Modeling and identifying dynamic derivatives of a delta-wing aircraft using gaussian basis functions

An aerodynamic model and its identification method for investigating the variations of the pitch dynamic derivatives of a delta-wing aircraft model with respect to the angle of attack (AOA) were proposed in this study. Wind tunnel tests were conducted during two maneuvers: steady pitch sweep and pitch sweep with an overlaid 1 Hz pitch oscillation. To subtract the forces and moments that act under no-wind conditions from balance data during wind tunnel tests, no-wind forces and moments were modeled using Gaussian basis functions. The extracted net aerodynamic forces and moments were processed to model and identify its characteristics using the dynamic derivative model. By applying Gaussian basis functions to the representation of the dynamic derivatives, the model was able to express the dynamic derivatives that vary nonlinearly with the AOA. The identification was conducted using the regression analysis. The identified dynamic derivative due to the pitch rate exhibited a positive value in several AOA regimes; on the other hand, the dynamic derivative due to pitch acceleration exhibited a negative value over the entire AOA range of −5° to 20°. With respect to the pitching moment coefficient, the root mean square (RMS) value of the deviation between the proposed dynamic derivative model and wind tunnel test data was 0.0124 at 0° AOA. The RMS value of the deviation increased as the AOA increased, reaching 0.0869 at 17.4° AOA.