This guide is designed to help a student helicopter pilot prepare for the oral portion of their check ride. The guide is set up on the following manner for each section: question, brief statement, expanded explanation, and reference(s).
The four aerodynamic forces are thrust, drag, lift, and weight.
Lift is created through the combination of Bernoulli’s principle and Newton’s 3rd law.
The lift formula or equation is CL ½ p V2 S.
Induced flow is the downward vertical movement of air through the rotor system due to the production of lift, often referred to as downwash.
Relative wind is the angle of airflow as it impacts an airfoil.
Rotational relative wind is the relative wind produced by the rotation of the rotor blades.
Resultant relative wind is angle airflow at the rotor blades considering rotational relative wind and induced flow.
Dissymmetry of lift is the unequal rotor thrust, or lift, produced by the rotor disc due to forward flight or wind.
Flapping is the vertical movement of a blade up or down to increase or decrease lift in order to compensate for dissymmetry of lift.