Research on the wind tunnel test techniques for micro-pitching-aerodynamics of re-entry body

To accurately measure the micro-asymmetric pitching-aerodynamics of re-entry body remains a challenge for wind tunnel tests.An articulated free-oscillation system based on ball bearings is introduced to measure the dynamic stability derivatives and the static moment simultaneously.The ball bearings provide the degree of freedom in the pitching channel and pro-tect the test model from rupture when elastic beams are fractured because of fatigue.The oscilla-tion frequency and signal quality of the model can be regulated by optimizing the structural di-mension of the detachable elastic beam.The pitching free-oscillation test conducted in Φ500 hy-personic wind tunnel,where the pitching moment reaches the order of 10-6 ,demonstrates the ac-curacy and reliability of this system.