The Aerodynamic Characterization of Generic Tail Fin Shapes

This paper describes the experimental characterization of the yawresponse of a range of generic tail fin shapes: delta wings, right triangles, rectangles, and ellipses. The fins were tested in a wind tunnel without the complication of blades and nacelle. They were released from an initial angle, usually 45 degrees, and the subsequent response recorded using an accurate potentiometer. Unsteady tail fin performance can be analysed using unsteady slender body theory and the quasi-steady analysis originally developed for wind vanes. Both predict a linear, second order response so the measured responses are quantified in terms of the natural frequency and damping ratio. It is shown that unsteady slender body theory is slightly more accurate, but both fail to describe the full complexity of the response.