CAKA: CPL aeronautical knowledge – aeroplane Flashcards
(37 cards)
What is the difference between fixed pitch and variable pitch propellers?
Fixed pitch propellers have a fixed blade angle, while variable pitch propellers allow blade angle adjustment for optimal efficiency.
How does engine operation at high manifold pressure (MP) and low RPM affect performance?
It increases torque and engine stress but can improve fuel efficiency and reduce noise.
How does engine operation at low MP and high RPM affect performance?
It increases wear and fuel consumption and may cause inefficient combustion.
What is the difference between normally aspirated and turbocharged/supercharged engines?
Turbocharged/supercharged engines compress intake air for better performance at high altitudes
What does centrifugal twisting moment (CTM) do when oil pressure is lost in a variable pitch propeller?
CTM tends to reduce blade pitch (move it toward fine).
What is the role of counterweights in a variable pitch propeller?
They increase blade pitch (toward coarse) when oil pressure is lost.
How does oil pressure affect blade pitch when counterweights are used?
Oil pressure decreases blade pitch (moves it toward fine).
How does oil pressure affect blade pitch if no counterweights are used?
Oil pressure increases blade pitch (moves it toward coarse).
What is blade angle?
The angle between the chord line of the propeller blade and the plane of rotation.
What is helix angle or pitch?
The angle between the relative airflow and the blade’s rotational path.
What is propeller thrust?
The forward force produced by the propeller as it accelerates air backwards.
What is propeller torque?
The resistance to rotation caused by aerodynamic drag on the blades.
What is thrust horsepower (THP)?
The power delivered by the propeller to produce thrust.
What is brake horsepower (BHP)?
The engine’s output before losses from the propeller or other components.
What is asymmetric blade effect (P-factor)?
A yawing moment due to the descending blade producing more thrust than the ascending blade at high angles of attack.
How does a propeller convert engine power into thrust?
By accelerating air rearward, creating a forward reaction force (thrust).
What is meant by fine and coarse pitch stops?
Mechanical limits that prevent the blades from rotating beyond a certain fine or coarse angle.
What is the principle of operation of a constant speed unit (CSU)?
Automatically adjusts blade pitch to maintain a constant RPM by balancing engine power and propeller load.
What happens if a CSU malfunctions?
The engine may overspeed or underspeed due to loss of RPM regulation.
How do you manage a CSU malfunction using engine controls?
Use throttle and RPM levers to manually control power and propeller speed as best as possible.
What cockpit indication could signify engine icing in a variable pitch propeller aircraft?
A drop in RPM or manifold pressure without throttle movement.
How do you know when engine ice has been cleared after applying carb heat?
RPM or manifold pressure returns to normal levels.
What is the effect of using carburettor heat in an aircraft with a CSU?
Initially causes a drop in MP or RPM, followed by a rise as ice melts
How is power output controlled in a variable pitch propeller aircraft?
Throttle controls manifold pressure (power), and propeller lever controls RPM.
