Transition Flight Feasibility of a Fluidic Thrust Vectored Aerial Tail-Sitter: Numerical Approach

This paper describes a feasibility study of using numerical analysis technique, coupled with a non-linear simulation model of a conceptual fluidic-thrust-vectored unmanned aerial tail-sitter to obtain required thrust deflection angles for a transition manoeuvre in take-off. It also studies the aircraft behaviour in transition subjected to the changes in specified parameters like the thrust value and the engine distance from the centre of gravity. The focus of the research presented was to get the vehicle from zero speed on the ground, in vertical position, to a specified velocity at a specified attitude, in cruise position. It was also specified that, when the vehicle was considered to be flying, it should not reduce speed or be descending and that its angle of attack should remain within a reasonable bound, since extreme angle of attack region causes the simulation and analysis to fall in the uncertain zone. The aircraft pitch attitude was also specified to decrease steadily in every integration step regarding the aircraft velocity. The transition problem was mathematically constructed and coded into Matlab/Simulink for the purpose of analysis and simulation. The inputs to the simulation program were simply series of thrust deflection angles at a number of different instants of time. Simulation was performed for a constant vehicle configuration. It was found that transition was feasible for the thrust to weight ratio around 1.0947 and it took 15 seconds to accomplish, while no attempt was made for time optimization.