We explain how the rotor blades of a helicopter acting like a pair wings generate lift and the expense of torsion of the rotor axis to overcome drag.
Rotor Blades Act Like Wings
- Helicopter Flight Theory: Yet, though the term “planing” is helpful in creating a visual image of the action of a lifting surface, it must be said that this does nothing to explain how the actual lift forces are produced or show the real effect on the air mass. The theoretical aspects cannot be adequately explained here…
- Helicopter Aviation: The shape of the airfoil causes a low pressure area above the airfoil according to Bernoulli’s Principle, and the decrease in pressure on top of the airfoil exerts an upward aerodynamic force.
- Principles of Helicopter Aerodynamics: Aerodynamically the airflow through the helicopter rotor is extremely difficult to define and even after many years of study it still defies a fully adequate description.
Shortcut to the Action of a Wing
Sideview of velocity and pressure, and topview of streamwise vorticity of Naca0012 wing at aoa = 14. Observe the turbulent streamwise vorticity emanating from top separation, as sketched above. Computed solution of the Navier-Stokes equations with small friction force boundary condition .Principle of action of a wing: Potential flow (upper left) with zero lift/drag modified by low-pressure counter-rotating rolls of streamwise vorticity from instability mechanism at separation (upper right), switching the pressure on rear wing (bottom) to give both lift and drag (H high, L low pressure).Lift and circulation (x2) of Naca0012 as functions of the angle of attack.
Variable Angle of Attack