Piston Engines

Question 1

How do you measure power using rpm?

Answer 1

Power = RPM X torque

Question 2

How do you measure torque?

Answer 2

Torque = force x distance

Question 3

How is torque proportional to engine speed?

Answer 3

Torque is proportional to 1/speed

Question 4

How does chemical energy become mechanical energy in a piston engine?

Answer 4

Chemical - heat - pressure - mechanical

Question 5

What is the charge flow?

Answer 5

Air + fuel

Question 6

What does it mean if a movement is reciprocal?

Answer 6

Up and down.

Question 7

Whats the difference between a constant volume engine and a reciprocal engine?

Answer 7

They’re the same thing.

Question 8

Whats the distance between the top dead centre and the bottom dead centre called?

Answer 8

Stroke.

Question 9

How many degrees of rotation occur when the piston moves between the bottom dead centre and the top dead centre?

Answer 9

180 degrees.

Question 10

How many strokes does an OTTO cycle have?

Answer 10

4.

Question 11

What are the different strokes in the otto cycle?

Answer 11

Ignition - compression - power - exhaust.

Question 12

What happens between a compression stroke and a power stroke in an otto cycle?

Answer 12

Ignition.

Question 13

Which strokes in the otto cycle will you see the inlet and exhaust valves closed?

Answer 13

Compression and power stroke.

Question 14

At the ineffective crank angle, how would you describe the linear movement of the piston?

Answer 14

Small.

Question 15

What is the defintion for when the inlet valve is still open as the compression stroke begins in a piston engine cylinder?

Answer 15

Inlet valve lag.

Question 16

What happens to the inlet and exhaust valve positions when there is an inlet valve lead in a piston engine aircraft?

Answer 16

The inlet valve and exhaust valve are both open.

Question 17

A car that has 6000 revolutions per minute has how many combustions per second?

Answer 17

25.

Question 18

At what angle of rotation does peak torque occur?

Answer 18

90 degrees.

Question 19

What happens to the pressure and volume when the piston descends?

Answer 19

Volume increases causing pressure to decrease.

Question 20

What does stoichiometric mean?

Answer 20

Chemically balanced.

Question 21

What is the recommended step to take in case you experience detonation during take-off?

Answer 21

Retard the throttle.

Question 22

A waste gate controls the output of a turbocharger by varying the amount of exhaust gasses passing through the turbocharger’s (1) _____. A fully (2) _____ waste gate will achieve the maximum turbocharger RPM. (Turbine/compressor) (open/closed)

Answer 22

Turbine closed

Question 23

The ignition system of a running piston engine receives electrical energy from…

Answer 23

Magnets

Question 24

What could be said about exhaust back pressure when using a supercharged (but not turbocharged) engine?

Exhaust back pressure decreases/increases with altitude and increases engine power slightly.

Answer 24

Decreases

Question 25

Consider a fuel injection system. Which is the central point from where fuel is distributed to the individual cylinders? Blank valve.

Answer 25

Manifold

Question 26

Which of these can be controlled by the FADEC system on a piston engine? Improve blank timing when RPM varies.

Answer 26

Ignition

Question 27

The part of a piston engine that transforms reciprocating movement into rotary motion is called the…

Answer 27

Crankshaft

Question 28

The thermal efficiency of a piston engine is about…

Answer 28

30%

Question 29

In a piston engine, applying carburettor heat decreases the (1) _____ of air entering the engine, thereby making the mixture (2) _____. Density/pressure. Leaner/richer

Answer 29

Density richer

Question 30

Which of the following factors contribute to the process of combustion within a piston engine? (Pressure/temperature/viscosity)

Answer 30

Pressure

Question 31

Which of the following is the safest way to prime a piston engine for start-up? Injecting fuel straight into the

Answer 31

Inlet valves

Question 32

To maintain a constant mixture in a piston engine at low and high power settings, a carburettor is fitted with…

Answer 32

Diffuser

Question 33

When applying precautionary carburettor heating on a reciprocating engine with a fixed pitch propeller mixture becomes leaner/richer

Answer 33

Richer

Question 34

Why do we use cowl flaps?

Answer 34

Increase cooling

Question 35

True or false : Ice accretion affects both fuel injection systems and engines equipped with carburettors.

Answer 35

True

Question 36

The dry sump oil system for a piston engine incorporates an oil tank with normally two stack pipes installed. Stack pipes can be found... (top+bottom/both top/both bottom)

Answer 36

Bottom