Does centrifugal twisting moment on a propeller blade tend to move the blades toward high pitch or toward low pitch?

Does centrifugal twisting moment on a propeller blade tend to move the blades toward high pitch or toward low pitch?

• A. Toward high pitch.
• B. Toward neutral.
• C. Toward low pitch.
• D. No effect.

Answer: (C)

Centrifugal twisting moment arises from outward inertia of blade segments as the propeller spins. This outward force acts along the blade length and creates a twisting torque about the root. Because the blade is designed with more twist toward the tip to optimize angle of attack, the tendency of the centrifugal load is to straighten the blade, reducing that twist. So the effect is to lower the overall pitch rather than raise it. The impact grows with RPM and along the blade where the outward force is larger. Hence the centrifugal twisting moment tends to move the blades toward low pitch.

Centrifugal twisting moment arises from outward inertia of blade segments as the propeller spins. This outward force acts along the blade length and creates a twisting torque about the root. Because the blade is designed with more twist toward the tip to optimize angle of attack, the tendency of the centrifugal load is to straighten the blade, reducing that twist. So the effect is to lower the overall pitch rather than raise it. The impact grows with RPM and along the blade where the outward force is larger. Hence the centrifugal twisting moment tends to move the blades toward low pitch.