Research on the dynamic derivatives test technology of 4.5 m × 3.5 m low speed wind tunnel

The dynamic derivatives are the a necessary parameters in the process of analyzing the stability of the aircraft and designing the control law, in order to meet the demand for obtaining high-precision dynamic derivatives data for large-scale aircraft. Aerodynamics Research Institute of Aviation Industry Corporation of China （AVIC） developed a dynamic derivatives test system with five kinds of oscillations in the 4.5 m × 3.5 m low-speed wind tunnel. The test system uses servo hydraulic swing motor and servo hydraulic cylinder as the driving components of the motion, and directly generates arbitrary waveform motion with the control of the servo valve. The driving mode of the system has the characteristics of small movement transmission gap, high movement control precision, and high automation. The scale of the test model is up to 2.5 m, with the wind speed v =30～60 m/s, the angle of attack α= −36°～36°, and the sideslip angle β= −40°～40°. The verification tests of the dynamic standard model and a wing-body model were carried out, and the test results show that the dynamic derivatives data obtained by the test system is reasonable, the accuracy of the repeatability test data is within 3%, and the test system can provide high-quality dynamic derivatives data for large-scale aircraft.