Module 17 - Propeller Flashcards
What is the primary function of a propeller?
To convert engine torque into thrust for propulsion.
What are the main types of propellers?
Fixed-pitch, variable-pitch, constant-speed, and feathering propellers.
What is the purpose of a constant-speed propeller?
To maintain a set RPM by varying the blade pitch based on engine power and airspeed.
What is blade pitch?
The angle between the propeller blade chord line and the plane of rotation.
What is the propeller slip?
The difference between the geometric and effective pitch, caused by inefficiencies.
What is geometric pitch?
The theoretical distance a propeller moves forward in one revolution without slip.
What is effective pitch?
The actual distance a propeller moves forward in one revolution with slip accounted for.
How does angle of attack (AoA) affect propeller performance?
Increased AoA improves thrust but may lead to drag and stalling if excessive.
What is propeller wash?
The accelerated airflow produced by the propeller during operation.
What causes propeller cavitation?
Low pressure on the blade surface causing vapor bubbles to form and collapse.
What is propeller torque?
The rotational force generated by the engine and applied to the propeller.
What is thrust distribution?
The variation of thrust along the length of the propeller blade.
What is the purpose of a feathering propeller?
To minimize drag by aligning the blade with the airflow during engine failure.
What is propeller blade twist?
A gradual change in blade angle from root to tip to optimize efficiency.
What is the purpose of blade cuffs?
To improve airflow to the engine and reduce noise.
What is a propeller hub?
The central part of the propeller that connects the blades to the engine shaft.
What are counterweights on a propeller used for?
To assist in moving the blades to a higher pitch position.
What is the governor in a constant-speed propeller system?
A device that controls oil flow to adjust blade pitch and maintain a constant RPM.
What is the function of the propeller spinner?
To streamline the airflow over the hub and protect the propeller assembly.
What is a beta range?
The blade pitch range used for ground operations like taxiing and reverse thrust.
What is an alpha range?
The blade pitch range used during normal flight operations.
What is a synchrophaser?
A system that reduces noise and vibration by synchronizing the phase of multiple propellers.
What is the purpose of a propeller anti-icing system?
To prevent ice formation on the propeller blades using electric heat or fluid.
What is propeller blade resonance?
A vibration phenomenon caused by certain rotational speeds matching blade natural frequencies.
What is a propeller blade station?
A reference point along the length of a blade, measured from the center of the hub.
What materials are commonly used in propeller construction?
Aluminum alloy, wood, and composite materials.
What is the purpose of a wooden propeller laminating process?
To strengthen the propeller and prevent warping.
What is the function of a pitch change mechanism?
To adjust the propeller blade angle for various flight conditions.
What is dynamic balancing of a propeller?
Balancing the propeller assembly during operation to reduce vibrations.
What is the purpose of a de-icing boot on a propeller?
To remove ice by inflating rubber boots with pneumatic pressure.
What is the critical range of a propeller?
The RPM range where vibrations are most pronounced, to be avoided during operation.
What is a ground adjustable propeller?
A propeller whose pitch can be adjusted on the ground but not in flight.
What is a hydraulically operated propeller?
A propeller system that uses oil pressure to change blade pitch.
What is a fixed-pitch propeller?
A propeller with a non-adjustable blade angle.
What is the purpose of counter-rotating propellers?
To eliminate torque effects by rotating in opposite directions.
What is a reversing propeller?
A propeller that can move blades to a negative pitch for reverse thrust.
What is blade tracking?
The process of ensuring all blades follow the same path during rotation.
What is a propeller spinner bulkhead?
A structural component that supports the spinner and attaches it to the hub.
What is a pitch-lock mechanism?
A safety feature that prevents blade pitch reduction in case of system failure.
What is a propeller reduction gearbox?
A mechanism that reduces engine RPM to optimal propeller RPM.
What is propeller feathering?
Adjusting the blades parallel to airflow to reduce drag in case of engine failure.
What is blade back?
The curved surface of a propeller blade that faces forward.
What is blade face?
The flat surface of a propeller blade that faces the rear.
What is a composite propeller blade?
A blade made of layered materials such as carbon fiber or fiberglass for strength and weight reduction.
What is blade root?
The portion of the blade nearest the hub.
What is blade tip?
The outermost portion of the blade farthest from the hub.
What is a spinner dome?
The forward part of the spinner that covers the hub and blades.
What is the primary inspection method for wooden propellers?
Visual inspection for cracks, delamination, and damage.
