Experimental Measurements of Store Separation Using Dry Ice Models in a Subsonic Flow

Testing free-drop store separation from a cavity in wind tunnels proves a difficult task because the models are typically destroyed during the test. Furthermore, there is potential for damage to wind tunnel components. Prior work has shown that small dry ice models released within the test section do not cause damage to the AFIT pressure-vacuum wind tunnel components or vacuum chamber. Rather, the dry ice models break apart and sublimate harmlessly into gaseous carbon dioxide. Therefore, this study was undertaken to determine whether dry ice models might prove useful in free-drop store separation testing. A generic aircraft cavity was constructed for testing in the AFIT low speed wind tunnel. Stores were formed by directly injecting pressurized liquid carbon dioxide into a mold. The store geometry used is a circular cylinder with spherical nosecone, with 1.0-inch diameter by 1.8 inches in length. Three 5mW lasers fitted with pattern generating optics were mounted on the wind tunnel sting to illuminate the store and cavity. Three high-speed cameras recorded each test at 700 frames per second and the models were tracked using laser dot projection photogrammetry. Experiments were conducted at nominal freestream velocities of 0, 50, and 100 mph.