Reciprocating Engines Flashcards
How are reciprocating engines classified?
•Cylinder arrangement and number
•Cooling method
•Number of strokes per cycle
What are the 4 most common cylinder arrangements?
•In-line
•V-Type
•Radial
•Opposed
With a rotary radial engine, the ______ is mounted directly to the airframe with propeller mounted to the crankcase and cylinders spinning around.
Crankshaft
Radial engines are well cooled but have poor _____ ______ and bad ____ ____.
Poor engine control
Bad torque rolling
What are the 2 types of cooling classifications?
Air & Liquid
2-stroke engines have a power pulse every _____ degrees of crankshaft rotation.
360
*not as fuel efficient
4 stroke engines have a power pulse every _____ degrees of crankshaft rotation.
720
*more fuel efficient but less powerful
What are the identification letter prefixes for:
O -
G -
S -
T -
I -
A -
H -
V -
L -
L -
R -
Opposed
Geared
Supercharged
Turbocharged
I = Fuel Injected
Horizontal
Vertical
L = Left rotation
L = Liquid Cooled
Radial
Maintenance must be done in accordance with the ______
Manufactures Maintenance
What is the color coding for Chrome cylinders?
Orange
What is the color coding for nitrided cylinders?
Blue
What is the cylinder barrel skirt?
Extends beyond the flange into the crankcase
What does the skirt do?
Prevents oil from running into the cylinder
What is housed in the cylinder head?
The intake and exhaust valves, valve guides, valve seats and rocker arms as well as the spark plug holes
What are intake valves ground at?
ground at 30 degrees
What are exhaust valves on high powered engines filled with?
Metallic Sodium
What are exhaust valves normally ground at?
Ground at 45 degree angle
What are 5 types of Pistons?
Flat
Recessed
Concave
Dome
Truncated Cone
Why do piston rings have gaps at the ends?
To allow for expansion at operating temperatures
What is a valve lifter?
Also called a Tappet
Transmits force from camshaft to the push rod
2 types of valve lifters:
Hydraulic or Solid
What do push rods do?
Transmits force from lifter to rocker arm
What do rocker arms do?
Transmits force from pushrod to valve
What is found in the accessory section?
Mounting Pads
Pumps
Starter
Generator
Magnetos
What are bearings?
A cylindrical surface that supports another surface for freedom of rotation along an axis
what are 3 styles of bearings?
Plain
Roller
Ball
What is the most common bearing?
Plain
What are 4 parts of the crankshaft?
Main Journal
Crankpin
Crank cheek or arm
Counterweights
What are 3 reasons crankpins are hollow?
Reduces weight
Passage for oil
Sludge chamber
What is the purpose of counterweights?
Provide static balance
What is the main purpose of a dynamic damper?
To relieve whip and vibration
What do connecting rods do?
Connect the piston and crank throw
(H or I beam shape)
What is Charle’s law?
The pressure of a confined gas is directly proportional to its absolute temperature
During each stroke, the crankshaft travels ____ degrees
180
1 full revolution is 360 degrees
What are the 4 strokes?
Intake
Compression
Power
Exhaust
What’re the 5 events?
Intake
Compression
Ignition
Power
Exhaust
3 types of horsepower:
Indicated
Brake
Friction
When calculating Indicated Horsepower, What does PLANK mean?
• P= indicated mean effective pressure (IMEP)
• L= length of stroke in feet
• A = area of the piston head in sq Inches
• N = number of power strokes per min, per cylinder
• K = number of cylinders
What is brake horsepower?
The actual amount of power delivered to the propeller shaft
(85-90% of indicated HP)
What is friction horsepower?
Horsepower used by the engine to overcome the friction of moving parts
(10-15% of indicated HP)
What is detonation?
Uncontrolled, explosive combustion
-High cylinder temps
-Rough-running engine
-Power loss
-Damages, destroys engines
What is preignition?
Combustion starts too early
Ignition before spark
Preignition and detonation can cause what?
Engine roughness
High operating temps
Does the intake or exhaust side of the cylinder have more cooling fins?
Exhaust
What is it called when the intake valve opens early during the exhaust cycle and the escaping fumes ignite with the fuel?
Backfiring
One Kilowatt is equal to how many watts?
1000 watts