What is the component of relative wind produced by rotation of the rotor blades?

• A. Rotational Velocity
• B. Translational Wind
• C. Induced Wind
• D. Relative Wind

Answer: (A)

Rotational velocity is the tangential speed of a blade element as it spins around the hub. As the rotor turns, each element moves through the air in a circular path, creating a velocity component that is sideways to the rotor plane. This tangential motion is the portion of the relative wind caused purely by rotation.

The other factors that contribute to the relative wind are translational wind, which comes from the helicopter’s forward or backward motion through the air, and induced wind, which is the downward flow produced by the rotor’s lift (downwash). The overall relative wind is the vector sum of rotational velocity, translational wind, and induced wind.