Which term describes the mechanical change of rotor blade pitch at different azimuths to alter lift and drag during rotation?

Which term describes the mechanical change of rotor blade pitch at different azimuths to alter lift and drag during rotation?

• A. Cyclic Feathering
• B. Delta Hinge
• C. Coning
• D. Coriolis Effect

Answer: (A)

The ability to control where and how much lift the rotor produces as each blade passes around the hub is essential for directing the helicopter. Changing the blade pitch differently at various azimuths—so one part of the rotor disc produces more lift while another produces less—tilts the rotor thrust and steers the aircraft. This cyclic variation of blade pitch is what’s described by cyclic feathering. It directly describes altering pitch as the blade rotates to change lift and drag around the disk, enabling forward, backward, or lateral movement. Delta hinge refers to a mechanical hinge feature that affects flap or feather motion, not the deliberate, azimuth-dependent pitch change used for steering. Coning is the outward bowing of blades due to centrifugal forces at speed, not a control method. The Coriolis effect involves inertial forces in a rotating frame and is a secondary effect, not the primary mechanism used to vary lift and drag with azimuth.

The ability to control where and how much lift the rotor produces as each blade passes around the hub is essential for directing the helicopter. Changing the blade pitch differently at various azimuths—so one part of the rotor disc produces more lift while another produces less—tilts the rotor thrust and steers the aircraft. This cyclic variation of blade pitch is what’s described by cyclic feathering. It directly describes altering pitch as the blade rotates to change lift and drag around the disk, enabling forward, backward, or lateral movement.

Delta hinge refers to a mechanical hinge feature that affects flap or feather motion, not the deliberate, azimuth-dependent pitch change used for steering. Coning is the outward bowing of blades due to centrifugal forces at speed, not a control method. The Coriolis effect involves inertial forces in a rotating frame and is a secondary effect, not the primary mechanism used to vary lift and drag with azimuth.