Figure 3-13.Rate gyro (single degree of freedom).
If you attempt to change the gyro's plane of rotor spin by rotating the case about the input axis, the
gyro will precess as shown in figure 3-14. From what you learned earlier in this chapter, the gyro does not
appear to be obeying the rules for precession. However, turning the gyro case has the same effect as
applying a torque on the spin axis. This is illustrated by arrow F in figure 3-14. You can determine the
direction of precession by using the right-hand rule we discussed earlier.
Figure 3-14.Rate gyro precession.
The force applied at F will cause the gyro to precess at right angles to the force. Likewise, attempting
to turn the gyro case will cause the same result. The gyro will precess, as shown by the arrows, around the
Y-Y axis (output axis).
Since the rate of precession is proportional to the applied force, you can increase the precession by
increasing the speed with which you are moving the gyro case. In other words, you have a rate gyro. The