements;

1458-449: The guns to the HADT and thence to the HACP, again increasing the accuracy of the solution, if the target maintains a straight line course. Most guns controlled by the HACS had Fuze Setting Pedestals or Fuze Setting Trays where the correct fuze timing was set on a clockwork mechanism within the AA shell warhead, so that the shell would explode in the vicinity of the target aircraft. The HACS

1512-502: The intersection of the outer edge of the ellipse where it was crossed by the rotating metal wire. The intersection of the ellipse and the target direction was used as a basis for calculating elevation and training of the guns. The ellipse method had the advantage of requiring very little in the way of mechanical computation and essentially modelled target position in real-time with a consequent rapid solution time. The HADT provides target direction, range, speed, altitude and bearing data to

1566-658: The island. The Permesta force's surrender was as quick as its capture of the island less than a month before. It alarmed the Permesta rebels who had captured Jailolo, many of whom promptly fled back to North Sulawesi . Thereafter the rebellion was largely confined to the Minahasa Peninsula of Sulawesi, where Permesta remnants waged a guerilla campaign until the last unit surrendered in January 1962. Morotai became its own regency on 29 October 2008, separating from

1620-477: The islets and reefs of the west coast of Morotai is the Morotai Strait, which is about 10 km (6.2 mi) wide. In mid 2022 it had an estimated population of 78,270. The island is the location of the last known Japanese holdout , Teruo Nakamura , who surrendered in 1974, almost 30 years after the end of hostilities in 1945. During the fifteenth and sixteenth centuries, Morotai was generally within

1674-539: The lag time in the computer and the minimum range of optical rangefinders. In common with other contemporary navies, pre-war designed RN destroyers suffered from a lack of short-range, rapid-fire AA with which to engage dive bombers. The Auto Barrage Unit or ABU, was a specialised gunnery computer and radar ranging system that used Type 283 radar . It was developed to provide computer prediction and radar anti-aircraft fire control to main and secondary armament guns that did not have inherent anti-aircraft capability. The ABU

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1728-597: The late 1940s, after which the new Indonesian Air Force (AURI) kept one of the Allied-built airstrips in use. During the Permesta rebellion in 1958, AURI North American B-25 Mitchell bomber aircraft used the airstrip in transit on their way to attack the rebel center at Manado in North Sulawesi . Permesta had its own "Revolutionary Air Force", AUREV, whose aircraft, munitions and pilots were supplied by

1782-454: The maximum target speed to 500 knots (930 km/h; 580 mph), and were combined with Gyro Rate Units (GRU) which gave tachometric capabilities to the system, and radar which greatly improved ranging and rate keeping accuracy. The FKC saw extensive use during the war on British Commonwealth naval ships, typically on destroyers and sloops. Prior to the widespread use of radar, optical detection and ranging on high altitude aerial targets

1836-433: The mission from the island in 1571, as a part of a larger Portuguese retreat in the region. In the seventeenth century, Ternate further exerted its power over Morotai by repeatedly forcing major parts of the population to move off the island. Early in the century most of the population was moved to Dodinga, a small town in a strategic spot on Halmahera's west coast. Later, in 1627 and 1628, Sultan Hamzah of Ternate had much of

1890-444: The number of administrative villages (all rural desa ) in each district, and the post codes. Note: (a) the population in 2010 of Rao Island is included in the figure for Morotai Selatan Barat District, from which it was cut out. The island is heavily wooded and produces timber and resin and has a subsistence fishing industry. Currently 3MW Diesel generators across 3 locations one with 2MW, and 2 at 0.5MW. The electrification ratio

1944-422: The possibility of destroying expensive targets. The RN allowed media coverage of AA target practice and a 1936 newsreel has footage of a shoot. In 1935 the RN also began to practice HACS controlled shoots of target aircraft at night. The RN moved quickly to add true tachometric target motion prediction and radar ranging to the HACS by mid 1941. The RN was the first navy to adopt dedicated FC AA radars. However

1998-497: The regency. It stretches 80 km (50 mi) north-south and no more than 42 km (26 mi) wide. The island's largest town is Daruba, on the island's south coast. Leo Wattimena Airport is located on the island. Almost all of Morotai's numerous villages are coastal settlements; a paved road linking those on the east coast starts from Daruba and will eventually reach Berebere , the principal town on Morotai's east coast, 68 km (42 mi) from Daruba. Between Halmahera and

2052-532: The runway and pronounced that Boeing B-29 Superfortress heavy bomber aircraft could use it. In May 1958 Indonesian National Armed Forces started to gather amphibious forces to retake both Morotai and the rebel-held town of Jailolo on the neighboring island of Halmahera . By May 16 the assault fleet started to gather in Ambon harbour and on May 20 its troops landed on Morotai while élite Pasukan Gerak Tjepat (PGT or "Quick Reaction Force") troops parachuted onto

2106-512: The shortcomings of HACS are often blamed for the loss of Force Z , the scope of the Japanese attack far exceeded anything the HACS had been designed to handle in terms of aircraft numbers and performance. The failure of anti-aircraft gunnery to deter the Japanese bombers was also influenced by unique circumstances. The HACS was originally designed with Atlantic conditions in mind and Prince of Wales ' s AA FC radars had become unserviceable in

2160-437: The sphere of influence of the powerful sultanate on the island of Ternate . It was the core of a larger region, called Moro , that included the island and the coastline of Halmahera closest to Morotai to the south. In the mid-sixteenth century, the island was also the site of a Portuguese Jesuit mission . The Muslim states on Ternate and Halmahera resented the outpost for its proselytising activities, and managed to drive

2214-426: The sun, they have been extremely difficult to see. 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: Saturday 20th September, Two bombing attacks took place on the Convoy. During the first attack bombs were dropped over the convoy at some distance from "Parramatta" and one merchant ship

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2268-497: The system, in common with all World War II-era mechanical AA fire control system still had severe limitations as even the highly advanced United States Navy (USN) Mk 37 system in 1944 needed an average of 1,000 rounds of 5-inch (127 mm) ammunition fired per kill. In 1940 the Gyro Rate Unit (GRU) was added to the HACS system, an analogue computer capable of directly calculating target speed and direction, converting

2322-606: The target if the target became obscured. The angle measured by the graticule also caused a metal wire to rotate around the face of a large circular display on one side of the HACS, known as the Deflection Display . The measured value of altitude and range, and estimated value of target speed, caused optics to focus a lamp onto a ground glass screen behind the wire, displaying an ellipse whose shape changed based on these measures. The deflection operator used two controls to move additional wire indicators so they lay on top of

2376-474: 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. Type 285 radar 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

2430-695: Was a British anti-aircraft fire-control system employed by the Royal Navy from 1931 and used widely during World War II . HACS calculated the necessary deflection required to place an explosive shell in the location of a target flying at a known height, bearing and speed. The HACS was first proposed in the 1920s and began to appear on Royal Navy (RN) ships in January 1930, when HACS I went to sea in HMS ; Valiant . HACS I did not have any stabilisation or power assist for director training. HACS III which appeared in 1935, had provision for stabilisation,

2484-422: Was a daunting task, as shown by HMAS  Parramatta 's Report of Proceedings, for 3 September 1940: Tuesday 3rd September. An air attack by a single Italian machine took place on Aden. I was A/A guard. The Italian aircraft are painted with a light sand under-colour, which at the very high level bombing height favoured (13 to 16,000 feet) merges very successfully into the usual hard bright sky. At times when near

2538-500: Was designed to allow the guns to be pre-loaded with time fused ammunition, and it then tracked incoming enemy aircraft, aimed the guns continuously to track the aircraft, and then fired the guns automatically when the predicted aircraft position reached the preset fuse range of the previously loaded shells. The ABU was also used with guns that were nominally controlled by the HACS to provide a limited blind fire capability. By May 1941, RN cruisers, such as HMS  Fiji , were engaging

2592-403: Was divided into five districts ( kecamatan ), but a sixth district has subsequently been added by cutting off Rao Island from Morotai Selatan Barat District. The districts are tabulated below with their areas and their populations at the 2010 census and 2020 census, together with the official estimates as at mid 2023. The table also includes the locations of the district administrative centres,

2646-438: Was fitted with centimetric Type 275 radar . Another improvement was the addition of Remote Power Control ( RPC ), in which the anti-aircraft guns automatically trained with the director tower, with the necessary changes in bearing and elevation to allow for convergent fire. Previously the gun crews had to follow mechanical pointers that indicated where the director tower wanted the guns to train. HACS Directors fitted to ships in

2700-454: Was hit and damaged, although she subsequently reached Aden afloat with assistance from various ships. The Escort engaged the planes without visible results. The second attack took place during the first dog watch. The five Italian planes, inexplicably gave H.M.S. "Auckland" and myself considerable warning by dropping several bombs some miles away before attacking. The remainder of the bombs (about 30) were aimed with obvious intention of attacking

2754-471: Was hydraulically driven, featured much improved data transmission and it introduced the HACS III Table. The HACS III table (computer) had numerous improvements including raising maximum target speed to 350 kn (650 km/h; 400 mph), continuous automatic fuze prediction, improved geometry in the deflection Screen, and provisions for gyro inputs to provide stabilisation of data received from

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2808-423: Was increased by the use of radar for gunnery and to provide warning against surprise attack, as demonstrated by this account of HMAS  Warrego bringing down a Japanese A6M Zero fighter aircraft (a "HAMP"), in 1944: On 18th September H.M.A.S. "WARREGO" was at anchor near Soemoe Soemoe Island (off Morotai Island ) and had closed up to dawn action stations at 0530I... Just after 0600 an aircraft appeared in

2862-539: Was measured by aligning a binocular graticule with the target aircraft fuselage. The early versions of HACS, Mk. I through IV, did not measure target speed directly, but estimated this value based on the target type. All of these values were sent via selsyn to the HACS in the High Angle Calculating Position (HACP) located below decks. The HACS used these values to calculate the range rate (often called rate along in RN parlance), which

2916-491: Was the first Naval AA system to be used against radio controlled aircraft , and achieved the first AA kill against these targets in 1933. In March 1936, six Queen Bee targets were destroyed by the RN Mediterranean Fleet during intensive AA practice at a time of extreme tension between the UK and Italy. Target practice against target drones was carried out using special shells which were designed to minimise

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