OP-2074   September, 1956
Computer Mark 48 Mod 1


The Iowa Class Battleships were the only BB's to get a Mk 48 computer.  This happened during the Korean War.  The Mk 48 simplified the shore bombardment problem, because it did a lot of the work for you.

Computer Mk 48 Mod 1 operates in conjunction with the gun order computer, stable element, and director to provide an accurate solution to the problem of shore bombardment by indirect fire. It is designed to operate with the main and secondary batteries of cruisers and battleships, and may be used with antiaircraft or surface fire directors and computers or range keepers.

Computer Mk 48 Mod 1 primarily is designed to solve a fire control problem by using a visible reference point to direct fire at an obscured target whose map location with respect to the reference point is known.  This computer translates data that describe reference point position with respect to the ship into data that describe actual target position with respect to the ship. The figure below shows the data flow for direct and for indirect fire control.  The data that describe target position with respect to the ship then are transmitted to the gun order computer for computation of firing data.Chart 1

In indirect fire, Computer Mk 48 Mod 1 computes the quantities involved in target location by combining three sets of data:

Location of the reference point with respect to the ship.

The reference point, at which the director is continuously aimed, is located by its relative bearing, range and height.

Location of the target with respect to the reference point. This is established by X-Y map coordinates, reference point height, and target height. Level and cross level referenced to the target line-of-sight.

By combining these three sets of data, Computer Mk 48 Mod 1 furnishes to the gun order computer the following quantities: Offset relative target bearing, (director train to target), Target slant range and Target elevation.

In addition to transmitting target data to the gun order computer, Computer Mk 48 Mod 1 transmits data to the gun director to keep it aimed at the reference point.

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OP-2074 Part 1 Pages 1-151           22.8 mb

     OP-2074 Part 2 Pages 152-303         17.6 mb   

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    Related Material: The Stable Element

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