Vertical Entry of Missiles into Water

Investigations, carried out principally on the vertical water entry of steel spheres, are described. Graphs show the effect of several experimental parameters on the time and place of occurrence of various events in the life of the cavity which accompanies the entry. These parameters include the density and pressure of the atmosphere above the water, and the velocity, size, and nose shape of the missile. Froude-scaling is found to be a good first approximation in describing cavity behavior, and some improvement is effected by the pressure-density scaling of the atmosphere above the water. The energy lost by a missile during the open-cavity phase of its water entry is found to be used up principally in the formation of the cavity, and the cavity shape is not dependent on the nose shape of the missile for a given drag force.