Wind tunnel measurements of the dynamic stability derivatives of a fin-stabilized projectile by means of a 3-axis freely rotating test bench

The needs to improve performances of artillery projectiles require accurate aerodynamic investigation methods. The aerodynamic design of a projectile usually starts from numerical analyses which mostly include semi-empirical methods and/or Computational Fluid Dynamic simulations (CFD) up to experimental techniques consisting of wind-tunnel measurements or free flight validations. This process should as far as possible simultaneously account for both static and dynamic effects. In this context, the present paper proposes a new measurement methodology able to simultaneously determine the pitching moment derivative coefficient and the pitch damping moment coefficient in a wind tunnel by means of a single metrological set-up. The method is based on the stereovision principle and a three-axis freely-rotating mechanical test bench, called MiRo (Mise en Rotation). The holding joint of the device is set inside the model and located at its center of gravity. An investigation was conducted on the impact of the holding device in order to evaluate the reliability of the obtained results.