Experimental Determination of Pitch Damping Coefficients Using a Wire Suspension

An experimental method for the determination of the pitch damping moment coefficient sum Cmq + Cm in a wind tunnel is presented. A low-interference wire suspension is used, thus enabling the investigation of projectile configurations in wind tunnels with a low-diameter test section at transonic Mach numbers. Two reference models, the Basic Finner and the Army-Navy Spinner Rocket (ANSR) are examined at Mach numbers ranging from 0.6 to 2. An evaluation procedure for estimating an average coefficient sum based on multiple tests at the same experimental conditions is outlined and validated using rigid-body simulations. The influence of the wires on the flow field is investigated in flow visualization experiments and CFD simulations. The method shows improved accuracy of up to an order of magnitude at transonic Mach numbers in comparison to free-flight tests. While the flow field changes significantly due to the wires, their influence on Cmq +Cm is shown to be negligible.