AME T109 Reciprocating Engine Theory (Part One) Flashcards
What is efficient about the Radial Engine?
What is inefficient?
Efficient: The Overall Engine Design.
Inefficient: It is Bulky and not Aerodynami.
What are the six Reciprocating Engine Designs?
1) Radial / Rotary
2) Horizontal
3) Inline
4) V-Type
5) W-Type
6) “H” Block
What are the two different versions of the Inline Engine Design?
Inverted and Un-inverted.
What is the method of cooling used on a Horizontally Opposed Engine?
Air Cooling
What is the downfall of the Horizontally Opposed Engine?
It has a limited frontal area.
What are the two methods used to cool an engine?
Air Cooling and Liquid Cooling
What does each letter identify on engines?
G: T: S: R: V: L: H: A: O: I:
G: Gear Reduction T: Turbo Charged S: Supercharged R: Radial V: V-Type L: Left-Hand Rotation H: Horizontally Mounted (For Helicopters) A: Aeobatic Modified Engine O: Opposed I: Injected
What five things must be found on an Engine Data Plate?
1) Manufacturer
2) Model Number
3) Serial Number
4) Type Certificate Number
5) Power Rating
What is the downfall of the Inline Style Engine?
Has a lower frontal area.
What is the downfall of the Horizontally Opposed Engine?
What is an advantage?
Downfall: Has a lower frontal area.
Advantage: Runs and operates smoothly.
What is special about a Radial engine in regards to power / weight ratio?
In regards to cooling?
It has the highest power / weight ratio of all engines.
Has very even cooling.
How do cooling fins work to reduce engine heat?
What kind of engines utilize cooling fins?
They increase surface area and disperse heat.
Air cooled engines use cooling fins.
How else is an internal combustion engine referred to?
It is also known as the Heat Engine.
What three principles is Engine Efficiency based on?
1) Efficiency
2) Weight
3) Power
Explain Volumetric Efficiency.
Refers to the volume that can be contained within the piston cavity.
Explain Mechanical Efficiency.
This is how much Horsepower (Hp) can be generated.
Or, how much energy is spent through the generation of more Hp.
Explain Thermal Efficiency.
This is how much energy is being wasted through the creation of heat / exhaust.
What are the four key components to an Engine?
The main power making components
Cylinder
Piston
Connecting Rod
Crankshaft
What is the job of the Valve Train in regards to the cylinder?
Its job is to pull air into the cylinder.
What are the four strokes of a typical reciprocating engine?
1) Intake
2) Compression
3) Combustion
4) Exhaust
The four strokes occur in how many crankshaft revolutions?
Two.
What is the third stroke of a typical reciprocating engine also known as?
The Power Stroke.
What does the following abbreviation stand for?
TDC:
BDC:
TDC: Top Dead Center
BDC: Bottom Dead Center
What is the purpose of the intake stroke?
Pulling a mixture of fuel and air is pulled into the cylinder.
What is the purpose of the compression stroke?
The air and fuel is put under pressure.
What is the purpose of ignition of the fuel / air mixture in the cylinder?
(Also known as the Combustion Stroke).
This is what creates power.
The compressed gases are ignited.
What occurs during the Exhaust Stroke?
The residue gases from ignition are left behind and are pushed out of the cylinder.
What does the term “Valve Overlap” mean?
When does this occur?
Both the intake and exhaust valves are open.
Occurs during the Exhaust and Intake strokes.
What two things occur at 75 Degrees TDC?
The maximum piston speed is reached.
The maximum amount of gas flow is achieved.
What occurs at 55 Degrees BDC?
This is the beginning of the Compression Stroke.
What occurs at 25 Degrees TDC?
Gases within the cylinder are ignited.
This is when combustion occurs.
On Naturally Aspirated Engines, where is air pulled from and then exhausted to?
It is pulled from outside through a filter.
Once the four strokes occur, this air is sent back outside.
In regards to mathematics and reciprocating engines, what does each letter stand for?
F: A: P: W: D:
F: Force A: Area P: Pressure within the Cylinder. W: Work D: Distance or Length
What is the mathematic equation for:
Force:
Area:
Work: (There are two versions).
Force: A x P
Area: πr²
Work: P x L x A or F x D
What does the abbreviation “IMEP” stand for?
Indicated Mean Effective Pressure.
What occurs at 45 Degrees before BDC?
The piston is slowing.
What is the PLANK formula?
Hp = PLANK / 33 000
What does each letter stand for in the PLANK formula?
P: MEP L: Length of Stroke (in Ft.) A: Area of Cylinder N: Number of Power Strokes per Minute ( RPM / 2) K: Number of Cylinders
What does each stand for?
IHp:
BHp:
FHp:
IHp: Indicated Hp
BHp: Brake Hp
FHp: Friction Hp
What is the mathematic equation for Friction Hp?
FHp = IHp - BHp
What is the equation for Mechanical Efficiency?
Mechanical Efficiency: BHp / IHp
What is the equation for Specific Fuel Consumption?
Horsepower
If you divide inches per pound by twelve to get what?
Inches per Foot.
What does early ignition within a reciprocating engine result in?
(Two things)
A power decrease.
A temperature increase.
What does late ignition within a reciprocating engine result in?
A power decrease.
What are some variables that effect Volumetric Efficiency?
Outside Air Temperature Cylinder Head Temperature Scavenging Changes in Altitude INduction Friction Valve Timing The Throttle Valve
In regards to Mechanical Efficiency:
What is the maximm efficiency rating of an engine?
(A Percentage)
How else could this be expressed?
Engines have a 90% Efficiency Rating Maximum.
Could also be expressed as the IHp : BHp Ratio.
What does BSFC Stand for?
Explain what BSFC is.
BSFC: Brake Specific Fuel Consumption
BSFC is how much fuel is used compared to how much power is produced.
At what ratio of Air / Fuel mixture does Fuel Burn Out occur?
What is the ideal Air / Fuel mixture?
8: 1 to 18:1 with oxygen.
15: 1 BY WEIGHT
What is the Air / Fuel Ratio Full Rich utilized for?
What is the ratio for the Full Rich condition?
This is for full power applications. (Such as Take-Off).
It is an 8:1 Ratio.
What is the Air / Fuel Ratio Best Power utilized for?
High Speed Cruise.
What is the Air / Fuel Ratio Economy used for?
This ratio is used during slow cruise.
What is the Air / Fuel Ratio Idle Cut-Off used for?
This is solely for Engine Shut-Down.
