Effect of Gyroscopic Couple on Aeroplane:
The top front view of an aeroplane are shown in fig:
Let engine or propeller rotates in the clockwise direction when seen from the rear or tail end and the aeroplane takes a turn to the left.
Effect of Gyroscopic Couple on Ship:
The top and front views of a naval ship are shown in fig:
The fore end of the ship is called bow and the rear end is known as stern or aft. The left hand and right hand sides of the ship, when viewed from the stern are called port and star-board respectively. We shall now explain the effect of gyroscopic couple on the naval ship in the following three cases:
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1. Steering
2. Pitching
3. Rolling
Effect of Gyroscopic Couple on a Ship during Steering:
Steering is the turning of a complete ship in a curve towards left or right, while it moves forward. Consider the ship taking a left turn and rotor rotates in the clockwise direction when viewed from the stern as shown as in below fig:
The effect of gyroscopic couple on a naval ship during steering taking left or right turn may be obtained in the similar way as for an aeroplane. When the rotor of the ship rotates in the clockwise direction when viewed from the stern, it will have its angular momentum vector in the direction. As the ship steers to the left, the active gyroscopic couple will change the angular momentum vector from ox to ox’.
The vector xx’ now represents the active gyroscopic couple and is perpendicular to ox. Thus the plane of active gyroscopic couple is perpendicular to xx’ and its direction in the axis OZ for left hand turn is clockwise. The reactive gyroscopic couple of the same magnitude will act in the opposite direction. The effect of this reactive gyroscopic couple is to raise the bow and lower the stern.
Effect of Gyroscopic Couple on a Ship during Pitching:
Pitching is the movement of a complete ship up and down in a vertical plane about transverse axis as shown in below fig:
In this case, the transverse axis is the axis of precession. The pitching of the ship is assumed to take place with simple harmonic motion, the motion of the axis of spin about transverse axis is simple harmonic.
Effect of Gyroscopic Couple on a Ship during Rolling:
We know that for the effect of gyroscopic couple to occur, the axis of precession should always be perpendicular to the axis of spin. If, however, the axis of precession becomes parallel to the axis of spin, there will be no effect of the gyroscopic couple acting on the body of the ship.
In case of rolling of a ship, the axis of precession is always parallel to the axis of spin for all positions. Hence, there is no effect of the gyroscopic couple acting on the body of a ship.