The blade twist description corresponds to which of the following?

The blade twist description corresponds to which of the following?

• A. Uniform Twist
• B. Higher Angle Of Incidence At The Root; Lower Angle Of Incidence At The Tip
• C. No Twist
• D. Higher Angle At The Root; Lower Angle At The Tip

Answer: (B)

Blade twist is used to control the angle of attack along the blade span as rotor speed and induced velocity vary with radius. Because the tangential speed increases with distance from the hub, a fixed pitch would cause the angle of attack at the tip to be larger than at the root, leading to more lift (and possible stall) near the tip while the root is under‑lifted. To even out lift and avoid tip stall, the blade is designed with a higher angle of incidence at the root and a lower angle toward the tip. So, the description matches having a higher incidence at the root and a lower incidence at the tip.

Blade twist is used to control the angle of attack along the blade span as rotor speed and induced velocity vary with radius. Because the tangential speed increases with distance from the hub, a fixed pitch would cause the angle of attack at the tip to be larger than at the root, leading to more lift (and possible stall) near the tip while the root is under‑lifted. To even out lift and avoid tip stall, the blade is designed with a higher angle of incidence at the root and a lower angle toward the tip. So, the description matches having a higher incidence at the root and a lower incidence at the tip.