Why is the coning angle greatest at the tip of the rotor blade?

• A. Greatest blade velocity (lift is at the tip)
• B. Largest blade thickness
• C. Lowest air density at the tip
• D. Greatest blade mass at the tip

Answer: (A)

The coning angle is driven mainly by how much lift the blade section along its span is generating and how that lift interacts with the centrifugal stiffening from rotation. Lift grows with the square of local velocity, and the blade tip moves fastest because V = ωr. That means the tip produces the most lift per unit span, creating a larger upward bending moment there. The blade flexes upward most at the tip, so the coning angle—the tilt of the blade away from the rotor plane—is greatest at the tip.

The other factors don’t set the maximum coning at the tip: blade thickness, density variations along the span, or mass distribution don’t directly cause the tip to cone more than the inner sections in the same steady condition; their effects are much smaller or relate more to dynamic response than to the steady coning shape.