Piston Engines

Question 1

Radial Engines

Answer 1

• Circular
• Cylinders arranged around the crank case
• Odd number of cylinders (Usually 9 max)
• Odd so that no cylinder fires twice in a row
• Good cooling, relatively good power
• Easy to maintain
• Poor forward visibility and excessive drag

Question 2

In-Line Engines

Answer 2

• Cylinders side by side in a row
• Usually a maximum of 6 due to vibration
• Engine may be inverted for better visibility
• Greatest weight to horsepower ratio
• Less drag and better visibility

Question 2

Horizontally Opposed Engines

Answer 2

• Most common in small aircraft
• 2 rows of cylinders arranged horizontally
• Even number of cylinders
• Small frontal area
• Less drag
• Automatic system if air intake gets blocked, uses unfiltered air already inside the cowling

Question 3

Parts of the Reciprocating Engine - Intake Valve

Answer 3

Provides fuel-air mixture to cylinder

Question 4

Parts of the Reciprocating Engine - Exhaust Valve

Question 5

Parts of the Reciprocating Engine - Spark Plugs

Question 6

Parts of the Reciprocating Engine - Cylinder

Question 7

Parts of the Reciprocating Engine - Piston

Question 8

Parts of the Reciprocating Engine - Combustion Chamber

Question 9

Parts of the Reciprocating Engine - Crankshaft

Question 10

Parts of the Reciprocating Engine - Connecting Rod

Question 11

Parts of the Reciprocating Engine - Piston Pin

Question 12

Parts of the Reciprocating Engine - Piston Rings

Question 13

Parts of the Reciprocating Engine - Cylinder Flange

Question 14

Parts of the Reciprocating Engine - Camshaft

Answer 14

Opens and closes intake and exhaust valves

Question 15

Parts of the Reciprocating Engine - Valve Lifter

Question 16

Parts of the Reciprocating Engine - Push Rod

Question 17

Parts of the Reciprocating Engine - Rocker Arm

Question 18

Parts of the Reciprocating Engine - Crankcase

Answer 18

Where crankshaft is located

Question 19

Four Stroke Cycle

Answer 19

• Intake
• Compression
• Ignition
• Exhaust

Question 20

Compression Ratio

Answer 20

Volume of the cylinder above the piston at the bottom of the compression stroke compared to the top of the compression stroke

Question 21

Power Calculation (BHP)

Answer 21

BHP = PLAN / 33000
- P = Mean pressure in PSI
- L = Length of stroke in feet
- A = Area of piston in square inches
- N = Number of impulses per minute

Question 22

Engine Timing

Answer 22

• Timing of opening or closing of the intake and exhaust valves and the ignition of the fuel/air mixture
• Can lead to better performance is valves open early or close late so there is no waste
• Valve lead, valve lag, valve overlap

Question 23

Two Stroke Cycle

Answer 23

• One rotation of the crankshaft
• Intake and compression stroke, then ignition and exhaust stroke

Question 24

Engine Cooling

Answer 24

- Air Cooling (Fins and Cowl Flaps) - Liquid Cooled (Coolant)

Question 25

4 Functions of Oil

Answer 25

- Cooling - Sealing - Lubrication - Flushing

Question 26

Requirements of Oil

Answer 26

- Proper Viscosity (Resistance to flow) - High flash point (Ignition point) - Low carbon content (deposits) - Low Pour Point (Freezing point

Question 27

Types of Oil - Mineral Oil

Answer 27

- No additives - Used to break-in engine - Granular

Question 28

Types of Oil - Ashless Dispersant

Answer 28

- Contains Dispersants - Suspends Contaminants such as carbon and lead

Question 29

Additives - Detergents

Answer 29

Cleans inside of engine

Question 30

Additives - Oxidation Inhibitors

Answer 30

Improves oil stability

Question 31

Additives - Anticorrosion Additives

Answer 31

Deter Corrosion

Question 32

Additives - Pour Point Depressants

Answer 32

Lowers pour point temperature

Question 33

Methods of Lubrication - Splash Oil

Answer 33

- Oil contained in sump or reservoir - Revolving crankshaft splashed down into oil - Droplets spray over various engine parts - Cheap, simple, effective, lightweight - No aerobatics

Question 34

Methods of Lubrication - Force Feed (Dry Sump)

Answer 34

- Oil forced under pressure from a pump through the hollow crankshaft - Oil exits crankshaft through tiny holes directed at critical parts - Oil contained in a seperate tank - Oil drained from pump through a scavenging pump - Oil goes through a cooler and then back into tank

Question 35

Methods of Lubrication - Forced Feed (Wet Sump)

Answer 35

- Oil forced under pressure from a pump through the hollow crankshaft - Oil exits crankshaft through tiny holes directed at critical parts - Oil contained in a pan (sump) under crankcase - Pumped to crankshaft, pushrods, bearings, etc. - Some parts splashed lubricated as well - Oil then drains back into sump - Oil cooler may be installed in return line

Question 36

Venting

Answer 36

- Allows changes in pressure within the tank - Temperature changes cause density changes - Can be in the cap of oil tank

Question 37

Filters

Answer 37

- Have bypass valves in case of clogging - Dirty oil is better then no oil

Question 38

Pumps

Answer 38

Also have bypass valves to allow oil to return to tank if excessive pressure

Question 39

Oil Cooler

Answer 39

Same as a radiator, heat dissipated into the air

Question 40

Octane

Answer 40

- Ignition Inhibitor - Used to prevent detonation of fuel and promote smooth controlled burning of the mixture - Type determined by compression ratio of engine

Question 41

Heptane

Answer 41

Ignition Promoter

Question 42

Fuel Grades

Answer 42

- IE 80/87 - 80% Octane at Lean mixture - 87% Octane at Rich mixture - Above 100 expressed as performance number - Always use higher fuel grade

Question 43

Anti-Icing Additives

Answer 43

Prevents formation of ice crystals which may clog filters

Question 44

Lead Scavenging Additives

Answer 44

Helps reduce plug fouling due to lead and carbon deposits

Question 45

Turbocharger

Answer 45

- Fools the engine into thinking it is working at sea level - Uses the energy of the hot exhaust gases to power a compressor - Boosts intake air pressure

Question 46

Supercharger

Answer 46

- Fools the engine into thinking it is working at sea level - Uses rotational energy of the crankshaft to power a compressor - Boosts fuel/air mixture pressure