31-10 Thomson Avenue
Long Island City 1, New York

Ford Instrument Computer Mark 1

Computer Mark 1 w/o covers
Interior of the Computer Mark 1
Computer Mark 1
Ford Instrument Company
Long Island City, New York
This is navy shipboard based mechanical analog computer used on aircraft carriers, battleships, cruisers, and destroyers during WWII. As part of a Gun Director Mark 37 system, it is used for the aiming of 5"/38 cal, 5"/54 cal, 6"/47 cal, and 8"/55 cal guns against air and surface targets.
Cost of computer new:about $75000
Computing Elements: 9 Component Solvers
  1 Vector Solver
  6 Disk Integrators
  4 Component Integrators
  9 Multipliers
  6 Computing Multipliers
  8 Cams
  5 Single-Speed Receivers
  4 Double-Speed Receivers
  10 Single-Speed Transmitters
  10 Double-Speed Transmitters
  22 Follow-up Controls
  3 Solenoid Clutches
  2 Solenoid Locks
  24 Handcranks
  150 Differentials
  The Computer Mark 1 consists of four sections:

  The Relative Motion Group combines the motions of OwnShip and Target into three rates of Relative Motion in relation to the Line of Sight, Elevation Rate, Deflection Rate, and Range Rate.
  The Integrator Group uses these rates to generate changes of Target Position in Range, Elevation, and Bearing. These changes are continuously transmitted to the Director to position the telescopes and the Range Finder.
  If the generated values of Target Position do not keep the sights on the Target, the operators in the Director press their Rate Control keys and turn their handwheels to keep the sights on the Target.
  Turning the handwheels with the Rate Control keys closed sends Rate Control corrections to the Rate Control Group in the Computer.
  The Rate Control Group applies these corrections to the values of Target Motion and sends the corrected values back to the Relative Motion Group.
  The Deck Tilt Group computes the correction necessary to convert Director Train in the deck plane to Relative Target Bearing in the horizontal plane.
  The Synchronize Elevation Group converts Director Elevation above the deck to Target Elevation above the horizontal.

  Uses the three Relative Motion Rates to compute the amount the guns must lead the Target. It computes two lead angles and a fuse setting order.
  The Lead Angles include computation for the change in Target Position while the projectile is in the air and for the projectile's curved path. The Prediction Section computes the Target Position at the end of the Time of Flight and corrections for the effect of gravity, drift, wind, and changes in initial velocity on the projectile's path.
  The Fuse Setting Order includes a correction for the change in Range during the time the projectile is being loaded.

  Computes corrections for the effects of pitch and roll on the gun trunnions. The lead angles and the Trunnion Tilt Corrections are combined with Director Elevation and Train to form the two Gun Orders.

  Computes Train and Elevation Parallax Corrections for a horizontal distance of 100 yards along the fore and aft axis. Each gun or Director may use a fraction of each correction acording to its distance from the Reference Point.

Labeled exterior features of Computer Mark 1
Labeled exterior features of the Computer Mark 1.
Click on picture for a better view.
Specifications of the Computer Mark 1:
- Without handcranks, the Computer Mark 1 measures approximately 62 inches long, 38 inches wide, and 45 inches high. With the Star Shell Computer Mark 1 in place, the overall height is 65 inches.
WEIGHT - The Computer Mark 1 weights about 3125 lbs. The Star Shell Computer Mark 1 weighs about 215 lbs.
POWER SUPPLY - The Computer Mark 1 and the Star Shell Computer operates on 115 volts AC, single phase. And uses between 57.5 and 140 amperes.

Ships using the Computer Mark 1:
- all types after DD409 and some earlier.
Light and Heavy Cruisers - after CL51 and CA68.
Battleships - after BB55 and some earlier.
Aircraft Carriers - type CV9 and CVB41.
  There are three operator stations around the Computer Mark 1. On the left side is the Elevation Station, on the right side is the Bearing Station, and in front of the computer is the Range Station. Each station may be manned by one or more operators, according to the ship's doctrine.

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