What is meant by resultant relative wind?

Resultant relative wind refers to the airflow experienced by an aircraft as it moves through the air, taking into account the effects of both the forward motion of the aircraft and the induced airflow from the rotor system. The correct answer emphasizes that this airflow is specifically modified by the induced flow created by the rotor blades as they generate lift.

When a helicopter hovers or moves forward, the rotor blades create an induced flow downward, which interacts with the forward motion of the helicopter to produce a resultant relative wind. Understanding this concept is crucial for helicopter pilots as it affects various aspects of flight dynamics, including lift, drag, and overall performance of the helicopter.

The other options do not accurately capture the specific relationship between the rotor-induced flow and the resultant wind experienced by the aircraft. For example, combined airflow from all directions lacks the specificity of how the rotor blades influence the airflow. Similarly, wind experienced by a stationary observer does not clarify the influence of rotor dynamics, and wind generated by the rotor only focuses on one aspect without considering the effect of the helicopter’s movement through the air. Therefore, the proper definition of resultant relative wind includes the critical consideration of induced flow from the rotor system.