What are the basic types of propellers?

What are the basic types of propellers?

• A. Fixed pitch, ground adjustable, constant-speed non-feathering, and constant-speed feathering.
• B. Variable pitch, fixed pitch, and adjustable pitch
• C. Fixed blade, rotating blade, stationary blade
• D. Wood, aluminum, composite

Answer: (A)

Understanding how propeller pitch is controlled is key here. Propellers are classified by how their blade angle is set. A fixed-pitch propeller has one fixed blade angle that cannot be changed after installation. A ground-adjustable propeller can be preset on the ground for different conditions, but its pitch cannot be changed in flight. A constant-speed propeller uses a governor to automatically adjust the blade pitch to keep engine RPM near a set value; within this type, there are non-feathering props, which cannot be easily set to minimize drag if the engine stops, and feathering props, which can be pitched to nearly parallel the airflow to dramatically reduce drag when the engine is not producing thrust. Together, these four categories cover the common ways pilots and mechanics think about propeller pitch control. The other options mix in concepts that aren’t the standard basic categories. One emphasizes materials or blade shapes rather than how pitch is controlled, and another uses broad terms like variable pitch without distinguishing the critical ground-adjustable and the two constant-speed subtypes.

Understanding how propeller pitch is controlled is key here. Propellers are classified by how their blade angle is set. A fixed-pitch propeller has one fixed blade angle that cannot be changed after installation. A ground-adjustable propeller can be preset on the ground for different conditions, but its pitch cannot be changed in flight. A constant-speed propeller uses a governor to automatically adjust the blade pitch to keep engine RPM near a set value; within this type, there are non-feathering props, which cannot be easily set to minimize drag if the engine stops, and feathering props, which can be pitched to nearly parallel the airflow to dramatically reduce drag when the engine is not producing thrust. Together, these four categories cover the common ways pilots and mechanics think about propeller pitch control.

The other options mix in concepts that aren’t the standard basic categories. One emphasizes materials or blade shapes rather than how pitch is controlled, and another uses broad terms like variable pitch without distinguishing the critical ground-adjustable and the two constant-speed subtypes.