Flying Your Propeller

Remember that propeller blades are airfoils moving in a plane different from and usually perpendicular to the direction of flight. As an airfoil, the amount of lift the blade creates when moving through the air depends on its angle of attack, and its angle of attack-plus drag-can depend on a variety of factors, including the airplanes pitch attitude. Remember, too, that the outer portions of long prop blades move faster-they cover greater distance in the same amount of time-than shorter ones.

Sunday, June 02, 2019 at 12:00 AM ET

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Key Takeaways:

Propellers are primarily categorized into **fixed-pitch** types, which have a preset blade angle optimized for either climb or cruise but not both, and **constant-speed** types.
**Constant-speed propellers** automatically adjust blade pitch to maintain a pilot-selected engine RPM, allowing for optimal engine performance and efficiency across various flight conditions, particularly for higher-horsepower engines.
Operating constant-speed propellers involves managing both propeller RPM (which controls pitch via a governor) and **manifold pressure** (which indicates engine power/airflow).
Advanced propeller features like **feathering** (minimizing drag from a failed engine) and **reversing** (providing reverse thrust) are also discussed, primarily found on multi-engine or turboprop aircraft.

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A reader recently wrote to request an article on propellers: Why are “constant-speed” props called what they are, how can a fixed-pitch prop “lug” the engine and how does the number of propeller blades affect performance were some of the questions posed, and we promised to follow up. We’ll talk mainly about how to fly common propeller systems on piston-powered small airplanes.

Remember that propeller blades are airfoils moving in a plane different from and usually perpendicular to the direction of flight. As an airfoil, the amount of lift the blade creates when moving through the air depends on its angle of attack, and its angle of attack—plus drag—can depend on a variety of factors, including the airplane’s pitch attitude. Remember, too, that the outer portions of long prop blades move faster—they cover greater distance in the same amount of time—than shorter ones.