# If the RPM of the Gyro is increased due to high Vacuum Pressure. Will it increase rigidity and resist precession?

If the RPM of the GYRO of the Attitude Indicator or Heading Indicator is increased due to high vacuum pressure. Will it increase rigidity in space and resist any force applied and it will not precess? or will the precession be more exaggerate the reading?

it will hold position more tenaciously with a faster-spinning rotor in it. But it will also wear out its bearings faster, and thereby fail sooner, that a slower-turning rotor. Gyro instrument performance is a compromise between locking on and holding a certain attitude or gimbal position, and bearing longevity.

Basic physics will help in understanding (From my ATPL book)

When the rotor is made to spin, the device becomes a gyroscope possessing two properties :

1. Rigidity (or gyroscopic inertia); and
2. Precession.

Rigidity

Rigidity is the property of a gyroscope which resists any force tending to change the plane of rotation of its rotor. As a result of rigidity, the spin axis tends to maintain a fixed direction in space. Rigidity is dependent on three factors : (a) the mass of the rotor; (b) the speed of the rotation (RPM); and (c) the distance of the mass from the centre of the rotor (radius).

The mass and radius of the rotor determine its moment of inertia. Rigidity is proportional to the rotor's moment of inertia (I) and its angular velocity (represented by the letter omega)

Rigidity is the property of the gyro which allows the gyro to be used as an independent stable reference.

Precession

Precession is the change of direction (angular change) of the plane of rotation of the rotor caused by an applied force. The amount and rate of precession is dependent on three factors :-

(a) the magnitude and direction of the applied force;

(b) the moment of inertia of the rotor and

(c) the angular velocity of the rotor (RPM).

• Rate of precession is directly proportional to the applied torque(T).
• Rate of precession is indirectly proportional to rigidity.

From the text above it is quite clear that if the RPM of any mechanical GYRO is increased due to whatever reason, it will increase rigidity in space and resist any force applied and it will precess mechanically less (aparent wander or precession due to rotation of the earth or travelling still present).