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Elmer Sperry: Gyroscopic Compass, 1914

Isolating the Problem

Using the gyroscope as a compass indeed seemed an ingenious idea, but several problems presented themselves to Sperry and other inventors struggling to create compasses that incorporated the gyro. In a publication of U.S. Naval Proceedings these problems are outlined as follows:
  1. To suspend the gyro with perfect freedom about the vertical axis so that it is free to precess toward the meridian.
  2. To damp the oscillations of the gyro across the meridian so that it will quickly settle down with its axis north and south.
  3. To constantly impress just exactly the right degree of force to keep it precessing to follow the component of the earth's rotation, which is normal to the earth's surface.
  4. To drive the gyro at a high rate of speed in order to furnish the directive force required.
  5. The following problems would need to be solved if the compass were to be placed onboard a ship: To so suspend the gyro that forces of acceleration and deceleration introduced by movements of the ship will not cause it to oscillate off the meridian, making its readings incorrect. These forces of acceleration and deceleration introduced by the ship are:
    1. a.) Acceleration and deceleration arising from starting and stopping the ship and changing its speed.
    2. b.) Centrifugal forces introduced by the ship in turning.
    3. c.) Forces due to non-coincidence of the center of the gyroscope with the center of oscillation of the ship, that is, forces introduced by rolling and pitching of the ship.
  6. To correct the compass for deflection, due to northerly and southerly components of the ship's movement, which, of course, act on the compass just as the movement due to the earth's rotation, except, of course, in a very much less degree.