Which rotor system feature describes a blade that can move up and down and fore and aft in its plane of rotation while connected to the hub?

• A. Fully Articulated Rotor System
• B. Rigid Rotor System
• C. Semi-Rigid Rotor System
• D. Simple Rotor System

Answer: (A)

Independent blade articulation is what makes this possible. In a fully articulated rotor system, each rotor blade is mounted on its own hinge at the hub, allowing it to move freely in two directions within the plane of rotation: flap (up and down) and lead-lag (fore and aft). This means a single blade can respond to aerodynamic loads and cyclic inputs by changing its position and pitch without forcing the other blades to move in the same way. That capability—movement up and down as well as forward and backward while still attached to the hub—is the hallmark of fully articulated rotors. Other rotor types restrict blade motion: rigid rotors have no hinges, so blades don’t move independently; semi-rigid rotors rely on a teetering action that ties blades together about a single axis; simple rotors lack this articulation altogether.