Comparison of Aerodynamic Performance of Fenestron and Open Tail Rotors

The effectiveness of the counter-torque capabilities of rotorcraft tail rotors has undergone extensive study and development due to its critical role in balance and maneuverability. The Fenestron provides an interesting alternative to the conventional open tail rotor, improving upon several key elements, but still demonstrates drawbacks in others. This paper seeks to provide a side-by-side comparison of Fenestron and open tail rotor performance, in terms of thrust and power, using the mid-fidelity surface-vorticity panel-method flow solver FlightStream® to simulate Fenestron and open rotor configurations in hover and cruise conditions. While this work is not a comprehensive analysis, as it does not compare to experimental data, nor implements exact geometrical representation, it does propose trends between the Fenestron and open tail rotor cases.