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Detection, Observation, and Fire Control Systems

Detection, Observation, and Fire Control Systems. Hitting a distant moving target requires observing its range and bearing, estimating its speed and direction, extrapolating into the future to compute the lead, and then calculating ballistics (that is, how to set a gun with the proper angle and elevation to hit a target at a particular range and bearing). Before the twentieth century, gunners performed these tasks manually or aided by small instruments, observing with optical telescopes and rangefinders, looking up ballistics in firing tables, and setting guns by hand. Beginning around World War I, however, these operations became progressively automated and combined into specialized fire control systems. The apparatus integrated target detection and tracking, ballistics calculation, and gun command into a connected set of machines. For much of the twentieth century, fire control ranked among the most secret and delicate technologies in the American arsenal.

Automated fire control began in the navy with the adoption of “director firing,” which controlled all guns on a ship from a centralized location. Before World War I, Arthur Hungerford Pollen designed an early automated plotting system for British ships. In America, the Sperry Gyroscope Company connected instruments that collected observed data about a target into a central plotting room. An automatic plotter drew the paths of both the firing ship and the target ship on paper, from which a gunnery officer could read the range and bearing for the guns to fire. He then electrically transmitted these data to gunners in the turrets. In 1915, Sperry's chief designer, Hannibal Ford, left to start the Ford Instrument Company and introduced the Ford Rangekeeper, which both incorporated British technology and added new mechanisms of Ford design. The Rangekeeper, a mechanical analog computer, estimated the course and speed of a target ship based on repeated observations of range and bearing, continually updating the estimate in accord with new observations. The U.S. Navy enthusiastically adopted the Ford Rangekeeper, at first for battleships and then for destroyers and cruisers. Before World War II, the secret and novel military‐industrial alliance of the Bureau of Ordnance and the Ford Instrument Company, the Arma Engineering Company, and General Electric built nearly all fire control systems for the navy. Ford Rangekeepers, in numerous updates and modifications, directed guns on American warships into the 1990s. Arma also designed the famous Torpedo Data Computer (TDC) for submarines and surface ships. Sperry and another spinoff, Carl Norden Inc., began building bombsights, a technology similar to Rangekeepers that played a critical role in World War II.

Naval fire control systems achieved a certain technical maturity between the world wars, but the critical problem in fire control shifted from hitting surface targets to a new challenge: aircraft. This problem, including all the difficulty of surface fire but at higher speed and in three dimensions, pushed fire control technology to its limits. Both the army and the navy developed antiaircraft directors, which tracked airplanes (at first with telescopes and then with radar), calculated the “lead,” and directed guns to proper aiming positions. During World War II, lightweight, low‐cost “lead computing sights,” mounted directly on manually controlled guns, approximated the solution for close‐in attacks. An extensive research program under the National Defense Research Committee extended the scope and sophistication of fire control technology, covering theory, electronics, bombsights, fuses, radar, fire control for aerial guns, and automation. This led not only to new fire control technologies but also to fundamental advances in computers, including work by Norbert Wiener (founder of cybernetics), Claude Shannon (founder of information theory), and George Stibitz (builder of the first digital computers). Automated, radar‐directed fire control systems achieved critical successes during the war, especially against the German V‐1 “buzz bombs” in Britain, and against Japanese air attacks in the western Pacific. Still, researchers never adequately solved the general problem of hitting rapidly maneuvering targets with ballistic shells (although the current Phalanx system does so at short ranges). Engineers, then, moved the control system into the projectile itself so it could continue to observe the target and control the shell during flight. The proximity fuse, developed during World War II for antiaircraft munitions accomplished this control in a single dimension, detecting a target with a miniature radio transmitter and detonating the shell at the optimum time. Extending control to further dimensions and adding rocket motors for propulsion produced guided missiles.

Today, numerous military systems, including tanks, aircraft, and submarines, have their own specialized fire control systems. Guided missiles rely on fire control to find, track, and select targets. Large, computerized command and control systems, such as Sage and BMEWs for air defense, and NTDS and Aegis for naval warfare, also inherited the legacy of fire control and made significant contributions to computer science. The problem of directing fire against rapidly moving targets still drives military technology, even in public perception. The Stark and Vincennes incidents in the Persian Gulf in the 1980s, the questionable performance of the Patriot missile system in the Persian Gulf War (1991), and the continuing controversy over ballistic missile defenses such as the Strategic Defense Initiative all illustrate that fire control remains a critical and difficult component of American technological warfare.
[See also Consultants; Heat‐Seeking Technology; Lasers; Missiles; Radar; Sonar.]


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David A. Mindell

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