# Gun data computer

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{{Short description|Artillery computers used by the U.S. Army}}
{{More footnotes needed|date=March 2010}}
{{Use American English|date=October 2024}}
{{Use dmy dates|date=October 2024}}
The '''gun data computer''' was a series of [artillery computer](/source/fire_control_system)s used by the [U.S. Army](/source/U.S._Army) for [coastal artillery](/source/coastal_artillery), [field artillery](/source/field_artillery) and [anti-aircraft artillery](/source/anti-aircraft_artillery) applications. For antiaircraft applications they were used in conjunction with a [director](/source/director_(military)) computer.
<!-- Deleted image removed: thumb|right|200px|title|M3 and M4 gun data computer 1944 -->

==Variations==
right|thumb|FADAC M18
[[File:FADAC gun computer.jpg|right|thumb|TACFIRE communications terminal box at [Fort Sill](/source/Fort_Sill) ]]
* M1: This was used by seacoast artillery for major-caliber seacoast guns. It computed continuous firing data for a battery of two guns that were separated by not more than {{convert|1000|ft||||}}. It utilised the same type of input data furnished by a range section with the then-current (1940) types of position-finding and fire-control equipment.
* M3: This was used in conjunction with the M9 and M10 directors to compute all required firing data, i.e. [azimuth](/source/azimuth), [elevation](/source/elevation_(ballistics)) and fuze time. The computations were made continuously, so that the gun was at all times correctly pointed and the fuze correctly timed for firing at any instant. The computer was mounted in the M13 or M14 director trailer.
* M4: This was identical to the M3 except for some mechanisms and parts which were altered to allow for different ammunition being used.
* M8: This was an electronic computer (using vacuum tube technology) built by [Bell Labs](/source/Bell_Labs) and used by coast artillery with medium-caliber guns (up to {{convert|8|in|disp=or|||}}). It made the following corrections: wind, drift, Earth's rotation, muzzle velocity, air density, height of site and spot corrections.
* [M9](/source/M9_Gun_Director): This was identical to the M8 except for some mechanisms and parts which were altered to accommodate anti-aircraft ammunition and guns.
* M10: A ballistics computer, part of the M38 fire control system, for [Skysweeper](/source/Skysweeper) anti-aircraft guns.
* M13: A ballistics computer for [M48 tank](/source/M48_tank)s.
* M14: A ballistics computer for [M103 heavy tank](/source/M103_heavy_tank)s.
* M15: A part of the M35 field artillery fire-control system, which included the M1 gunnery officer console and M27 power supply.
* M16: A ballistics computer for [M60A1](/source/M60A1) tanks.
* M18: ''FADAC'' (field artillery digital automatic computer),<ref>{{cite book |last1=Kempf |first1=Karl |title=Electronic Computers Within The Ordnance Corps, Computers for Solving Gunnery Problems |date=November 1961 |url=http://ftp.arl.mil/mike/comphist/61ordnance/chap6.html |chapter=CHAPTER VI -- COMPUTERS FOR SOLVING GUNNERY PROBLEMS |archive-url= https://web.archive.org/web/20240907214159/http://ftp.arl.mil/mike/comphist/61ordnance/chap6.html |archive-date= September 7, 2024}}</ref><ref>{{cite journal |title=Field Artillery Digital Automatic Computer (FADAC) |journal=Department of Defense Appropriations for 1970, Part 5. Hearings 91st Congress 1st Session 1969 |volume=9 |pages=644–645, 647–648 |url=https://hdl.handle.net/2027/mdp.35112202783561?urlappend=%3Bseq=650 |publisher=U.S. Government Printing Office|hdl=2027/mdp.35112202783561?urlappend=%3Bseq=650 |language=en}}</ref> an all-transistorized general-purpose digital computer<ref>{{cite magazine |last= Milavec |first= Lt Albert R |date= May 1968 |title= On FADAC Maintenance |url= https://sill-www.army.mil/firesbulletin/archives/1968/MAY_1968/MAY_1968_FULL_EDITION.pdf |page= 32 |magazine= Artillery Trends |location= |publisher= US Army Artillery and Missile School |access-date=May 25, 2025 |archive-url= https://web.archive.org/web/20180929162232/https://sill-www.army.mil/firesbulletin/archives/1968/MAY_1968/MAY_1968_FULL_EDITION.pdf |archive-date= September 29, 2018 |quote= The FADAC is an all-transistorized, stored-program, general purpose digital computer... Weighing approximately 200 pounds... the FADAC components utilize approximately 1,600 [transistors](/source/transistor_count), 9,000 diodes, 6,000 resistors, 500 capacitors, and many other switches, transformers, and neon lamps.}}</ref> manufactured by Amelco ([Teledyne Systems, Inc.](/source/Teledyne),)<ref>{{Citation |url= https://babel.hathitrust.org/cgi/pt?id=uc1.b4291573;view=1up;seq=1421 |title= Department of Defense appropriations for 1965 - Hearings before a subcommittee of the Committee on Appropriations |page= 283 |date= 1964 |access-date= May 25, 2025 |publisher= US Government Printing Office}}</ref> and [North American](/source/North_American_Aviation)—[Autonetics](/source/Autonetics).<ref>{{Citation |url= https://ed-thelen.org/comp-hist/BRL61-f.html#FADAC |title= A Third Survey of Domestic Electronic Digital Computing Systems - FADAC - Field Artillery Digital Automatic Computer |first= Martin H. |last= Weik |page=254 |date= 1961 |access-date= May 25, 2025 |publisher= Ballistic Research Laboratories |location= |archive-url= https://web.archive.org/web/20240627235240/https://ed-thelen.org/comp-hist/BRL61-f.html#FADAC |archive-date= June 27, 2024}}</ref> FADAC was first fielded during 1960,<ref>{{Cite web |url= http://sill-www.army.mil/famag/1960/sep_1960/SEP_1960_PAGES_8_15.pdf |title= "First Round Hits" With FADAC |date= September 1960 |website= sill-www.army.mil |page= 9 |language= en |access-date= May 25, 2025 |archive-url= https://web.archive.org/web/20110617062042/http://sill-www.army.mil/famag/1960/sep_1960/SEP_1960_PAGES_8_15.pdf |archive-date= June 17, 2011}}</ref> and was the first [semiconductor-based](/source/Solid_state_(electronics)) [digital electronics](/source/digital_electronics) field-artillery computer.
* M19: A ballistics computer for [M60A2](/source/M60A2) tanks.
* M21: A ballistics computer for [M60A3](/source/M60A3) tanks.
* M23: A mortar ballistics computer.
* M26: A fire-control computer for [AH-1 Cobra](/source/AH-1_Cobra) helicopters, (AH-1F).
* M31: A mortar ballistics computer.
* M32: A mortar ballistics computer, (handheld).
* M1: A ballistics computer for [M1 Abrams](/source/M1_Abrams) [main battle tank](/source/main_battle_tank)s.

==Systems==
right|thumb|AN/GSG-10 TACFIRE
* The Battery Computer System (BCS) '''AN/GYK-29''' was a computer used by the [United States Army](/source/United_States_Army) for computing [artillery](/source/artillery) fire mission data. It replaced the FADAC and was small enough to fit into the [HMMWV](/source/HMMWV) combat vehicle.
* The '''AN/GSG-10 TACFIRE''' (Tactical Fire) direction system automated [field artillery](/source/field_artillery) command and control functions.<ref>{{Citation |url= https://www.sciencedirect.com/science/article/abs/pii/0164121279900153 |title= TACFIRE: A case history of a weapon system software development |first=Alan B. |last= Salisbury |journal= Journal of Systems and Software |volume= 1 |year= 1979 |pages= 155–175 |doi= 10.1016/0164-1212(79)90015-3 |access-date= 11 August 2024|url-access= subscription }}</ref> It was composed of computers and remote devices such as the Variable Format Message Entry Device (VFMED), the '''AN/PSG-2''' Digital Message Device (DMD) and the '''[AN/TPQ-36 Firefinder](/source/AN%2FTPQ-36_Firefinder_radar)''' field artillery target acquisition [radar](/source/radar) system linked by digital communications using existing radio and wire communications equipment. Later it also linked with the BCS which had more advanced targeting algorithms.

The last TACFIRE fielding was completed during 1987. Replacement of TACFIRE equipment began during 1994.{{Citation needed|date=August 2024}}

TACFIRE used the '''[AN/GYK-12](/source/AN%2FGYK-12)''', a second-generation mainframe computer developed primarily by [Litton Industries](/source/Litton_Industries) for Army divisional field artillery (DIVARTY) units. It had two configurations (division and battalion level) housed in mobile command shelters. Field artillery brigades also use the division configuration.

Components of the system were identified using acronyms:
* '''CPU''' {{En dash}} [Central Processing Unit](/source/Central_Processing_Unit)
* '''IOU''' {{En dash}} Input/Output Unit
* '''MCMU''' {{En dash}} Mass [Core Memory](/source/Core_Memory) Unit
* '''DDT''' {{En dash}} Digital Data Terminal
* '''MTU''' {{En dash}} Magnetic Tape Unit
* '''PCG''' {{En dash}} Power Converter Group
* '''ELP''' {{En dash}} Electronic Line Printer
* '''DPM''' {{En dash}} Digital Plotter Map
* '''ACC''' {{En dash}} Artillery Control Console
* '''RCMU''' {{En dash}} Remote Control Monitoring Unit

The successor to the TACFIRE system is the [Advanced Field Artillery Tactical Data System](/source/Project_Manager_Battle_Command) (AFATDS). The AFATDS is the "Fires XXI" computer system for both tactical and technical fire control. It replaced both BCS (for technical fire solutions) and IFSAS/L-TACFIRE (for tactical fire control) systems in U.S. Field Artillery organizations, as well as in maneuver fire support elements at the battalion level and higher.  By 2009, the U.S. Army was transitioning from a version based on a [Sun Microsystems](/source/Sun_Microsystems) [SPARC](/source/SPARC) computer running the [Linux kernel](/source/Linux_kernel) to a version based on laptop computers running the [Microsoft Windows](/source/Microsoft_Windows) operating system.

===Surviving examples===
One reason for a lack of surviving examples of early units was the use of [radium](/source/radium) on the dials. As a result they were classified as [hazardous waste](/source/hazardous_waste) and were disposed of by the [United States Department of Energy](/source/United_States_Department_of_Energy). Currently there is one surviving example of a FADAC computer at the [Fort Sill](/source/Fort_Sill) artillery museum.{{cn|date= May 2025}}

==See also==
{{Portal|Electronics}}
<!-- New links in alphabetical order please -->
* [Director (military)](/source/Director_(military))
* [Fire-control system](/source/Fire-control_system)
* [Kerrison Predictor](/source/Kerrison_Predictor)
*[List of military electronics of the United States](/source/List_of_military_electronics_of_the_United_States)
* [Mark I Fire Control Computer](/source/Mark_I_Fire_Control_Computer) – US Navy system for 5-inch guns
* [Numerical control](/source/Numerical_control)
* [Rangekeeper](/source/Rangekeeper)

==References==
{{reflist}}

== Further reading ==
* TM 9-2300 Standard Artillery and Fire Control Materiel dated 1944
* TM 9-2300 Artillery Materiel and Associated Equipment dated May 1949
* ST 9-159 Handbook of Ordnance materiel dated 1968

==External links==
* [https://web.archive.org/web/20040511174351/http://combatindex.com/mil_docs/pdf/hdbk/0700/MIL-HDBK-799.pdf ''Web Archive'' - DoD Handbook - Fire Control Systems - General]
* [https://web.archive.org/web/20110720002347/https://rdl.train.army.mil/soldierPortal/atia/adlsc/view/public/12288-1/FM/3-22.91/chap1.htm ''Web Archive'' - FM 3-22.91 Chap 1 - Introduction and Fundamentals of Mortar Fire Direction]
* [https://web.mit.edu/STS.035/www/PDFs/Newell.pdf ''MIT.edu'' - The Mechanical Analog Computers of Hannibal Ford and William Newell]
* [https://www.globalsecurity.org/military/library/report/1988/MJR.htm ''GlobalSecurity'' - Taking Marine Artillery Into The Twenty-First Century]
* [https://www.globalsecurity.org/military/library/policy/army/fm/6-50/Appl.htm ''GlobalSecurity'' - FM 6-50 Appendix L - Gun Display Unit]

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Category:Military electronics of the United States
Category:Artillery operation
Category:Applications of control engineering
Category:Analog computers
Category:Ballistics
Category:World War II American electronics
Category:Fire-control computers of World War II

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Adapted from the Wikipedia article [Gun data computer](https://en.wikipedia.org/wiki/Gun_data_computer) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Gun_data_computer?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.
