The aerodynamic twisting force tends to turn the blades how?

The aerodynamic twisting force tends to turn the blades how?

• A. to a high blade angle
• B. to a low blade angle
• C. to the mid position
• D. to feathered position

Answer: (A)

When a rotor blade is loaded by air, the lift generated along the blade acts to twist the blade around its axis. Because the outer portions move faster and produce more lift, the torque from these forces tends to rotate the blade toward a higher pitch angle. In other words, the aerodynamic twisting moment pushes the blade toward a larger blade angle (higher pitch) rather than toward a mid, low, or fully feathered position. Blades are designed with a pre-twist and are pitch-controlled to balance this tendency so the angle of attack stays appropriate along the span under operating loads.

When a rotor blade is loaded by air, the lift generated along the blade acts to twist the blade around its axis. Because the outer portions move faster and produce more lift, the torque from these forces tends to rotate the blade toward a higher pitch angle. In other words, the aerodynamic twisting moment pushes the blade toward a larger blade angle (higher pitch) rather than toward a mid, low, or fully feathered position. Blades are designed with a pre-twist and are pitch-controlled to balance this tendency so the angle of attack stays appropriate along the span under operating loads.