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:

Fixed-pitch propellers have a static blade angle, optimizing performance for either climb or cruise but not both, and limiting an engine's ability to achieve full rated power across varying flight conditions.
Constant-speed propellers automatically adjust their blade angle via a governor to maintain a pilot-selected RPM, allowing the engine to operate at peak efficiency and power throughout different flight phases.
More advanced propeller systems include feathering, which aligns blades to minimize drag from a failed engine, and reversing, which provides reverse thrust, both 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.