How free gyroscope is made north seeking under influence of gravity control?
To get gyro compass, free gyroscope is made:
North seeking.
North settling.
North seeking:
To get north seeking, gravity is used to apply force/torque.
So, North end of spin axis will precess.
This method is called gravity control.
Gravity control can convert trace out circular path into elliptical path.
Gravity control can make North end of spin axis to oscillate forward and backward across meridian.
Two methods of gravity control:
Top heavy weight control. (Sperry)
Bottom heavy weight control. (Anschutz)
Top heavy: Sperry
To get north seeking, North end of spin axis will have to precess:
To west – when North end of spin axis is tilted up above horizon.
To east – when North end of spin axis is tilted down below horizon.
To get such precession, all top heavy weight control gyro must rotate anticlockwise when viewed from South.
Bottom heavy: Anschutz
To get north seeking, North end of spin axis will have to precess:
To west – when North end of spin axis is tilted up above horizon.
To east – when North end of spin axis is tilted down below horizon.
To get such precession, all bottom heavy weight control gyro must rotate clockwise when viewed from South.
We know, Rate of precession ∝ applied torque.
Again, Applied torque ∝ angle of tilt.
Therefore, Rate of control precession ∝ angle of tilt.
Rate of control precession varies as angle of tilt.
