Copyright © A. Filippone (1999-2003). All Rights Reserved.

Rotary Wing Aerodynamics

In this Chapter

Rotary aerodynamics encompasses a very large part of aerodynamics. In fact it includes rotors for helicopters, aeronautic and marine propellers, wind turbines, and axial turbomachinery (turbines and compressors), which are designed to operate in a wide variety of conditions.

Importance of the Subject

Propeller aerodynamics is historically the oldest field of interest of rotary aerodynamics. Propellers were first studied for marine propulsion (Rankine, 1860s; Froude, 1870s) and then for aeronautic applications (Drzewiecki, 1890s; Glauert, 1930s). Recently the development of physical models seems to have reached a stall, and priority has been given to the numerical solution, that is a problem in itself.


Rotor-craft aerodynamics is that branch of rotary aerodynamics concerned with helicopter propulsion. Studies in this field started in the late 1930s, after Sikorski invented the helicopter. The state of operation of the rotor can be hover, forward flight and manoeuvre (descent or other).

Full Aircraft

Consideration of the full aircraft leads to a complex interference problem: rotor to fuselage and vice versa. Methods of calculations may include only some of the aspects of the whole physics: inviscid or viscous flow, two- or three- dimensional, airfoil or blade aerodynamics, single or multi-bladed rotors, and rotor-fuselage interaction.

Areas of Research

In the last decade or so rotor-craft aerodynamics has evolved into a very specialized area of research, that features items such as transonic flows past rotary blades, unsteady aerodynamics, dynamic stall, blade-vortex interaction, aeroacoustics, tip effects, maximum power and thrust prediction, aeroelasticity and other multi-disciplinary aspects.

Rotor-craft aerodynamics is one of the fields where CFD has had the major impact. The literature is already extensive (for example AGARD, 1994). For general rotor-craft problems see Stepniewski-Keys, 1984.

Wind Turbines

Wind turbine aerodynamics is also a relatively young branch of applied aerodynamics, although the idea of using the wind energy might be as old as modern technology. After borrowing theories and technology from rotor-craft it is now at a mature stage (De Vries, 1983).


Turbomachinery has also evolved in its own direction, partially because of peculiarly difficult problems, not least related the the number of different configu- rations. As in rotorcraft, the use of CFD has made possible tremendous advances (AGARD LS-195, 1994).

Propeller Characteristics

Basic propeller characteristics include thrust, torque, power coefficient, and efficiency as function of the advance ratio for different configurations (prop diameter, pitch angle, number of blades, etc.). Also of interest is the radial distribution of these quantities.

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Selected References

  • Stepniewski WZ, Keys CN, Rotary-Wing Aerodynamics, Dover ed., 1984.

  • Glauert H. Airplane Propellers, Vol. 4, Div. L in Aerodynamic Theory, Durand WF (editor), Dover ed. 1943.

  • Kerwin JE. Marine Propellers, in Ann. Rev. Fluid Mech., Vol. 18

  • Landgrebe AJ, New Directions in Rotorcraft Computational Aerodynamics Research in the U.S., in Aerodynamics and Aeroacoustics of Rotorcraft, AGARD CP-552, Berlin 1994.

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Copyright © A. Filippone (1999-2003). All Rights Reserved.