Recip Midterm Mod 1-6 Flashcards
what are the two types of cylinder valves
Intake - where air/fuel mixture enters the piston
exhaust - where exhaust gasses leave the cylinder
what is the otto cycle
the standard compression cycle in a piston engine. 4 or 2 stroke
what is compression ratio
comparison of the volume of space in a cylinder when piston is at BDC and TDC.
increase in manifold pressure = increase in compression ratio
TDC
top dead centre
BDC
bottom dead centre
2 main types of oil pumps
gear pump and Gearotor pump
how do you calculate compression ratio
volume of cylinder at BDC divided by volume of cylinder at TDC
what is horsepower? how do you calculate it
horsepower is standard unit of mechanical power
1HP = foot-pounds divided by 33,000
what is plank
P = IMEP 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 indicated 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 absorbs heat seals cushions cleans protects against corrosion
flash point
temp when oil gives off ignitable vapors
cloud point
temp when wax separates and solidifies into crystals
fire point
temp when there are sufficient vapors to support a flame
pour point
lowest temp at which oil can flow or be poured
how is oil classified
classified by a number that indicates viscosity. higher number = higher viscosity
viscosity
a liquids ability to flow. higher viscosity means thicker liquid that is more resistant to flow
what are the 4 types of oil
Straight mineral oil
ashless dispersant
multi viscosity
synthetic
2 types of oil systems
wet sump - all oil held within crankcase of the engine. more simple system
dry sump - separate oil tank. most common in radial engines. requires more components such as scavenge pump
what is a pressure relief valve
a valve that maintains a constant pressure in the oil system. adjusted by screw or washer thickness
3 types of check valves
ball
cone
swing
bypass valves
used to allow oil to bypass oil cooler until the oil 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 - forming neat butterfly valve
fuel evaporation ice - causes moisture released by evaporation to freeze i
impact ice - visible moisture striking an aircraft and freezing
