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ATPL - [Mod 2] AGK - Engines > 09. Piston Engine Power, Efficiency and Control > Flashcards

09. Piston Engine Power, Efficiency and Control Flashcards

1
Q

Power

The power of an engine is dicated by which 2 things in relation to the cylinders

A
  1. MASS - mass of charge into the cylinder
  2. TIMING - number of times per second mass of charge is put int

Pg 200

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2
Q

Power

On a fixed propeller engine, which instrument gives an indication of power being produced

A

RPM INDICATOR
(Tachometer)

Increased RPM roughly equates to an increased power for a given air density

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3
Q

Power

On a variable pitch propeller which 2 indicators should be monitored to gauge power

A
  1. RPM
  2. MAP

Resolution per minute
Manifold Absolute Pressure

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4
Q

Power

What is the dedicated guage for indicating power on a larger more sophisticated engine

This usually means Constant Speed Propeller Unit according to Padpilot

A

TORQUE GAUGE

Pg 202

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5
Q

GENERAL REVISION

Pressure
Length
Area
Number of cylinders
Engine power (proportional to RPM)

A

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6
Q

Power

What is the formula derived from Torque to determine power

A

POWER = TORQUE x RPM

T P R

Pg 202

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7
Q

Power

Where is torque measured

A

GEARBOX
Betwee engine and propeller

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8
Q

Efficiency

THe mechanical efficiency of a piston engine is never more than ____%

A

80%

This is the ratio of the actual power produced at the propeller shaft to the theoretical power

Pg 203

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9
Q

Efficiency

What is the greatest contributor to the loss of mechanical efficiency in a piston engine

A

POOR THERMAL EFFICIENCY

Thermal efficiency is the ratio of work done by the engine to the mechanical equivalent of the heat energy released by combusting fuel

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10
Q

Effiency

Thermal efficiency is expressed as a ratio of what to what

A

WORK DOWN to HEAT ENERGY

Thermal efficiency is the ratio of work done by the engine to the mechanical equivalent of the heat energy released by combusting fuel

Pg 203

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11
Q

Efficiency

Modern piston engines are around ____% thermally efficient

A

33%

Pg 203

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12
Q

Efficiency

As the compression ratio is increase, ____ is also increased

A

THERMAL EFFICIENCY

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13
Q

Efficiency

Thermal efficiency indcreases with what

A

INCREASED COMPRESSION RATIO

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14
Q

Efficiency

When the piston is at TDC, the tight space between the top of the piston and cylinder is known as what

A

CLEARANCE VOLUME

Pg 204

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15
Q

Efficiency

WHen the piston is at BDC, the larger space between the top of the piston and the cylinder is known as what

A

TOTAL VOLUME

Pg 204

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16
Q

Efficiency

What is the name given to the difference between the clearance volume and the total volume

A

SWEPT VOLUME

Pg 204

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17
Q

Efficiency

What is the swept volume derived from

A

CLEARANCE VOLUME and TOTAL VOLUME
Difference between

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18
Q

Efficiency

What does a HIGH compression ratio improve

A

THERMAL EFFICIENCY

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19
Q

Efficiency

What is the formula for working out displacement

A

Displacement = Piston area x stroke x no. of cylinders

Swept volume multipled by the numebr of cylinders gives displacement

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20
Q

Efficiency

The ____ volume multipled by ____ gives the displacement

A
  1. SWEPT
  2. No. of CYLINDERS

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21
Q

Efficiency

Modern aero engines have a relatively short stroke. A short stroke INCREASES or DECREASES the width of the engine

A

DECREASES

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22
Q

Efficiency

On a modern aero engine, what effect does a short stroke have on the engine

A

DECREASES OVERALL WIDTH

Pg 205

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23
Q

Efficiency

What is signfiicant about the connecting rods on a short stroke engine

A

SHORTER = LESS INERTIA

Pg 205

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24
Q

Efficiency

What is the less inertia created in a short stroke engine

A

SHORTED CONNECTING RODS

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25
Q

Efficiency

In regards to the engine, what happens as a result of shorted connecting rods

A

MORE RESPONSIVE to RPM CHANGE

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26
Q

Efficiency

How do aero engines compensate for shorter strokes

A

LARGE PISTON AREA

Pg 205

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27
Q

Efficiency

What is the name given when the cylinder diameter equals the stroke

A

SQUARE or SQUARE CAGED

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28
Q

Effciency

Square or square caged is the term given when what condition exists

A

CYLINDER DIAMETER equals the STROKE

Pg 205

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29
Q

Efficiency

If a cylinder diameter exceeds the stroke, what name is given

A

OVER SQUARE

Pg 205

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30
Q

Efficiency

Over square is a term used when what conditions exists

A

CYLINDER DIAMETER > stroke

Cylinder diameter is greater than stroke

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31
Q

Efficiency

What is defined by the term volumetric efficiency

A

RATIO of MASS OF MIXTURE to MASS OF AIR
introduced to the cylinder

Pg 206

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32
Q

Efficiency

The ratio of mass of mixture to the mass of air introduced into the cylinder is known as what

A

VOLUMETRIC EFFICIENCY

Pg 206

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33
Q

Efficiency

What happens as a result of increased volumetric efficiency

A

INCREASED ENGINE POWER

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34
Q

Efficiency

What 3 factors influence volumetric efficiency in a normally aspirated engine

A
  1. MIXTURE - ease mixture can enter cylinder
  2. DENSITY - density of air (alt, temp, humidity)
  3. EXHAUST - ease exhaust can leave cylinder

Pg 206

35
Q

Efficiency

Why does volumetric efficiency in a normally aspirated engine increase with altitude (when MAP remains constant)

A

REDUCED AIR DENSITY

Pg 206

36
Q

Efficiency

Why does volumetric efficiency in a normally aspirated engine increase with RPM

A

INCREASED MOMENTUM OF GASES

Pg 206

37
Q

Efficiency

Volumetric efficiency in normally aspirated engines increases under which 2 circumstances

A
  1. ALTITUDE - increased altitude means reduced density
    (ONLY while MAP remains constant)
  2. RPM - Increased momentum of the gases

Pg 206

38
Q

Efficiency

In a normally aspirated engine the maximum obtainable MAP will INCREASE or DECREASE with altitude.
Why does this happen

A
  1. DECREASE
  2. REDUCING ATMOSPHERIC PRESSURE

Pg 207

39
Q

Efficiency

What will happen to the MAP as altitude increases and why

A
  1. DECREASE
  2. REDUCING ATMOSPHERIC PRESSURE

Pg 207

40
Q

Efficiency

Maximum power in a normally aspirated engine is obtained where in terms of altitude

A

LOW PRESSURE ALTITUDE

Pg 207

41
Q

Efficiency

What will happen to power as altitude increases in a normally aspirated engine

A

REDUCES

Pg 207

42
Q

Efficiency

On a normally aspirated engine with a variable pitch propeller, if the aircraft climbs at maximum continuous power (NOT MAX POWER!), ____ and ____ can be kept constant by using which 2 levers

A
  1. MAP
  2. RPM
  3. THROTTLE & RPM

If an aircraft is climbing intially at less than full power, for example at max continuous power, both MAP and RPM can be kept constant using the throttle and RPM levers.

Pg 207

43
Q

Efficiency

On a normally aspirated engine with a variable pitch propeller, if the aircraft climbs at maximum continuous power and MAP and RPM are kept constant, power would INCREASE or DECREASE with altitude until the throttle is ____ and MAP can no longer be obtained

A
  1. INCREASE
  2. OPENED

Pg 207

44
Q

Control and handling

Piston engine instrumentation may include which following instruments
1. RPM Gauge [ ]
2. MAP Gauge [ ]
3. Boost Pressure Gauge [ ]
4. Oil Pressure Gauge [ ]
5. Oil Temperature Gauge [ ]
6. CHT gauge [ ]
7. EGT Gauge [ ]
8. Fuel Pressure Gauge [ ]
9. Induction System Temperature Gauge [ ]

A

ALL CORRECT

1, 2, 3, 4, 5, 6, 7, 8, 9

Pg 208

45
Q

Control and handling

What does the RPM gauge measure

A

CRANKSHAFT RPM

Pg 208

46
Q

Control and handling

What does the Manifold Absolute Pressure (MAP) gauge measure and in what unit

A

MANIFOLD PRESSURE
(Hg in)

Pg 208

47
Q

Control and handling

Where does the oil pressure gauge measure the oil pressure

A

AFTER PRESSURE FILTER

Pressure filter immediately after the pressure pump

Pg 208

48
Q

Control and handling

Where does the oil temperature gauge measure the oil temperature

A

OIL RETURN LINE

Pg 208

49
Q

Control and handling

Specifically, what does the cylinder head temperature gauge (CHT) measure

A

HOTTEST CYLINDER

Pg 208

50
Q

Control and handling

On a carburettor engine, what does the fuel pressure gauge measure

A

FUEL PUMP OUTPUT PRESSURE

Pg 208

51
Q

Control and handling

On a fuel injected engine what does the fuel pressure gauge measure

A

MINFOLD OUTPUT PRESSURE

Pg 208

52
Q

Control and handling

What does an induction system temperature gauge measure

A

TEMPERATURE at CARBURETTOR INLET

Pg 208

53
Q

Control and handling

Piston engine controls may include the following;
1. Throttle lever [ ]
2. RPM lever [ ]
3. Mixture control [ ]
4. Carburettor heat control [ ]
5. Alternate air [ ]
6. Cowl flap lever [ ]
7. Ignition switch [ ]
8. Engine priming pump [ ]
9. Engine prime switch [ ]

A

ALL CORRECT

1, 2, 3, 4, 5, 6, 7, 8, 9

Pg 210

54
Q

Control and handling

On a fixed pitch propeller, the throttle lever alters the position of what component to control MAP or engine RPM

A

BUTTERFLY VALVE

Pg 210

55
Q

Control and handling

What sort of engine uses an RPM lever, and what does it set the RPM on

A
  1. CONSTANT SPEED ENGINE
  2. ENGINE/PROPELLER RPM

Pg 210

56
Q

Control and handling

What does the mixture control adjust

A

FUEL FLOW from CARBUERETTOR

Pg 210

57
Q

Control and handling

What does the carburettor heat control select

A

HOT, UNFILTERED ALTERNATE AIR

Pg 210

58
Q

Control and handling

What sort of engine has an alternate air control, and why would this be used

A
  1. INJECTED ENGINES
  2. If FILTERED AIR becomes BLOCKED

Pg 210

59
Q

Control and handling

What is the purpose of adjusting the cowl flap lever

A

REGULATE CHT

ADjust position of cowl flap to introduce or remove cooling air to CHT

Pg 210

60
Q

Control and handling

What are 2 overriding principles of engine management that must be adopted for all types of engines

A
  1. MINIMISE THERMAL STRESS
  2. AVOID OVERBOOSTING

Pg 212

61
Q

Control and handling

What sort of system does the term “Rev UP, Throttle BACK” apply to

A

CONSTANT SPEED PROPELLER UNIT

Pg 212

62
Q

Control and handling

What is meant by the term “Rev UP, Throttle BACK”.

A

INCREASEING SPEED - (REV UP) - Increase RPM (rev) before Throttle (MAP)
DECREASE SPEED - (THROTTLE BACK) - Decrease Throttle (MAP) before RPM (rev)

ON A CONSTANT SPEED PROPELLER UNIT

Pg 212

63
Q

Control and handling

Where are fuel drains situated on an aircraft and why

A

LOWEST POINT of fuel system
WATER HEAVIER than fuel

Pg 213

64
Q

Control and handling

What are 2 reasons why starting an engine in cold temperatures is difficult when considering the fuel and electrical systems

A
  1. FUEL VAPORISING - ability is reduced in the cold
  2. BATTERY PERFORMANCE - reduced in cold

Pg 213

65
Q

Control and handling

Why should carb heat be avoided when the engine is running on the ground

A

UNFILTERED AIR

Risk of drawing particles up into the engine from the ground

Pg 214

66
Q

Control and handling

What is a risk of prolonged idling of the engine in regards to spark plugs

A

EXCESSIVE FOULING

Pg 214

67
Q

Control and handling

What are the 2 power ratings that some high performance rated engines will have

A
  1. TAKE-OFF POWER
  2. MAX CONTINUOUS POWER

Pg 214

68
Q

Control and handling

On some high performance rated engines, there are 2 power modes, Take-off and max continuous power. What is the main difference between the 2 in regards to time and when should each be used

A

TAKE OFF POWER
Time limited
Used for take-off and go around
MAX CONTINUOUS POWER
NOT time limited
Used for prolonged climb

Pg 214

69
Q

Control and handling

When changing power settings, how should the throttle lever be operated

A

SLOWLY and SMOOTHLY

Reduce stress on the engine

Pg 214

70
Q

Control and handling

What power setting should the engine be set to as soon as possible after take-off

A

MAX CONTINUOUS POWER

Pg 214

71
Q

Control and handling

How can thermal shock be avoided on engine shut-down

A

RUN ON LOW RPM

Run engine on low RPM for a few minutes to be allowed to cool

Pg 214

72
Q

Control and handling

  1. What can excessively weak mixture cause to the cylinder heads.
  2. What does this increase the risk of
A
  1. EXCESSIVELY HOT CHT
  2. DETONATION

Pg 215

73
Q

Control and handling

What 4 things could cause rough running in a SEP engine

I See Moist Fuel

A
  1. ICING - carb icing
  2. COMPRESSION - uneven compression in cylinder
  3. MOISTURE - in the ignition circuit
  4. FUEL - issues with fuel delivery

Pg 215

74
Q

Control and handling

  1. What does black smoke in the exhaust indicate
  2. Black smoke in the exhaust immediately after engine start may indicate what
A
  1. EXCESSIVELY RICH MIXTURE
  2. OVER PRIMING or UNLOCKED PRIMER PUMP

Pg 215

75
Q

Control and handling

  1. Blue smoke in the exhaust is caused by what
  2. This may indicate what problem
A
  1. OIL BURNING
  2. WORN or BROKEN PISTON RINGS

Pg 215

76
Q

Control and handling

A HIGH or LOW CHT may indicate cowl flaps being left closed

A

HIGH

Pg 215

77
Q

Control and handling

If the cowl flaps are left closed during ground running and taxing, what might likely be a probable result

A

EXCESSIVE CHT

Pg 215

78
Q

Control and handling

What is the technique to attempt to extinguish a carburettor fire as a result of excessive priming

A

CRANK THE ENGINE

This should ingest all the excess fuel into the engine

Pg 215

79
Q

Control and handling

What does FADEC stand for

A

Full Authority Digital Engine Control

Pg 216

80
Q

Control and handling

A FADEC monitors multiple parameters. It is able to adjust fule flow to injectors. To achieve this, specifically what 4 things will it be monitoring to make these adjustments

A
  1. AIR - Temperature and pressure
  2. THROTTLE - lever angle
  3. ENGINE - Internal conditions

Pg 216

81
Q

Control and handling

a FADEC controls fuel and air ratio. This means that there is no need for what control by the pilot

A

MIXTURE CONTROL

Pg 216

82
Q

Control and handling

A FADEC system is critical to engine control and therefore must be provided with what

A

REDUNDANCY

Pg 216

83
Q

On a modern FADEC system, to provide electrically isolated channels, each channel has a dedicated what

A

PERMANENT MAGNET ALTERNATOR
(PMG)

Pg 216

84
Q

summary

Power increasaes with increased ____. This is the ratio of ____ mixture to mixture at ____.

A
  1. VOLUMETRIC EFFICIENCY
  2. COMPRESSED
  3. AMBIENT TEMPERATURE

Summary

ATPL - [Mod 2] AGK - Engines (23 decks)

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