Zephyr: A High Altitude Long Endurance Unmanned Air Vehicle ...

motion of the aircraft including roll, pitch and yaw. The roll, pitch and yaw are theangles the aircraft is at in relation to the longitudinal, lateral and vertical axis, asshown in figure 7.Figure 7. Diagram to show the roll, pitch and yaw of an aircraft [6].The information from the avionics system is then sent to the FCS and is alsotransmitted as telemetry for manual monitoring. Using this information the flight ofthe aircraft can be monitored and thus the aircraft can be controlled. The controlactuators (any mechanical device used to control Zephyr) and the motors are bothcontrolled via the avionics system onboard the aircraft. Control is either manual fromthe ground control system or direct through the FCS when in autopilot mode (this istrue in the case of elevator and spoiler control).Launch and landing is performed under manual flight control and automatic flightcontrol is normally enabled at all other times. Automatic flight control isimplemented through angle of attack and roll stabilization, heading control, waypoint21