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Foundation > Acoustics > Flashcards

Acoustics Flashcards

1
Q

What are the 7 propulsion modes?

A

Turbo Reduction
Turbo Electric

Diesel Direct
Diesel Reduction
Diesel Electric

Battery Drive
Air Independant Propulsion

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2
Q

What is the advantage of Nuclear Engine?

A

Range, speed and endurance

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3
Q

What is the disadvantage of Nuclear

A

Constant noise sources

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4
Q

Advantage of Diesel?

A

Very quiet on batteries

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5
Q

Disadvantage of Diesel

A

Must snort to recharge batteries

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6
Q

Define sound

A

Periodic variation of pressure, particle displacement or particle velocity in an elastic medium.

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7
Q

Define a choke point

A

Geographical feature, above or below the surface of the sea, that restricts the freedom of movement of a submarine.

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8
Q

Example of a choke point?

A

The English Channel

The Straits of Gibraltar

Greenland-Iceland-UK Gaps

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9
Q

What are the three main requirements of a successful underwater detection system?

A

Good penetration (active) or sensitivity (passive)
High resolution
High data rate

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10
Q

What three factors affect the speed of sound in water?

A

Temperature
Pressure
Salinity

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11
Q

Which of the three factors that affect the speed of sound has the greatest effect?

A

Temperature

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12
Q

Define the Doppler Phenomenon

A

Apparent change in frequency due to the relative motion between a source and receiver.

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13
Q

What does DIFAR stand for?

A

Directional Frequency Analysis & Recording

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14
Q

What are the selectable DIFAR Depths?

A

90, 200, 400, 1,000 ft

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15
Q

What does DICASS stand for?

A

Directional Command Activated Sonobuoy System

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16
Q

What is the DICASS operating life?

A

60 minutes (50 ping seconds)

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17
Q

What information can be gained from a CPA?

A 
Speed
Range
Bearing
Track
F0
Depth
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18
Q

What does HALT stand for?

A

High Away, Low Towards

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19
Q

What are the submarine types?

A

SSK Submersible Ship Killer
SSC Submersible Ship Coastal
SSP Submersible Ship Air Independant Propulsion
SSN Submersible Ship Nuclear
SSAN Submersible Ship Auxillary Nuclear
SSBN Submersible Ship Ballistic Missile Nuclear
SSGN Submersible Ship Guided Missile Nuclear

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20
Q

What are the 2 types of seamounts that can be found in the ocean?

A

Pinnacles

Guyots

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21
Q

Define Ambient Noise

A

Any noise within the ocean that is not target related.

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22
Q

What are the two types of ambient noise?

A

Man-made and Natural

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23
Q

What are the man-made sources of ambient noise?

A

Shipping noise
Seismic surveying
Drilling
Active transmissions

24
Q

What are the natural sources of ambient noise?

A

Biological
Ice
Weather
Seismic

25
Q

What are the main types of bottom composition?

A

Sand
Rock
Mud and Silt (Ooze)

26
Q

What are the 4 dimensions of a LOFARgram

A

Time
Frequency
Colour
Intensity

27
Q

What propulsion modes are not common in submarines?

A

Diesel Direct

Diesel Reduction

28
Q

What equipment is involved in Snorting?

A

1st: Sonar underwater
2nd: ESM
3rd: Radar
4th: Periscope
5th: Snort induction mast

29
Q

Reasons to surface?

A

Battery Charging
Communications
Attack solutions
Emergency

30
Q

What is the difference between active and passive sonar?

A

Active two way transmission

Passive one way transmission

31
Q

What is the effect of ambient noise?

A

The lower the amount of ambient noise, the greater the range of detection.

32
Q

What is the definition of frequency?

A

number of complete waves cycles passing a fixed point in 1 second, measured in Hz

33
Q

How does temperature affect the speed of sound in water?

A

1 degree Celsius increase = increase by 3m/s

34
Q

How does pressure affect the speed of sound in water?

A

100m increase in depth = increase by 2m/s

35
Q

How does salinity affect the speed of sound in water?

A

Increase of 1 part per thousand = increase by 1.1 m/s

36
Q

What are the three types of Sonobuoys?

A

SSQ-53F DIFAR
SSQ-62E DICASS
SSQ-36B Expendable Bathythermograph

37
Q

What is the operating life of a DIFAR?

A

05, 1, 2, 4, or 8 hours

38
Q

What is the operating depth of a DICASS?

A

D1 (Shallow): 50, 150, or 300ft

D2 (Deep): 90, 400, or 1500ft

39
Q

What is the life of a Bathy?

A

12 minutes

40
Q

What is the operating depth of a Bathy?

41
Q

Three layer ocean model?

A 
Temperature going across
Depth doing down
Mixed layer (straight line)
Thermocline (line angled to left)
Deep water (straight line)
42
Q

Ocean topography model?

A 
Shelf
Slope
Rise
Abyssal Plain
Deep Trench
Seamount/ridge
Abyssal Plain
43
Q

What is BR?

A

Blade Rate - the no. of times the blades pass a given point ‘A’ in 1 second, measured in Hz

44
Q

What is SR?

A

Shaft Rate - the no. of times a propeller shaft rotates in one second.

45
Q

What is fundamental frequency?

A

The base or origin frequency measured in cycles per second and expressed in Hz

46
Q

What is Harmonic Frequency?

A

An echo or numerous echos of the fundamental frequency throughout the spectrum.

47
Q

What is SRPM?

A

Shaft revolutions per minute.

48
Q

What is CSR?

A

Crank Shaft Rate - the no. of times the crankshaft rotates in one second

49
Q

What is CFR?

A

Cylinder Firing Rate - the no. of times an individual cylinder fires in one second

50
Q

What is EFR?

A

Engine Firing Rate - the no. of times the engine fires in one second

51
Q

What is ERPM?

A

Engine Revolutions Per Minute - the number of times the crankshaft rotates in on minute

52
Q

Diesel Electric diagram?

A

Diesel Engine -> Generator -> Batteries -> Motor -> Propeller

53
Q

Primary Coolant Loop in a Turbo Reduction?

A

Pressurizer Steam Generator

Reactor

Main Coolant Pump

54
Q

Secondary Coolant Loop in a Turbine Reduction Engine

A

Turbo Generator, Main Turbine, Electrical Propulsion Motor

Motor Generator, SSTG, Clutch, Reduction Gearing

AC/DC, Main Condensor, Battery

55
Q

Formula for F0

A

(Fmax + Fmin)/2

56
Q

Formula for Speed?

A

Speed = [(Fmax-Fmin)/F0] x AV

In kts

57
Q

Formula for Range

A

Range = speed x time x 17

In yards

Foundation (2 decks)

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