In this paper we study the problem of autopilot design for a small Unmanned Aerial Vehicle (UAV). To this end a 12th order nonlinear model is introduced and a strategy for waypoint tracking is presented. Two control strategies, a dynamic inversion approach and a P controller, are designed. Waypoint tracking maneuvers in lateral and longitudinal direction are compared using the Aerosonde simulation model. Under windy conditions the tracking results of both controllers look similar which makes the P controller more attractive due to its simplicity. The P controller is finally extended to control the real UAV – the Multiplex Twinstar II. Measurements show that the presented and implemented control law is appropriate for smooth flight maneuvers.