11 Piston Engines Performance and Power Augmentation – LMS

📄 Detailed Notes ⚡ Cheat Sheet

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📄 Notes ⚡ Cheat Sheet

Q1. In a piston engine, turbocharger boost pressure may be monitored by:

both a CHT gauge and manifold pressure gauge

both engine rpm readings and a manifold pressure gauge

a cylinder head temperature gauge (CHT), a manifold pressure gauge, and engine rpm readings

a manifold pressure gauge only

Q2. The air in a piston engine turbo-supercharger centrifugal compressor:

enters at a tangent to the rotor and leaves via the stator

enters via the diffuser and is fed to the impeller at the optimum angle of attack

enters at the periphery and leaves via the eye of the impeller

enters the eye of the impeller and leaves at a tangent to the periphery

Q3. With which instrument(s) do you monitor the power output of an aeroplane fitted with a fixed pitch propeller?

Fuel Flow indicator

RPM indicator

RPM and MAP indicator

Cylinder head temperature indicator

Q4. The conditions most likely to produce the highest engine power are:

warm and dry air at high pressure

cold air at high pressure with high relative humidity

warm air at low pressure with high relative humidity

cold and dry air at high pressure

Q5. The power output of a piston engine is directly proportional to:

Exhast back pressure and RPM

Work and velocity

Force and distance

Torque and RPM

Q6. A manifold pressure gauge of a piston engine measures :

absolute pressure in intake system near the inlet valve

absolute air pressure entering the carburetor

vacuum in the carburetor

fuel pressure leaving the carburetor

Q7. On a normally aspirated engine, the manifold pressure gauge always indicates:

zero on the ground when the engine is stopped

a greater value than atmospheric pressure when the engine is running

a value equal to the atmospheric pressure when the engine is at full power on the ground

a lower value than atmospheric pressure when the engine is running

Q8. On a normally aspirated engine (non turbo-charged), the manifold pressure gauge always indicates

a greater value than atmospheric pressure when the engine is running

a lower value than atmospheric pressure when the engine is running

zero on the ground when the engine is stopped

a value equal to the QFE when the engine is at full power on the ground

Q9. On a normally aspirated aero-engine fitted with a fixed pitch propeller:

the propeller setting is constant at all indicated airspeeds

manifold pressure decreases as the aircraft climbs at a fixed throttle setting

in level flight, manifold pressure will remain constant when the rpm is increased by opening the throttle

in a descent at a fixed throttle setting manifold pressure will always remain constant

Q10. During climb with constant throttle and RPM lever setting (mixture being constant) the:

RPM increases

Manifold Absolute Pressure (MAP) increases

Manifold Absolute Pressure (MAP) decreases

RPM decreases

Q11. During a climb in a standard atmosphere with constant Manifold Absolute Pressure (MAP) and RPM indications and at a constant mixture setting, the power output of a piston engine:

stays constant

decreases

only stays constant if the propeller lever is pushed

increases

Q12. One of the advantages of a turbosupercharger is that :

it has a better propulsive efficiency

it uses the exhaust gas energy which normally is lost

there is no torsion at the crankshaft

there is no danger of knocking

Q13. The primary purpose of a supercharger is to:

Maintain power at altitude

Provide a richer mixture at high altitudes

Increase quantity of fuel at metering jet

Provide leaner mixtures at altitudes below 5000 ft

Q14. The power output of a piston engine without supercharging increases with increasing altitude in standard atmosphere at constant Manifold Air Pressure (MAP) and RPM because of the:

lower losses during the gas change

leaner mixture at higher altitudes

lower friction losses

increase of the air density behind the throttle valve

Q15. A turbocharger in a reciprocating engine consists of a:

compressor and turbine on individual shafts

compressor and turbine mounted on a common shaft

compressor driving a turbine via a reduction gear

turbine driving a compressor via a reduction gear

Q16. A turbocharger system in a reciprocating engine is normally driven by:

an electric motor

an hydraulic motor

an electrically activated hydraulically powered clutch

the exhaust system

Q17. The main purpose of a turbocharger is to:

reduce the fuel flow

provide a richer mixture at high altitudes

provide a leaner mixture at sea level

maintain power with increasing altitude

Q18. Assume an initial condition at a high cruise altitude with a constant speed propeller. What will happen if the altitude is decreased while the throttle remains fully open and the waste gate is seized in the cruise position:

The manifold absolute pressure (MAP) value will stay constant

The blade angle may reach the full fine limit

The manifold absolute pressure (MAP) value may exceed the maximum allowed value

The power of the engine will decrease

Q19. The power output of a piston engine can be calculated by:

Work times velocity

Force times distance

Torque times RPM

Pressure times arm

Q20. The power output of a normally aspirated piston engine increases with increasing altitude at constant Manifold Air Pressure (MAP) and RPM because of the :

lower back pressure

leaner mixture at higher altitudes

lower friction losses

lower losses during the gas change

Q21. An intercooler is sometimes fitted between supercharger and inlet manifold to:

Increase the combustion temperature

Reduce the mass flow through the engine

Reduce pre-ignition

Minimise the risk of detonation

Q22. Excessive pressure in the cylinders of an engine equipped with a constant speed propeller, can be caused by the combination of:

low manifold pressure and high RPM

high manifold pressure and high RPM

low manifold pressure and low RPM

high manifold pressure and low RPM

Q23. The maximum horsepower output which can be obtained from an engine when it is operated at specified rpm and manifold pressure conditions established as safe for continuous operation is termed :

maximum power

rated power

critical power

take-off power

Q24. The function of a constant speed drive (CSD) is to ensure:

that the CSD output remains at a constant RPM irrespective of generator RPM

that the generator produces a constant frequency

that the starter-motor maintains a constant RPM irrespective of engine acceleration/deceleration

an equal AC voltage output from all generators

Q25. One of the advantages of a turbocharger is:

to make the power available less affected by altitude

an increased propulsive efficiency

that there is no danger of detonation

that there is no torsion at the crankshaft

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