Misplaced Pages

#367632

135-574: Ship gun fire-control systems ( GFCS ) are analogue fire-control systems that were used aboard naval warships prior to modern electronic computerized systems, to control targeting of guns against surface ships, aircraft, and shore targets, with either optical or radar sighting. Most US ships that are destroyers or larger (but not destroyer escorts except Brooke class DEG's later designated FFG's or escort carriers) employed gun fire-control systems for 5-inch (127 mm) and larger guns, up to battleships, such as Iowa class . Beginning with ships built in

270-530: A Mark 4 fire-control radar added to the roof of the director, while others had a Mark 4 radar added over the open director. With the Mark 4 large aircraft at up to 40,000 yards could be targeted. It had less range against low-flying aircraft, and large surface ships had to be within 30,000 yards. With radar, targets could be seen and hit accurately at night, and through weather. The Mark 33 and 37 systems used tachymetric target motion prediction. The USN never considered

405-557: A car, about 3,125 pounds (1,417 kg), with the Star Shell Computer Mark 1 adding another 215 pounds (98 kg). It used 115 volts AC, 60 Hz, single phase, and typically a few amperes or even less. Under worst-case fault conditions, its synchros apparently could draw as much as 140 amperes, or 15,000 watts (about the same as 3 houses while using ovens). Almost all of the computer's inputs and outputs were by synchro torque transmitters and receivers. Its function

540-569: A computer, stabilizing device or gyro, and equipment in a plotting room. For the US Navy, the most prevalent gunnery computer was the Ford Mark 1, later the Mark 1A Fire Control Computer , which was an electro-mechanical analog ballistic computer that provided accurate firing solutions and could automatically control one or more gun mounts against stationary or moving targets on the surface or in

675-409: A constant rate of altitude change. The Kerrison Predictor is an example of a system that was built to solve laying in "real time", simply by pointing the director at the target and then aiming the gun at a pointer it directed. It was also deliberately designed to be small and light, in order to allow it to be easily moved along with the guns it served. The radar-based M-9/SCR-584 Anti-Aircraft System

810-471: A critical part of an integrated fire-control system. The incorporation of radar into the fire-control system early in World War II provided ships the ability to conduct effective gunfire operations at long range in poor weather and at night. For U.S. Navy gun fire control systems, see ship gun fire-control systems . The use of director-controlled firing, together with the fire control computer, removed

945-472: A few degrees during a turn of the "own ship". In 1908 Frederic Dreyer suggested an improvement, adding gears so that the enemy bar would alter direction automatically when the dial plate was rotated. This allowed an automatic correction of enemy direction as the home ship changed course. A similar "helm-free" Mark VI* model with a range and bearing clock and fixed dial plate permitted a gyrocompass input to automatically track own ship as it altered course, and

1080-563: A group led by Dreyer designed a similar system. Although both systems were ordered for new and existing ships of the Royal Navy, the Dreyer system eventually found most favour with the Navy in its definitive Mark IV* form. The addition of director control facilitated a full, practicable fire control system for World War I ships, and most RN capital ships were so fitted by mid 1916. The director

1215-419: A local control option for use when battle damage prevented the director setting the guns. Guns could then be fired in planned salvos, with each gun giving a slightly different trajectory. Dispersion of shot caused by differences in individual guns, individual projectiles, powder ignition sequences, and transient distortion of ship structure was undesirably large at typical naval engagement ranges. Directors high on

1350-478: A main armament of one size of gun across a number of turrets (which made corrections simpler still), facilitating central fire control via electric triggering. The UK built their first central system before the Great War. At the heart was an analogue computer designed by Commander (later Admiral Sir) Frederic Charles Dreyer that calculated range rate, the rate of change of range due to the relative motion between

1485-460: A mechanism in part like that of a traditional computer mouse, converted the received corrections into target motion vector values. The Mark 1 computer attempted to do the coordinate conversion (in part) with a rectangular-to polar converter, but that didn't work as well as desired (sometimes trying to make target speed negative!). Part of the design changes that defined the Mark 1A were a re-thinking of how to best use these special coordinate converters;

SECTION 10

#1732775534368

1620-484: A new computerized bombing predictor, called the Low Altitude Bombing System (LABS), began to be integrated into the systems of aircraft equipped to carry nuclear armaments. This new bomb computer was revolutionary in that the release command for the bomb was given by the computer, not the pilot; the pilot designated the target using the radar or other targeting system , then "consented" to release

1755-465: A new target. Up to four Mark 37 Gun Fire Control Systems were installed on battleships. On a battleship, the director was protected by 1 + 1 ⁄ 2 inches (38 mm) of armor, and weighs 21 tons. The Mark 37 director aboard USS  Joseph P. Kennedy, Jr. is protected with one-half inch (13 mm) of armor plate and weighs 16 tons. Stabilizing signals from the Stable Element kept

1890-665: A potential adversary through The Great Game , and sent Lieutenant Walter Lake of the Navy Gunnery Division and Commander Walter Hugh Thring of the Coastguard and Reserves, the latter with an early example of Dumaresq , to Japan during the Russo-Japanese War . Their mission was to guide and train the Japanese naval gunnery personnel in the latest technological developments, but more importantly for

2025-399: A rifle-like sight for directly obtaining a bearing to the target ship. By 1913 approximately 1000 devices of various versions had been purchased by the Royal Navy at a cost of £10,000. The mark II Dumaresq was the same as the Mark I, but larger and was in production by Elliotts by 1907. In 1909 it was proposed to add a compass ring to the dial plate, and another mounted on the cross bar for

2160-642: A role in Center Force's battleships' dismal performance in the Battle off Samar in October 1944. In that action, American destroyers pitted against the world's largest armored battleships and cruisers dodged shells for long enough to close to within torpedo firing range, while lobbing hundreds of accurate automatically aimed 5-inch (127 mm) rounds on target. Cruisers did not land hits on splash-chasing escort carriers until after an hour of pursuit had reduced

2295-561: A separate plotting room as in the RN HACS, or the later Mark 37 GFCS, and this made it difficult to upgrade the Mark 33 GFCS. It could compute firing solutions for targets moving at up to 320 knots, or 400 knots in a dive. Its installations started in the late 1930s on destroyers, cruisers and aircraft carriers with two Mark 33 directors mounted fore and aft of the island. They had no fire-control radar initially, and were aimed only by sight. After 1942, some of these directors were enclosed and had

2430-523: A solution on a target even during maneuvers. By the start of World War II British, German and American warships could both shoot and maneuver using sophisticated analog fire-control computers that incorporated gyro compass and gyro Level inputs. In the Battle of Cape Matapan the British Mediterranean Fleet using radar ambushed and mauled an Italian fleet, although actual fire was under optical control using starshell illumination. At

2565-675: A straight-line path at a constant speed, to keep complexity to acceptable limits. A sonar rangekeeper was built to include a target circling at a constant radius of turn, but that function had been disabled. Only the RN and USN achieved 'blindfire' radar fire-control, with no need to visually acquire the opposing vessel. The Axis powers all lacked this capability. Classes such as Iowa and South Dakota battleships could lob shells over visual horizon, in darkness, through smoke or weather. American systems, in common with many contemporary major navies, had gyroscopic stable vertical elements, so they could keep

2700-524: A variety of armament, ranging from 12-inch coast defense mortars, through 3-inch and 6-inch mid-range artillery, to the larger guns, which included 10-inch and 12-inch barbette and disappearing carriage guns, 14-inch railroad artillery, and 16-inch cannon installed just prior to and up through World War II. Fire control in the Coast Artillery became more and more sophisticated in terms of correcting firing data for such factors as weather conditions,

2835-543: Is an analog computer that relates vital variables of the fire control problem to the movement of one's own ship and that of a target ship. It was often used with other devices, such as a Vickers range clock , to generate range and deflection data so the gun sights of the ship could be continuously set. A number of versions of the Dumaresq were produced of increasing complexity as development proceeded. The dumaresq relies on sliding and rotating bars and dials to represent

SECTION 20

#1732775534368

2970-401: Is being tracked. Typically, weapons fired over long ranges need environmental information—the farther a munition travels, the more the wind, temperature, air density, etc. will affect its trajectory, so having accurate information is essential for a good solution. Sometimes, for very long-range rockets, environmental data has to be obtained at high altitudes or in between the launching point and

3105-408: Is for the Mark 12 FC radar, and the parabolic antenna on the left ("orange peel") is for the Mark 22 FC radar. They were part of an upgrade to improve tracking of aircraft. The director was manned by a crew of 6: Director Officer, Assistant Control Officer, Pointer, Trainer, Range Finder Operator and Radar Operator. The Director Officer also had a slew sight used to quickly point the director towards

3240-403: Is oriented to match the heading of one's own ship. A sliding assembly can be moved backwards along a scale etched on this bar to indicate the ship's speed in knots. Suspended below the slider is a second bar, which recorded the speed and heading of the enemy ship by rotating and sliding against a similar scale to that on the main cross-bar. The result of these two settings are such that the tip of

3375-601: Is possible to control several same-type guns on a single platform simultaneously, while both the firing guns and the target are moving. Though a ship rolls and pitches at a slower rate than a tank does, gyroscopic stabilization is extremely desirable. Naval gun fire control potentially involves three levels of complexity: Corrections can be made for surface wind velocity, roll and pitch of the firing ship, powder magazine temperature, drift of rifled projectiles, individual gun bore diameter adjusted for shot-to-shot enlargement, and rate-of-change of range with additional modifications to

3510-517: The Sims class employed one of these computers, battleships up to four. The system's effectiveness against aircraft diminished as planes became faster, but toward the end of World War II upgrades were made to the Mark 37 System, and it was made compatible with the development of the VT (Variable Time) proximity fuze which exploded when it was near a target, rather than by timer or altitude, greatly increasing

3645-625: The Battle of Tsushima during 27–28 May 1905. Centralized naval fire control systems were first developed around the time of World War I . Local control had been used up until that time, and remained in use on smaller warships and auxiliaries through World War II . Specifications of HMS  Dreadnought were finalized after the report on the Battle of Tsushima was submitted by the official observer to IJN onboard Asahi , Captain Pakenham (later Admiral), who observed how Kato's system worked first hand. From this design on, large warships had

3780-797: The Imperial Japanese Navy (IJN), they were well aware of the experiments. During the 10 August 1904 Battle of the Yellow Sea against the Russian Pacific Fleet , the British-built IJN battleship Asahi and her sister ship, the fleet flagship Mikasa , were equipped with the latest Barr and Stroud range finders on the bridge, but the ships were not designed for coordinated aiming and firing. Asahi ' s chief gunnery officer , Hiroharu Kato (later Commander of Combined Fleet ), experimented with

3915-478: The Naval Battle of Guadalcanal USS  Washington , in complete darkness, inflicted fatal damage at close range on the battleship Kirishima using a combination of optical and radar fire-control; comparisons between optical and radar tracking, during the battle, showed that radar tracking matched optical tracking in accuracy, while radar ranges were used throughout the battle. The last combat action for

4050-623: The grenade launcher developed for use on the Fabrique Nationale F2000 bullpup assault rifle. Fire-control computers have gone through all the stages of technology that computers have, with some designs based upon analogue technology and later vacuum tubes which were later replaced with transistors . Fire-control systems are often interfaced with sensors (such as sonar , radar , infra-red search and track , laser range-finders , anemometers , wind vanes , thermometers , barometers , etc.) in order to cut down or eliminate

4185-423: The heads-up display (HUD). The pipper shows the pilot where the target must be relative to the aircraft in order to hit it. Once the pilot maneuvers the aircraft so that the target and pipper are superimposed, he or she fires the weapon, or on some aircraft the weapon will fire automatically at this point, in order to overcome the delay of the pilot. In the case of a missile launch, the fire-control computer may give

Ship gun fire-control system - Misplaced Pages Continue

4320-444: The 1890s. These guns were capable of such great range that the primary limitation was seeing the target, leading to the use of high masts on ships. Another technical improvement was the introduction of the steam turbine which greatly increased the performance of the ships. Earlier reciprocating engine powered capital ships were capable of perhaps 16 knots, but the first large turbine ships were capable of over 20 knots. Combined with

4455-478: The 1960s, warship guns were largely operated by computerized systems, i.e. systems that were controlled by electronic computers, which were integrated with the ship's missile fire-control systems and other ship sensors. As technology advanced, many of these functions were eventually handled fully by central electronic computers. The major components of a gun fire-control system are a human-controlled director , along with or later replaced by radar or television camera,

4590-400: The Dreyer table) for HMS Hood ' s main guns housed 27 crew. Directors were largely unprotected from enemy fire. It was difficult to put much weight of armour so high up on the ship, and even if the armour did stop a shot, the impact alone would likely knock the instruments out of alignment. Sufficient armour to protect from smaller shells and fragments from hits to other parts of the ship

4725-576: The Mark 1, design modifications were extensive enough to change it to "Mark 1A". The Mark 1A appeared post World War II and may have incorporated technology developed for the Bell Labs Mark 8, Fire Control Computer . Sailors would stand around a box measuring 62 by 38 by 45 inches (1.57 by 0.97 by 1.14 m). Even though built with extensive use of an aluminum alloy framework (including thick internal mechanism support plates) and computing mechanisms mostly made of aluminum alloy, it weighed as much as

4860-439: The Mark 33 to be a satisfactory system, but wartime production problems, and the added weight and space requirements of the Mark 37 precluded phasing out the Mark 33: Although superior to older equipment, the computing mechanisms within the range keeper ([Mark 10]) were too slow, both in reaching initial solutions on first picking up a target and in accommodating frequent changes in solution caused by target maneuvers. The [Mark 33]

4995-422: The Mark 33, it supplied them with greater reliability and gave generally improved performance with 5-inch (13 cm) gun batteries, whether they were used for surface or antiaircraft use. Moreover, the stable element and computer, instead of being contained in the director housing were installed below deck where they were less vulnerable to attack and less of a jeopardy to a ship's stability. The design provided for

5130-589: The Type 98 Hoiban and Shagekiban on the Yamato class were more up to date, which eliminated the Sokutekiban , but it still relied on seven operators. In contrast to US radar aided system, the Japanese relied on averaging optical rangefinders, lacked gyros to sense the horizon, and required manual handling of follow-ups on the Sokutekiban , Shagekiban , Hoiban as well as guns themselves. This could have played

5265-590: The U.K.). In battleships, the Secondary Battery Plotting Rooms were down below the waterline and inside the armor belt. They contained four complete sets of the fire control equipment needed to aim and shoot at four targets. Each set included a Mark 1A computer, a Mark 6 Stable Element, FC radar controls and displays, parallax correctors, a switchboard, and people to operate it all. (In the early 20th century, successive range and/or bearing readings were probably plotted either by hand or by

5400-510: The US Navy's Mark 37 system required nearly 1000 rounds of 5 in (127 mm) mechanical fuze ammunition per kill, even in late 1944. The Mark 37 Gun Fire Control System incorporated the Mark 1 computer, the Mark 37 director, a gyroscopic stable element along with automatic gun control, and was the first US Navy dual-purpose GFCS to separate the computer from the director. Naval fire control resembles that of ground-based guns, but with no sharp distinction between direct and indirect fire. It

5535-532: The accuracy of the directors fell off sharply; even at intermediate ranges they left much to be desired. The weight and size of the equipments militated against rapid movement, making them difficult to shift from one target to another.Their efficiency was thus in inverse proportion to the proximity of danger. The computer was completed as the Ford Mark 1 computer by 1935. Rate information for height changes enabled complete solution for aircraft targets moving over 400 miles per hour (640 km/h). Destroyers starting with

Ship gun fire-control system - Misplaced Pages Continue

5670-561: The air, and other adjustments. Around 1905, mechanical fire control aids began to become available, such as the Dreyer Table , Dumaresq (which was also part of the Dreyer Table), and Argo Clock , but these devices took a number of years to become widely deployed. These devices were early forms of rangekeepers . Arthur Pollen and Frederic Charles Dreyer independently developed the first such systems. Pollen began working on

5805-566: The air. This gave American forces a technological advantage in World War II against the Japanese, who did not develop remote power control for their guns; both the US Navy and Japanese Navy used visual correction of shots using shell splashes or air bursts, while the US Navy augmented visual spotting with radar. Digital computers would not be adopted for this purpose by the US until the mid-1970s; however, it must be emphasized that all analog anti-aircraft fire control systems had severe limitations, and even

5940-418: The amount of information that must be manually entered in order to calculate an effective solution. Sonar, radar, IRST and range-finders can give the system the direction to and/or distance of the target. Alternatively, an optical sight can be provided that an operator can simply point at the target, which is easier than having someone input the range using other methods and gives the target less warning that it

6075-493: The analog rangekeepers, at least for the US Navy, was in the 1991 Persian Gulf War when the rangekeepers on the Iowa -class battleships directed their last rounds in combat. An early use of fire-control systems was in bomber aircraft , with the use of computing bombsights that accepted altitude and airspeed information to predict and display the impact point of a bomb released at that time. The best known United States device

6210-421: The analog rangekeepers, at least for the US Navy, was in the 1991 Persian Gulf War when the rangekeepers on the Iowa -class battleships directed their last rounds in combat. The Mark 33 GFCS was a power-driven fire control director, less advanced than the Mark 37. The Mark 33 GFCS used a Mark 10 Rangekeeper , analog fire-control computer. The entire rangekeeper was mounted in an open director rather than in

6345-680: The astonishing feat of shooting down V-1 cruise missiles with less than 100 shells per plane (thousands were typical in earlier AA systems). This system was instrumental in the defense of London and Antwerp against the V-1. Although listed in Land based fire control section anti-aircraft fire control systems can also be found on naval and aircraft systems. In the United States Army Coast Artillery Corps , Coast Artillery fire control systems began to be developed at

6480-668: The barrels and distortion due to heating. These sorts of effects are noticeable for any sort of gun, and fire-control computers have started appearing on smaller and smaller platforms. Tanks were one early use that automated gun laying had, using a laser rangefinder and a barrel-distortion meter. Fire-control computers are useful not just for aiming large cannons , but also for aiming machine guns , small cannons, guided missiles , rifles , grenades , and rockets —any kind of weapon that can have its launch or firing parameters varied. They are typically installed on ships , submarines , aircraft , tanks and even on some small arms —for example,

6615-570: The bearings and elevations for the guns to fire upon. In the turrets, the gunlayers adjusted the elevation of their guns to match an indicator for the elevation transmitted from the Fire Control table—a turret layer did the same for bearing. When the guns were on target they were centrally fired. Even with as much mechanization of the process, it still required a large human element; the Transmitting Station (the room that housed

6750-409: The centre bar to represent the enemy ship motion and the moving portions to represent the dumaresq ship. This allows it to be used "backwards", a process called a "cross cut", to take sequential estimates of the range and bearing of an enemy vessel and discover its speed and heading that would be consistent. To aid the operation of the system, the dumaresq is normally co-located with instruments showing

6885-425: The clear superiority of US radar-assisted systems at night. The rangekeeper's target position prediction characteristics could be used to defeat the rangekeeper. For example, many captains under long range gun attack would make violent maneuvers to "chase salvos." A ship that is chasing salvos is maneuvering to the position of the last salvo splashes. Because the rangekeepers are constantly predicting new positions for

SECTION 50

#1732775534368

7020-406: The command to commence firing. Unfortunately, this process of inferring the target motion vector required a few seconds, typically, which might take too long. The process of determining the target's motion vector was done primarily with an accurate constant-speed motor, disk-ball-roller integrators, nonlinear cams, mechanical resolvers, and differentials. Four special coordinate converters, each with

7155-461: The computer were closed, and movement of the gun director (along with changes in range) made the computer converge its internal values of target motion to values matching those of the target. While converging, the computer fed aided-tracking ("generated") range, bearing, and elevation to the gun director. If the target remained on a straight-line course at a constant speed (and in the case of aircraft, constant rate of change of altitude ("rate of climb"),

7290-668: The condition of powder used, or the Earth's rotation. Provisions were also made for adjusting firing data for the observed fall of shells. As shown in Figure 2, all of these data were fed back to the plotting rooms on a finely tuned schedule controlled by a system of time interval bells that rang throughout each harbor defense system. It was only later in World War II that electro-mechanical gun data computers , connected to coast defense radars, began to replace optical observation and manual plotting methods in controlling coast artillery. Even then,

7425-622: The control of the gun laying from the individual turrets to a central position; although individual gun mounts and multi-gun turrets would retain a local control option for use when battle damage limited director information transfer (these would be simpler versions called "turret tables" in the Royal Navy). Guns could then be fired in planned salvos, with each gun giving a slightly different trajectory. Dispersion of shot caused by differences in individual guns, individual projectiles, powder ignition sequences, and transient distortion of ship structure

7560-462: The coordinate converter ("vector solver") was eliminated. The Stable Element, which in contemporary terminology would be called a vertical gyro, stabilized the sights in the director, and provided data to compute stabilizing corrections to the gun orders. Gun lead angles meant that gun-stabilizing commands differed from those needed to keep the director's sights stable. Ideal computation of gun stabilizing angles required an impractical number of terms in

7695-417: The crowded wartime production program were responsible for the fact the [Mark 33's] service was lengthened to the cessation of hostilities. The Mark 33 was used as the main director on some destroyers and as secondary battery / anti-aircraft director on larger ships (i.e. in the same role as the later Mark 37). The guns controlled by it were typically 5 inch weapons: the 5-inch/25 or 5-inch/38 . The Mark 34

7830-427: The current bearing to the target. When correctly set, the enemy pointer will point to a location on the coordinate plate. The coordinates can be read to directly provide the "range rate" (the component of motion along the line of bearing) and "dumaresq deflection" (or "speed across", the component perpendicular to the range rate). This was normally measured as the yards per minute in range and knots in deflection. Based on

7965-403: The direction and elevation of the guns. Pollen aimed to produce a combined mechanical computer and automatic plot of ranges and rates for use in centralised fire control. To obtain accurate data of the target's position and relative motion, Pollen developed a plotting unit (or plotter) to capture this data. To this he added a gyroscope to allow for the yaw of the firing ship. Like the plotter,

8100-404: The direction and speed of the ship, while the operators set the enemy bearing, heading and speed based on calls from the rangetellers. In some versions, the rotation of the bar is automated through the use of a gyrocompass and selsyn , in other the speed input was automated using a Forbes Log . The design of the dumaresq consists of a circular dial with a cross-bar passing over the centre which

8235-578: The directors, with individual installations varying from one aboard destroyers to four on each battleship. The development of the Gun Directors Mark 33 and 37 provided the United States Fleet with good long range fire control against attacking planes. But while that had seemed the most pressing problem at the time the equipments were placed under development, it was but one part of the total problem of air defense. At close-in ranges

SECTION 60

#1732775534368

8370-505: The end of the 19th century and progressed on through World War II. Early systems made use of multiple observation or base end stations (see Figure 1 ) to find and track targets attacking American harbors. Data from these stations were then passed to plotting rooms , where analog mechanical devices, such as the plotting board , were used to estimate targets' positions and derive firing data for batteries of coastal guns assigned to interdict them. U.S. Coast Artillery forts bristled with

8505-418: The enemy bar records enemy movement minus own movement as a vector sum. This is equivalent to the relative motion of the target ship. The base disc of the Dumaresq features a graph which can be rotated along the line of bearing. When so aligned, the axis along the line of bearing indicates the range rate and the perpendicular axis indicates speed across. A pointer stem dangling from the enemy ship bar allows

8640-417: The enemy ship. This was added to a revised Mark II and Mark III versions. The mark IV version was developed in 1910, intended to be used within a gun turret operating independently from the centralised fire control. The device cost £4.50. This version included a hand wheel on the side, which rotated the dial plate, and with it the enemy bar. Relative direction of the enemy ship could be maintained to within

8775-471: The engagement of targets within visual range (also referred to as direct fire ). In fact, most naval engagements before 1800 were conducted at ranges of 20 to 50 yards (20 to 50 m). Even during the American Civil War , the famous engagement between USS  Monitor and CSS  Virginia was often conducted at less than 100 yards (90 m) range. Rapid technical improvements in

8910-484: The fall of shot. Visual range measurement (of both target and shell splashes) was difficult prior to the availability of radar. The British favoured coincidence rangefinders while the Germans favoured the stereoscopic type . The former were less able to range on an indistinct target but easier on the operator over a long period of use, the latter the reverse. Submarines were also equipped with fire control computers for

9045-409: The fire control computer became integrated with ordnance systems, the computer can take the flight characteristics of the weapon to be launched into account. By the start of World War II , aircraft altitude performance had increased so much that anti-aircraft guns had similar predictive problems, and were increasingly equipped with fire-control computers. The main difference between these systems and

9180-424: The fire control devices (or both). Humans were very good data filters, able to plot a useful trend line given somewhat-inconsistent readings. As well, the Mark 8 Rangekeeper included a plotter. The distinctive name for the fire-control equipment room took root, and persisted even when there were no plotters.) The Mark 1A Fire Control Computer was an electro-mechanical analog ballistic computer. Originally designated

9315-436: The fire control system early in World War II provided ships with the ability to conduct effective gunfire operations at long range in poor weather and at night. In a typical World War II British ship the fire control system connected the individual gun turrets to the director tower (where the sighting instruments were) and the analogue computer in the heart of the ship. In the director tower, operators trained their telescopes on

9450-413: The fire control system was initially installed, a surveyor, working in several stages, transferred the position of the gun director into Plot so the stable element's own internal mechanism was properly aligned to the director. Although the rangefinder had significant mass and inertia, the crosslevel servo normally was only lightly loaded, because the rangefinder's own inertia kept it essentially horizontal;

9585-573: The firing and target ships. The Dreyer Table was to be improved and served into the interwar period at which point it was superseded in new and reconstructed ships by the Admiralty Fire Control Table . The use of Director-controlled firing together with the fire control computer moved the control of the gun laying from the individual turrets to a central position (usually in a plotting room protected below armor), although individual gun mounts and multi-gun turrets could retain

9720-425: The firing solution based upon the observation of preceding shots. The resulting directions, known as a firing solution , would then be fed back out to the turrets for laying. If the rounds missed, an observer could work out how far they missed by and in which direction, and this information could be fed back into the computer along with any changes in the rest of the information and another shot attempted. At first,

9855-459: The firing solution based upon the observation of preceding shots. More sophisticated fire control systems consider more of these factors rather than relying on simple correction of observed fall of shot. Differently colored dye markers were sometimes included with large shells so individual guns, or individual ships in formation, could distinguish their shell splashes during daylight. Early "computers" were people using numerical tables. The Royal Navy

9990-426: The first director system of fire control, using speaking tube (voicepipe) and telephone communication from the spotters high on the mast to his position on the bridge where he performed the range and deflection calculations, and from his position to the 12-inch (305 mm) gun turrets forward and astern. With the semi-synchronized salvo firing upon his voice command from the bridge, the spotters using stopwatches on

10125-475: The first installation of a Mark 33. The objective of weight reduction was not met, since the resulting director system actually weighed about 8,000 pounds (3,600 kg) more than the equipment it was slated to replace, but the Gun Director Mark 37 that emerged from the program possessed virtues that more than compensated for its extra weight. Though the gun orders it provided were the same as those of

10260-629: The gun turrets, he was steps away from the ship commander giving orders to change the course and the speed in response to the incoming reports on target movements. Kato was transferred to the fleet flagship Mikasa as the Chief Gunnery Officer, and his primitive control system was in fleet-wide operation by the time the Combined Fleet destroyed the Russian Baltic Fleet (renamed the 2nd and 3rd Pacific Fleet) in

10395-508: The guns were aimed using the technique of artillery spotting . It involved firing a gun at the target, observing the projectile's point of impact (fall of shot), and correcting the aim based on where the shell was observed to land, which became more and more difficult as the range of the gun increased. Between the American Civil War and 1905, numerous small improvements, such as telescopic sights and optical rangefinders , were made in fire control. There were also procedural improvements, like

10530-460: The individual gun crews. Director control aims all guns on the ship at a single target. Coordinated gunfire from a formation of ships at a single target was a focus of battleship fleet operations. Corrections are made for surface wind velocity, firing ship roll and pitch, powder magazine temperature, drift of rifled projectiles, individual gun bore diameter adjusted for shot-to-shot enlargement, and rate of change of range with additional modifications to

10665-492: The individual gun turrets to the director tower (where the sighting instruments were located) and the analogue computer in the heart of the ship. In the director tower, operators trained their telescopes on the target; one telescope measured elevation and the other bearing. Rangefinder telescopes on a separate mounting measured the distance to the target. These measurements were converted by the Fire Control Table into

10800-548: The late 19th century greatly increased the range at which gunfire was possible. Rifled guns of much larger size firing explosive shells of lighter relative weight (compared to all-metal balls) so greatly increased the range of the guns that the main problem became aiming them while the ship was moving on the waves. This problem was solved with the introduction of the gyroscope , which corrected this motion and provided sub-degree accuracies. Guns were now free to grow to any size, and quickly surpassed 10 inches (250 mm) calibre by

10935-473: The long range of the guns, this meant that the target ship could move a considerable distance, several ship lengths, between the time the shells were fired and landed. One could no longer eyeball the aim with any hope of accuracy. Moreover, in naval engagements it is also necessary to control the firing of several guns at once. Naval gun fire control potentially involves three levels of complexity. Local control originated with primitive gun installations aimed by

11070-464: The manual methods were retained as a back-up through the end of the war. Land based fire control systems can be used to aid in both Direct fire and Indirect fire weapon engagement. These systems can be found on weapons ranging from small handguns to large artillery weapons. Modern fire-control computers, like all high-performance computers, are digital. The added performance allows basically any input to be added, from air density and wind, to wear on

11205-446: The mast could identify the distant salvo of splashes created by the shells from their own ship more effectively than trying to identify a single splash among the many. Kato gave the firing order consistently at a particular moment in the rolling and pitching cycles of the ship, simplifying firing and correction duties formerly performed independently with varying accuracy using artificial horizon gauges in each turret. Moreover, unlike in

11340-480: The mathematical expression, so the computation was approximate. To compute lead angles and time fuze setting, the target motion vector's components as well as its range and altitude, wind direction and speed, and own ship's motion combined to predict the target's location when the shell reached it. This computation was done primarily with mechanical resolvers ("component solvers"), multipliers, and differentials, but also with one of four three-dimensional cams. Based on

11475-409: The metal bar is a device that is slid along the bar to represent the speed of the ship. This sliding part is normally in the form of a ring, sometimes referred to as the "inclination ring", that is suspended just above the coordinate plate. The motion of the enemy ship is represented by a bar connected to the sliding ring, the "enemy bar". This is normally in the form of a long pointer that extends from

11610-418: The motion of the two ships. Normally the motion of the ship carrying the dumaresq is represented by a metal bar running above the instrument. Below the bar is a round metal plate inscribed with a coordinate plot, and an angle scale around its outer rim. The fixed bar is mounted on a bearing that allows it to be turned to represent the direction of motion of the ship, measured against the scale. Hanging down from

11745-549: The ones on ships was size and speed. The early versions of the High Angle Control System , or HACS, of Britain 's Royal Navy were examples of a system that predicted based upon the assumption that target speed, direction, and altitude would remain constant during the prediction cycle, which consisted of the time to fuze the shell and the time of flight of the shell to the target. The USN Mk 37 system made similar assumptions except that it could predict assuming

11880-517: The optical sight telescopes, rangefinder, and radar antenna free from the effects of deck tilt. The signal that kept the rangefinder's axis horizontal was called "crosslevel"; elevation stabilization was called simply "level". Although the stable element was below decks in Plot, next to the Mark 1/1A computer, its internal gimbals followed director motion in bearing and elevation so that it provided level and crosslevel data directly. To do so, accurately, when

12015-463: The pilot feedback about whether the target is in range of the missile and how likely the missile is to hit if launched at any particular moment. The pilot will then wait until the probability reading is satisfactorily high before launching the weapon. Dumaresq The Dumaresq is a mechanical calculating device invented around 1902 by Lieutenant John Dumaresq of the Royal Navy . It

12150-471: The plane maintain a constant attitude (usually level), though dive-bombing sights were also common. The LABS system was originally designed to facilitate a tactic called toss bombing , to allow the aircraft to remain out of range of a weapon's blast radius . The principle of calculating the release point, however, was eventually integrated into the fire control computers of later bombers and strike aircraft, allowing level, dive and toss bombing. In addition, as

12285-406: The predictions became accurate and, with further computation, gave correct values for the gun lead angles and fuze setting. The target's movement was a vector, and if that didn't change, the generated range, bearing, and elevation were accurate for up to 30 seconds. Once the target's motion vector became stable, the computer operators told the gun director officer ("Solution Plot!"), who usually gave

12420-404: The predictions, the other three of the three-dimensional cams provided data on ballistics of the gun and ammunition that the computer was designed for; it could not be used for a different size or type of gun except by rebuilding that could take weeks. Fire-control system The original fire-control systems were developed for ships. The early history of naval fire control was dominated by

12555-520: The present gun range and its markings indicated an additional correction to deflection to be applied to the gun sights in order to negate the crosswind's influence. This figure was read off by projecting the vector sum pipper to the roller graph. The more sophisticated dumaresqs slowly died out after WWI, their functionality being manifested in other hardware. The design of the dumaresq was not well-suited to integration in larger schemes of automated fire control. A wind dumaresq, however, can still be found in

12690-420: The present range. These special accoutrements were overtaking the inherent complexity of the dumaresqs themselves. This dumaresq (as Admiralty pattern 5969A) lasted into service through WWII. It was compact, had a fixed cross-bar and special gearing maintained enemy heading when alterations to own heading were made. All adjustments were manual on this model. A special graph spindle in the dial plate oriented along

12825-543: The primitive gyroscope of the time required substantial development to provide continuous and reliable guidance. Although the trials in 1905 and 1906 were unsuccessful, they showed promise. Pollen was encouraged in his efforts by the rapidly rising figure of Admiral Jackie Fisher , Admiral Arthur Knyvet Wilson and the Director of Naval Ordnance and Torpedoes (DNO), John Jellicoe . Pollen continued his work, with occasional tests carried out on Royal Navy warships. Meanwhile,

12960-461: The probability that any one shell would destroy a target. The function of the Mark 37 Director, which resembles a gun mount with "ears" rather than guns, was to track the present position of the target in bearing, elevation, and range. To do this, it had optical sights (the rectangular windows or hatches on the front), an optical rangefinder (the tubes or ears sticking out each side), and later models, fire control radar antennas. The rectangular antenna

13095-402: The problem after noting the poor accuracy of naval artillery at a gunnery practice near Malta in 1900. Lord Kelvin , widely regarded as Britain's leading scientist first proposed using an analogue computer to solve the equations which arise from the relative motion of the ships engaged in the battle and the time delay in the flight of the shell to calculate the required trajectory and therefore

13230-515: The range to 5 miles (8.0 km). Although the Japanese pursued a doctrine of achieving superiority at long gun ranges, one cruiser fell victim to secondary explosions caused by hits from the carriers' single 5-inch guns. Eventually with the aid of hundreds of carrier based aircraft, a battered Center Force was turned back just before it could have finished off survivors of the lightly armed task force of screening escorts and escort carriers of Taffy 3. The earlier Battle of Surigao Strait had established

13365-479: The rangekeeper's commands with no manual intervention, though pointers still worked even if automatic control was lost. The Mark 1 and Mark 1A computers contained approximately 20 servomechanisms, mostly position servos, to minimize torque load on the computing mechanisms. During their long service life, rangekeepers were updated often as technology advanced and by World War II they were a critical part of an integrated fire control system. The incorporation of radar into

13500-696: The rangekeeper. The effectiveness of this combination was demonstrated in November 1942 at the Third Battle of Savo Island when the USS ; Washington engaged the Japanese battleship Kirishima at a range of 8,400 yards (7.7 km) at night. Kirishima was set aflame, suffered a number of explosions, and was scuttled by her crew. She had been hit by at least nine 16-inch (410 mm) rounds out of 75 fired (12% hit rate). The wreck of Kirishima

13635-471: The rangekeepers would generate the necessary angles automatically but sailors had to manually follow the directions of the rangekeepers. This task was called "pointer following" but the crews tended to make inadvertent errors when they became fatigued during extended battles. During World War II, servomechanisms (called "power drives" in the US Navy) were developed that allowed the guns to automatically steer to

13770-417: The ring towards the edge of the plot, which allows the angle of the enemy ship to be input by rotating the pointer (and ring) as measured against the angle scale at the edge of the plot. A smaller pointer connected to this bar, the "enemy pointer", extends downward from the bar, and can slide along it to represent the speed of the enemy ship. The central coordinate plate also rotates, which is used to represent

13905-461: The same for bearing. When the guns were on target they were centrally fired. The Aichi Clock Company first produced the Type 92 Shagekiban low angle analog computer in 1932. The US Navy Rangekeeper and the Mark 38 GFCS had an edge over Imperial Japanese Navy systems in operability and flexibility. The US system allowing the plotting room team to quickly identify target motion changes and apply appropriate corrections. The newer Japanese systems such as

14040-414: The same reasons, but their problem was even more pronounced; in a typical "shot", the torpedo would take one to two minutes to reach its target. Calculating the proper "lead" given the relative motion of the two vessels was very difficult, and torpedo data computers were added to dramatically improve the speed of these calculations. In a typical World War II British ship the fire control system connected

14175-459: The servo's task was usually simply to ensure that the rangefinder and sight telescopes remained horizontal. Mark 37 director train (bearing) and elevation drives were by D.C. motors fed from Amplidyne rotary power-amplifying generators. Although the train Amplidyne was rated at several kilowatts maximum output, its input signal came from a pair of 6L6 audio beam tetrode vacuum tubes (valves, in

14310-459: The speed-across axis could be spun to the present gun range and could quickly convert the speed-across to a gun deflection. That this was done by simple thumb work suggests that this dumaresq was meant to operate in the absence of advanced systems such as the Admiralty Fire Control Table that was then in service. Before World War I was over, a specialised dumaresq proposed by Captain FC Dreyer

14445-420: The superstructure had a better view of the enemy than a turret mounted sight, and the crew operating it were distant from the sound and shock of the guns. Unmeasured and uncontrollable ballistic factors like high altitude temperature, humidity, barometric pressure, wind direction and velocity required final adjustment through observation of fall of shot. Visual range measurement (of both target and shell splashes)

14580-401: The target or flying the aircraft. Even if the system is unable to aim the weapon itself, for example the fixed cannon on an aircraft, it is able to give the operator cues on how to aim. Typically, the cannon points straight ahead and the pilot must maneuver the aircraft so that it oriented correctly before firing. In most aircraft the aiming cue takes the form of a " pipper " which is projected on

14715-420: The target, it is unlikely that subsequent salvos will strike the position of the previous salvo. The direction of the turn is unimportant, as long as it is not predicted by the enemy system. Since the aim of the next salvo depends on observation of the position and speed at the time the previous salvo hits, that is the optimal time to change direction. Practical rangekeepers had to assume that targets were moving in

14850-410: The target. Often, satellites or balloons are used to gather this information. Once the firing solution is calculated, many modern fire-control systems are also able to aim and fire the weapon(s). Once again, this is in the interest of speed and accuracy, and in the case of a vehicle like an aircraft or tank, in order to allow the pilot/gunner/etc. to perform other actions simultaneously, such as tracking

14985-499: The target; one telescope measured elevation and the other bearing. Rangefinder telescopes on a separate mounting measured the distance to the target. These measurements were converted by the Fire Control Table into bearings and elevations for the guns to fire on. In the turrets, the gunlayers adjusted the elevation of their guns to match an indicator which was the elevation transmitted from the Fire Control Table—a turret layer did

15120-404: The time-of-flight using the instantaneous range between the two ships at the time of firing, these two measurements are added to the initial calculation of the firing solution to produce the corrections for motion. Because the dumaresq is an analogue model of the relative motion of the two ships, it does not intrinsically favour which of its settings is an input and which is an output - one can use

15255-454: The transmitting stations of HMS  Belfast and HMCS  Sackville . Simple dumaresqs of almost regressive simplicity continued to be issued through WWII in auxiliaries and transports. An example of the Spartan dumaresqs that survived beyond World War I, these were very simple, with fixed cross-bars and an own-speed of 12 knots that could not be altered. The standard speed suggests it

15390-409: The two computers is their ballistics calculations. The amount of gun elevation needed to project a 5-inch (130 mm) shell 9 nautical miles (17 km) is very different from the elevation needed to project a 16-inch (41 cm) shell the same distance. In operation, this computer received target range, bearing, and elevation from the gun director. As long as the director was on target, clutches in

15525-481: The ultimate addition of radar, which later permitted blind firing with the director. In fact, the Mark 37 system was almost continually improved. By the end of 1945 the equipment had run through 92 modifications—almost twice the total number of directors of that type which were in the fleet on December 7, 1941. Procurement ultimately totalled 841 units, representing an investment of well over $ 148,000,000. Destroyers, cruisers, battleships, carriers, and many auxiliaries used

15660-482: The use of plotting boards to manually predict the position of a ship during an engagement. Then increasingly sophisticated mechanical calculators were employed for proper gun laying , typically with various spotters and distance measures being sent to a central plotting station deep within the ship. There the fire direction teams fed in the location, speed and direction of the ship and its target, as well as various adjustments for Coriolis effect , weather effects on

15795-470: The values to be easily read off in convenient units (in 1902, range rate was expressed as the number of seconds required for the range to alter 50 yards, but was soon standardised on yards per minute). The mark I Dumaresq was manufactured by Elliott Brothers , who paid for and obtained a patent on the device in the name of its inventor, John Dumaresq, in August 1904. By 1906 the device had been amended to add

15930-444: The weapon, and the computer then did so at a calculated "release point" some seconds later. This is very different from previous systems, which, though they had also become computerized, still calculated an "impact point" showing where the bomb would fall if the bomb were released at that moment. The key advantage is that the weapon can be released accurately even when the plane is maneuvering. Most bombsights until this time required that

16065-508: The world at that time, only three percent of their shots actually struck their targets. At that time, the British primarily used a manual fire control system. This experience contributed to computing rangekeepers becoming standard issue. The US Navy's first deployment of a rangekeeper was on USS  Texas in 1916. Because of the limitations of the technology at that time, the initial rangekeepers were crude. For example, during World War I

16200-540: Was aware of the fall of shot observation advantage of salvo firing through several experiments as early as 1870 when Commander John A. Fisher installed an electric system enabling a simultaneous firing of all the guns to HMS Ocean , the flagship of the China Station as the second in command. However, the Station or Royal Navy had not yet implemented the system fleet-wide in 1904. The Royal Navy considered Russia

16335-399: Was difficult prior to availability of radar. The British favoured coincidence rangefinders while the Germans and the US Navy, stereoscopic type. The former were less able to range on an indistinct target but easier on the operator over a long period of use, the latter the reverse. During the Battle of Jutland , while the British were thought by some to have the finest fire control system in

16470-435: Was discovered in 1992 and showed that the entire bow section of the ship was missing. The Japanese during World War II did not develop radar or automated fire control to the level of the US Navy and were at a significant disadvantage. By the 1950s gun turrets were increasingly unmanned, with gun laying controlled remotely from the ship's control centre using inputs from radar and other sources. The last combat action for

16605-467: Was fitted, sitting atop a range clock. Like the Mark VI*, it was helm-free, a gyro applied own course continuously, and a bearing clock tried to keep the bearing plate set appropriately. Its new wrinkle was an elaborate electrical device which would, when engaged, continuously and automatically apply the indicated range rate to its range clock and convert the indicated speed-across to a gunnery deflection at

16740-555: Was high up over the ship where operators had a superior view over any gunlayer in the turrets . It was also able to co-ordinate the fire of the turrets so that their combined fire worked together. This improved aiming and larger optical rangefinders improved the estimate of the enemy's position at the time of firing. The system was eventually replaced by the improved " Admiralty Fire Control Table " for ships built after 1927. During their long service life, rangekeepers were updated often as technology advanced, and by World War II they were

16875-479: Was incorporated into the Dreyer Fire Control Table alongside the main one to track and nullify the influence of cross-range winds on the shells as they flew toward the target. In the wind dumaresq, the vector bars subtracted own ship's motion from the real wind vector to produce the relative wind vector, which was called "wind you feel". A rolling spindle graph across the dial plate was spun to

17010-419: Was intended for use in transport type ships in convoy. The dial plate lacks markings for range rate, implying the fire control staff of the ship would have no range clock at all and that this device was solely to give an idea of what deflection should be used on the gun sights. A further indication that these were to be used by less intensively trained personnel is that the dial plate helpfully features an image of

17145-454: Was the Norden bombsight . Simple systems, known as lead computing sights also made their appearance inside aircraft late in the war as gyro gunsights . These devices used a gyroscope to measure turn rates, and moved the gunsight's aim-point to take this into account, with the aim point presented through a reflector sight . The only manual "input" to the sight was the target distance, which

17280-410: Was the limit. The performance of the analog computer was impressive. The battleship USS  North Carolina during a 1945 test was able to maintain an accurate firing solution on a target during a series of high-speed turns. It is a major advantage for a warship to be able to maneuver while engaging a target. Night naval engagements at long range became feasible when radar data could be input to

17415-607: Was the one incorporated in the Dreyer Fire Control Table Mark III and III*. Such equipment was quite specialized to a larger fire control context. This model is the zenith in complexity for the dumaresq, and was created for use in the most modern Dreyer tables of WWI, the Mark IV and IV*. The electrical dumaresq's special features were very particular to its use in the Dreyer FCTs in which it

17550-412: Was thus distinctly inadequate, as indicated to some observers in simulated air attack exercises prior to hostilities. However, final recognition of the seriousness of the deficiency and initiation of replacement plans were delayed by the below decks space difficulty, mentioned in connection with the [Mark 28] replacement. Furthermore, priorities of replacements of older and less effective director systems in

17685-585: Was to automatically aim the guns so that a fired projectile would collide with the target. This is the same function as the main battery's Mark 8 Rangekeeper used in the Mark 38 GFCS except that some of the targets the Mark 1A had to deal with also moved in elevation—and much faster. For a surface target, the Secondary Battery's Fire Control problem is the same as the Main Battery's with the same type inputs and outputs. The major difference between

17820-523: Was typically handled by dialing in the size of the target's wing span at some known range. Small radar units were added in the post-war period to automate even this input, but it was some time before they were fast enough to make the pilots completely happy with them. The first implementation of a centralized fire control system in a production aircraft was on the B-29 . By the start of the Vietnam War,

17955-562: Was undesirably large at typical naval engagement ranges. Directors high on the superstructure had a better view of the enemy than a turret mounted sight, and the crew operating them were distant from the sound and shock of the guns. Gun directors were topmost, and the ends of their optical rangefinders protruded from their sides, giving them a distinctive appearance. Unmeasured and uncontrollable ballistic factors, like high-altitude temperature, humidity, barometric pressure, wind direction and velocity, required final adjustment through observation of

18090-566: Was used to control the main batteries of large gun ships. Its predecessors include Mk18 ( Pensacola class ), Mk24 ( Northampton class ), Mk27 ( Portland class ) and Mk31 ( New Orleans class ) According to the US Navy Bureau of Ordnance, While the defects were not prohibitive and the Mark 33 remained in production until fairly late in World War II, the Bureau started the development of an improved director in 1936, only 2 years after

18225-473: Was used to direct air defense artillery since 1943. The MIT Radiation Lab's SCR-584 was the first radar system with automatic following, Bell Laboratory 's M-9 was an electronic analog fire-control computer that replaced complicated and difficult-to-manufacture mechanical computers (such as the Sperry M-7 or British Kerrison predictor). In combination with the VT proximity fuze , this system accomplished

#367632