Which term denotes the axis about which rotor blade pitch is varied, often called the spanwise axis?

Which term denotes the axis about which rotor blade pitch is varied, often called the spanwise axis?

• A. Feathering Axis
• B. Direct Shaft Turbine
• C. Disk Area
• D. Drag

Answer: (A)

The pitch of helicopter rotor blades changes about the feathering axis, which is a hinge running spanwise along the blade (from root to tip). This spanwise hinge allows the blade to tilt and set its angle of attack as it rotates, so pilot inputs (collective and cyclic) move the blade through different pitch positions to control lift and thrust. The other terms aren’t related to how blade pitch is varied: the direct shaft turbine is part of the engine or drivetrain, disk area describes the rotor’s swept area, and drag is a force, not an axis. So the term that denotes the axis about which blade pitch is varied is the feathering axis.

The pitch of helicopter rotor blades changes about the feathering axis, which is a hinge running spanwise along the blade (from root to tip). This spanwise hinge allows the blade to tilt and set its angle of attack as it rotates, so pilot inputs (collective and cyclic) move the blade through different pitch positions to control lift and thrust. The other terms aren’t related to how blade pitch is varied: the direct shaft turbine is part of the engine or drivetrain, disk area describes the rotor’s swept area, and drag is a force, not an axis. So the term that denotes the axis about which blade pitch is varied is the feathering axis.