Everything Gadgets

Mechanical Computer Basics

YouTube user gwz40 uploaded a series of fascinating videos on mechanical computers and how they were used in in the US Navy for controlling projectiles fired from one moving ship to another moving target.   The movies were produced as part of a US Navy training program and illustrate the basic components that are used inside a mechanical range fire control computer.  Each mathematical operation is translated in to a mechanical component and the components are combined to provide a desired calculation based on (up to) 25 inputs.  Basic geometric shapes are used for shockingly complex operations.

After watching the videos, it is amazing to think that these devices, built in the 1920’s achieved such precision.  Calculations were not preformed by hand, but by the contours of a gear that was precision ground by a machinist. (More info below the videos)

Vintage Fire Control Computer

Video #1: Basic Mechanisms in Fire Control Computers Part 1 (3 sections)

Video #2: Basic Mechanisms in Fire Control Computers Part 2 (4 sections)

I believe the machine show in the video and the photo on this site is the Mark 1 computer.  From Wikipedia:

The Mark 1, and later the Mark 1A, Fire Control Computer was a component of the Mark 37 Gun Fire Control System deployed by the United States Navy during World War II and up to 1969. It was used on a variety of ships, ranging from destroyers (one per ship) to battleships (four per ship). The Mark 37 system used tachymetric target motion prediction to compute a fire control solution. Weighing more than 3000 pounds (1363 kilograms), the Mark 1 itself was installed in the plotting room, a water tight compartment that was located deep inside the ship’s hull to provide as much protection against battle damage as was possible.

Essentially an electromechanical analog computer, the Mark 1 was electrically linked to the gun turrets and the Mark 37 gun director, the latter mounted as high on the superstructure as possible to afford maximum visual and radar range. The gun director was equipped with both optical and radar range finding, and was able to rotate on a small barbette-like structure. Using the range finders, the director was able to produce a continuously varying set of outputs, referred to as line-of-sight (LOS) data, that were electrically relayed to the Mark 1 via synchro motors. The LOS data provided the target’s present range, bearing, and in the case of aerial targets, altitude. Additional inputs to the Mark 1 were continuously generated from the stable vertical, a gyroscopic device that reacted to the roll and pitch of the ship, the pitometer log, which measured the ship’s speed through the water, and an anemometer, which provided wind speed and direction.

Mark 1 Fire Computer

Image from: http://www.flickr.com/photos/thewayofthegun/ / CC BY-NC 2.0

Wikipedia Entry: http://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer

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