This paper presents the development of a Guidance, Navigation and Control (GNC) system for a rotorcraft unmanned aerial vehicle (UAV). The air-frame and its associated mathematical model are explained. The vehicle electronics system is based on a FPGA development board with its peripherals. The GNC routines were coded using hardware description language VHDL with 32 bits floating point arithmetic and CORDIC algorithms. An Inertial Navigation System (INS) complemented by GPS, implemented by an Extended Kalman Filter is included. A hybrid approach using PID and Fuzzy controllers is proposed for GNC system design. System identification and calibration was done using a test stand that includes a gimbal mechanism where the vehicle is fixed and a LabVIEW application for control parameters tuning and data visualization purposes. Results derived from flights tests using the proposed system support our approach for FPGA based GNC system for the UAV tricopter.