Aerial vehicles have proved their usefulness in military (combat, deployment of units, patrolling, surveillance, reconnaissance, etc.) and civil areas (transport, search and rescue, fire-fighting, etc.) of applications over a hundred years. Tiltrotor UAVs provide a unique platform that fulfills the needs for ever-changing mission requirements by combining the desired features; hovering like a helicopter and reaching high forward speeds like an airplane. In this book, the conceptual design and aerodynamical model of a realizable small-sized Tiltrotor UAV is constructed, the linearized state-space models are obtained around the trim points for airplane, helicopter and conversion modes, controllers are designed using Linear Quadratic Regulator methods and gain-scheduling is employed to obtain a simulation for the whole flight envelope. Eventually, the ideas for making a real flying model are established according to simulation results. The analysis should help to both theorists and practitioners who are eager to explore the features of the new aircraft types.