Exam 1 Review Flashcards
Types of Reciprocating Engines (6)
Rotary-Type Radial Engines
In-Line Engines
V-Type Engines
Radial Engines
Multiple-Row Radial Engines
Opposed and Flat Type Engines
Rotary Types Radial Engines
Crankshaft is held stationary to the engine mount
Cylinders rotate about the crankshaft
Propeller is attached to the engine case
In-Line Engines
Cylinders of an in-line engine are arranged in a row parallel to the crankshaft
Cylinders can be above or below (inverted) the crankshaft
V-Type Engines
Cylinders are arranged in two rows, formed the letter V
Angles between the rows are usually 90, 60, or 45°
There are always an even number of cylinders per row
Single-Row Radial Engine
Odd number of cylinders extending radially from the centerline of the crankshaft
Cylinders range from 5-9
All pistons are connected to a single-throw 360° crankshaft
Double-Row Radial Engine
Resembles two single-row radial engines on a single crankshaft
Cylinders range from 14-18
A two-throw 180° crankshaft is used to allow stagger between each row of cylinders
Multiple-Row Radial Engines
The largest and most powerful reciprocating engine
Opposed and Flat Engine Type
Most popular for light conventional aircraft and helicopters
Engine Classification (In-line)
Upright, inverted
Engine Classification (V-Type)
Upright, inverted, Double V, X
Engine Classification (Opposed and Flat)
Opposed, flat
Engine Classification (Radial)
Single row, double row, multiple row
Difference between letters and numbers to determine engine designation
Letters are employed to indicate characteristics
Numerical are employed to indicate displacement
L
Left-hand rotation
T
Turbocharged
I
Fuel Injected
G
Geared
S
Supercharged
O
Opposed Cylinders
R
Radial Engine
#
Displacement to the nearest 5 in^3
Air Cooled vs. Liquid Cooled
Air: Uses the air flow around the engine
Liquid: Passages used to deliver liquid to hot spots on the engine
Crankcase
The foundation of the engine
Sections of the Crankcase (4)
The Front Section (Nose)
Main Power Section
Fuel Induction and Distribution Section
Accessory Section
Parts of Accessory Section (6)
Mounting pads
Fuel Pump
Vacuum Pump
Lubrication Oil Pump
Starters
Magnetos
Types of bearings (3)
Plain
Roller
Ball
Bearing functions
A part in which devices turns or revolves on a, Journal, Pivot, Pin, Shaft, etc.
Plain Bearings
Low-power engines
Mainly designed to take radial loads
Can also be used as a thrust bearing when flanges added
Roller Bearings
High-power applications
Made in a variety of shapes and sizes
Tapered rollers can withstand both radial and thrust loads
Straight rollers are used for radial loads
Ball Bearings
Provides less friction than any other bearing types
Function of the Crankshaft
Transforms reciprocating motion of the piston to rotary motion to turn the propeller
Parts of the crankshaft (4)
Main Journal
Crankpin
Crank Cheek or Crank Arm
Counterweights and Dampers
Types of crankshafts (4)
Single Throw
Double Throw
Four Throw
Six Throw
Single Throw Crankshaft
Also known as “360°”
Used for single row radial
May be single or two piece
Two piece are referred to as a split-clamp crankshaft
Double Throw Crankshaft
Also known as “180°”
Generally for double row radials
One throw for each row of cylinders
May be constructed in one or three piece
Four Throw Crankshaft
For four cylinder opposed and inline engines
V-8 engines
Two throws are 180° apart from the other two throws
Six Throw Crankshaft
For six-cylinder inline and opposed engines
V-12 Engines
Throws are 60° apart from each other
Connecting Rod
Connects to the crankshaft
Connecting Rod types (3)
Plain
Fork and Blade
Master and Articulated
Plain Connecting Rod
Commonly used for in-line and opposed engines
Fork and Blade Connecting Rod
Used for V-type engines
Master and Articulated
Used in radial engines
Types of Pistons (5)
Flat
Recessed
Concave
Convex
Truncated Cone
Piston Ring
Are split so they can be slipped over the outside of the piston into ring grooves
Types of Piston Rings (3)
Plain Butt Joint
Step Joint
Angle Joint
Parts of a Cylinder (7)
Cylinder Barrel
Cylinder Head
Valve Guides
Valve Rocker-Arm Supports
Valve Seats
Spark Plug Bushings
Cooling Fins
Cylinder Barrel
High-strength steel alloy
Surface roughness in the barrel is carefully controlled
Cylinder Head
Encloses the combustion chamber
Types of Valves (3)
Poppet Type
Intake
Exhaust
Poppet Type Valve
Forged in one piece
General configurations of Poppet Types (4)
Flat-Headed
Semi-Tulip
Tulip
Mushroom
Exhaust Valve
Operates in very high temperatures
Must be designed to dissipate heat rapidly
Accomplished by hollowing the stem and sometimes the head
The hollow portions of the valve is filled with metallic sodium
Intake Valve
Solid stems
Heads are usually flat for low-power engines
Tulip type are usually for high-power engines
Forged from one piece alloy steel and machined for smooth finish
Valve Guides
Positioned to support and guide the stems of the valves
Valve Seats
Are shrunk or screwed into the circular edge of the valve opening in the cylinder head
Rocker-Arm
For opening and closing the valves
Four Stroke/Five Event Cycle
Intake Stroke (Suck)
Compression Stroke (Squeeze)
Power Stroke (Bang)
Exhaust Stroke (Blow)
Intake Stroke
Piston starts at TDC
Intake valve is open
Exhaust valve is closed
Piston moves downward
Air fuel mixture is drawn into the cylinder
Compression Stroke
Intake valve closes
Piston moves back up
Air fuel mixture is compressed in the cylinder
Before piston reached TDC, ignition happens
Ignition is timed to happen few degrees before TDC
Ignition is caused by a sparkplug
Spark ignites the air fuel mixture
Power Stroke
Also known as expansion stroke
Heat and pressure from ignited air fuel mixture force the piston down
Power is developed during this stroke
Exhaust Stroke
Also known as Scavenging stroke
Before the piston reaches BDC on the power stroke, exhaust valve opens
Gases in the cylinder are forced out as the piston moves back up
Stroke
The distance which the piston travels
BDC
Bottom Dead Center
TDC
Top Dead Center
Two Stroke Engine
Mechanically simpler than the four stroke engine
Less efficient
More difficult to lubricate
Similar to four stroke engine with cylinder, piston, crankshaft, connecting rod, and crankcase
Diesel
Operation principle resembles that of the four stroke gasoline engine
Pure diesel engine requires no electric ignition
Fuel and oils are heavier and cheaper than gasoline engine
Displacement
Obtained by multiplying the area of a cross section of the cylinder bore by the total distance that the piston moves during one stroke
Critical Attitude
Highest level at which an engine will maintain a given horsepower output
Detonation & Pre-Ignition
D: Caused when temperature and pressure of the compressed mixture reach levels to cause explosion
P: Caused when there is a hot spot in the engine that ignites the air fuel mixture before the spark plug fires
Types of oil (lubricant) (4)
Animal
Vegetable
Mineral
Synthetic
Animal Lubricants
Highly stable at normal temperatures
Lubricate firearms, sewing machines, clocks, and other light machinery
Unsuitable for engines because fatty acids are produced at high temperatures
Vegetable Lubricants
Oxidizes when exposed to air
Lower coefficient of friction than mineral oils
Wears away steel rapidly
Mineral Lubricants
Largely used in aircraft engines
Classified as Solid, Semisolid, & Fluid
Synthetic Lubricants
Tolerate high temperatures
Mainly used for gas-turbine engines
Does not evaporate and break down at high temperatures
Not made from natural crude oils
Characteristics of oil (8)
Viscosity
High antifriction characteristics
Maximum fluidity at low temperatures
Minimum changes in viscosity with changes in temperature
High anti-wear properties
Maximum cooling ability
Maximum resistance to oxidation
Noncorrosive
Functions of oil
Reduce friction between moving parts
Cools various parts of the engine
Seal combustion chamber by filling the spaces between the cylinder walls and piston rings
Cleans the engine by carrying sludge and residues away from moving engine parts to oil filter
Prevent corrosion by protecting metal from oxygen, water, and corrosive agents
Serves as cushion between parts that sees impact loads
