Development of a simulation tool for flight dynamics and control investigations of articulated VTOL unmanned aircraft
A simulation tool for flight dynamics and control investigations of three different Vertical Take Off and Landing (VTOL) unmanned aircraft configurations has been developed. A control concept has been proposed in order to take advantage of the fast response characteristics of the ordinary small engine/propeller propulsion systems in such aircraft, as well as replacing the complex rotors used previously in VTOL concepts for small unmanned aircraft. The simulation model has been established on the basis of the proposed concept so that it can also be used to study the feasibility of this idea. An Object-based methodology has been introduced so as to reduce the amount of aerodynamic required data for the simulation model. The equations of motion associated with the aircraft multibody system with ten degrees of freedom have been derived using the Newton-Euler method. The modelling of various subsystems including the propeller model, the airframe aerodynamics and the engine model has been carried out. A method for calculating the propellers' slipstream effects on the other components has been presented. Input data for the simulation model have been estimated, using different sources. The Advanced Continuous Simulation Language (ACSL) has been used for the programming of the mathematical model. A series of comprehensive tests have been carried out in order to demonstrate the validity of the simulation model. The ability of the simulation model to explain the aircraft modes of motion as well as to discover unknown nonlinear behaviours and to describe them has been demonstrated.