Abstract: The experiment about the four geometries are carried out. A digital high-speed camera is used to record the evolution of the water-entry process and cavity shapes. The flat-trajectory curves of the four different geometries are obtained, and the effects of the head shape, entry angle and velocity on the trajectory are analyzed . The results show that the projectile body with oval-beveled warhead is easier to form the curved trajectory because of its special warhead. The other three kinds of trajectories are more stabilized. When it is at certain speed range, the trajectories verge to be linear; when it is at a higher speed, the trajectory may be curved. The effect of entry angle on the trajectory is obvious. When the entry angle is little, its trajectory deflects to the free surface quickly; when it is larger, the trajectory deflects to the bottom of the cylinder. The conclusions provide reference for the research on the water-entry weapons.

Key words: ordnance science and technology, curved trajectory, experimental investigation, high-speed water-entry, supercavity