As part of a study of high-speed water entry an investigation was made of spherical missiles entering water at supersonic speeds up to 7,000 ft/sec. (Spark shadowgrams were obtained of l/S-inch spheres entering vertically. By using exploratory beams from the spark it was possible to obtain a qualiuative picture of the pressure field between the shock front and the water surface. This pressure field was observed in general to increase downward in the region between the shock front and the water surface and to increase upward near or at the shock front. The shadowgram recorded pattern of wavelets and lines which were produced by the oscillating spherical missile. One pattern of lines was believed to originate with the wavelets in the pressure field immediately behind the shock front. Shadowgrams recorded on films within several sphere diameters of the missile path revealed that illuminstion accompanied impact. The average drag coefficient near sonic speeds in water was measured and data between 0.3 and 0.7 were obtained.
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