Investigation of aerodynamic interactions between a rotor and a T-tail empennage

Experiments were conducted to study the aerodynamic interactions between a small-scale helicopter rotor and a T-tail type empennage. Time-averaged and unsteady pressure measurements were made at various chordwise and spanwise stations on a horizontal tailplane. Flow visualization was performed using the wide-field shadowgraph method to identify the locations of the rotor wake and blade tip vortices relative to the empennage, and supported the interpretations of the surface pressure responses. The results have shown that the tailplane operated in a highly unsteady environment, with large spanwise and chordwise variations in aerodynamic loading. The proximity of the blade tip vortices and rotor wake boundary to the tail was found to be a fundamental factor influencing the flow environment.