The angle of attack and the sideslip angle are significant parameters describing the aerodynamics of the aircraft. Specifically, these angles are required for identification of the system parameters such as aerodynamic forces and moment derivatives. For exact measurements, it is necessary to install appropriate air data sensors on board. However, it is sometime difficult to install such apparatus on small UAVs. Inertial sensor measurements, aerodynamic derivatives and equations of motions are used to determine the aerodynamic angles. In this paper, three approaches are followed to estimate airflow angles. The first concept uses navigational equations for the estimation. In the second approach, inertial sensor data has been used. Third concept uses aerodynamic derivative obtained from wind tunnel testing. Estimated angles from all three approaches are shown for simulated and flight data. Complementary filter has been used for combining estimated angles obtained using inertial measurements and aerodynamic derivative based approaches. Improved filtered angles are compared with simulated airflow angles for the same flight condition
