ON THE DYNAMICS OF TAIL FINS AND WIND VANES

This paper describes some investigations of the dynamic yaw behaviour of tail fins and wind vanes employing delta wing planforms. Both singl e and twin wings were tested, the later were formed from two single wi ngs joined at their apices. Comparisons were made using simple wind tu nnel models with aspect ratios from 0.7 to 3.07, and various arm lengt hs, wind speeds and planform areas. The twin wing was found more highl y damped than an equivalent single wing, with damping increasing as th e angle between the wings increased. Stall related problems became evi dent as this angle approached or exceeded that for static stall. A com putational model based on unsteady potential slender wing theory was d eveloped to predict yawing motions of both tail fin types and compared with experiments. The computational model was found remarkably accura te for the single wing case even at high initial angles of yaw, but ge nerally inaccurate for the twin wing. Possible reasons for this inaccu racy and the superior twin wing response are given.