This paper explores the development of a control architecture for hybrid or convertible Unmanned Aerial Vehicles (UAVs) by employing Incremental Nonlinear Dynamic Inversion (INDI), which is a type of input-output linearization control algorithm involving estimated acceleration feedback. Hybrid UAVs possess compound wings, enabling them to merge the advantages of fixed-wing UAVs which can take off and land vertically like a helicopter and fly fast and energy saving like an airplane. Thus traditional control approaches divide the flight modes into hover, airplane, and transition, and then predefine the gains in different modes. To avert the switching of control laws and achieve model-free principles, a unified control architecture based on INDI that handles the dynamics of hybrid UAVs without the predefine procedure of flight phase is presented. The proposed controller enables attitude stabilization without discrete switch. Simulation results demonstrate that the proposed control architecture offers an efficient attitude control performance for the entire flight envelope.