Ship Gun Fire-control System - US Navy Systems - MK 37 Gun Fire Control System (GFCS)

MK 37 Gun Fire Control System (GFCS)

"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 the first installation of a Mark 33. The objective of weight reduction was not met, since the resulting director system actually weighed about 8000 pounds 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 the Mark 33, it supplied them with greater reliability and gave generally improved performance with 5-inch 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 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 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 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 Mk 1 computer by 1935. Rate information for height changes enabled complete solution for aircraft targets moving over 400 mph. Destroyers starting with 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 Mk37 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 the probability that any one shell would destroy a target.