Fire-control system
A fire-control system (FCS) is a number of components working together, usually a gun data computer, a director and radar, which is designed to assist a ranged weapon system to target, track, and hit a target. It performs the same task as a human gunner firing a weapon, but attempts to do so faster and more accurately.
Origins
The original fire-control systems were developed for ships.
The early history of naval fire control was dominated by 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).[1] 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.[2]
Rapid technical improvements in the late 19th century greatly increased the range at which gunfire was possible.
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 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 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 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, the guns were aimed using the technique of
Between the
World War I
Then increasingly sophisticated
Pollen aimed to produce a combined
Meanwhile, 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 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.[9]
World War II
During their long service life, rangekeepers were updated often as technology advanced, and by
The use of director-controlled firing, together with the fire control computer, removed 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 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 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 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 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 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.[11]
Even with as much mechanization of the process, it still required a large human element; the Transmitting Station (the room that housed 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 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[12] on a target during a series of high-speed turns. [13] 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 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).[1] The wreck of Kirishima was discovered in 1992 and showed that the entire bow section of the ship was missing.[14] 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.[15]
Post-1945
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 the analog rangekeepers, at least for the US Navy, was in the 1991
directed their last rounds in combat.Aircraft based fire control
World War II bomb sights
An early use of fire-control systems was in
World War II aerial gunnery sights
Simple systems, known as lead computing sights also made their appearance inside aircraft late in the war as
Post-World War II systems
By the start of the Vietnam War, a new computerized bombing predictor, called the
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 the fire control computer became integrated with ordnance systems, the computer can take the flight characteristics of the weapon to be launched into account.
Land based fire control
Anti-aircraft based fire control
By the start of
The radar-based
Although listed in Land based fire control section anti-aircraft fire control systems can also be found on naval and aircraft systems.
Coast artillery fire control
In the United States Army Coast Artillery Corps, Coast Artillery fire control systems began to be developed at the end of the 19th century and progressed on through World War II.[21]
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[22] bristled with 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
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, the manual methods were retained as a back-up through the end of the war.
Direct and indirect fire control systems
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 systems
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 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
Fire-control systems are often interfaced with
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 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 "
See also
- Target acquisition
- Counter-battery radar
- Director (military)
- Fire-control radar
- List of U.S. Army fire control and sighting material by supply catalog designation
- Predicted impact point
- Ship gun fire-control systems
- Tartar Guided Missile Fire Control System
References
- ^ S2CID 6500043. Retrieved 2006-08-26.
- ^ "Chronology of the USS Monitor: From Inception to Sinking". The Mariner's Museum. USS Monitor Center. Archived from the original on 2006-07-13. Retrieved 2006-08-26.
- UAVsspotted fire for the Iowa-class battleships involved in shore bombardment.
- ^ See, for example US Naval Fire Control, 1918.
- ISBN 0-8018-8057-2.
- ^ The reasons were for this slow deployment are complex. As in most bureaucratic environments, institutional inertia and the revolutionary nature of the change required caused the major navies to move slow in adopting the technology.
- ^ Pollen 'Gunnery' p. 23
- ^ Pollen 'Gunnery' p. 36
- ^ For a description of an Admiralty Fire Control Table in action: Cooper, Arthur. "A Glimpse at Naval Gunnery". Ahoy: Naval, Maritime, Australian History.
- ^ The degree of updating varied by country. For example, the US Navy used servomechanisms to automatically steer their guns in both azimuth and elevation. The Germans used servomechanisms to steer their guns only in elevation, and the British began to introduce Remote Power Control in elevation and deflection of 4-inch, 4.5-inch and 5.25-inch guns in 1942, according to Naval Weapons of WW2, by Campbell. For example HMS Anson's 5.25-inch guns had been upgraded to full RPC in time for her Pacific deployment.
- ^ B.R. 901/43, Handbook of The Admiralty Fire Control Clock Mark I and I*
- ^ The rangekeeper in this exercise maintained a firing solution that was accurate within a few hundred yards (or meters), which is within the range needed for an effective rocking salvo. The rocking salvo was used by the US Navy to get the final corrections needed to hit the target.
- ^ Jurens, W.J. (1991). "The Evolution of Battleship Gunnery in the U.S. Navy, 1920–1945". Warship International (3): 255. Archived from the original on 2006-11-20. Retrieved 2006-10-18.
- ^ Anthony P. Tully (2003). "Located/Surveyed Shipwrecks of the Imperial Japanese Navy". Mysteries/Untold Sagas Of The Imperial Japanese Navy. CombinedFleet.com. Retrieved 2006-09-26.
- ISBN 0-8018-8057-2.
- ^ "Older weapons hold own in high-tech war". Dallas Morning News. 1991-02-10. Archived from the original on 2006-10-06. Retrieved 2006-09-30.
- ^ Moore, Christopher (12 August 2020). "Defending the Superbomber: The B-29's Central Fire Control System". National Air and Space Museum. Smithsonian Institution. Retrieved 18 August 2020.
- ^ "BLOW HOT-BLOW COLD - The M9 never failed". Bell Laboratories Record. XXIV (12): 454–456. Dec 1946.
- ^ Baxter, "Scientists Against Time"
- ^ Bennett, "A History of Control Engineering"
- ^ For early background, see "Fire Control and Position Finding: Background" by Bolling W. Smith in Mark Berhow, Ed., "American Seacoast Defenses: A Reference Guide," CDSG Press, McLean, VA, 2004, p. 257.
- ^ See for example, the write-up on Fort Andrews in Boston Harbor for a summary of artillery assets and fire control systems typical of these defenses.
- ^ For a complete description of fire control in the Coast Artillery, see "FM 4-15 Coast Artillery Field Manual-Seacoast Artillery Fire Control and Position Finding," U.S. War Department, Government Printing Office, Washington, 1940.
Further reading
- Baxter, James Phinney (1946). Scientists Against Time. Little, Brown and Company. ISBN 0-26252-012-5.
- Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
- Fairfield, A.P. (1921). Naval Ordnance. The Lord Baltimore Press.
- Frieden, David R. (1985). Principles of Naval Weapons Systems. Naval Institute Press. ISBN 0-87021-537-X.
- Friedman, Norman (2008). Naval Firepower: Battleship Guns and Gunnery in the Dreadnought Era. Seaforth. ISBN 978-1-84415-701-3.
- Hans, Mort; Taranovich, Steve (10 December 2012). "Design hindsight from the tail-gunner position of a WWII bomber, Part one". EDN. Retrieved 18 August 2020.
- Pollen, Antony (1980). The Great Gunnery Scandal — The Mystery of Jutland. Collins. ISBN 0-00-216298-9.
- Roch, Axel. "Fire-Control and Human-Computer Interaction: Towards a History of the Computer Mouse (1940-1965)". Stanford University. Archived from the original on 15 February 2020. Retrieved 18 August 2020.
- Schleihauf, William (2001). "The Dumaresq and the Dreyer". Warship International. XXXVIII (1). International Naval Research Organization: 6–29. ISSN 0043-0374.
- Schleihauf, William (2001). "The Dumaresq and the Dreyer, Part II". Warship International. XXXVIII (2). International Naval Research Organization: 164–201. ISSN 0043-0374.
- Schleihauf, William (2001). "The Dumaresq and the Dreyer, Part III". Warship International. XXXVIII (3). International Naval Research Organization: 221–233. ISSN 0043-0374.
- Wright, Christopher C. (2004). "Questions on the Effectiveness of U.S. Navy Battleship Gunnery: Notes on the Origin of U.S. Navy Gun Fire Control System Range Keepers". Warship International. XLI (1): 55–78. ISSN 0043-0374.
External links
- Between Human and Machine: Feedback, Control, and Computing Before Cybernetics – Google Books
- BASIC programs for battleship and antiaircraft gun fire control Archived 2012-10-03 at the Wayback Machine
- National Fire Control Symposium