ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND ABERDEEN PROVING GROUND MD CHEMICAL SYSTEMS LAB
Many Army weapon systems involve spinning aerodynamic bodies such as artillery shells, guided missiles, and Magnus rotor submunitions. The source of numerous flight instability problems has been related to the effect of body spin on the aerodynamic surface pressures. Although wind tunnel testing is the major means for determining the aerodynamic characteristics of these configurations, measurement of the surface pressures has been limited to non-spinning models. This paper describes a new and unique method to experimentally measure the aerodynamic pressure distribution on the surface of spinning wind tunnel models incorporating a special instrumentation scheme. A pressure tap located in the non-spinning inner portion of the wind tunnel model detects the surface pressure through a series of vent holes in the spinning outer portion of the model, the pressure being retained for measurement by means if a sliding seal arrangement. The feasibility of the method was thoroughly demonstrated by means of wind tunnel tests of fundamental model configurations. The test program was conducted in two phases. The test method measured the surface pressure distribution acting on a spinning smooth surfaced cylinder in crossflow in the critical Reynolds number regime. This proved the methods capability to measure a steady state flow condition under various spin rate and free stream velocity conditions.