Abstract: A projectile is propelled from a location in air, through an air/water interface, and toward a submerged underwater object. The projectile includes a forward end that forms a cavitation void around the projectile in water, avoiding water drag on the remainder of the projectile. The projectile further includes an outwardly flared or finned rearward end that aerodynamically stabilizes the projectile in air and flare stabilizes it in water, in each case against yaw.

Abstract: Apparatus for determining rheological parameters of viscoelastic fluids is provided. The apparatus comprises two similar cylinder-piston assemblies ending at identical flow orifices. The pistons are pushed conjointly by a motor at an adjusted speed. A differential manometer is arranged between the cylinders immediately upstream of the orifices. One of the cylinders contains fluid to be studied and the other a Newtonian comparison fluid. The strain rates of the fluids are defined by the adjusted flow rates, and the pressure differential expresses elongation stress of the viscoelastic fluid. This apparatus is applicable in the rheological study of dilute solutions of macromolecular compositions.