Low Speed Tunnel Semi-Free Dynamic Flying Study of the High Angle of Attack Pitch Derivatives of HF-24 Using MLE (Maximum Likelihood Estimates) Procedure

摘要

The high angle of attack pitch stability and control derivatives of a 1/13 model of the HF-24 are generated using a semi-free flying technique. The model is similarity scaled and is flown in a single degree of freedom with a pitch gimble at its center of gravity. The fully instrumented model with its servoed elevator is initially trimmed to the desired angle of attack and is disturbed by a doublet elevator pulse. The model responses are analyzed using a Maximum Likelihood parameter estimation procedure. The results indicate that the semi-free dynamic flying and analysis of the associated motion responses using inertial sensors can provide derivative data which compare well with derivatives generated by traditional methods in wind tunnels. Static stability, pitch damping, control derivatives with the trim data are presented a functions of angle of attack from -10 deg to +25 deg with flaps set at -10, 0, 10, 20 and 30 deg and side slip settings of -10, 0 and 10 deg. The capability of semi-free flying to generate high angle of attack pitch derivatives is demonstrated.