Recip Final Flashcards
what are the two cylinder valves
Intake - where air/fuel mixture enters the piston exhaust - where exhaust gasses leave the cylinder
what is the otto cycle
standard compression cycle in a 2 or 4 stroke piston engine
what is a compression ratio
the compression of the total volume of the cylinder when piston is at BDC and TDC. increase in manifold pressure = increase in compression ratio
TDC stands for
Top dead center
BDC stands for
Bottom dead center
2 types of oil pumps are
gear pump and Gerotor pump
how is compression ratio calculated
the cylinder volume at BDC divided b the volume at TDC
what is horespower? how is it calculated
horsepower is a standard unit of mechanical power.
1HP = number of foot-pounds divided by 33,000
what does PLANK stand for
P = IMEP (indicated manifold effective pressure)
L = length of stroke in feet
A = area of piston
N = # of power strokes per minute
K = Number of cylinders
what is the difference between break and indicted horsepower
indicated HP - theoretical, does not account for friction.
Break HP - actual horsepower delivered by the engine to the propeller
what are the 6 functions of oil
reduce friction absorb heat seals and cushions cleans protects against corrosion
what is flash point
temperature at which oil gives off ignitable vapors
what is cloud point
temperature at which wax separates and solidifies into crystals
what is fire point
temperature at which there are sufficient vapors to support a flame
pour point
the lowest temperature that oil can flow or be poured
how are aircraft oils classified
oils are classified by viscosity levels. higher viscosity = a higher oil number
what is viscosity
a liquids resistance to flow. high viscosity = a thicker liquid
what are the four types of oil used for aircrafts
mineral
ashless dispersant
synthetic
multi viscosity
what are the two types of oil systems
wet sump - oil is located within the crankcase. simpler
dry sump - oil is located in a separate oil tank. most common in radial engines. uses a scavenge pump to disperse oil
what is a pressure relief valve
a valve that maintains a constant pressure within the oil system by bleeding off excess. can be adjusted using a screw or washers
3 types of check valves
ball, cone, and swing
what are bypass valves used for
allowing oil to bypass the oil cooler until it is brought up to temperature
2 types of oil filters
full flow and bypass
what is SOAP
Spectrometric oil analysis program
what are the different types of icing
throttle ice
fuel evaporation
impact ice
what is the idle valve in the pressure carburetor used for
maintaining fuel flow at idle speeds
how is the mixture controlled in a carburetor
controlled by varying pressure between the two fuel chambers, A and B
what is density altitude
the pressure altitude corrected for non standard temperature variations.
affects the takeoff distance as well as rate of climb
what effect does carb heat have on the fuel/air mixture
lowers the density of the air causing mixture to become more rich
what happens when an aircraft climbs to altitude
mass and density of air will decrease. the same volume of air provides less oxygen
what is MAP and where is it measured?
Maximum absolute pressure measured after the throttle plate (butterfly valve)
engine operation on a clear cool day can lead to _______ if the relative humidity is too high
Carburetor icing
why is the carburetor pre-heater not used on takeoff
causes loss of power, rough running engine and detonation
where is the “hot spot” in the 0-320 engine
in the oil sump. heats air to improve vaporization
what denotes a “standard day”
29.92 InHG
15 degrees celcius
what happens to engine power as an aircraft climbs to altitude
power reduces due to the reduced air density
how does an increase in carburetor air temperature affect BMEP
warmer air will decrease BMEP
