NVSC 401 Exam 2 (From Quizlet!)

What affects the speed of sound in water?

Temperature

Pressure

Salinity

All of these increase the speed of sound in water.
Order changes after 1000 ft

What are the propagation paths in water?

- Direct Path

- Half Channel

- Surface Duct

- Convergence Zone (CZ)

- Bottom Bounce (BB)

- Sound Channel

Be able to draw the picture from slides

What is a Direct Path?

Direct contact, close ranges, “straight” line

What is a Bottem Bounce?

Beam bounces back towards surface
Needs relatively smooth, hard bottom

What is a Surface Duct?

Beam gets trapped near surface because of positve gradient

What is a Half Channel?

Pretty much just a surface duct all the way to the bottem

What is a Sound Channel?

Longest range transmission possible avaliable
Only loss is absorption
Negative over positive gradient

What is a Convergance Zone?

Needs greater than 200 m depth excess
Sound beam goes so deep that it bends back up

What is a negative gradient & what does it cause?

SVP bent backwards like /
Causing sound to travel down & create shadow zones

What is a positive gradient & what does it cause?

SVP bent backward like this \
Causing sound to travel up & create shadow zones

Draw an SVP (Sound Velocity Profile)

Picture!

What are broadband and narrowband?

Broadband: wide range of frequencies, noise we think we can hear (propellers/shafts, flow of water over a ships hull, propulsion system, etc)

Narrowband: composed of specific frequencies or ranges, noise you don't generally hear (pumps, motors, dolphins)

What is Self-noise?

Noise generated by own ship:
Machinery noise (hull noise, narrowband)
Flow noise (water over hull, broadband)
Cavitation.

What is Ambient-noise?

Noise generated by external and environmental factors:
Currents
Hydrodynamic (storms)
Ocean traffic/operating environment
Biological noises
Seismic

Due to the doppler effect, a target approaching you will have __________ frequency.

Higher

What are the signal terms for active sonar?

- Source level: your sonar's sonic transmission (SL)

- Target strength: based on the "strength" of the reflected sound, same as radar cross section, MASS = material, aspect angle, size, shape (TS)

What are noise limited and reverb limited?

Noise limited: return of sonar ping is masked by self and ambient noises

Reverb limited: reverberation of target is masked by reverberations surrounding the submarine

Draw a picture

How is a submarine vulnerable to detection from non-acoustic sources?

Know and give explanations:

- visual = scope sighting, wade

- infared detection = IR "Wake", diesel exhaust

- radar = periscope, sail "broach"

- magnetic anomaly detection = subs disturb magnetic field underwater

Propellant Types

- progressive: burning surface area increases with time, rocket

- neutral: burning surface area stays constant, rifle

- regressive: burning surface area decreases with time, pistol

What are the five exterior ballistics?

gravity, drag, wind, drift, coriolis effect

What are the three types of launchers?

gravity, impulse, reaction

What are the types of reaction launchers?

rail, zero length, canister

How can you reduce recoil?

- recoil/counter recoil systems: gun after firing moves back

- soft recoil systems

- muzzle braking: baffles attached to end of barrel

- recoiless system: shoulder launch rocket

Three phases of weapons guidance?

- boost: when weapon recieves launch signal to flight

- midcourse: missle en route/course, longest phase

- terminal: high accuracy, fast responses to evasive manuvers

What are the types of self-contained guidance?

- Preset: path is predetermined prior to weapon launch

- GPS: global positioning system, satellite based navigation system

- Celestial: references position to fixed stars and adjusts (ICBM)

- Inertial: senses weapon movement and makes adjustments

- Terrestrial: compares actual terrain with predicted flight path and adjsuts accordingly

Semi-active homing uses?

uses the active homing from another active source to find the target, SPARROW

What are the 4 steps of a jet engine?

intake, compression, combustion, exhaust

Explain the difference between fuze and fuse

Fuse: a cord or tube that transmits flame or explosion

Fuze: a device with explosive components designed to initiate a main charge

List the components of the HE train in order

detonator -> booster -> main charge

What is safing & arming device? What does it do?

Physically isolates the detonator from the high explosive train
Prevents unintentional warhead detonation

List and describe the five types of fuses

- Impact/Contact: senses physical contact, must impact to detonate, found on point of projectile/bomb, can have a built in delay

- Ambient: senses changes in environment, depth charge

- Timer: detonates after preset elapsed time (hand grenade),
- Command: waits for a signal from control station

- Proximity: actuated by some influence of target = electromagnetic, magnetostatic, acoustic, electro-optical, (missiles use radar)

What are the three types of explosives?

- Mechanical: over-pressurized container

- Chemical: change in chemical bonds

- Nuclear: change nucleus of atoms (fission and fusion)

How would you increase fragmentation in a warhead?

more fragmentation pieces, higher pressure inside the warhead, softer warhead shell to explode outward

How are mines delivered?

- air-delivered mines

- surface-delivered mines

- submarine-delivered mines

- asymmetric (civilian)

- asset protection: impeding/defeating enemy attacks

- interdiction: obstructing shipping lanes, critical areas, etc

- attrition: attempting to trap enemy HVUs into an area

- force multiplication: influencing movement of enemy to select locations so as to engage with other weapons

- terrorism: disruption of commerce, political motives

What are the types of mine sweeping/clearance?

hunting = searching, sweeping = activate them

Mine clearing: cable cutting, detonation by towed sled, remotely operated robotic vehicles

Mine sweeping = cut cables then activate to destroy, use acoustic/magnetic noisemakers to activate

Mine hunting = search and neutralize individual mines, use sonar then investigate every possible target

What are the six pillars of cybersecurity?

Confidentiality
Integrity
Availability
Non-repudiation
Authenticity

What is required for a convergence zone?

> 200m depth, sound beam will bounce off of bottom of seafloor and back up to the surface after 50km, depth excess determines zone width

Range is directly impacted by __________ when firing a projectile

muzzle velocity

What is functional reliability and how do you increase it?

the confidence that your system will detonate when intended, increase using parallel connections

NORFOLK TO NORFOLK

atlantic ocean - Gibraltar strait - Mediterranean sea - Sicilian channel - Suez Canal - red sea - BAM - Indian ocean - strait of malacca - south china sea - Luzon strait - philippine sea - pacific ocean - Panama canal - gulf of America - back to atlantic