Piston Engines Flashcards
How do you measure power using rpm?
Power = RPM X torque
How do you measure torque?
Torque = force x distance
How is torque proportional to engine speed?
Torque is proportional to 1/speed
How does chemical energy become mechanical energy in a piston engine?
Chemical - heat - pressure - mechanical
What is the charge flow?
Air + fuel
What does it mean if a movement is reciprocal?
Up and down.
Whats the difference between a constant volume engine and a reciprocal engine?
They’re the same thing.
Whats the distance between the top dead centre and the bottom dead centre called?
Stroke.
How many degrees of rotation occur when the piston moves between the bottom dead centre and the top dead centre?
180 degrees.
How many strokes does an OTTO cycle have?
4.
What are the different strokes in the otto cycle?
Ignition - compression - power - exhaust.
What happens between a compression stroke and a power stroke in an otto cycle?
Ignition.
Which strokes in the otto cycle will you see the inlet and exhaust valves closed?
Compression and power stroke.
At the ineffective crank angle, how would you describe the linear movement of the piston?
Small.
What is the defintion for when the inlet valve is still open as the compression stroke begins in a piston engine cylinder?
Inlet valve lag.
What happens to the inlet and exhaust valve positions when there is an inlet valve lead in a piston engine aircraft?
The inlet valve and exhaust valve are both open.
A car that has 6000 revolutions per minute has how many combustions per second?
25.
At what angle of rotation does peak torque occur?
90 degrees.
What happens to the pressure and volume when the piston descends?
Volume increases causing pressure to decrease.
What does stoichiometric mean?
Chemically balanced.
What is the recommended step to take in case you experience detonation during take-off?
Retard the throttle.
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)
Turbine closed
The ignition system of a running piston engine receives electrical energy from…
Magnets
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.
Decreases
Consider a fuel injection system. Which is the central point from where fuel is distributed to the individual cylinders? Blank valve.
Manifold
Which of these can be controlled by the FADEC system on a piston engine? Improve blank timing when RPM varies.
Ignition
The part of a piston engine that transforms reciprocating movement into rotary motion is called the…
Crankshaft
The thermal efficiency of a piston engine is about…
30%
In a piston engine, applying carburettor heat decreases the (1) _____ of air entering the engine, thereby making the mixture (2) _____. Density/pressure. Leaner/richer
Density richer
Which of the following factors contribute to the process of combustion within a piston engine?
(Pressure/temperature/viscosity)
Pressure
Which of the following is the safest way to prime a piston engine for start-up? Injecting fuel straight into the
Inlet valves
To maintain a constant mixture in a piston engine at low and high power settings, a carburettor is fitted with…
Diffuser
When applying precautionary carburettor heating on a reciprocating engine with a fixed pitch propeller mixture becomes leaner/richer
Richer
Why do we use cowl flaps?
Increase cooling
True or false : Ice accretion affects both fuel injection systems and engines equipped with carburettors.
True
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)
Bottom
