Abstract: The wind tunnel test technique for dynamic stability derivatives of the model free to tumble at hypersonic speeds has been developed to meet the urgent needs for dynamic derivative measurements of aerospace vehicles at angles of attack of 0°～360° and for mechanism study of limit cycle oscillation phenomenon. Both the hardware of the test technique, such as free tumbling test rigs, liquid bearing, angular measurement system, etc. , and the software, non linear system identification data processing technique are introduced concisely in this paper. By this technique, applicable hypersonic dynamic stability derivatives data of the escape capsule model have been obtained successfully.

Key words: dynamic st ability derivative, fr ee-to-tumble, test technique, liquid bea ring, system identificat ion