What allows for the upward and downward movement of the rotor blades?

• A. Fixed pitch control
• B. Flapping hinge
• C. Flexible neck
• D. Swashplate mechanism

Answer: (C)

The mechanism that facilitates the upward and downward movement of rotor blades on a helicopter is primarily the swashplate mechanism. This innovative design operates by allowing the pitch of each rotor blade to be adjusted in relation to their rotational position, which in turn controls their angle of attack and enables them to move up or down in response to pilot input.

When the pilot maneuvers the controls, the swashplate tilts, altering the pitch angle of the blades as they rotate. This change in pitch is what enables the rotor blades to create lift or descend, effectively controlling the helicopter's vertical movement. The swashplate mechanism is crucial for maintaining stable flight and provides the helicopter with the versatility it needs for various flying conditions.

While the other options might refer to different components or concepts related to rotor systems and their motion, they do not independently facilitate the direct upward and downward movement of the rotor blades in the same manner as the swashplate mechanism. The flapping hinge allows the rotor blades to adapt to changes in lift and aerodynamic forces during flight but does not directly control their vertical movement. Similarly, fixed pitch control and a flexible neck design serve other functions in rotorcraft operation and design but do not effectively enable the vertical movement needed for ascent and descent like the