In-Trim Flight Investigations of a Conceptual Fluidic Thrust-Vectored Unmanned Tail-Sitter Aircraft

The feasibility of using a stand alone Fluidic Thrust- Vectoring (FTV) system for the purpose of longitudinal trim of an unmanned aerial vehicle is the [ocus of the research presented in this paper. Since the fluidic thrust vectoring requires high pressure secondary air to deflect the engine exhaust gases, this research also provides an analytical toolset for the preliminary sizing of a suitable secondary air supply. The study is based on a conceptual model of a Vertical Take-Off and Landing (VTOL) Tail-sitter type unmanned aerial vehicle in three common phases of flight named as Hovering, Transition and Cruise. A relationship is finally presented between the thrust-vectoring angle and the required secondary mass flow rate. It is found that, just by use of FTV system the aircraft trim is possible. In addition. the mathematical model developed in this study can be used ali a preliminary tool for overall performance evaluation of such a conceptual aircraft, especially for sensitivity analysi8 of thrust-vectoring control and finding the optimum values of the parameter s like centre of gravity and engine location.