Which factor is listed as contributing to excessive coning?

Which factor is listed as contributing to excessive coning?

• A. Turbulent Air
• B. High G-Maneuvers
• C. Low RPM
• D. High Gross Weight

Answer: (A)

Turbulent air is the factor that most directly leads to excessive coning. Coning is the upward tilt of the rotor plane caused by blade flapping under lift. When air is turbulent, gusts across the rotor disk cause rapid, uneven changes in lift from moment to moment. This uneven loading makes the blades flap more than usual, and because the flap motion is resisted by the rotor’s centrifugal stiffness and hub mechanics, the rotor disk adopts a larger conical shape. In smooth air, lift across the disk is more uniform, so coning stays moderate. The other factors affect overall loading or rotor behavior in different ways, but gusty, turbulent flow specifically drives the increased blade flapping and the resulting excessive coning.

Turbulent air is the factor that most directly leads to excessive coning. Coning is the upward tilt of the rotor plane caused by blade flapping under lift. When air is turbulent, gusts across the rotor disk cause rapid, uneven changes in lift from moment to moment. This uneven loading makes the blades flap more than usual, and because the flap motion is resisted by the rotor’s centrifugal stiffness and hub mechanics, the rotor disk adopts a larger conical shape. In smooth air, lift across the disk is more uniform, so coning stays moderate. The other factors affect overall loading or rotor behavior in different ways, but gusty, turbulent flow specifically drives the increased blade flapping and the resulting excessive coning.