AME T109 Reciprocating Engine Theory (Part One)

Question 1

What is efficient about the Radial Engine?

What is inefficient?

Answer 1

Efficient: The Overall Engine Design.

Inefficient: It is Bulky and not Aerodynami.

Question 2

What are the six Reciprocating Engine Designs?

Answer 2

1) Radial / Rotary
2) Horizontal
3) Inline
4) V-Type
5) W-Type
6) “H” Block

Question 3

What are the two different versions of the Inline Engine Design?

Answer 3

Inverted and Un-inverted.

Question 4

What is the method of cooling used on a Horizontally Opposed Engine?

Answer 4

Air Cooling

Question 5

What is the downfall of the Horizontally Opposed Engine?

Answer 5

It has a limited frontal area.

Question 6

What are the two methods used to cool an engine?

Answer 6

Air Cooling and Liquid Cooling

Question 7

What does each letter identify on engines?

G:
T:
S:
R:
V: 
L:
H:
A:
O:
I:

Answer 7

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

Question 8

What five things must be found on an Engine Data Plate?

Answer 8

1) Manufacturer
2) Model Number
3) Serial Number
4) Type Certificate Number
5) Power Rating

Question 9

What is the downfall of the Inline Style Engine?

Answer 9

Has a lower frontal area.

Question 10

What is the downfall of the Horizontally Opposed Engine?

What is an advantage?

Answer 10

Downfall: Has a lower frontal area.

Advantage: Runs and operates smoothly.

Question 11

What is special about a Radial engine in regards to power / weight ratio?

In regards to cooling?

Answer 11

It has the highest power / weight ratio of all engines.

Has very even cooling.

Question 12

How do cooling fins work to reduce engine heat?

What kind of engines utilize cooling fins?

Answer 12

They increase surface area and disperse heat.

Air cooled engines use cooling fins.

Question 13

How else is an internal combustion engine referred to?

Answer 13

It is also known as the Heat Engine.

Question 14

What three principles is Engine Efficiency based on?

Answer 14

1) Efficiency
2) Weight
3) Power

Question 15

Explain Volumetric Efficiency.

Answer 15

Refers to the volume that can be contained within the piston cavity.

Question 16

Explain Mechanical Efficiency.

Answer 16

This is how much Horsepower (Hp) can be generated.

Or, how much energy is spent through the generation of more Hp.

Question 17

Explain Thermal Efficiency.

Answer 17

This is how much energy is being wasted through the creation of heat / exhaust.

Question 18

What are the four key components to an Engine?

The main power making components

Answer 18

Cylinder
Piston
Connecting Rod
Crankshaft

Question 19

What is the job of the Valve Train in regards to the cylinder?

Answer 19

Its job is to pull air into the cylinder.

Question 20

What are the four strokes of a typical reciprocating engine?

Answer 20

1) Intake
2) Compression
3) Combustion
4) Exhaust

Question 21

The four strokes occur in how many crankshaft revolutions?

Answer 21

Two.

Question 22

What is the third stroke of a typical reciprocating engine also known as?

Answer 22

The Power Stroke.

Question 23

What does the following abbreviation stand for?
TDC:
BDC:

Answer 23

TDC: Top Dead Center
BDC: Bottom Dead Center

Question 24

What is the purpose of the intake stroke?

Answer 24

Pulling a mixture of fuel and air is pulled into the cylinder.

Question 25

What is the purpose of the compression stroke?

Answer 25

The air and fuel is put under pressure.

Question 26

What is the purpose of ignition of the fuel / air mixture in the cylinder? (Also known as the Combustion Stroke).

Answer 26

This is what creates power. | The compressed gases are ignited.

Question 27

What occurs during the Exhaust Stroke?

Answer 27

The residue gases from ignition are left behind and are pushed out of the cylinder.

Question 28

What does the term "Valve Overlap" mean? When does this occur?

Answer 28

Both the intake and exhaust valves are open. Occurs during the Exhaust and Intake strokes.

Question 29

What two things occur at 75 Degrees TDC?

Answer 29

The maximum piston speed is reached. The maximum amount of gas flow is achieved.

Question 30

What occurs at 55 Degrees BDC?

Answer 30

This is the beginning of the Compression Stroke.

Question 31

What occurs at 25 Degrees TDC?

Answer 31

Gases within the cylinder are ignited. | This is when combustion occurs.

Question 32

On Naturally Aspirated Engines, where is air pulled from and then exhausted to?

Answer 32

It is pulled from outside through a filter. | Once the four strokes occur, this air is sent back outside.

Question 33

In regards to mathematics and reciprocating engines, what does each letter stand for? ``` F: A: P: W: D: ```

Answer 33

``` F: Force A: Area P: Pressure within the Cylinder. W: Work D: Distance or Length ```

Question 34

What is the mathematic equation for: Force: Area: Work: (There are two versions).

Answer 34

Force: A x P Area: πr² Work: P x L x A or F x D

Question 35

What does the abbreviation "IMEP" stand for?

Answer 35

Indicated Mean Effective Pressure.

Question 36

What occurs at 45 Degrees before BDC?

Answer 36

The piston is slowing.

Question 37

What is the PLANK formula?

Answer 37

Hp = PLANK / 33 000

Question 38

What does each letter stand for in the PLANK formula?

Answer 38

``` 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 ```

Question 39

What does each stand for? IHp: BHp: FHp:

Answer 39

IHp: Indicated Hp BHp: Brake Hp FHp: Friction Hp

Question 40

What is the mathematic equation for Friction Hp?

Answer 40

FHp = IHp - BHp

Question 41

What is the equation for Mechanical Efficiency?

Answer 41

Mechanical Efficiency: BHp / IHp

Question 42

What is the equation for Specific Fuel Consumption?

Answer 42

Pounds of Fuel / Hour ------------------------------------ Horsepower

Question 43

If you divide inches per pound by twelve to get what?

Answer 43

Inches per Foot.

Question 44

What does early ignition within a reciprocating engine result in? (Two things)

Answer 44

A power decrease. | A temperature increase.

Question 45

What does late ignition within a reciprocating engine result in?

Answer 45

A power decrease.

Question 46

What are some variables that effect Volumetric Efficiency?

Answer 46

``` Outside Air Temperature Cylinder Head Temperature Scavenging Changes in Altitude INduction Friction Valve Timing The Throttle Valve ```

Question 47

In regards to Mechanical Efficiency: What is the maximm efficiency rating of an engine? (A Percentage) How else could this be expressed?

Answer 47

Engines have a 90% Efficiency Rating Maximum. Could also be expressed as the IHp : BHp Ratio.

Question 48

What does BSFC Stand for? | Explain what BSFC is.

Answer 48

BSFC: Brake Specific Fuel Consumption BSFC is how much fuel is used compared to how much power is produced.

Question 49

At what ratio of Air / Fuel mixture does Fuel Burn Out occur? What is the ideal Air / Fuel mixture?

Answer 49

8: 1 to 18:1 with oxygen. 15: 1 BY WEIGHT

Question 50

What is the Air / Fuel Ratio Full Rich utilized for? | What is the ratio for the Full Rich condition?

Answer 50

This is for full power applications. (Such as Take-Off). | It is an 8:1 Ratio.

Question 51

What is the Air / Fuel Ratio Best Power utilized for?

Answer 51

High Speed Cruise.

Question 52

What is the Air / Fuel Ratio Economy used for?

Answer 52

This ratio is used during slow cruise.

Question 53

What is the Air / Fuel Ratio Idle Cut-Off used for?

Answer 53

This is solely for Engine Shut-Down.