Flight Investigation of Bell Model 206 Ring Fin

A flight investigation was conducted to evaluate several configurations of a ring fin installation on a Model 206 helicopter. The conventional vertical fin was removed and replaced with one that provided a protective ring around the tail rotor in the plane of rotation. The design variables studied during this test were ring and dorsal fin incidence and area. A history of the development of the ring fin with Bell is presented, as well as results of the handling qualities tests. They indicate the feasibility of the ring fin as an alternative to protect the tail rotor. This study was supported by the Applied Technology Laboratories, Research and Technology Laboratories (AVRADCOM) under Contract DAAK51-83-C- 0025.