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First Semester (BSMT) > Gyro Compass (MIDTERM AND FINALS) > Flashcards

Gyro Compass (MIDTERM AND FINALS) Flashcards

1
Q

a non magnetic compass in which the direction of true north is maintained by a continuously driven gyroscope whose axis is parallel to the earth’s axis of rotation

A

gyro compass

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2
Q

consists of a spinning wheel or rotor contained within gimbals which permit movement about three mutually perpendicular axes, known as the horizontal axis, the vertical axis, and the spin axis

A

gyroscope

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3
Q

two basic properties of gyroscopes

A

Rigidity and Precession

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4
Q

The axis of rotation (spin axis) of the gyro wheel tends to remain in a fixed direction in space if no force is applied to it.(gyroscopic inertia)

A

RIGIDITY

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5
Q

depends on the angular velocity, mass, and radius of the wheel or rotor

A

Gyroscopic inertia

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6
Q

The axis of rotation has a tendency to turn at a right angle to the direction of an applied force

A

PRECESSION

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7
Q

the rate of precession is proportional to the

A

applied torque

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8
Q

a change in the orientation of the rotational axis of a rotating body

A

PRECISSION

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9
Q

This phenomenon is found only in spinning bodies. It is the movement of the spin axis when a force is applied to the spin axis of gyroscope. When a couple is applied about its horizontal axis, the spin axis will turn at right angles to the applied force in the direction of the spin of the wheel. Similarly couple applied about the vertical axis will make the spin axis turn about the horizontal axis in the direction of the spin axis of the wheel

A

PRECESSION

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10
Q

If the applied torque has a component which is perpendicular to the initial angular momentum the gyroscope will

A

PRECESS

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11
Q

is a measure of how much a force acting on an object causes that object to rotate

A

Torque

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12
Q

three vectors

A

torque, spin, and precession

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13
Q

are all oriented with respect to each other according to the right-hand rule

A

three vectors, (torque, spin, and precession)

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14
Q

It has 3 degrees of freedom:

A
  1. It is free to spin about spinning axis
  2. It is free to rotate about vertical axis
  3. It is free to rotate about horizontal axis
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15
Q

The motion of the spin axis in the horizontal plane is known as

A

drift

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16
Q

The movement of spin axis in the direction of Azimuth is

A

drift

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17
Q

The rate of change of drift is

A

drifting

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18
Q

The motion of spin axis in the vertical plane is known as

A

tilt

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19
Q

The angle of elevation or depression of the spin axis above or below the horizontal is

A

tilt

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20
Q

The rate of change of tilt is

A

tilting

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21
Q

The gyrocompass depends upon four natural phenomena:

A

gyroscopic inertia, precession, earth’s rotation, and gravity

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22
Q

To make a gyroscope into a gyro compass, the wheel or rotor is mounted in a sphere, called the _, and the sphere is then supported in a _

A

gyro sphere, vertical ring

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23
Q

The whole is mounted on a base called the

A

phantom

24
Q

The rotor may weigh as little as half a kilogram to

A

over 25 kg

25
Q

To make the gyro seek north, a system of reservoirs filled with mercury, known as _, is used to apply a force against the spin axis

A

mercury ballistics

26
Q

used to apply a force against the spin axis

A

mercury ballistics

27
Q

usually four in number, are placed so that their centers of gravity exactly coincide with the CG of the gyroscope

A

ballistics

28
Q

then causes the spin axis to trace an ellipse, one ellipse taking about 84 minutes to complete

A

Precession

29
Q

To make it seek and maintain true north, three things are necessary.

A

First, the gyro must be made to stay on the plane of the meridian.
*Second, it must be made to remain horizontal.
*Third, it must stay in this position once it reaches it regardless of what the vessel on which it is mounted does or where it goes on the earth

30
Q

one ellipse taking about _ to complete

A

84 minutes

31
Q

two methods of damping:

A

Damping in tilt and Damping in azimuth

32
Q

In this method a force is applied in the horizontal plane (a torque to the vertical axis) which results in a precession in the vertical plane, reducing the

A

Damping in tilt

33
Q

In this method a precession is developed which assists the movement in the azimuth plane when the axis moves towards the meridian, and opposes the movement when the spin axis moves away from the meridian

A

Damping in azimuth

34
Q

means that when the North-seeking end of the gyroscope axis is - a damping torque is applied in a horizontal plane in such a direction that the resultant precession in a vertical plane causes the - of the axis to decrease

A

Damping in tilt

35
Q

The amplitude of each oscillation is reduced to _ and thereby resulting in the axis finally setting down in the meridian

A

1/3 of the previous oscillation

36
Q

is achieved by introducing a torque in a vertical plane, which causes a precession opposite to the gravity control precession but out of phase with it, i.e, with a time delay.

A

Damping in azimuth

37
Q

The _ causes the axis to overshoot the meridian less each time it crosses it until the gyroscope axis reaches its setting position

A

resultant precession in a horizontal plane

38
Q

is a very important and unique tool in marine navigation as it does not operate automatically like other magnetic compasses

A

Fluxgate compass

39
Q

is an electromagnetic compass which solves the purpose of a conventional compass

A

fluxgate compass

40
Q

is a device that helps to correctly pinpoint the geographical direction while on a sea going vessel

A

compass

41
Q

is a very important and unique tool in marine navigation as it does not operate automatically like other magnetic compasses

A

fluxgate compass

42
Q

is an electromagnetic compass which solves the purpose of a conventional compass

A

fluxgate compass

43
Q

is used in ships mainly for the purpose of steering.

A

fluxgate compass

44
Q

the compass is an electronic one, the scope of errors is greatly reduced. In addition to manual steering, such a compass can also be utilised when the ship is on autopilot. Even chart plotters and radars use this system to provide them with accurate geographic indications

A

fluxgate compass

45
Q

there are no pointers that specify the direction

A

electronic compass

46
Q

There are two coils of wire that are located perpendicular to each other around a permeable magnetic material. When electric current is passed through the coils the core material works an electromagnet and senses the direction of the horizontal component of the earth’s magnetic field. This completely eradicates the problem caused due to the interference of the magnetic north is completely avoided

A

electronic compass

47
Q

Another advantage of installing this type of compass in the ship is that these types of compasses are unaffected by their placement on the ship.

A

electronic compass

48
Q

They can be placed anywhere and the directions pointed by the compass can be relied on completely.

A

electronic compass

49
Q

can prove very useful during rough seas as they are unaffected by position and unusual movements

A

Fluxgate compass

50
Q

is one of the best navigating technologies that are available in the marine industry

A

fluxgate compass

51
Q

which detects and transmits the ship’s Compass Heading over a digital connection to one or more CompassHeading Repeaters at any convenient location on a vessel.

A

Transmitting Magnetic Compass (TMC) System

52
Q

provides a complete alternative (or a backup) to a gyro compass as a source of Heading.Magnetic Variation andDeviation can be corrected using theMarine Data to give True Heading.

A

TMC system

53
Q

can provide a source of Heading for Compass Repeaters and other navigation equipment.

A

TMC

54
Q

refers to electronic components, devices, and systems based entirely on the semiconductor

A

Solid-state

55
Q

The expression was especially prevalent in the late 1950s and early 1960s, during the transition from vacuum tube technology to the semiconductor diode and transistor

A

Solid-state

First Semester (BSMT) (22 decks)

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