Exam 2 Flashcards
advantages of split bus system
one entire bus can fail with other systems operating normally
starter generator
one unit
direct drive (saves weight, less complex)
parallel generators advantages
safer
more power
generators carry load equally
parallel generator disadvantage
unable to maintain full output at low rpm
type 1 and type 2 ac generators
type 1 - constant RPM
type 2 - variable RPM
Parallel bus systems
older aircraft
load shared equally by all working generators
split bus
each generator powers only one main AC bus
two generators can’t power the same bus simultaneously
most apps are operational
split parallel power
safer
parallel - normal
split - isolated during malfuciton
constant speed drive
installed between variable speed engine and constant speed generator
integrated drive generators
generator and speed control to one unit
integrated drive advantages
weight / size reduction
higher RPM and power output
improved cooling
similarities CSD and IDG
hydraulic units
share oil with AC generator
oil cooling
variable rpm generators
type two
115V AC
frequency may change with engine rpm
variable speed constant frequency
400 hz output
solid-state circuitry
no need for CSD - more reliable
variable speed constant frequency advantages
no CSD
smaller / lighter
more versatile installation
variable speed constant frequency disadvantages
relatively lower power output
not as proven through one term operating
variable speed variable frequency AC generator
newer
output frequency changes with engine rpm
frequency made constant as needed during power distribution
high power output
RAT
provides limited electrical power if all engines are lost
static inverter
most critical AC power source
must be checked every night during routing maintenance
line replaceable unit
what is fluid power
transmission and conversion of power using a fluid
what is the application of fluid power
transmission of force and power through a distance
Boyle’s Law
PV/T = PV/T
Pascal’s Law
when a force is exerted on a confined fluid, the resultant pressure is transmitted equally and undiminished in all directions
gas vs liquid compressibility
liquids - non compressible
high % output achieved (low loss, high efficiency)
gas - highly compressible
loss in efficiency
stroke
distance piston moves in a cylinder
inches
volume
quantity of fluid contained in a reservoir, displaced by a pump, or displaced by an actuating cylinde
in cubic inches
hydraulic fluid
medium by which power is transferred within an aircraft
hydraulic equations
F=PA
V=AL
f=force, p=pressure, a=area, L=length, V=volume
what is mechanical advantage
amount by which the applied effort is multiplied in the output of the device
less distance = more forceq
what is flow rate measured in
gallons per minute
where do hydraulics have loss
friction within line
component loss in motors and filters
better hydraulic fluids have _____ viscosity
low
what thermal characteristics do we want for hydraulic fluid
stable structure in all temperatures
what flammability for hydraulic fluid
high flash and fire point
what is flash point
lowest temperature at which a combustible liquid produces sufficient vapor to generate an ignitable mixture
What chemical stability for hydraulic fluid
high chemical stability
vegetable base fluid
blue
older and not used much
extremely flammable