ORAL BOARD Flashcards
draw and explain a quadrant diagram of refrigeration cycle
top= expansion valve
generates low p liquid
gets to the evaporator= heat transfer to ref rig.
gen low p gas to the COMPRESSOR
gen high p gas
CONDENSER gives of heat transfer from refrig. and then gen. high p liquid.
list and describe various types of water purification units on board ships
- flash type= usedon most combatans, high capacity , heated by auxiliary steam
- vertical basket= used on older subs, medium capacity, auxiliary steam
- vapor compression= non-steam ships, low capacity, electricity heated
- reverse osmosis= water passed thru a semi-permeable membrane
What is the primary diff between continuous wave and pulse radars?
what type does the navy utilize now?
discuss adv and diasadv of each
-continuous wave relies on contact motion for detection
-pulse radar does not rely on contact motion
-navy primarily uses pulse radars
continuous wave radars difficult to jam
-pulse radars can look for exact frequencies and can filter stationary targets
what is the purpose of a fuse and what are the different types?
to trigger an explosive reaction and to keep a weapon safe when not needed -must be safe and reliable -types: impact ambient timer proximity
describe the functionality of a diesel engine
internal combustion engine converts chemical energy into mechanical energy
- mechanical energy moves pistons up and down inside cylinders
- pistons connected to crankshaft, where their linear motion creates rotary motion
- rotor can be connected to propeller or conductor
apply the 1st law of thermodynamics and the concept of “mass defect” in order to explain how energy is released in a nuclear reaction in the form of heat
energy in= energy out mass defect (fuel) - mass defect (fission fragments)= energy from fission
discuss how archimedes’ principle relates to a ship floating in water. describe the forces acting on a floating ship
AP= a body floating or submerged is buoyed up by a force equal to the weight of water it displaces
total weight of ship = gravitational force
buoyancy= counteracs weight
-if B is less than G -> ship sinks
discribe the gas turbine in thermodynamics terms. be able to draw a basic sketch of a gas turbine engine and discuss the basic operation of each of the three main components
- compressor, combustion chamber, turbine
- atmospheric air brought in to compressor, which brings it to higher energy
- fule sprayed into copressed air and ignighted which combusts and realeases energy
- high temperature, high pressure gas goes to turbine, expands down to exhaust pressure and produces shaft work output
- open cycle steady flow, unheated engine
what are the different conditions for steaming ships?
-
how are you supposed to enter and leave a traffic separation scheme?
process in appropriate travel lane
leave or join at the termination of the lane or enter/leave at a small angle
cross lane at right angel
why is corrosion an important ship design consideration? list corrosion controls
-hull will eventually rust away:
-hull treatment
hull tiling
sacrificial anodes
chipping and painting
discuss how a 2-stroke engine operates
1power stroke every crankshaft revolution
can produce twice as much power as 4 stroke
power stroke= cylinder contains charge of highly compressed air when piston is at top of its travel- fuel injected -> combusts
compression stroke= pistorn moves down, real easing exhaust and allowing pressurized air to refill the cylinder.
for the 4 major classes of fire, discuss the characteristics of each type of fire
- alpha:ash producing fire: put out w/water, COZ,PKP, AFFF
- bravo: oil/fuel fire: w/AFFF PKP
- charlie= electrical fire: with co2
- delta: burning metal: with jettison
what are the different type of denial jamming?
- spot
- barrage
- sweep
- deception
state all the adv of utilizing nuclear power as a source of power for naval vessels
- long life
- unlimited endurance, range
- no need for outside support
- less logistical support
- more room for aircraft, fuel, etc
what does C5ISR
command control computers comm combat systems intelligence surveillance reconnaissance
describe the basic operation and function of a centrifugal pump. what energy transformations are taking place within the pump?
converts mechanical energy from a motor to energy of a moving fluid
compare shipboard and residential electricity? why does navy use 3-phase, ungrounded electrical distribution systems?
SHIPBOARD: -450volts, 60hz -3 phases AC -ungrounded RESIDENTIAL: -120volts, 60hz -single phase AC -grounded
- 3 phase generates more electrical power and increases equipment reliability
- ungrouwnded increases reliability
- requires 2 faults to cause failure
discuss the construction and operation of an AC gen and DC gen. list some exp where these types of generators are used on board naval ships
Direct current: current flow is undirectional and of constant magnitude; coil of wire rotates in a steady magetic field
shipboard motors
-Alternating current: magnitude and direction of flow constantly changing; roating magnetic field “cutting thru” a conductor
-shipboard generators
what are some factors that affect projectile motion within a gun tube?
bullet weight
gas pressure
length of gun barrel
friction inside barrel
what different methods exist for detecting submarines?
visual
infrared
acoustic
radars
how much anchor chain should you put out for a specific depth?
5-7 times the depth
what is the order of colors for a P and D line? what is the purpose of a P and D line?
go rub you belliy with grease
provides a visual representation of distance between the two ships
define refrigeration. how is it the reverse of the power cycle?
- the cooling of an object and subsequent maintaining of its temp below that of its surroundings.
- heat absorbed in low temperature region and released in high temp region
what are the four classes of electronic attack?
jamming
medium modifiers
stealth/echo enhancement
physical destruction
name the different types of sonobouys
- DICASS
- DIFAR
- VLAD
Describe the coriolis effect
-caused by eath’s rotation
earth moving faster at the equator than at the poles
-deflects weapons fired to right in N. hem and to left in S. hemisph
-effect increases as distance to target increases.
list and describe the phases of guidance for a missile
- boos: once launched, missile needs to get into stable flight pattern in direction of incoming threat
- midcourse: places the weapon in target aquisition gate
- terminal : requires most maneuvering and responsiveness, generally turns to active homing to get to target
